Provided by: ffmpeg_4.2.7-0ubuntu0.1_amd64 
NAME
ffmpeg-filters - FFmpeg filters
DESCRIPTION
This document describes filters, sources, and sinks provided by the libavfilter library.
FILTERING INTRODUCTION
Filtering in FFmpeg is enabled through the libavfilter library.
In libavfilter, a filter can have multiple inputs and multiple outputs. To illustrate the
sorts of things that are possible, we consider the following filtergraph.
[main]
input --> split ---------------------> overlay --> output
| ^
|[tmp] [flip]|
+-----> crop --> vflip -------+
This filtergraph splits the input stream in two streams, then sends one stream through the
crop filter and the vflip filter, before merging it back with the other stream by
overlaying it on top. You can use the following command to achieve this:
ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT
The result will be that the top half of the video is mirrored onto the bottom half of the
output video.
Filters in the same linear chain are separated by commas, and distinct linear chains of
filters are separated by semicolons. In our example, crop,vflip are in one linear chain,
split and overlay are separately in another. The points where the linear chains join are
labelled by names enclosed in square brackets. In the example, the split filter generates
two outputs that are associated to the labels [main] and [tmp].
The stream sent to the second output of split, labelled as [tmp], is processed through the
crop filter, which crops away the lower half part of the video, and then vertically
flipped. The overlay filter takes in input the first unchanged output of the split filter
(which was labelled as [main]), and overlay on its lower half the output generated by the
crop,vflip filterchain.
Some filters take in input a list of parameters: they are specified after the filter name
and an equal sign, and are separated from each other by a colon.
There exist so-called source filters that do not have an audio/video input, and sink
filters that will not have audio/video output.
GRAPH
The graph2dot program included in the FFmpeg tools directory can be used to parse a
filtergraph description and issue a corresponding textual representation in the dot
language.
Invoke the command:
graph2dot -h
to see how to use graph2dot.
You can then pass the dot description to the dot program (from the graphviz suite of
programs) and obtain a graphical representation of the filtergraph.
For example the sequence of commands:
echo <GRAPH_DESCRIPTION> | \
tools/graph2dot -o graph.tmp && \
dot -Tpng graph.tmp -o graph.png && \
display graph.png
can be used to create and display an image representing the graph described by the
GRAPH_DESCRIPTION string. Note that this string must be a complete self-contained graph,
with its inputs and outputs explicitly defined. For example if your command line is of
the form:
ffmpeg -i infile -vf scale=640:360 outfile
your GRAPH_DESCRIPTION string will need to be of the form:
nullsrc,scale=640:360,nullsink
you may also need to set the nullsrc parameters and add a format filter in order to
simulate a specific input file.
FILTERGRAPH DESCRIPTION
A filtergraph is a directed graph of connected filters. It can contain cycles, and there
can be multiple links between a pair of filters. Each link has one input pad on one side
connecting it to one filter from which it takes its input, and one output pad on the other
side connecting it to one filter accepting its output.
Each filter in a filtergraph is an instance of a filter class registered in the
application, which defines the features and the number of input and output pads of the
filter.
A filter with no input pads is called a "source", and a filter with no output pads is
called a "sink".
Filtergraph syntax
A filtergraph has a textual representation, which is recognized by the -filter/-vf/-af and
-filter_complex options in ffmpeg and -vf/-af in ffplay, and by the
"avfilter_graph_parse_ptr()" function defined in libavfilter/avfilter.h.
A filterchain consists of a sequence of connected filters, each one connected to the
previous one in the sequence. A filterchain is represented by a list of ","-separated
filter descriptions.
A filtergraph consists of a sequence of filterchains. A sequence of filterchains is
represented by a list of ";"-separated filterchain descriptions.
A filter is represented by a string of the form:
[in_link_1]...[in_link_N]filter_name@id=arguments[out_link_1]...[out_link_M]
filter_name is the name of the filter class of which the described filter is an instance
of, and has to be the name of one of the filter classes registered in the program
optionally followed by "@id". The name of the filter class is optionally followed by a
string "=arguments".
arguments is a string which contains the parameters used to initialize the filter
instance. It may have one of two forms:
• A ':'-separated list of key=value pairs.
• A ':'-separated list of value. In this case, the keys are assumed to be the option
names in the order they are declared. E.g. the "fade" filter declares three options in
this order -- type, start_frame and nb_frames. Then the parameter list in:0:30 means
that the value in is assigned to the option type, 0 to start_frame and 30 to
nb_frames.
• A ':'-separated list of mixed direct value and long key=value pairs. The direct value
must precede the key=value pairs, and follow the same constraints order of the
previous point. The following key=value pairs can be set in any preferred order.
If the option value itself is a list of items (e.g. the "format" filter takes a list of
pixel formats), the items in the list are usually separated by |.
The list of arguments can be quoted using the character ' as initial and ending mark, and
the character \ for escaping the characters within the quoted text; otherwise the argument
string is considered terminated when the next special character (belonging to the set
[]=;,) is encountered.
The name and arguments of the filter are optionally preceded and followed by a list of
link labels. A link label allows one to name a link and associate it to a filter output
or input pad. The preceding labels in_link_1 ... in_link_N, are associated to the filter
input pads, the following labels out_link_1 ... out_link_M, are associated to the output
pads.
When two link labels with the same name are found in the filtergraph, a link between the
corresponding input and output pad is created.
If an output pad is not labelled, it is linked by default to the first unlabelled input
pad of the next filter in the filterchain. For example in the filterchain
nullsrc, split[L1], [L2]overlay, nullsink
the split filter instance has two output pads, and the overlay filter instance two input
pads. The first output pad of split is labelled "L1", the first input pad of overlay is
labelled "L2", and the second output pad of split is linked to the second input pad of
overlay, which are both unlabelled.
In a filter description, if the input label of the first filter is not specified, "in" is
assumed; if the output label of the last filter is not specified, "out" is assumed.
In a complete filterchain all the unlabelled filter input and output pads must be
connected. A filtergraph is considered valid if all the filter input and output pads of
all the filterchains are connected.
Libavfilter will automatically insert scale filters where format conversion is required.
It is possible to specify swscale flags for those automatically inserted scalers by
prepending "sws_flags=flags;" to the filtergraph description.
Here is a BNF description of the filtergraph syntax:
<NAME> ::= sequence of alphanumeric characters and '_'
<FILTER_NAME> ::= <NAME>["@"<NAME>]
<LINKLABEL> ::= "[" <NAME> "]"
<LINKLABELS> ::= <LINKLABEL> [<LINKLABELS>]
<FILTER_ARGUMENTS> ::= sequence of chars (possibly quoted)
<FILTER> ::= [<LINKLABELS>] <FILTER_NAME> ["=" <FILTER_ARGUMENTS>] [<LINKLABELS>]
<FILTERCHAIN> ::= <FILTER> [,<FILTERCHAIN>]
<FILTERGRAPH> ::= [sws_flags=<flags>;] <FILTERCHAIN> [;<FILTERGRAPH>]
Notes on filtergraph escaping
Filtergraph description composition entails several levels of escaping. See the "Quoting
and escaping" section in the ffmpeg-utils(1) manual for more information about the
employed escaping procedure.
A first level escaping affects the content of each filter option value, which may contain
the special character ":" used to separate values, or one of the escaping characters "\'".
A second level escaping affects the whole filter description, which may contain the
escaping characters "\'" or the special characters "[],;" used by the filtergraph
description.
Finally, when you specify a filtergraph on a shell commandline, you need to perform a
third level escaping for the shell special characters contained within it.
For example, consider the following string to be embedded in the drawtext filter
description text value:
this is a 'string': may contain one, or more, special characters
This string contains the "'" special escaping character, and the ":" special character, so
it needs to be escaped in this way:
text=this is a \'string\'\: may contain one, or more, special characters
A second level of escaping is required when embedding the filter description in a
filtergraph description, in order to escape all the filtergraph special characters. Thus
the example above becomes:
drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters
(note that in addition to the "\'" escaping special characters, also "," needs to be
escaped).
Finally an additional level of escaping is needed when writing the filtergraph description
in a shell command, which depends on the escaping rules of the adopted shell. For example,
assuming that "\" is special and needs to be escaped with another "\", the previous string
will finally result in:
-vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters"
TIMELINE EDITING
Some filters support a generic enable option. For the filters supporting timeline editing,
this option can be set to an expression which is evaluated before sending a frame to the
filter. If the evaluation is non-zero, the filter will be enabled, otherwise the frame
will be sent unchanged to the next filter in the filtergraph.
The expression accepts the following values:
t timestamp expressed in seconds, NAN if the input timestamp is unknown
n sequential number of the input frame, starting from 0
pos the position in the file of the input frame, NAN if unknown
w
h width and height of the input frame if video
Additionally, these filters support an enable command that can be used to re-define the
expression.
Like any other filtering option, the enable option follows the same rules.
For example, to enable a blur filter (smartblur) from 10 seconds to 3 minutes, and a
curves filter starting at 3 seconds:
smartblur = enable='between(t,10,3*60)',
curves = enable='gte(t,3)' : preset=cross_process
See "ffmpeg -filters" to view which filters have timeline support.
OPTIONS FOR FILTERS WITH SEVERAL INPUTS
Some filters with several inputs support a common set of options. These options can only
be set by name, not with the short notation.
eof_action
The action to take when EOF is encountered on the secondary input; it accepts one of
the following values:
repeat
Repeat the last frame (the default).
endall
End both streams.
pass
Pass the main input through.
shortest
If set to 1, force the output to terminate when the shortest input terminates. Default
value is 0.
repeatlast
If set to 1, force the filter to extend the last frame of secondary streams until the
end of the primary stream. A value of 0 disables this behavior. Default value is 1.
AUDIO FILTERS
When you configure your FFmpeg build, you can disable any of the existing filters using
"--disable-filters". The configure output will show the audio filters included in your
build.
Below is a description of the currently available audio filters.
acompressor
A compressor is mainly used to reduce the dynamic range of a signal. Especially modern
music is mostly compressed at a high ratio to improve the overall loudness. It's done to
get the highest attention of a listener, "fatten" the sound and bring more "power" to the
track. If a signal is compressed too much it may sound dull or "dead" afterwards or it
may start to "pump" (which could be a powerful effect but can also destroy a track
completely). The right compression is the key to reach a professional sound and is the
high art of mixing and mastering. Because of its complex settings it may take a long time
to get the right feeling for this kind of effect.
Compression is done by detecting the volume above a chosen level "threshold" and dividing
it by the factor set with "ratio". So if you set the threshold to -12dB and your signal
reaches -6dB a ratio of 2:1 will result in a signal at -9dB. Because an exact manipulation
of the signal would cause distortion of the waveform the reduction can be levelled over
the time. This is done by setting "Attack" and "Release". "attack" determines how long
the signal has to rise above the threshold before any reduction will occur and "release"
sets the time the signal has to fall below the threshold to reduce the reduction again.
Shorter signals than the chosen attack time will be left untouched. The overall reduction
of the signal can be made up afterwards with the "makeup" setting. So compressing the
peaks of a signal about 6dB and raising the makeup to this level results in a signal twice
as loud than the source. To gain a softer entry in the compression the "knee" flattens the
hard edge at the threshold in the range of the chosen decibels.
The filter accepts the following options:
level_in
Set input gain. Default is 1. Range is between 0.015625 and 64.
mode
Set mode of compressor operation. Can be "upward" or "downward". Default is
"downward".
threshold
If a signal of stream rises above this level it will affect the gain reduction. By
default it is 0.125. Range is between 0.00097563 and 1.
ratio
Set a ratio by which the signal is reduced. 1:2 means that if the level rose 4dB above
the threshold, it will be only 2dB above after the reduction. Default is 2. Range is
between 1 and 20.
attack
Amount of milliseconds the signal has to rise above the threshold before gain
reduction starts. Default is 20. Range is between 0.01 and 2000.
release
Amount of milliseconds the signal has to fall below the threshold before reduction is
decreased again. Default is 250. Range is between 0.01 and 9000.
makeup
Set the amount by how much signal will be amplified after processing. Default is 1.
Range is from 1 to 64.
knee
Curve the sharp knee around the threshold to enter gain reduction more softly.
Default is 2.82843. Range is between 1 and 8.
link
Choose if the "average" level between all channels of input stream or the
louder("maximum") channel of input stream affects the reduction. Default is "average".
detection
Should the exact signal be taken in case of "peak" or an RMS one in case of "rms".
Default is "rms" which is mostly smoother.
mix How much to use compressed signal in output. Default is 1. Range is between 0 and 1.
acontrast
Simple audio dynamic range compression/expansion filter.
The filter accepts the following options:
contrast
Set contrast. Default is 33. Allowed range is between 0 and 100.
acopy
Copy the input audio source unchanged to the output. This is mainly useful for testing
purposes.
acrossfade
Apply cross fade from one input audio stream to another input audio stream. The cross
fade is applied for specified duration near the end of first stream.
The filter accepts the following options:
nb_samples, ns
Specify the number of samples for which the cross fade effect has to last. At the end
of the cross fade effect the first input audio will be completely silent. Default is
44100.
duration, d
Specify the duration of the cross fade effect. See the Time duration section in the
ffmpeg-utils(1) manual for the accepted syntax. By default the duration is determined
by nb_samples. If set this option is used instead of nb_samples.
overlap, o
Should first stream end overlap with second stream start. Default is enabled.
curve1
Set curve for cross fade transition for first stream.
curve2
Set curve for cross fade transition for second stream.
For description of available curve types see afade filter description.
Examples
• Cross fade from one input to another:
ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:c1=exp:c2=exp output.flac
• Cross fade from one input to another but without overlapping:
ffmpeg -i first.flac -i second.flac -filter_complex acrossfade=d=10:o=0:c1=exp:c2=exp output.flac
acrossover
Split audio stream into several bands.
This filter splits audio stream into two or more frequency ranges. Summing all streams
back will give flat output.
The filter accepts the following options:
split
Set split frequencies. Those must be positive and increasing.
order
Set filter order, can be 2nd, 4th or 8th. Default is 4th.
acrusher
Reduce audio bit resolution.
This filter is bit crusher with enhanced functionality. A bit crusher is used to audibly
reduce number of bits an audio signal is sampled with. This doesn't change the bit depth
at all, it just produces the effect. Material reduced in bit depth sounds more harsh and
"digital". This filter is able to even round to continuous values instead of discrete bit
depths. Additionally it has a D/C offset which results in different crushing of the lower
and the upper half of the signal. An Anti-Aliasing setting is able to produce "softer"
crushing sounds.
Another feature of this filter is the logarithmic mode. This setting switches from linear
distances between bits to logarithmic ones. The result is a much more "natural" sounding
crusher which doesn't gate low signals for example. The human ear has a logarithmic
perception, so this kind of crushing is much more pleasant. Logarithmic crushing is also
able to get anti-aliased.
The filter accepts the following options:
level_in
Set level in.
level_out
Set level out.
bits
Set bit reduction.
mix Set mixing amount.
mode
Can be linear: "lin" or logarithmic: "log".
dc Set DC.
aa Set anti-aliasing.
samples
Set sample reduction.
lfo Enable LFO. By default disabled.
lforange
Set LFO range.
lforate
Set LFO rate.
acue
Delay audio filtering until a given wallclock timestamp. See the cue filter.
adeclick
Remove impulsive noise from input audio.
Samples detected as impulsive noise are replaced by interpolated samples using
autoregressive modelling.
w Set window size, in milliseconds. Allowed range is from 10 to 100. Default value is 55
milliseconds. This sets size of window which will be processed at once.
o Set window overlap, in percentage of window size. Allowed range is from 50 to 95.
Default value is 75 percent. Setting this to a very high value increases impulsive
noise removal but makes whole process much slower.
a Set autoregression order, in percentage of window size. Allowed range is from 0 to 25.
Default value is 2 percent. This option also controls quality of interpolated samples
using neighbour good samples.
t Set threshold value. Allowed range is from 1 to 100. Default value is 2. This
controls the strength of impulsive noise which is going to be removed. The lower
value, the more samples will be detected as impulsive noise.
b Set burst fusion, in percentage of window size. Allowed range is 0 to 10. Default
value is 2. If any two samples detected as noise are spaced less than this value then
any sample between those two samples will be also detected as noise.
m Set overlap method.
It accepts the following values:
a Select overlap-add method. Even not interpolated samples are slightly changed with
this method.
s Select overlap-save method. Not interpolated samples remain unchanged.
Default value is "a".
adeclip
Remove clipped samples from input audio.
Samples detected as clipped are replaced by interpolated samples using autoregressive
modelling.
w Set window size, in milliseconds. Allowed range is from 10 to 100. Default value is
55 milliseconds. This sets size of window which will be processed at once.
o Set window overlap, in percentage of window size. Allowed range is from 50 to 95.
Default value is 75 percent.
a Set autoregression order, in percentage of window size. Allowed range is from 0 to 25.
Default value is 8 percent. This option also controls quality of interpolated samples
using neighbour good samples.
t Set threshold value. Allowed range is from 1 to 100. Default value is 10. Higher
values make clip detection less aggressive.
n Set size of histogram used to detect clips. Allowed range is from 100 to 9999.
Default value is 1000. Higher values make clip detection less aggressive.
m Set overlap method.
It accepts the following values:
a Select overlap-add method. Even not interpolated samples are slightly changed with
this method.
s Select overlap-save method. Not interpolated samples remain unchanged.
Default value is "a".
adelay
Delay one or more audio channels.
Samples in delayed channel are filled with silence.
The filter accepts the following option:
delays
Set list of delays in milliseconds for each channel separated by '|'. Unused delays
will be silently ignored. If number of given delays is smaller than number of channels
all remaining channels will not be delayed. If you want to delay exact number of
samples, append 'S' to number. If you want instead to delay in seconds, append 's' to
number.
Examples
• Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave the
second channel (and any other channels that may be present) unchanged.
adelay=1500|0|500
• Delay second channel by 500 samples, the third channel by 700 samples and leave the
first channel (and any other channels that may be present) unchanged.
adelay=0|500S|700S
aderivative, aintegral
Compute derivative/integral of audio stream.
Applying both filters one after another produces original audio.
aecho
Apply echoing to the input audio.
Echoes are reflected sound and can occur naturally amongst mountains (and sometimes large
buildings) when talking or shouting; digital echo effects emulate this behaviour and are
often used to help fill out the sound of a single instrument or vocal. The time difference
between the original signal and the reflection is the "delay", and the loudness of the
reflected signal is the "decay". Multiple echoes can have different delays and decays.
A description of the accepted parameters follows.
in_gain
Set input gain of reflected signal. Default is 0.6.
out_gain
Set output gain of reflected signal. Default is 0.3.
delays
Set list of time intervals in milliseconds between original signal and reflections
separated by '|'. Allowed range for each "delay" is "(0 - 90000.0]". Default is 1000.
decays
Set list of loudness of reflected signals separated by '|'. Allowed range for each
"decay" is "(0 - 1.0]". Default is 0.5.
Examples
• Make it sound as if there are twice as many instruments as are actually playing:
aecho=0.8:0.88:60:0.4
• If delay is very short, then it sound like a (metallic) robot playing music:
aecho=0.8:0.88:6:0.4
• A longer delay will sound like an open air concert in the mountains:
aecho=0.8:0.9:1000:0.3
• Same as above but with one more mountain:
aecho=0.8:0.9:1000|1800:0.3|0.25
aemphasis
Audio emphasis filter creates or restores material directly taken from LPs or emphased CDs
with different filter curves. E.g. to store music on vinyl the signal has to be altered by
a filter first to even out the disadvantages of this recording medium. Once the material
is played back the inverse filter has to be applied to restore the distortion of the
frequency response.
The filter accepts the following options:
level_in
Set input gain.
level_out
Set output gain.
mode
Set filter mode. For restoring material use "reproduction" mode, otherwise use
"production" mode. Default is "reproduction" mode.
type
Set filter type. Selects medium. Can be one of the following:
col select Columbia.
emi select EMI.
bsi select BSI (78RPM).
riaa
select RIAA.
cd select Compact Disc (CD).
50fm
select 50Xs (FM).
75fm
select 75Xs (FM).
50kf
select 50Xs (FM-KF).
75kf
select 75Xs (FM-KF).
aeval
Modify an audio signal according to the specified expressions.
This filter accepts one or more expressions (one for each channel), which are evaluated
and used to modify a corresponding audio signal.
It accepts the following parameters:
exprs
Set the '|'-separated expressions list for each separate channel. If the number of
input channels is greater than the number of expressions, the last specified
expression is used for the remaining output channels.
channel_layout, c
Set output channel layout. If not specified, the channel layout is specified by the
number of expressions. If set to same, it will use by default the same input channel
layout.
Each expression in exprs can contain the following constants and functions:
ch channel number of the current expression
n number of the evaluated sample, starting from 0
s sample rate
t time of the evaluated sample expressed in seconds
nb_in_channels
nb_out_channels
input and output number of channels
val(CH)
the value of input channel with number CH
Note: this filter is slow. For faster processing you should use a dedicated filter.
Examples
• Half volume:
aeval=val(ch)/2:c=same
• Invert phase of the second channel:
aeval=val(0)|-val(1)
afade
Apply fade-in/out effect to input audio.
A description of the accepted parameters follows.
type, t
Specify the effect type, can be either "in" for fade-in, or "out" for a fade-out
effect. Default is "in".
start_sample, ss
Specify the number of the start sample for starting to apply the fade effect. Default
is 0.
nb_samples, ns
Specify the number of samples for which the fade effect has to last. At the end of the
fade-in effect the output audio will have the same volume as the input audio, at the
end of the fade-out transition the output audio will be silence. Default is 44100.
start_time, st
Specify the start time of the fade effect. Default is 0. The value must be specified
as a time duration; see the Time duration section in the ffmpeg-utils(1) manual for
the accepted syntax. If set this option is used instead of start_sample.
duration, d
Specify the duration of the fade effect. See the Time duration section in the
ffmpeg-utils(1) manual for the accepted syntax. At the end of the fade-in effect the
output audio will have the same volume as the input audio, at the end of the fade-out
transition the output audio will be silence. By default the duration is determined by
nb_samples. If set this option is used instead of nb_samples.
curve
Set curve for fade transition.
It accepts the following values:
tri select triangular, linear slope (default)
qsin
select quarter of sine wave
hsin
select half of sine wave
esin
select exponential sine wave
log select logarithmic
ipar
select inverted parabola
qua select quadratic
cub select cubic
squ select square root
cbr select cubic root
par select parabola
exp select exponential
iqsin
select inverted quarter of sine wave
ihsin
select inverted half of sine wave
dese
select double-exponential seat
desi
select double-exponential sigmoid
losi
select logistic sigmoid
nofade
no fade applied
Examples
• Fade in first 15 seconds of audio:
afade=t=in:ss=0:d=15
• Fade out last 25 seconds of a 900 seconds audio:
afade=t=out:st=875:d=25
afftdn
Denoise audio samples with FFT.
A description of the accepted parameters follows.
nr Set the noise reduction in dB, allowed range is 0.01 to 97. Default value is 12 dB.
nf Set the noise floor in dB, allowed range is -80 to -20. Default value is -50 dB.
nt Set the noise type.
It accepts the following values:
w Select white noise.
v Select vinyl noise.
s Select shellac noise.
c Select custom noise, defined in "bn" option.
Default value is white noise.
bn Set custom band noise for every one of 15 bands. Bands are separated by ' ' or '|'.
rf Set the residual floor in dB, allowed range is -80 to -20. Default value is -38 dB.
tn Enable noise tracking. By default is disabled. With this enabled, noise floor is
automatically adjusted.
tr Enable residual tracking. By default is disabled.
om Set the output mode.
It accepts the following values:
i Pass input unchanged.
o Pass noise filtered out.
n Pass only noise.
Default value is o.
Commands
This filter supports the following commands:
sample_noise, sn
Start or stop measuring noise profile. Syntax for the command is : "start" or "stop"
string. After measuring noise profile is stopped it will be automatically applied in
filtering.
noise_reduction, nr
Change noise reduction. Argument is single float number. Syntax for the command is :
"noise_reduction"
noise_floor, nf
Change noise floor. Argument is single float number. Syntax for the command is :
"noise_floor"
output_mode, om
Change output mode operation. Syntax for the command is : "i", "o" or "n" string.
afftfilt
Apply arbitrary expressions to samples in frequency domain.
real
Set frequency domain real expression for each separate channel separated by '|'.
Default is "re". If the number of input channels is greater than the number of
expressions, the last specified expression is used for the remaining output channels.
imag
Set frequency domain imaginary expression for each separate channel separated by '|'.
Default is "im".
Each expression in real and imag can contain the following constants and functions:
sr sample rate
b current frequency bin number
nb number of available bins
ch channel number of the current expression
chs number of channels
pts current frame pts
re current real part of frequency bin of current channel
im current imaginary part of frequency bin of current channel
real(b, ch)
Return the value of real part of frequency bin at location (bin,channel)
imag(b, ch)
Return the value of imaginary part of frequency bin at location (bin,channel)
win_size
Set window size. Allowed range is from 16 to 131072. Default is 4096
win_func
Set window function. Default is "hann".
overlap
Set window overlap. If set to 1, the recommended overlap for selected window function
will be picked. Default is 0.75.
Examples
• Leave almost only low frequencies in audio:
afftfilt="'real=re * (1-clip((b/nb)*b,0,1))':imag='im * (1-clip((b/nb)*b,0,1))'"
afir
Apply an arbitrary Frequency Impulse Response filter.
This filter is designed for applying long FIR filters, up to 60 seconds long.
It can be used as component for digital crossover filters, room equalization, cross talk
cancellation, wavefield synthesis, auralization, ambiophonics, ambisonics and
spatialization.
This filter uses second stream as FIR coefficients. If second stream holds single
channel, it will be used for all input channels in first stream, otherwise number of
channels in second stream must be same as number of channels in first stream.
It accepts the following parameters:
dry Set dry gain. This sets input gain.
wet Set wet gain. This sets final output gain.
length
Set Impulse Response filter length. Default is 1, which means whole IR is processed.
gtype
Enable applying gain measured from power of IR.
Set which approach to use for auto gain measurement.
none
Do not apply any gain.
peak
select peak gain, very conservative approach. This is default value.
dc select DC gain, limited application.
gn select gain to noise approach, this is most popular one.
irgain
Set gain to be applied to IR coefficients before filtering. Allowed range is 0 to 1.
This gain is applied after any gain applied with gtype option.
irfmt
Set format of IR stream. Can be "mono" or "input". Default is "input".
maxir
Set max allowed Impulse Response filter duration in seconds. Default is 30 seconds.
Allowed range is 0.1 to 60 seconds.
response
Show IR frequency response, magnitude(magenta), phase(green) and group delay(yellow)
in additional video stream. By default it is disabled.
channel
Set for which IR channel to display frequency response. By default is first channel
displayed. This option is used only when response is enabled.
size
Set video stream size. This option is used only when response is enabled.
rate
Set video stream frame rate. This option is used only when response is enabled.
minp
Set minimal partition size used for convolution. Default is 8192. Allowed range is
from 8 to 32768. Lower values decreases latency at cost of higher CPU usage.
maxp
Set maximal partition size used for convolution. Default is 8192. Allowed range is
from 8 to 32768. Lower values may increase CPU usage.
Examples
• Apply reverb to stream using mono IR file as second input, complete command using
ffmpeg:
ffmpeg -i input.wav -i middle_tunnel_1way_mono.wav -lavfi afir output.wav
aformat
Set output format constraints for the input audio. The framework will negotiate the most
appropriate format to minimize conversions.
It accepts the following parameters:
sample_fmts
A '|'-separated list of requested sample formats.
sample_rates
A '|'-separated list of requested sample rates.
channel_layouts
A '|'-separated list of requested channel layouts.
See the Channel Layout section in the ffmpeg-utils(1) manual for the required syntax.
If a parameter is omitted, all values are allowed.
Force the output to either unsigned 8-bit or signed 16-bit stereo
aformat=sample_fmts=u8|s16:channel_layouts=stereo
agate
A gate is mainly used to reduce lower parts of a signal. This kind of signal processing
reduces disturbing noise between useful signals.
Gating is done by detecting the volume below a chosen level threshold and dividing it by
the factor set with ratio. The bottom of the noise floor is set via range. Because an
exact manipulation of the signal would cause distortion of the waveform the reduction can
be levelled over time. This is done by setting attack and release.
attack determines how long the signal has to fall below the threshold before any reduction
will occur and release sets the time the signal has to rise above the threshold to reduce
the reduction again. Shorter signals than the chosen attack time will be left untouched.
level_in
Set input level before filtering. Default is 1. Allowed range is from 0.015625 to 64.
mode
Set the mode of operation. Can be "upward" or "downward". Default is "downward". If
set to "upward" mode, higher parts of signal will be amplified, expanding dynamic
range in upward direction. Otherwise, in case of "downward" lower parts of signal
will be reduced.
range
Set the level of gain reduction when the signal is below the threshold. Default is
0.06125. Allowed range is from 0 to 1. Setting this to 0 disables reduction and then
filter behaves like expander.
threshold
If a signal rises above this level the gain reduction is released. Default is 0.125.
Allowed range is from 0 to 1.
ratio
Set a ratio by which the signal is reduced. Default is 2. Allowed range is from 1 to
9000.
attack
Amount of milliseconds the signal has to rise above the threshold before gain
reduction stops. Default is 20 milliseconds. Allowed range is from 0.01 to 9000.
release
Amount of milliseconds the signal has to fall below the threshold before the reduction
is increased again. Default is 250 milliseconds. Allowed range is from 0.01 to 9000.
makeup
Set amount of amplification of signal after processing. Default is 1. Allowed range
is from 1 to 64.
knee
Curve the sharp knee around the threshold to enter gain reduction more softly.
Default is 2.828427125. Allowed range is from 1 to 8.
detection
Choose if exact signal should be taken for detection or an RMS like one. Default is
"rms". Can be "peak" or "rms".
link
Choose if the average level between all channels or the louder channel affects the
reduction. Default is "average". Can be "average" or "maximum".
aiir
Apply an arbitrary Infinite Impulse Response filter.
It accepts the following parameters:
z Set numerator/zeros coefficients.
p Set denominator/poles coefficients.
k Set channels gains.
dry_gain
Set input gain.
wet_gain
Set output gain.
f Set coefficients format.
tf transfer function
zp Z-plane zeros/poles, cartesian (default)
pr Z-plane zeros/poles, polar radians
pd Z-plane zeros/poles, polar degrees
r Set kind of processing. Can be "d" - direct or "s" - serial cascading. Default is
"s".
e Set filtering precision.
dbl double-precision floating-point (default)
flt single-precision floating-point
i32 32-bit integers
i16 16-bit integers
mix How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
response
Show IR frequency response, magnitude(magenta), phase(green) and group delay(yellow)
in additional video stream. By default it is disabled.
channel
Set for which IR channel to display frequency response. By default is first channel
displayed. This option is used only when response is enabled.
size
Set video stream size. This option is used only when response is enabled.
Coefficients in "tf" format are separated by spaces and are in ascending order.
Coefficients in "zp" format are separated by spaces and order of coefficients doesn't
matter. Coefficients in "zp" format are complex numbers with i imaginary unit.
Different coefficients and gains can be provided for every channel, in such case use '|'
to separate coefficients or gains. Last provided coefficients will be used for all
remaining channels.
Examples
• Apply 2 pole elliptic notch at around 5000Hz for 48000 Hz sample rate:
aiir=k=1:z=7.957584807809675810E-1 -2.575128568908332300 3.674839853930788710 -2.57512875289799137 7.957586296317130880E-1:p=1 -2.86950072432325953 3.63022088054647218 -2.28075678147272232 6.361362326477423500E-1:f=tf:r=d
• Same as above but in "zp" format:
aiir=k=0.79575848078096756:z=0.80918701+0.58773007i 0.80918701-0.58773007i 0.80884700+0.58784055i 0.80884700-0.58784055i:p=0.63892345+0.59951235i 0.63892345-0.59951235i 0.79582691+0.44198673i 0.79582691-0.44198673i:f=zp:r=s
alimiter
The limiter prevents an input signal from rising over a desired threshold. This limiter
uses lookahead technology to prevent your signal from distorting. It means that there is
a small delay after the signal is processed. Keep in mind that the delay it produces is
the attack time you set.
The filter accepts the following options:
level_in
Set input gain. Default is 1.
level_out
Set output gain. Default is 1.
limit
Don't let signals above this level pass the limiter. Default is 1.
attack
The limiter will reach its attenuation level in this amount of time in milliseconds.
Default is 5 milliseconds.
release
Come back from limiting to attenuation 1.0 in this amount of milliseconds. Default is
50 milliseconds.
asc When gain reduction is always needed ASC takes care of releasing to an average
reduction level rather than reaching a reduction of 0 in the release time.
asc_level
Select how much the release time is affected by ASC, 0 means nearly no changes in
release time while 1 produces higher release times.
level
Auto level output signal. Default is enabled. This normalizes audio back to 0dB if
enabled.
Depending on picked setting it is recommended to upsample input 2x or 4x times with
aresample before applying this filter.
allpass
Apply a two-pole all-pass filter with central frequency (in Hz) frequency, and filter-
width width. An all-pass filter changes the audio's frequency to phase relationship
without changing its frequency to amplitude relationship.
The filter accepts the following options:
frequency, f
Set frequency in Hz.
width_type, t
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
k kHz
width, w
Specify the band-width of a filter in width_type units.
mix, m
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
channels, c
Specify which channels to filter, by default all available are filtered.
Commands
This filter supports the following commands:
frequency, f
Change allpass frequency. Syntax for the command is : "frequency"
width_type, t
Change allpass width_type. Syntax for the command is : "width_type"
width, w
Change allpass width. Syntax for the command is : "width"
mix, m
Change allpass mix. Syntax for the command is : "mix"
aloop
Loop audio samples.
The filter accepts the following options:
loop
Set the number of loops. Setting this value to -1 will result in infinite loops.
Default is 0.
size
Set maximal number of samples. Default is 0.
start
Set first sample of loop. Default is 0.
amerge
Merge two or more audio streams into a single multi-channel stream.
The filter accepts the following options:
inputs
Set the number of inputs. Default is 2.
If the channel layouts of the inputs are disjoint, and therefore compatible, the channel
layout of the output will be set accordingly and the channels will be reordered as
necessary. If the channel layouts of the inputs are not disjoint, the output will have all
the channels of the first input then all the channels of the second input, in that order,
and the channel layout of the output will be the default value corresponding to the total
number of channels.
For example, if the first input is in 2.1 (FL+FR+LF) and the second input is FC+BL+BR,
then the output will be in 5.1, with the channels in the following order: a1, a2, b1, a3,
b2, b3 (a1 is the first channel of the first input, b1 is the first channel of the second
input).
On the other hand, if both input are in stereo, the output channels will be in the default
order: a1, a2, b1, b2, and the channel layout will be arbitrarily set to 4.0, which may or
may not be the expected value.
All inputs must have the same sample rate, and format.
If inputs do not have the same duration, the output will stop with the shortest.
Examples
• Merge two mono files into a stereo stream:
amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge
• Multiple merges assuming 1 video stream and 6 audio streams in input.mkv:
ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv
amix
Mixes multiple audio inputs into a single output.
Note that this filter only supports float samples (the amerge and pan audio filters
support many formats). If the amix input has integer samples then aresample will be
automatically inserted to perform the conversion to float samples.
For example
ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT
will mix 3 input audio streams to a single output with the same duration as the first
input and a dropout transition time of 3 seconds.
It accepts the following parameters:
inputs
The number of inputs. If unspecified, it defaults to 2.
duration
How to determine the end-of-stream.
longest
The duration of the longest input. (default)
shortest
The duration of the shortest input.
first
The duration of the first input.
dropout_transition
The transition time, in seconds, for volume renormalization when an input stream ends.
The default value is 2 seconds.
weights
Specify weight of each input audio stream as sequence. Each weight is separated by
space. By default all inputs have same weight.
amultiply
Multiply first audio stream with second audio stream and store result in output audio
stream. Multiplication is done by multiplying each sample from first stream with sample at
same position from second stream.
With this element-wise multiplication one can create amplitude fades and amplitude
modulations.
anequalizer
High-order parametric multiband equalizer for each channel.
It accepts the following parameters:
params
This option string is in format: "cchn f=cf w=w g=g t=f | ..." Each equalizer band is
separated by '|'.
chn Set channel number to which equalization will be applied. If input doesn't have
that channel the entry is ignored.
f Set central frequency for band. If input doesn't have that frequency the entry is
ignored.
w Set band width in hertz.
g Set band gain in dB.
t Set filter type for band, optional, can be:
0 Butterworth, this is default.
1 Chebyshev type 1.
2 Chebyshev type 2.
curves
With this option activated frequency response of anequalizer is displayed in video
stream.
size
Set video stream size. Only useful if curves option is activated.
mgain
Set max gain that will be displayed. Only useful if curves option is activated.
Setting this to a reasonable value makes it possible to display gain which is derived
from neighbour bands which are too close to each other and thus produce higher gain
when both are activated.
fscale
Set frequency scale used to draw frequency response in video output. Can be linear or
logarithmic. Default is logarithmic.
colors
Set color for each channel curve which is going to be displayed in video stream. This
is list of color names separated by space or by '|'. Unrecognised or missing colors
will be replaced by white color.
Examples
• Lower gain by 10 of central frequency 200Hz and width 100 Hz for first 2 channels
using Chebyshev type 1 filter:
anequalizer=c0 f=200 w=100 g=-10 t=1|c1 f=200 w=100 g=-10 t=1
Commands
This filter supports the following commands:
change
Alter existing filter parameters. Syntax for the commands is :
"fN|f=freq|w=width|g=gain"
fN is existing filter number, starting from 0, if no such filter is available error is
returned. freq set new frequency parameter. width set new width parameter in herz.
gain set new gain parameter in dB.
Full filter invocation with asendcmd may look like this: asendcmd=c='4.0 anequalizer
change 0|f=200|w=50|g=1',anequalizer=...
anlmdn
Reduce broadband noise in audio samples using Non-Local Means algorithm.
Each sample is adjusted by looking for other samples with similar contexts. This context
similarity is defined by comparing their surrounding patches of size p. Patches are
searched in an area of r around the sample.
The filter accepts the following options.
s Set denoising strength. Allowed range is from 0.00001 to 10. Default value is 0.00001.
p Set patch radius duration. Allowed range is from 1 to 100 milliseconds. Default value
is 2 milliseconds.
r Set research radius duration. Allowed range is from 2 to 300 milliseconds. Default
value is 6 milliseconds.
o Set the output mode.
It accepts the following values:
i Pass input unchanged.
o Pass noise filtered out.
n Pass only noise.
Default value is o.
m Set smooth factor. Default value is 11. Allowed range is from 1 to 15.
Commands
This filter supports the following commands:
s Change denoise strength. Argument is single float number. Syntax for the command is :
"s"
o Change output mode. Syntax for the command is : "i", "o" or "n" string.
anull
Pass the audio source unchanged to the output.
apad
Pad the end of an audio stream with silence.
This can be used together with ffmpeg -shortest to extend audio streams to the same length
as the video stream.
A description of the accepted options follows.
packet_size
Set silence packet size. Default value is 4096.
pad_len
Set the number of samples of silence to add to the end. After the value is reached,
the stream is terminated. This option is mutually exclusive with whole_len.
whole_len
Set the minimum total number of samples in the output audio stream. If the value is
longer than the input audio length, silence is added to the end, until the value is
reached. This option is mutually exclusive with pad_len.
pad_dur
Specify the duration of samples of silence to add. See the Time duration section in
the ffmpeg-utils(1) manual for the accepted syntax. Used only if set to non-zero
value.
whole_dur
Specify the minimum total duration in the output audio stream. See the Time duration
section in the ffmpeg-utils(1) manual for the accepted syntax. Used only if set to
non-zero value. If the value is longer than the input audio length, silence is added
to the end, until the value is reached. This option is mutually exclusive with
pad_dur
If neither the pad_len nor the whole_len nor pad_dur nor whole_dur option is set, the
filter will add silence to the end of the input stream indefinitely.
Examples
• Add 1024 samples of silence to the end of the input:
apad=pad_len=1024
• Make sure the audio output will contain at least 10000 samples, pad the input with
silence if required:
apad=whole_len=10000
• Use ffmpeg to pad the audio input with silence, so that the video stream will always
result the shortest and will be converted until the end in the output file when using
the shortest option:
ffmpeg -i VIDEO -i AUDIO -filter_complex "[1:0]apad" -shortest OUTPUT
aphaser
Add a phasing effect to the input audio.
A phaser filter creates series of peaks and troughs in the frequency spectrum. The
position of the peaks and troughs are modulated so that they vary over time, creating a
sweeping effect.
A description of the accepted parameters follows.
in_gain
Set input gain. Default is 0.4.
out_gain
Set output gain. Default is 0.74
delay
Set delay in milliseconds. Default is 3.0.
decay
Set decay. Default is 0.4.
speed
Set modulation speed in Hz. Default is 0.5.
type
Set modulation type. Default is triangular.
It accepts the following values:
triangular, t
sinusoidal, s
apulsator
Audio pulsator is something between an autopanner and a tremolo. But it can produce funny
stereo effects as well. Pulsator changes the volume of the left and right channel based on
a LFO (low frequency oscillator) with different waveforms and shifted phases. This filter
have the ability to define an offset between left and right channel. An offset of 0 means
that both LFO shapes match each other. The left and right channel are altered equally - a
conventional tremolo. An offset of 50% means that the shape of the right channel is
exactly shifted in phase (or moved backwards about half of the frequency) - pulsator acts
as an autopanner. At 1 both curves match again. Every setting in between moves the phase
shift gapless between all stages and produces some "bypassing" sounds with sine and
triangle waveforms. The more you set the offset near 1 (starting from the 0.5) the faster
the signal passes from the left to the right speaker.
The filter accepts the following options:
level_in
Set input gain. By default it is 1. Range is [0.015625 - 64].
level_out
Set output gain. By default it is 1. Range is [0.015625 - 64].
mode
Set waveform shape the LFO will use. Can be one of: sine, triangle, square, sawup or
sawdown. Default is sine.
amount
Set modulation. Define how much of original signal is affected by the LFO.
offset_l
Set left channel offset. Default is 0. Allowed range is [0 - 1].
offset_r
Set right channel offset. Default is 0.5. Allowed range is [0 - 1].
width
Set pulse width. Default is 1. Allowed range is [0 - 2].
timing
Set possible timing mode. Can be one of: bpm, ms or hz. Default is hz.
bpm Set bpm. Default is 120. Allowed range is [30 - 300]. Only used if timing is set to
bpm.
ms Set ms. Default is 500. Allowed range is [10 - 2000]. Only used if timing is set to
ms.
hz Set frequency in Hz. Default is 2. Allowed range is [0.01 - 100]. Only used if timing
is set to hz.
aresample
Resample the input audio to the specified parameters, using the libswresample library. If
none are specified then the filter will automatically convert between its input and
output.
This filter is also able to stretch/squeeze the audio data to make it match the timestamps
or to inject silence / cut out audio to make it match the timestamps, do a combination of
both or do neither.
The filter accepts the syntax [sample_rate:]resampler_options, where sample_rate expresses
a sample rate and resampler_options is a list of key=value pairs, separated by ":". See
the "Resampler Options" section in the ffmpeg-resampler(1) manual for the complete list of
supported options.
Examples
• Resample the input audio to 44100Hz:
aresample=44100
• Stretch/squeeze samples to the given timestamps, with a maximum of 1000 samples per
second compensation:
aresample=async=1000
areverse
Reverse an audio clip.
Warning: This filter requires memory to buffer the entire clip, so trimming is suggested.
Examples
• Take the first 5 seconds of a clip, and reverse it.
atrim=end=5,areverse
asetnsamples
Set the number of samples per each output audio frame.
The last output packet may contain a different number of samples, as the filter will flush
all the remaining samples when the input audio signals its end.
The filter accepts the following options:
nb_out_samples, n
Set the number of frames per each output audio frame. The number is intended as the
number of samples per each channel. Default value is 1024.
pad, p
If set to 1, the filter will pad the last audio frame with zeroes, so that the last
frame will contain the same number of samples as the previous ones. Default value is
1.
For example, to set the number of per-frame samples to 1234 and disable padding for the
last frame, use:
asetnsamples=n=1234:p=0
asetrate
Set the sample rate without altering the PCM data. This will result in a change of speed
and pitch.
The filter accepts the following options:
sample_rate, r
Set the output sample rate. Default is 44100 Hz.
ashowinfo
Show a line containing various information for each input audio frame. The input audio is
not modified.
The shown line contains a sequence of key/value pairs of the form key:value.
The following values are shown in the output:
n The (sequential) number of the input frame, starting from 0.
pts The presentation timestamp of the input frame, in time base units; the time base
depends on the filter input pad, and is usually 1/sample_rate.
pts_time
The presentation timestamp of the input frame in seconds.
pos position of the frame in the input stream, -1 if this information in unavailable
and/or meaningless (for example in case of synthetic audio)
fmt The sample format.
chlayout
The channel layout.
rate
The sample rate for the audio frame.
nb_samples
The number of samples (per channel) in the frame.
checksum
The Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio,
the data is treated as if all the planes were concatenated.
plane_checksums
A list of Adler-32 checksums for each data plane.
asoftclip
Apply audio soft clipping.
Soft clipping is a type of distortion effect where the amplitude of a signal is saturated
along a smooth curve, rather than the abrupt shape of hard-clipping.
This filter accepts the following options:
type
Set type of soft-clipping.
It accepts the following values:
tanh
atan
cubic
exp
alg
quintic
sin
param
Set additional parameter which controls sigmoid function.
asr
Automatic Speech Recognition
This filter uses PocketSphinx for speech recognition. To enable compilation of this
filter, you need to configure FFmpeg with "--enable-pocketsphinx".
It accepts the following options:
rate
Set sampling rate of input audio. Defaults is 16000. This need to match speech
models, otherwise one will get poor results.
hmm Set dictionary containing acoustic model files.
dict
Set pronunciation dictionary.
lm Set language model file.
lmctl
Set language model set.
lmname
Set which language model to use.
logfn
Set output for log messages.
The filter exports recognized speech as the frame metadata "lavfi.asr.text".
astats
Display time domain statistical information about the audio channels. Statistics are
calculated and displayed for each audio channel and, where applicable, an overall figure
is also given.
It accepts the following option:
length
Short window length in seconds, used for peak and trough RMS measurement. Default is
0.05 (50 milliseconds). Allowed range is "[0.01 - 10]".
metadata
Set metadata injection. All the metadata keys are prefixed with "lavfi.astats.X",
where "X" is channel number starting from 1 or string "Overall". Default is disabled.
Available keys for each channel are: DC_offset Min_level Max_level Min_difference
Max_difference Mean_difference RMS_difference Peak_level RMS_peak RMS_trough
Crest_factor Flat_factor Peak_count Bit_depth Dynamic_range Zero_crossings
Zero_crossings_rate Number_of_NaNs Number_of_Infs Number_of_denormals
and for Overall: DC_offset Min_level Max_level Min_difference Max_difference
Mean_difference RMS_difference Peak_level RMS_level RMS_peak RMS_trough Flat_factor
Peak_count Bit_depth Number_of_samples Number_of_NaNs Number_of_Infs
Number_of_denormals
For example full key look like this "lavfi.astats.1.DC_offset" or this
"lavfi.astats.Overall.Peak_count".
For description what each key means read below.
reset
Set number of frame after which stats are going to be recalculated. Default is
disabled.
measure_perchannel
Select the entries which need to be measured per channel. The metadata keys can be
used as flags, default is all which measures everything. none disables all per
channel measurement.
measure_overall
Select the entries which need to be measured overall. The metadata keys can be used as
flags, default is all which measures everything. none disables all overall
measurement.
A description of each shown parameter follows:
DC offset
Mean amplitude displacement from zero.
Min level
Minimal sample level.
Max level
Maximal sample level.
Min difference
Minimal difference between two consecutive samples.
Max difference
Maximal difference between two consecutive samples.
Mean difference
Mean difference between two consecutive samples. The average of each difference
between two consecutive samples.
RMS difference
Root Mean Square difference between two consecutive samples.
Peak level dB
RMS level dB
Standard peak and RMS level measured in dBFS.
RMS peak dB
RMS trough dB
Peak and trough values for RMS level measured over a short window.
Crest factor
Standard ratio of peak to RMS level (note: not in dB).
Flat factor
Flatness (i.e. consecutive samples with the same value) of the signal at its peak
levels (i.e. either Min level or Max level).
Peak count
Number of occasions (not the number of samples) that the signal attained either Min
level or Max level.
Bit depth
Overall bit depth of audio. Number of bits used for each sample.
Dynamic range
Measured dynamic range of audio in dB.
Zero crossings
Number of points where the waveform crosses the zero level axis.
Zero crossings rate
Rate of Zero crossings and number of audio samples.
atempo
Adjust audio tempo.
The filter accepts exactly one parameter, the audio tempo. If not specified then the
filter will assume nominal 1.0 tempo. Tempo must be in the [0.5, 100.0] range.
Note that tempo greater than 2 will skip some samples rather than blend them in. If for
any reason this is a concern it is always possible to daisy-chain several instances of
atempo to achieve the desired product tempo.
Examples
• Slow down audio to 80% tempo:
atempo=0.8
• To speed up audio to 300% tempo:
atempo=3
• To speed up audio to 300% tempo by daisy-chaining two atempo instances:
atempo=sqrt(3),atempo=sqrt(3)
atrim
Trim the input so that the output contains one continuous subpart of the input.
It accepts the following parameters:
start
Timestamp (in seconds) of the start of the section to keep. I.e. the audio sample with
the timestamp start will be the first sample in the output.
end Specify time of the first audio sample that will be dropped, i.e. the audio sample
immediately preceding the one with the timestamp end will be the last sample in the
output.
start_pts
Same as start, except this option sets the start timestamp in samples instead of
seconds.
end_pts
Same as end, except this option sets the end timestamp in samples instead of seconds.
duration
The maximum duration of the output in seconds.
start_sample
The number of the first sample that should be output.
end_sample
The number of the first sample that should be dropped.
start, end, and duration are expressed as time duration specifications; see the Time
duration section in the ffmpeg-utils(1) manual.
Note that the first two sets of the start/end options and the duration option look at the
frame timestamp, while the _sample options simply count the samples that pass through the
filter. So start/end_pts and start/end_sample will give different results when the
timestamps are wrong, inexact or do not start at zero. Also note that this filter does not
modify the timestamps. If you wish to have the output timestamps start at zero, insert the
asetpts filter after the atrim filter.
If multiple start or end options are set, this filter tries to be greedy and keep all
samples that match at least one of the specified constraints. To keep only the part that
matches all the constraints at once, chain multiple atrim filters.
The defaults are such that all the input is kept. So it is possible to set e.g. just the
end values to keep everything before the specified time.
Examples:
• Drop everything except the second minute of input:
ffmpeg -i INPUT -af atrim=60:120
• Keep only the first 1000 samples:
ffmpeg -i INPUT -af atrim=end_sample=1000
bandpass
Apply a two-pole Butterworth band-pass filter with central frequency frequency, and
(3dB-point) band-width width. The csg option selects a constant skirt gain (peak gain =
Q) instead of the default: constant 0dB peak gain. The filter roll off at 6dB per octave
(20dB per decade).
The filter accepts the following options:
frequency, f
Set the filter's central frequency. Default is 3000.
csg Constant skirt gain if set to 1. Defaults to 0.
width_type, t
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
k kHz
width, w
Specify the band-width of a filter in width_type units.
mix, m
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
channels, c
Specify which channels to filter, by default all available are filtered.
Commands
This filter supports the following commands:
frequency, f
Change bandpass frequency. Syntax for the command is : "frequency"
width_type, t
Change bandpass width_type. Syntax for the command is : "width_type"
width, w
Change bandpass width. Syntax for the command is : "width"
mix, m
Change bandpass mix. Syntax for the command is : "mix"
bandreject
Apply a two-pole Butterworth band-reject filter with central frequency frequency, and
(3dB-point) band-width width. The filter roll off at 6dB per octave (20dB per decade).
The filter accepts the following options:
frequency, f
Set the filter's central frequency. Default is 3000.
width_type, t
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
k kHz
width, w
Specify the band-width of a filter in width_type units.
mix, m
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
channels, c
Specify which channels to filter, by default all available are filtered.
Commands
This filter supports the following commands:
frequency, f
Change bandreject frequency. Syntax for the command is : "frequency"
width_type, t
Change bandreject width_type. Syntax for the command is : "width_type"
width, w
Change bandreject width. Syntax for the command is : "width"
mix, m
Change bandreject mix. Syntax for the command is : "mix"
bass, lowshelf
Boost or cut the bass (lower) frequencies of the audio using a two-pole shelving filter
with a response similar to that of a standard hi-fi's tone-controls. This is also known as
shelving equalisation (EQ).
The filter accepts the following options:
gain, g
Give the gain at 0 Hz. Its useful range is about -20 (for a large cut) to +20 (for a
large boost). Beware of clipping when using a positive gain.
frequency, f
Set the filter's central frequency and so can be used to extend or reduce the
frequency range to be boosted or cut. The default value is 100 Hz.
width_type, t
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
k kHz
width, w
Determine how steep is the filter's shelf transition.
mix, m
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
channels, c
Specify which channels to filter, by default all available are filtered.
Commands
This filter supports the following commands:
frequency, f
Change bass frequency. Syntax for the command is : "frequency"
width_type, t
Change bass width_type. Syntax for the command is : "width_type"
width, w
Change bass width. Syntax for the command is : "width"
gain, g
Change bass gain. Syntax for the command is : "gain"
mix, m
Change bass mix. Syntax for the command is : "mix"
biquad
Apply a biquad IIR filter with the given coefficients. Where b0, b1, b2 and a0, a1, a2
are the numerator and denominator coefficients respectively. and channels, c specify
which channels to filter, by default all available are filtered.
Commands
This filter supports the following commands:
a0
a1
a2
b0
b1
b2 Change biquad parameter. Syntax for the command is : "value"
mix, m
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
bs2b
Bauer stereo to binaural transformation, which improves headphone listening of stereo
audio records.
To enable compilation of this filter you need to configure FFmpeg with "--enable-libbs2b".
It accepts the following parameters:
profile
Pre-defined crossfeed level.
default
Default level (fcut=700, feed=50).
cmoy
Chu Moy circuit (fcut=700, feed=60).
jmeier
Jan Meier circuit (fcut=650, feed=95).
fcut
Cut frequency (in Hz).
feed
Feed level (in Hz).
channelmap
Remap input channels to new locations.
It accepts the following parameters:
map Map channels from input to output. The argument is a '|'-separated list of mappings,
each in the "in_channel-out_channel" or in_channel form. in_channel can be either the
name of the input channel (e.g. FL for front left) or its index in the input channel
layout. out_channel is the name of the output channel or its index in the output
channel layout. If out_channel is not given then it is implicitly an index, starting
with zero and increasing by one for each mapping.
channel_layout
The channel layout of the output stream.
If no mapping is present, the filter will implicitly map input channels to output
channels, preserving indices.
Examples
• For example, assuming a 5.1+downmix input MOV file,
ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
will create an output WAV file tagged as stereo from the downmix channels of the
input.
• To fix a 5.1 WAV improperly encoded in AAC's native channel order
ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav
channelsplit
Split each channel from an input audio stream into a separate output stream.
It accepts the following parameters:
channel_layout
The channel layout of the input stream. The default is "stereo".
channels
A channel layout describing the channels to be extracted as separate output streams or
"all" to extract each input channel as a separate stream. The default is "all".
Choosing channels not present in channel layout in the input will result in an error.
Examples
• For example, assuming a stereo input MP3 file,
ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv
will create an output Matroska file with two audio streams, one containing only the
left channel and the other the right channel.
• Split a 5.1 WAV file into per-channel files:
ffmpeg -i in.wav -filter_complex
'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
-map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
side_right.wav
• Extract only LFE from a 5.1 WAV file:
ffmpeg -i in.wav -filter_complex 'channelsplit=channel_layout=5.1:channels=LFE[LFE]'
-map '[LFE]' lfe.wav
chorus
Add a chorus effect to the audio.
Can make a single vocal sound like a chorus, but can also be applied to instrumentation.
Chorus resembles an echo effect with a short delay, but whereas with echo the delay is
constant, with chorus, it is varied using using sinusoidal or triangular modulation. The
modulation depth defines the range the modulated delay is played before or after the
delay. Hence the delayed sound will sound slower or faster, that is the delayed sound
tuned around the original one, like in a chorus where some vocals are slightly off key.
It accepts the following parameters:
in_gain
Set input gain. Default is 0.4.
out_gain
Set output gain. Default is 0.4.
delays
Set delays. A typical delay is around 40ms to 60ms.
decays
Set decays.
speeds
Set speeds.
depths
Set depths.
Examples
• A single delay:
chorus=0.7:0.9:55:0.4:0.25:2
• Two delays:
chorus=0.6:0.9:50|60:0.4|0.32:0.25|0.4:2|1.3
• Fuller sounding chorus with three delays:
chorus=0.5:0.9:50|60|40:0.4|0.32|0.3:0.25|0.4|0.3:2|2.3|1.3
compand
Compress or expand the audio's dynamic range.
It accepts the following parameters:
attacks
decays
A list of times in seconds for each channel over which the instantaneous level of the
input signal is averaged to determine its volume. attacks refers to increase of volume
and decays refers to decrease of volume. For most situations, the attack time
(response to the audio getting louder) should be shorter than the decay time, because
the human ear is more sensitive to sudden loud audio than sudden soft audio. A typical
value for attack is 0.3 seconds and a typical value for decay is 0.8 seconds. If
specified number of attacks & decays is lower than number of channels, the last set
attack/decay will be used for all remaining channels.
points
A list of points for the transfer function, specified in dB relative to the maximum
possible signal amplitude. Each key points list must be defined using the following
syntax: "x0/y0|x1/y1|x2/y2|...." or "x0/y0 x1/y1 x2/y2 ...."
The input values must be in strictly increasing order but the transfer function does
not have to be monotonically rising. The point "0/0" is assumed but may be overridden
(by "0/out-dBn"). Typical values for the transfer function are "-70/-70|-60/-20|1/0".
soft-knee
Set the curve radius in dB for all joints. It defaults to 0.01.
gain
Set the additional gain in dB to be applied at all points on the transfer function.
This allows for easy adjustment of the overall gain. It defaults to 0.
volume
Set an initial volume, in dB, to be assumed for each channel when filtering starts.
This permits the user to supply a nominal level initially, so that, for example, a
very large gain is not applied to initial signal levels before the companding has
begun to operate. A typical value for audio which is initially quiet is -90 dB. It
defaults to 0.
delay
Set a delay, in seconds. The input audio is analyzed immediately, but audio is delayed
before being fed to the volume adjuster. Specifying a delay approximately equal to the
attack/decay times allows the filter to effectively operate in predictive rather than
reactive mode. It defaults to 0.
Examples
• Make music with both quiet and loud passages suitable for listening to in a noisy
environment:
compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2
Another example for audio with whisper and explosion parts:
compand=0|0:1|1:-90/-900|-70/-70|-30/-9|0/-3:6:0:0:0
• A noise gate for when the noise is at a lower level than the signal:
compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1
• Here is another noise gate, this time for when the noise is at a higher level than the
signal (making it, in some ways, similar to squelch):
compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1
• 2:1 compression starting at -6dB:
compand=points=-80/-80|-6/-6|0/-3.8|20/3.5
• 2:1 compression starting at -9dB:
compand=points=-80/-80|-9/-9|0/-5.3|20/2.9
• 2:1 compression starting at -12dB:
compand=points=-80/-80|-12/-12|0/-6.8|20/1.9
• 2:1 compression starting at -18dB:
compand=points=-80/-80|-18/-18|0/-9.8|20/0.7
• 3:1 compression starting at -15dB:
compand=points=-80/-80|-15/-15|0/-10.8|20/-5.2
• Compressor/Gate:
compand=points=-80/-105|-62/-80|-15.4/-15.4|0/-12|20/-7.6
• Expander:
compand=attacks=0:points=-80/-169|-54/-80|-49.5/-64.6|-41.1/-41.1|-25.8/-15|-10.8/-4.5|0/0|20/8.3
• Hard limiter at -6dB:
compand=attacks=0:points=-80/-80|-6/-6|20/-6
• Hard limiter at -12dB:
compand=attacks=0:points=-80/-80|-12/-12|20/-12
• Hard noise gate at -35 dB:
compand=attacks=0:points=-80/-115|-35.1/-80|-35/-35|20/20
• Soft limiter:
compand=attacks=0:points=-80/-80|-12.4/-12.4|-6/-8|0/-6.8|20/-2.8
compensationdelay
Compensation Delay Line is a metric based delay to compensate differing positions of
microphones or speakers.
For example, you have recorded guitar with two microphones placed in different location.
Because the front of sound wave has fixed speed in normal conditions, the phasing of
microphones can vary and depends on their location and interposition. The best sound mix
can be achieved when these microphones are in phase (synchronized). Note that distance of
~30 cm between microphones makes one microphone to capture signal in antiphase to another
microphone. That makes the final mix sounding moody. This filter helps to solve phasing
problems by adding different delays to each microphone track and make them synchronized.
The best result can be reached when you take one track as base and synchronize other
tracks one by one with it. Remember that synchronization/delay tolerance depends on
sample rate, too. Higher sample rates will give more tolerance.
It accepts the following parameters:
mm Set millimeters distance. This is compensation distance for fine tuning. Default is
0.
cm Set cm distance. This is compensation distance for tightening distance setup. Default
is 0.
m Set meters distance. This is compensation distance for hard distance setup. Default
is 0.
dry Set dry amount. Amount of unprocessed (dry) signal. Default is 0.
wet Set wet amount. Amount of processed (wet) signal. Default is 1.
temp
Set temperature degree in Celsius. This is the temperature of the environment.
Default is 20.
crossfeed
Apply headphone crossfeed filter.
Crossfeed is the process of blending the left and right channels of stereo audio
recording. It is mainly used to reduce extreme stereo separation of low frequencies.
The intent is to produce more speaker like sound to the listener.
The filter accepts the following options:
strength
Set strength of crossfeed. Default is 0.2. Allowed range is from 0 to 1. This sets
gain of low shelf filter for side part of stereo image. Default is -6dB. Max allowed
is -30db when strength is set to 1.
range
Set soundstage wideness. Default is 0.5. Allowed range is from 0 to 1. This sets cut
off frequency of low shelf filter. Default is cut off near 1550 Hz. With range set to
1 cut off frequency is set to 2100 Hz.
level_in
Set input gain. Default is 0.9.
level_out
Set output gain. Default is 1.
crystalizer
Simple algorithm to expand audio dynamic range.
The filter accepts the following options:
i Sets the intensity of effect (default: 2.0). Must be in range between 0.0 (unchanged
sound) to 10.0 (maximum effect).
c Enable clipping. By default is enabled.
dcshift
Apply a DC shift to the audio.
This can be useful to remove a DC offset (caused perhaps by a hardware problem in the
recording chain) from the audio. The effect of a DC offset is reduced headroom and hence
volume. The astats filter can be used to determine if a signal has a DC offset.
shift
Set the DC shift, allowed range is [-1, 1]. It indicates the amount to shift the
audio.
limitergain
Optional. It should have a value much less than 1 (e.g. 0.05 or 0.02) and is used to
prevent clipping.
deesser
Apply de-essing to the audio samples.
i Set intensity for triggering de-essing. Allowed range is from 0 to 1. Default is 0.
m Set amount of ducking on treble part of sound. Allowed range is from 0 to 1. Default
is 0.5.
f How much of original frequency content to keep when de-essing. Allowed range is from 0
to 1. Default is 0.5.
s Set the output mode.
It accepts the following values:
i Pass input unchanged.
o Pass ess filtered out.
e Pass only ess.
Default value is o.
drmeter
Measure audio dynamic range.
DR values of 14 and higher is found in very dynamic material. DR of 8 to 13 is found in
transition material. And anything less that 8 have very poor dynamics and is very
compressed.
The filter accepts the following options:
length
Set window length in seconds used to split audio into segments of equal length.
Default is 3 seconds.
dynaudnorm
Dynamic Audio Normalizer.
This filter applies a certain amount of gain to the input audio in order to bring its peak
magnitude to a target level (e.g. 0 dBFS). However, in contrast to more "simple"
normalization algorithms, the Dynamic Audio Normalizer *dynamically* re-adjusts the gain
factor to the input audio. This allows for applying extra gain to the "quiet" sections of
the audio while avoiding distortions or clipping the "loud" sections. In other words: The
Dynamic Audio Normalizer will "even out" the volume of quiet and loud sections, in the
sense that the volume of each section is brought to the same target level. Note, however,
that the Dynamic Audio Normalizer achieves this goal *without* applying "dynamic range
compressing". It will retain 100% of the dynamic range *within* each section of the audio
file.
f Set the frame length in milliseconds. In range from 10 to 8000 milliseconds. Default
is 500 milliseconds. The Dynamic Audio Normalizer processes the input audio in small
chunks, referred to as frames. This is required, because a peak magnitude has no
meaning for just a single sample value. Instead, we need to determine the peak
magnitude for a contiguous sequence of sample values. While a "standard" normalizer
would simply use the peak magnitude of the complete file, the Dynamic Audio Normalizer
determines the peak magnitude individually for each frame. The length of a frame is
specified in milliseconds. By default, the Dynamic Audio Normalizer uses a frame
length of 500 milliseconds, which has been found to give good results with most files.
Note that the exact frame length, in number of samples, will be determined
automatically, based on the sampling rate of the individual input audio file.
g Set the Gaussian filter window size. In range from 3 to 301, must be odd number.
Default is 31. Probably the most important parameter of the Dynamic Audio Normalizer
is the "window size" of the Gaussian smoothing filter. The filter's window size is
specified in frames, centered around the current frame. For the sake of simplicity,
this must be an odd number. Consequently, the default value of 31 takes into account
the current frame, as well as the 15 preceding frames and the 15 subsequent frames.
Using a larger window results in a stronger smoothing effect and thus in less gain
variation, i.e. slower gain adaptation. Conversely, using a smaller window results in
a weaker smoothing effect and thus in more gain variation, i.e. faster gain
adaptation. In other words, the more you increase this value, the more the Dynamic
Audio Normalizer will behave like a "traditional" normalization filter. On the
contrary, the more you decrease this value, the more the Dynamic Audio Normalizer will
behave like a dynamic range compressor.
p Set the target peak value. This specifies the highest permissible magnitude level for
the normalized audio input. This filter will try to approach the target peak magnitude
as closely as possible, but at the same time it also makes sure that the normalized
signal will never exceed the peak magnitude. A frame's maximum local gain factor is
imposed directly by the target peak magnitude. The default value is 0.95 and thus
leaves a headroom of 5%*. It is not recommended to go above this value.
m Set the maximum gain factor. In range from 1.0 to 100.0. Default is 10.0. The Dynamic
Audio Normalizer determines the maximum possible (local) gain factor for each input
frame, i.e. the maximum gain factor that does not result in clipping or distortion.
The maximum gain factor is determined by the frame's highest magnitude sample.
However, the Dynamic Audio Normalizer additionally bounds the frame's maximum gain
factor by a predetermined (global) maximum gain factor. This is done in order to avoid
excessive gain factors in "silent" or almost silent frames. By default, the maximum
gain factor is 10.0, For most inputs the default value should be sufficient and it
usually is not recommended to increase this value. Though, for input with an extremely
low overall volume level, it may be necessary to allow even higher gain factors. Note,
however, that the Dynamic Audio Normalizer does not simply apply a "hard" threshold
(i.e. cut off values above the threshold). Instead, a "sigmoid" threshold function
will be applied. This way, the gain factors will smoothly approach the threshold
value, but never exceed that value.
r Set the target RMS. In range from 0.0 to 1.0. Default is 0.0 - disabled. By default,
the Dynamic Audio Normalizer performs "peak" normalization. This means that the
maximum local gain factor for each frame is defined (only) by the frame's highest
magnitude sample. This way, the samples can be amplified as much as possible without
exceeding the maximum signal level, i.e. without clipping. Optionally, however, the
Dynamic Audio Normalizer can also take into account the frame's root mean square,
abbreviated RMS. In electrical engineering, the RMS is commonly used to determine the
power of a time-varying signal. It is therefore considered that the RMS is a better
approximation of the "perceived loudness" than just looking at the signal's peak
magnitude. Consequently, by adjusting all frames to a constant RMS value, a uniform
"perceived loudness" can be established. If a target RMS value has been specified, a
frame's local gain factor is defined as the factor that would result in exactly that
RMS value. Note, however, that the maximum local gain factor is still restricted by
the frame's highest magnitude sample, in order to prevent clipping.
n Enable channels coupling. By default is enabled. By default, the Dynamic Audio
Normalizer will amplify all channels by the same amount. This means the same gain
factor will be applied to all channels, i.e. the maximum possible gain factor is
determined by the "loudest" channel. However, in some recordings, it may happen that
the volume of the different channels is uneven, e.g. one channel may be "quieter" than
the other one(s). In this case, this option can be used to disable the channel
coupling. This way, the gain factor will be determined independently for each channel,
depending only on the individual channel's highest magnitude sample. This allows for
harmonizing the volume of the different channels.
c Enable DC bias correction. By default is disabled. An audio signal (in the time
domain) is a sequence of sample values. In the Dynamic Audio Normalizer these sample
values are represented in the -1.0 to 1.0 range, regardless of the original input
format. Normally, the audio signal, or "waveform", should be centered around the zero
point. That means if we calculate the mean value of all samples in a file, or in a
single frame, then the result should be 0.0 or at least very close to that value. If,
however, there is a significant deviation of the mean value from 0.0, in either
positive or negative direction, this is referred to as a DC bias or DC offset. Since a
DC bias is clearly undesirable, the Dynamic Audio Normalizer provides optional DC bias
correction. With DC bias correction enabled, the Dynamic Audio Normalizer will
determine the mean value, or "DC correction" offset, of each input frame and subtract
that value from all of the frame's sample values which ensures those samples are
centered around 0.0 again. Also, in order to avoid "gaps" at the frame boundaries, the
DC correction offset values will be interpolated smoothly between neighbouring frames.
b Enable alternative boundary mode. By default is disabled. The Dynamic Audio
Normalizer takes into account a certain neighbourhood around each frame. This includes
the preceding frames as well as the subsequent frames. However, for the "boundary"
frames, located at the very beginning and at the very end of the audio file, not all
neighbouring frames are available. In particular, for the first few frames in the
audio file, the preceding frames are not known. And, similarly, for the last few
frames in the audio file, the subsequent frames are not known. Thus, the question
arises which gain factors should be assumed for the missing frames in the "boundary"
region. The Dynamic Audio Normalizer implements two modes to deal with this situation.
The default boundary mode assumes a gain factor of exactly 1.0 for the missing frames,
resulting in a smooth "fade in" and "fade out" at the beginning and at the end of the
input, respectively.
s Set the compress factor. In range from 0.0 to 30.0. Default is 0.0. By default, the
Dynamic Audio Normalizer does not apply "traditional" compression. This means that
signal peaks will not be pruned and thus the full dynamic range will be retained
within each local neighbourhood. However, in some cases it may be desirable to combine
the Dynamic Audio Normalizer's normalization algorithm with a more "traditional"
compression. For this purpose, the Dynamic Audio Normalizer provides an optional
compression (thresholding) function. If (and only if) the compression feature is
enabled, all input frames will be processed by a soft knee thresholding function prior
to the actual normalization process. Put simply, the thresholding function is going to
prune all samples whose magnitude exceeds a certain threshold value. However, the
Dynamic Audio Normalizer does not simply apply a fixed threshold value. Instead, the
threshold value will be adjusted for each individual frame. In general, smaller
parameters result in stronger compression, and vice versa. Values below 3.0 are not
recommended, because audible distortion may appear.
earwax
Make audio easier to listen to on headphones.
This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio so that when
listened to on headphones the stereo image is moved from inside your head (standard for
headphones) to outside and in front of the listener (standard for speakers).
Ported from SoX.
equalizer
Apply a two-pole peaking equalisation (EQ) filter. With this filter, the signal-level at
and around a selected frequency can be increased or decreased, whilst (unlike bandpass and
bandreject filters) that at all other frequencies is unchanged.
In order to produce complex equalisation curves, this filter can be given several times,
each with a different central frequency.
The filter accepts the following options:
frequency, f
Set the filter's central frequency in Hz.
width_type, t
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
k kHz
width, w
Specify the band-width of a filter in width_type units.
gain, g
Set the required gain or attenuation in dB. Beware of clipping when using a positive
gain.
mix, m
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
channels, c
Specify which channels to filter, by default all available are filtered.
Examples
• Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz:
equalizer=f=1000:t=h:width=200:g=-10
• Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz with Q 2:
equalizer=f=1000:t=q:w=1:g=2,equalizer=f=100:t=q:w=2:g=-5
Commands
This filter supports the following commands:
frequency, f
Change equalizer frequency. Syntax for the command is : "frequency"
width_type, t
Change equalizer width_type. Syntax for the command is : "width_type"
width, w
Change equalizer width. Syntax for the command is : "width"
gain, g
Change equalizer gain. Syntax for the command is : "gain"
mix, m
Change equalizer mix. Syntax for the command is : "mix"
extrastereo
Linearly increases the difference between left and right channels which adds some sort of
"live" effect to playback.
The filter accepts the following options:
m Sets the difference coefficient (default: 2.5). 0.0 means mono sound (average of both
channels), with 1.0 sound will be unchanged, with -1.0 left and right channels will be
swapped.
c Enable clipping. By default is enabled.
firequalizer
Apply FIR Equalization using arbitrary frequency response.
The filter accepts the following option:
gain
Set gain curve equation (in dB). The expression can contain variables:
f the evaluated frequency
sr sample rate
ch channel number, set to 0 when multichannels evaluation is disabled
chid
channel id, see libavutil/channel_layout.h, set to the first channel id when
multichannels evaluation is disabled
chs number of channels
chlayout
channel_layout, see libavutil/channel_layout.h
and functions:
gain_interpolate(f)
interpolate gain on frequency f based on gain_entry
cubic_interpolate(f)
same as gain_interpolate, but smoother
This option is also available as command. Default is gain_interpolate(f).
gain_entry
Set gain entry for gain_interpolate function. The expression can contain functions:
entry(f, g)
store gain entry at frequency f with value g
This option is also available as command.
delay
Set filter delay in seconds. Higher value means more accurate. Default is 0.01.
accuracy
Set filter accuracy in Hz. Lower value means more accurate. Default is 5.
wfunc
Set window function. Acceptable values are:
rectangular
rectangular window, useful when gain curve is already smooth
hann
hann window (default)
hamming
hamming window
blackman
blackman window
nuttall3
3-terms continuous 1st derivative nuttall window
mnuttall3
minimum 3-terms discontinuous nuttall window
nuttall
4-terms continuous 1st derivative nuttall window
bnuttall
minimum 4-terms discontinuous nuttall (blackman-nuttall) window
bharris
blackman-harris window
tukey
tukey window
fixed
If enabled, use fixed number of audio samples. This improves speed when filtering with
large delay. Default is disabled.
multi
Enable multichannels evaluation on gain. Default is disabled.
zero_phase
Enable zero phase mode by subtracting timestamp to compensate delay. Default is
disabled.
scale
Set scale used by gain. Acceptable values are:
linlin
linear frequency, linear gain
linlog
linear frequency, logarithmic (in dB) gain (default)
loglin
logarithmic (in octave scale where 20 Hz is 0) frequency, linear gain
loglog
logarithmic frequency, logarithmic gain
dumpfile
Set file for dumping, suitable for gnuplot.
dumpscale
Set scale for dumpfile. Acceptable values are same with scale option. Default is
linlog.
fft2
Enable 2-channel convolution using complex FFT. This improves speed significantly.
Default is disabled.
min_phase
Enable minimum phase impulse response. Default is disabled.
Examples
• lowpass at 1000 Hz:
firequalizer=gain='if(lt(f,1000), 0, -INF)'
• lowpass at 1000 Hz with gain_entry:
firequalizer=gain_entry='entry(1000,0); entry(1001, -INF)'
• custom equalization:
firequalizer=gain_entry='entry(100,0); entry(400, -4); entry(1000, -6); entry(2000, 0)'
• higher delay with zero phase to compensate delay:
firequalizer=delay=0.1:fixed=on:zero_phase=on
• lowpass on left channel, highpass on right channel:
firequalizer=gain='if(eq(chid,1), gain_interpolate(f), if(eq(chid,2), gain_interpolate(1e6+f), 0))'
:gain_entry='entry(1000, 0); entry(1001,-INF); entry(1e6+1000,0)':multi=on
flanger
Apply a flanging effect to the audio.
The filter accepts the following options:
delay
Set base delay in milliseconds. Range from 0 to 30. Default value is 0.
depth
Set added sweep delay in milliseconds. Range from 0 to 10. Default value is 2.
regen
Set percentage regeneration (delayed signal feedback). Range from -95 to 95. Default
value is 0.
width
Set percentage of delayed signal mixed with original. Range from 0 to 100. Default
value is 71.
speed
Set sweeps per second (Hz). Range from 0.1 to 10. Default value is 0.5.
shape
Set swept wave shape, can be triangular or sinusoidal. Default value is sinusoidal.
phase
Set swept wave percentage-shift for multi channel. Range from 0 to 100. Default value
is 25.
interp
Set delay-line interpolation, linear or quadratic. Default is linear.
haas
Apply Haas effect to audio.
Note that this makes most sense to apply on mono signals. With this filter applied to
mono signals it give some directionality and stretches its stereo image.
The filter accepts the following options:
level_in
Set input level. By default is 1, or 0dB
level_out
Set output level. By default is 1, or 0dB.
side_gain
Set gain applied to side part of signal. By default is 1.
middle_source
Set kind of middle source. Can be one of the following:
left
Pick left channel.
right
Pick right channel.
mid Pick middle part signal of stereo image.
side
Pick side part signal of stereo image.
middle_phase
Change middle phase. By default is disabled.
left_delay
Set left channel delay. By default is 2.05 milliseconds.
left_balance
Set left channel balance. By default is -1.
left_gain
Set left channel gain. By default is 1.
left_phase
Change left phase. By default is disabled.
right_delay
Set right channel delay. By defaults is 2.12 milliseconds.
right_balance
Set right channel balance. By default is 1.
right_gain
Set right channel gain. By default is 1.
right_phase
Change right phase. By default is enabled.
hdcd
Decodes High Definition Compatible Digital (HDCD) data. A 16-bit PCM stream with embedded
HDCD codes is expanded into a 20-bit PCM stream.
The filter supports the Peak Extend and Low-level Gain Adjustment features of HDCD, and
detects the Transient Filter flag.
ffmpeg -i HDCD16.flac -af hdcd OUT24.flac
When using the filter with wav, note the default encoding for wav is 16-bit, so the
resulting 20-bit stream will be truncated back to 16-bit. Use something like -acodec
pcm_s24le after the filter to get 24-bit PCM output.
ffmpeg -i HDCD16.wav -af hdcd OUT16.wav
ffmpeg -i HDCD16.wav -af hdcd -c:a pcm_s24le OUT24.wav
The filter accepts the following options:
disable_autoconvert
Disable any automatic format conversion or resampling in the filter graph.
process_stereo
Process the stereo channels together. If target_gain does not match between channels,
consider it invalid and use the last valid target_gain.
cdt_ms
Set the code detect timer period in ms.
force_pe
Always extend peaks above -3dBFS even if PE isn't signaled.
analyze_mode
Replace audio with a solid tone and adjust the amplitude to signal some specific
aspect of the decoding process. The output file can be loaded in an audio editor
alongside the original to aid analysis.
"analyze_mode=pe:force_pe=true" can be used to see all samples above the PE level.
Modes are:
0, off
Disabled
1, lle
Gain adjustment level at each sample
2, pe
Samples where peak extend occurs
3, cdt
Samples where the code detect timer is active
4, tgm
Samples where the target gain does not match between channels
headphone
Apply head-related transfer functions (HRTFs) to create virtual loudspeakers around the
user for binaural listening via headphones. The HRIRs are provided via additional
streams, for each channel one stereo input stream is needed.
The filter accepts the following options:
map Set mapping of input streams for convolution. The argument is a '|'-separated list of
channel names in order as they are given as additional stream inputs for filter. This
also specify number of input streams. Number of input streams must be not less than
number of channels in first stream plus one.
gain
Set gain applied to audio. Value is in dB. Default is 0.
type
Set processing type. Can be time or freq. time is processing audio in time domain
which is slow. freq is processing audio in frequency domain which is fast. Default
is freq.
lfe Set custom gain for LFE channels. Value is in dB. Default is 0.
size
Set size of frame in number of samples which will be processed at once. Default value
is 1024. Allowed range is from 1024 to 96000.
hrir
Set format of hrir stream. Default value is stereo. Alternative value is multich. If
value is set to stereo, number of additional streams should be greater or equal to
number of input channels in first input stream. Also each additional stream should
have stereo number of channels. If value is set to multich, number of additional
streams should be exactly one. Also number of input channels of additional stream
should be equal or greater than twice number of channels of first input stream.
Examples
• Full example using wav files as coefficients with amovie filters for 7.1 downmix, each
amovie filter use stereo file with IR coefficients as input. The files give
coefficients for each position of virtual loudspeaker:
ffmpeg -i input.wav
-filter_complex "amovie=azi_270_ele_0_DFC.wav[sr];amovie=azi_90_ele_0_DFC.wav[sl];amovie=azi_225_ele_0_DFC.wav[br];amovie=azi_135_ele_0_DFC.wav[bl];amovie=azi_0_ele_0_DFC.wav,asplit[fc][lfe];amovie=azi_35_ele_0_DFC.wav[fl];amovie=azi_325_ele_0_DFC.wav[fr];[0:a][fl][fr][fc][lfe][bl][br][sl][sr]headphone=FL|FR|FC|LFE|BL|BR|SL|SR"
output.wav
• Full example using wav files as coefficients with amovie filters for 7.1 downmix, but
now in multich hrir format.
ffmpeg -i input.wav -filter_complex "amovie=minp.wav[hrirs];[0:a][hrirs]headphone=map=FL|FR|FC|LFE|BL|BR|SL|SR:hrir=multich"
output.wav
highpass
Apply a high-pass filter with 3dB point frequency. The filter can be either single-pole,
or double-pole (the default). The filter roll off at 6dB per pole per octave (20dB per
pole per decade).
The filter accepts the following options:
frequency, f
Set frequency in Hz. Default is 3000.
poles, p
Set number of poles. Default is 2.
width_type, t
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
k kHz
width, w
Specify the band-width of a filter in width_type units. Applies only to double-pole
filter. The default is 0.707q and gives a Butterworth response.
mix, m
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
channels, c
Specify which channels to filter, by default all available are filtered.
Commands
This filter supports the following commands:
frequency, f
Change highpass frequency. Syntax for the command is : "frequency"
width_type, t
Change highpass width_type. Syntax for the command is : "width_type"
width, w
Change highpass width. Syntax for the command is : "width"
mix, m
Change highpass mix. Syntax for the command is : "mix"
join
Join multiple input streams into one multi-channel stream.
It accepts the following parameters:
inputs
The number of input streams. It defaults to 2.
channel_layout
The desired output channel layout. It defaults to stereo.
map Map channels from inputs to output. The argument is a '|'-separated list of mappings,
each in the "input_idx.in_channel-out_channel" form. input_idx is the 0-based index of
the input stream. in_channel can be either the name of the input channel (e.g. FL for
front left) or its index in the specified input stream. out_channel is the name of the
output channel.
The filter will attempt to guess the mappings when they are not specified explicitly. It
does so by first trying to find an unused matching input channel and if that fails it
picks the first unused input channel.
Join 3 inputs (with properly set channel layouts):
ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT
Build a 5.1 output from 6 single-channel streams:
ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
'join=inputs=6:channel_layout=5.1:map=0.0-FL|1.0-FR|2.0-FC|3.0-SL|4.0-SR|5.0-LFE'
out
ladspa
Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin.
To enable compilation of this filter you need to configure FFmpeg with "--enable-ladspa".
file, f
Specifies the name of LADSPA plugin library to load. If the environment variable
LADSPA_PATH is defined, the LADSPA plugin is searched in each one of the directories
specified by the colon separated list in LADSPA_PATH, otherwise in the standard LADSPA
paths, which are in this order: HOME/.ladspa/lib/, /usr/local/lib/ladspa/,
/usr/lib/ladspa/.
plugin, p
Specifies the plugin within the library. Some libraries contain only one plugin, but
others contain many of them. If this is not set filter will list all available plugins
within the specified library.
controls, c
Set the '|' separated list of controls which are zero or more floating point values
that determine the behavior of the loaded plugin (for example delay, threshold or
gain). Controls need to be defined using the following syntax:
c0=value0|c1=value1|c2=value2|..., where valuei is the value set on the i-th control.
Alternatively they can be also defined using the following syntax:
value0|value1|value2|..., where valuei is the value set on the i-th control. If
controls is set to "help", all available controls and their valid ranges are printed.
sample_rate, s
Specify the sample rate, default to 44100. Only used if plugin have zero inputs.
nb_samples, n
Set the number of samples per channel per each output frame, default is 1024. Only
used if plugin have zero inputs.
duration, d
Set the minimum duration of the sourced audio. See the Time duration section in the
ffmpeg-utils(1) manual for the accepted syntax. Note that the resulting duration may
be greater than the specified duration, as the generated audio is always cut at the
end of a complete frame. If not specified, or the expressed duration is negative, the
audio is supposed to be generated forever. Only used if plugin have zero inputs.
Examples
• List all available plugins within amp (LADSPA example plugin) library:
ladspa=file=amp
• List all available controls and their valid ranges for "vcf_notch" plugin from "VCF"
library:
ladspa=f=vcf:p=vcf_notch:c=help
• Simulate low quality audio equipment using "Computer Music Toolkit" (CMT) plugin
library:
ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12
• Add reverberation to the audio using TAP-plugins (Tom's Audio Processing plugins):
ladspa=file=tap_reverb:tap_reverb
• Generate white noise, with 0.2 amplitude:
ladspa=file=cmt:noise_source_white:c=c0=.2
• Generate 20 bpm clicks using plugin "C* Click - Metronome" from the "C* Audio Plugin
Suite" (CAPS) library:
ladspa=file=caps:Click:c=c1=20'
• Apply "C* Eq10X2 - Stereo 10-band equaliser" effect:
ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2
• Increase volume by 20dB using fast lookahead limiter from Steve Harris "SWH Plugins"
collection:
ladspa=fast_lookahead_limiter_1913:fastLookaheadLimiter:20|0|2
• Attenuate low frequencies using Multiband EQ from Steve Harris "SWH Plugins"
collection:
ladspa=mbeq_1197:mbeq:-24|-24|-24|0|0|0|0|0|0|0|0|0|0|0|0
• Reduce stereo image using "Narrower" from the "C* Audio Plugin Suite" (CAPS) library:
ladspa=caps:Narrower
• Another white noise, now using "C* Audio Plugin Suite" (CAPS) library:
ladspa=caps:White:.2
• Some fractal noise, using "C* Audio Plugin Suite" (CAPS) library:
ladspa=caps:Fractal:c=c1=1
• Dynamic volume normalization using "VLevel" plugin:
ladspa=vlevel-ladspa:vlevel_mono
Commands
This filter supports the following commands:
cN Modify the N-th control value.
If the specified value is not valid, it is ignored and prior one is kept.
loudnorm
EBU R128 loudness normalization. Includes both dynamic and linear normalization modes.
Support for both single pass (livestreams, files) and double pass (files) modes. This
algorithm can target IL, LRA, and maximum true peak. To accurately detect true peaks, the
audio stream will be upsampled to 192 kHz unless the normalization mode is linear. Use
the "-ar" option or "aresample" filter to explicitly set an output sample rate.
The filter accepts the following options:
I, i
Set integrated loudness target. Range is -70.0 - -5.0. Default value is -24.0.
LRA, lra
Set loudness range target. Range is 1.0 - 20.0. Default value is 7.0.
TP, tp
Set maximum true peak. Range is -9.0 - +0.0. Default value is -2.0.
measured_I, measured_i
Measured IL of input file. Range is -99.0 - +0.0.
measured_LRA, measured_lra
Measured LRA of input file. Range is 0.0 - 99.0.
measured_TP, measured_tp
Measured true peak of input file. Range is -99.0 - +99.0.
measured_thresh
Measured threshold of input file. Range is -99.0 - +0.0.
offset
Set offset gain. Gain is applied before the true-peak limiter. Range is -99.0 -
+99.0. Default is +0.0.
linear
Normalize linearly if possible. measured_I, measured_LRA, measured_TP, and
measured_thresh must also to be specified in order to use this mode. Options are true
or false. Default is true.
dual_mono
Treat mono input files as "dual-mono". If a mono file is intended for playback on a
stereo system, its EBU R128 measurement will be perceptually incorrect. If set to
"true", this option will compensate for this effect. Multi-channel input files are
not affected by this option. Options are true or false. Default is false.
print_format
Set print format for stats. Options are summary, json, or none. Default value is
none.
lowpass
Apply a low-pass filter with 3dB point frequency. The filter can be either single-pole or
double-pole (the default). The filter roll off at 6dB per pole per octave (20dB per pole
per decade).
The filter accepts the following options:
frequency, f
Set frequency in Hz. Default is 500.
poles, p
Set number of poles. Default is 2.
width_type, t
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
k kHz
width, w
Specify the band-width of a filter in width_type units. Applies only to double-pole
filter. The default is 0.707q and gives a Butterworth response.
mix, m
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
channels, c
Specify which channels to filter, by default all available are filtered.
Examples
• Lowpass only LFE channel, it LFE is not present it does nothing:
lowpass=c=LFE
Commands
This filter supports the following commands:
frequency, f
Change lowpass frequency. Syntax for the command is : "frequency"
width_type, t
Change lowpass width_type. Syntax for the command is : "width_type"
width, w
Change lowpass width. Syntax for the command is : "width"
mix, m
Change lowpass mix. Syntax for the command is : "mix"
lv2
Load a LV2 (LADSPA Version 2) plugin.
To enable compilation of this filter you need to configure FFmpeg with "--enable-lv2".
plugin, p
Specifies the plugin URI. You may need to escape ':'.
controls, c
Set the '|' separated list of controls which are zero or more floating point values
that determine the behavior of the loaded plugin (for example delay, threshold or
gain). If controls is set to "help", all available controls and their valid ranges
are printed.
sample_rate, s
Specify the sample rate, default to 44100. Only used if plugin have zero inputs.
nb_samples, n
Set the number of samples per channel per each output frame, default is 1024. Only
used if plugin have zero inputs.
duration, d
Set the minimum duration of the sourced audio. See the Time duration section in the
ffmpeg-utils(1) manual for the accepted syntax. Note that the resulting duration may
be greater than the specified duration, as the generated audio is always cut at the
end of a complete frame. If not specified, or the expressed duration is negative, the
audio is supposed to be generated forever. Only used if plugin have zero inputs.
Examples
• Apply bass enhancer plugin from Calf:
lv2=p=http\\\\://calf.sourceforge.net/plugins/BassEnhancer:c=amount=2
• Apply vinyl plugin from Calf:
lv2=p=http\\\\://calf.sourceforge.net/plugins/Vinyl:c=drone=0.2|aging=0.5
• Apply bit crusher plugin from ArtyFX:
lv2=p=http\\\\://www.openavproductions.com/artyfx#bitta:c=crush=0.3
mcompand
Multiband Compress or expand the audio's dynamic range.
The input audio is divided into bands using 4th order Linkwitz-Riley IIRs. This is akin
to the crossover of a loudspeaker, and results in flat frequency response when absent
compander action.
It accepts the following parameters:
args
This option syntax is: attack,decay,[attack,decay..] soft-knee points
crossover_frequency [delay [initial_volume [gain]]] | attack,decay ... For
explanation of each item refer to compand filter documentation.
pan
Mix channels with specific gain levels. The filter accepts the output channel layout
followed by a set of channels definitions.
This filter is also designed to efficiently remap the channels of an audio stream.
The filter accepts parameters of the form: "l|outdef|outdef|..."
l output channel layout or number of channels
outdef
output channel specification, of the form:
"out_name=[gain*]in_name[(+-)[gain*]in_name...]"
out_name
output channel to define, either a channel name (FL, FR, etc.) or a channel number
(c0, c1, etc.)
gain
multiplicative coefficient for the channel, 1 leaving the volume unchanged
in_name
input channel to use, see out_name for details; it is not possible to mix named and
numbered input channels
If the `=' in a channel specification is replaced by `<', then the gains for that
specification will be renormalized so that the total is 1, thus avoiding clipping noise.
Mixing examples
For example, if you want to down-mix from stereo to mono, but with a bigger factor for the
left channel:
pan=1c|c0=0.9*c0+0.1*c1
A customized down-mix to stereo that works automatically for 3-, 4-, 5- and 7-channels
surround:
pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR
Note that ffmpeg integrates a default down-mix (and up-mix) system that should be
preferred (see "-ac" option) unless you have very specific needs.
Remapping examples
The channel remapping will be effective if, and only if:
*<gain coefficients are zeroes or ones,>
*<only one input per channel output,>
If all these conditions are satisfied, the filter will notify the user ("Pure channel
mapping detected"), and use an optimized and lossless method to do the remapping.
For example, if you have a 5.1 source and want a stereo audio stream by dropping the extra
channels:
pan="stereo| c0=FL | c1=FR"
Given the same source, you can also switch front left and front right channels and keep
the input channel layout:
pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5"
If the input is a stereo audio stream, you can mute the front left channel (and still keep
the stereo channel layout) with:
pan="stereo|c1=c1"
Still with a stereo audio stream input, you can copy the right channel in both front left
and right:
pan="stereo| c0=FR | c1=FR"
replaygain
ReplayGain scanner filter. This filter takes an audio stream as an input and outputs it
unchanged. At end of filtering it displays "track_gain" and "track_peak".
resample
Convert the audio sample format, sample rate and channel layout. It is not meant to be
used directly.
rubberband
Apply time-stretching and pitch-shifting with librubberband.
To enable compilation of this filter, you need to configure FFmpeg with
"--enable-librubberband".
The filter accepts the following options:
tempo
Set tempo scale factor.
pitch
Set pitch scale factor.
transients
Set transients detector. Possible values are:
crisp
mixed
smooth
detector
Set detector. Possible values are:
compound
percussive
soft
phase
Set phase. Possible values are:
laminar
independent
window
Set processing window size. Possible values are:
standard
short
long
smoothing
Set smoothing. Possible values are:
off
on
formant
Enable formant preservation when shift pitching. Possible values are:
shifted
preserved
pitchq
Set pitch quality. Possible values are:
quality
speed
consistency
channels
Set channels. Possible values are:
apart
together
sidechaincompress
This filter acts like normal compressor but has the ability to compress detected signal
using second input signal. It needs two input streams and returns one output stream.
First input stream will be processed depending on second stream signal. The filtered
signal then can be filtered with other filters in later stages of processing. See pan and
amerge filter.
The filter accepts the following options:
level_in
Set input gain. Default is 1. Range is between 0.015625 and 64.
mode
Set mode of compressor operation. Can be "upward" or "downward". Default is
"downward".
threshold
If a signal of second stream raises above this level it will affect the gain reduction
of first stream. By default is 0.125. Range is between 0.00097563 and 1.
ratio
Set a ratio about which the signal is reduced. 1:2 means that if the level raised 4dB
above the threshold, it will be only 2dB above after the reduction. Default is 2.
Range is between 1 and 20.
attack
Amount of milliseconds the signal has to rise above the threshold before gain
reduction starts. Default is 20. Range is between 0.01 and 2000.
release
Amount of milliseconds the signal has to fall below the threshold before reduction is
decreased again. Default is 250. Range is between 0.01 and 9000.
makeup
Set the amount by how much signal will be amplified after processing. Default is 1.
Range is from 1 to 64.
knee
Curve the sharp knee around the threshold to enter gain reduction more softly.
Default is 2.82843. Range is between 1 and 8.
link
Choose if the "average" level between all channels of side-chain stream or the
louder("maximum") channel of side-chain stream affects the reduction. Default is
"average".
detection
Should the exact signal be taken in case of "peak" or an RMS one in case of "rms".
Default is "rms" which is mainly smoother.
level_sc
Set sidechain gain. Default is 1. Range is between 0.015625 and 64.
mix How much to use compressed signal in output. Default is 1. Range is between 0 and 1.
Examples
• Full ffmpeg example taking 2 audio inputs, 1st input to be compressed depending on the
signal of 2nd input and later compressed signal to be merged with 2nd input:
ffmpeg -i main.flac -i sidechain.flac -filter_complex "[1:a]asplit=2[sc][mix];[0:a][sc]sidechaincompress[compr];[compr][mix]amerge"
sidechaingate
A sidechain gate acts like a normal (wideband) gate but has the ability to filter the
detected signal before sending it to the gain reduction stage. Normally a gate uses the
full range signal to detect a level above the threshold. For example: If you cut all
lower frequencies from your sidechain signal the gate will decrease the volume of your
track only if not enough highs appear. With this technique you are able to reduce the
resonation of a natural drum or remove "rumbling" of muted strokes from a heavily
distorted guitar. It needs two input streams and returns one output stream. First input
stream will be processed depending on second stream signal.
The filter accepts the following options:
level_in
Set input level before filtering. Default is 1. Allowed range is from 0.015625 to 64.
mode
Set the mode of operation. Can be "upward" or "downward". Default is "downward". If
set to "upward" mode, higher parts of signal will be amplified, expanding dynamic
range in upward direction. Otherwise, in case of "downward" lower parts of signal
will be reduced.
range
Set the level of gain reduction when the signal is below the threshold. Default is
0.06125. Allowed range is from 0 to 1. Setting this to 0 disables reduction and then
filter behaves like expander.
threshold
If a signal rises above this level the gain reduction is released. Default is 0.125.
Allowed range is from 0 to 1.
ratio
Set a ratio about which the signal is reduced. Default is 2. Allowed range is from 1
to 9000.
attack
Amount of milliseconds the signal has to rise above the threshold before gain
reduction stops. Default is 20 milliseconds. Allowed range is from 0.01 to 9000.
release
Amount of milliseconds the signal has to fall below the threshold before the reduction
is increased again. Default is 250 milliseconds. Allowed range is from 0.01 to 9000.
makeup
Set amount of amplification of signal after processing. Default is 1. Allowed range
is from 1 to 64.
knee
Curve the sharp knee around the threshold to enter gain reduction more softly.
Default is 2.828427125. Allowed range is from 1 to 8.
detection
Choose if exact signal should be taken for detection or an RMS like one. Default is
rms. Can be peak or rms.
link
Choose if the average level between all channels or the louder channel affects the
reduction. Default is average. Can be average or maximum.
level_sc
Set sidechain gain. Default is 1. Range is from 0.015625 to 64.
silencedetect
Detect silence in an audio stream.
This filter logs a message when it detects that the input audio volume is less or equal to
a noise tolerance value for a duration greater or equal to the minimum detected noise
duration.
The printed times and duration are expressed in seconds.
The filter accepts the following options:
noise, n
Set noise tolerance. Can be specified in dB (in case "dB" is appended to the specified
value) or amplitude ratio. Default is -60dB, or 0.001.
duration, d
Set silence duration until notification (default is 2 seconds).
mono, m
Process each channel separately, instead of combined. By default is disabled.
Examples
• Detect 5 seconds of silence with -50dB noise tolerance:
silencedetect=n=-50dB:d=5
• Complete example with ffmpeg to detect silence with 0.0001 noise tolerance in
silence.mp3:
ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null -
silenceremove
Remove silence from the beginning, middle or end of the audio.
The filter accepts the following options:
start_periods
This value is used to indicate if audio should be trimmed at beginning of the audio. A
value of zero indicates no silence should be trimmed from the beginning. When
specifying a non-zero value, it trims audio up until it finds non-silence. Normally,
when trimming silence from beginning of audio the start_periods will be 1 but it can
be increased to higher values to trim all audio up to specific count of non-silence
periods. Default value is 0.
start_duration
Specify the amount of time that non-silence must be detected before it stops trimming
audio. By increasing the duration, bursts of noises can be treated as silence and
trimmed off. Default value is 0.
start_threshold
This indicates what sample value should be treated as silence. For digital audio, a
value of 0 may be fine but for audio recorded from analog, you may wish to increase
the value to account for background noise. Can be specified in dB (in case "dB" is
appended to the specified value) or amplitude ratio. Default value is 0.
start_silence
Specify max duration of silence at beginning that will be kept after trimming. Default
is 0, which is equal to trimming all samples detected as silence.
start_mode
Specify mode of detection of silence end in start of multi-channel audio. Can be any
or all. Default is any. With any, any sample that is detected as non-silence will
cause stopped trimming of silence. With all, only if all channels are detected as
non-silence will cause stopped trimming of silence.
stop_periods
Set the count for trimming silence from the end of audio. To remove silence from the
middle of a file, specify a stop_periods that is negative. This value is then treated
as a positive value and is used to indicate the effect should restart processing as
specified by start_periods, making it suitable for removing periods of silence in the
middle of the audio. Default value is 0.
stop_duration
Specify a duration of silence that must exist before audio is not copied any more. By
specifying a higher duration, silence that is wanted can be left in the audio.
Default value is 0.
stop_threshold
This is the same as start_threshold but for trimming silence from the end of audio.
Can be specified in dB (in case "dB" is appended to the specified value) or amplitude
ratio. Default value is 0.
stop_silence
Specify max duration of silence at end that will be kept after trimming. Default is 0,
which is equal to trimming all samples detected as silence.
stop_mode
Specify mode of detection of silence start in end of multi-channel audio. Can be any
or all. Default is any. With any, any sample that is detected as non-silence will
cause stopped trimming of silence. With all, only if all channels are detected as
non-silence will cause stopped trimming of silence.
detection
Set how is silence detected. Can be "rms" or "peak". Second is faster and works better
with digital silence which is exactly 0. Default value is "rms".
window
Set duration in number of seconds used to calculate size of window in number of
samples for detecting silence. Default value is 0.02. Allowed range is from 0 to 10.
Examples
• The following example shows how this filter can be used to start a recording that does
not contain the delay at the start which usually occurs between pressing the record
button and the start of the performance:
silenceremove=start_periods=1:start_duration=5:start_threshold=0.02
• Trim all silence encountered from beginning to end where there is more than 1 second
of silence in audio:
silenceremove=stop_periods=-1:stop_duration=1:stop_threshold=-90dB
sofalizer
SOFAlizer uses head-related transfer functions (HRTFs) to create virtual loudspeakers
around the user for binaural listening via headphones (audio formats up to 9 channels
supported). The HRTFs are stored in SOFA files (see <http://www.sofacoustics.org/> for a
database). SOFAlizer is developed at the Acoustics Research Institute (ARI) of the
Austrian Academy of Sciences.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-libmysofa".
The filter accepts the following options:
sofa
Set the SOFA file used for rendering.
gain
Set gain applied to audio. Value is in dB. Default is 0.
rotation
Set rotation of virtual loudspeakers in deg. Default is 0.
elevation
Set elevation of virtual speakers in deg. Default is 0.
radius
Set distance in meters between loudspeakers and the listener with near-field HRTFs.
Default is 1.
type
Set processing type. Can be time or freq. time is processing audio in time domain
which is slow. freq is processing audio in frequency domain which is fast. Default
is freq.
speakers
Set custom positions of virtual loudspeakers. Syntax for this option is: <CH> <AZIM>
<ELEV>[|<CH> <AZIM> <ELEV>|...]. Each virtual loudspeaker is described with short
channel name following with azimuth and elevation in degrees. Each virtual
loudspeaker description is separated by '|'. For example to override front left and
front right channel positions use: 'speakers=FL 45 15|FR 345 15'. Descriptions with
unrecognised channel names are ignored.
lfegain
Set custom gain for LFE channels. Value is in dB. Default is 0.
framesize
Set custom frame size in number of samples. Default is 1024. Allowed range is from
1024 to 96000. Only used if option type is set to freq.
normalize
Should all IRs be normalized upon importing SOFA file. By default is enabled.
interpolate
Should nearest IRs be interpolated with neighbor IRs if exact position does not match.
By default is disabled.
minphase
Minphase all IRs upon loading of SOFA file. By default is disabled.
anglestep
Set neighbor search angle step. Only used if option interpolate is enabled.
radstep
Set neighbor search radius step. Only used if option interpolate is enabled.
Examples
• Using ClubFritz6 sofa file:
sofalizer=sofa=/path/to/ClubFritz6.sofa:type=freq:radius=1
• Using ClubFritz12 sofa file and bigger radius with small rotation:
sofalizer=sofa=/path/to/ClubFritz12.sofa:type=freq:radius=2:rotation=5
• Similar as above but with custom speaker positions for front left, front right, back
left and back right and also with custom gain:
"sofalizer=sofa=/path/to/ClubFritz6.sofa:type=freq:radius=2:speakers=FL 45|FR 315|BL 135|BR 225:gain=28"
stereotools
This filter has some handy utilities to manage stereo signals, for converting M/S stereo
recordings to L/R signal while having control over the parameters or spreading the stereo
image of master track.
The filter accepts the following options:
level_in
Set input level before filtering for both channels. Defaults is 1. Allowed range is
from 0.015625 to 64.
level_out
Set output level after filtering for both channels. Defaults is 1. Allowed range is
from 0.015625 to 64.
balance_in
Set input balance between both channels. Default is 0. Allowed range is from -1 to 1.
balance_out
Set output balance between both channels. Default is 0. Allowed range is from -1 to
1.
softclip
Enable softclipping. Results in analog distortion instead of harsh digital 0dB
clipping. Disabled by default.
mutel
Mute the left channel. Disabled by default.
muter
Mute the right channel. Disabled by default.
phasel
Change the phase of the left channel. Disabled by default.
phaser
Change the phase of the right channel. Disabled by default.
mode
Set stereo mode. Available values are:
lr>lr
Left/Right to Left/Right, this is default.
lr>ms
Left/Right to Mid/Side.
ms>lr
Mid/Side to Left/Right.
lr>ll
Left/Right to Left/Left.
lr>rr
Left/Right to Right/Right.
lr>l+r
Left/Right to Left + Right.
lr>rl
Left/Right to Right/Left.
ms>ll
Mid/Side to Left/Left.
ms>rr
Mid/Side to Right/Right.
slev
Set level of side signal. Default is 1. Allowed range is from 0.015625 to 64.
sbal
Set balance of side signal. Default is 0. Allowed range is from -1 to 1.
mlev
Set level of the middle signal. Default is 1. Allowed range is from 0.015625 to 64.
mpan
Set middle signal pan. Default is 0. Allowed range is from -1 to 1.
base
Set stereo base between mono and inversed channels. Default is 0. Allowed range is
from -1 to 1.
delay
Set delay in milliseconds how much to delay left from right channel and vice versa.
Default is 0. Allowed range is from -20 to 20.
sclevel
Set S/C level. Default is 1. Allowed range is from 1 to 100.
phase
Set the stereo phase in degrees. Default is 0. Allowed range is from 0 to 360.
bmode_in, bmode_out
Set balance mode for balance_in/balance_out option.
Can be one of the following:
balance
Classic balance mode. Attenuate one channel at time. Gain is raised up to 1.
amplitude
Similar as classic mode above but gain is raised up to 2.
power
Equal power distribution, from -6dB to +6dB range.
Examples
• Apply karaoke like effect:
stereotools=mlev=0.015625
• Convert M/S signal to L/R:
"stereotools=mode=ms>lr"
stereowiden
This filter enhance the stereo effect by suppressing signal common to both channels and by
delaying the signal of left into right and vice versa, thereby widening the stereo effect.
The filter accepts the following options:
delay
Time in milliseconds of the delay of left signal into right and vice versa. Default
is 20 milliseconds.
feedback
Amount of gain in delayed signal into right and vice versa. Gives a delay effect of
left signal in right output and vice versa which gives widening effect. Default is
0.3.
crossfeed
Cross feed of left into right with inverted phase. This helps in suppressing the mono.
If the value is 1 it will cancel all the signal common to both channels. Default is
0.3.
drymix
Set level of input signal of original channel. Default is 0.8.
superequalizer
Apply 18 band equalizer.
The filter accepts the following options:
1b Set 65Hz band gain.
2b Set 92Hz band gain.
3b Set 131Hz band gain.
4b Set 185Hz band gain.
5b Set 262Hz band gain.
6b Set 370Hz band gain.
7b Set 523Hz band gain.
8b Set 740Hz band gain.
9b Set 1047Hz band gain.
10b Set 1480Hz band gain.
11b Set 2093Hz band gain.
12b Set 2960Hz band gain.
13b Set 4186Hz band gain.
14b Set 5920Hz band gain.
15b Set 8372Hz band gain.
16b Set 11840Hz band gain.
17b Set 16744Hz band gain.
18b Set 20000Hz band gain.
surround
Apply audio surround upmix filter.
This filter allows to produce multichannel output from audio stream.
The filter accepts the following options:
chl_out
Set output channel layout. By default, this is 5.1.
See the Channel Layout section in the ffmpeg-utils(1) manual for the required syntax.
chl_in
Set input channel layout. By default, this is stereo.
See the Channel Layout section in the ffmpeg-utils(1) manual for the required syntax.
level_in
Set input volume level. By default, this is 1.
level_out
Set output volume level. By default, this is 1.
lfe Enable LFE channel output if output channel layout has it. By default, this is
enabled.
lfe_low
Set LFE low cut off frequency. By default, this is 128 Hz.
lfe_high
Set LFE high cut off frequency. By default, this is 256 Hz.
lfe_mode
Set LFE mode, can be add or sub. Default is add. In add mode, LFE channel is created
from input audio and added to output. In sub mode, LFE channel is created from input
audio and added to output but also all non-LFE output channels are subtracted with
output LFE channel.
angle
Set angle of stereo surround transform, Allowed range is from 0 to 360. Default is
90.
fc_in
Set front center input volume. By default, this is 1.
fc_out
Set front center output volume. By default, this is 1.
fl_in
Set front left input volume. By default, this is 1.
fl_out
Set front left output volume. By default, this is 1.
fr_in
Set front right input volume. By default, this is 1.
fr_out
Set front right output volume. By default, this is 1.
sl_in
Set side left input volume. By default, this is 1.
sl_out
Set side left output volume. By default, this is 1.
sr_in
Set side right input volume. By default, this is 1.
sr_out
Set side right output volume. By default, this is 1.
bl_in
Set back left input volume. By default, this is 1.
bl_out
Set back left output volume. By default, this is 1.
br_in
Set back right input volume. By default, this is 1.
br_out
Set back right output volume. By default, this is 1.
bc_in
Set back center input volume. By default, this is 1.
bc_out
Set back center output volume. By default, this is 1.
lfe_in
Set LFE input volume. By default, this is 1.
lfe_out
Set LFE output volume. By default, this is 1.
allx
Set spread usage of stereo image across X axis for all channels.
ally
Set spread usage of stereo image across Y axis for all channels.
fcx, flx, frx, blx, brx, slx, srx, bcx
Set spread usage of stereo image across X axis for each channel.
fcy, fly, fry, bly, bry, sly, sry, bcy
Set spread usage of stereo image across Y axis for each channel.
win_size
Set window size. Allowed range is from 1024 to 65536. Default size is 4096.
win_func
Set window function.
It accepts the following values:
rect
bartlett
hann, hanning
hamming
blackman
welch
flattop
bharris
bnuttall
bhann
sine
nuttall
lanczos
gauss
tukey
dolph
cauchy
parzen
poisson
bohman
Default is "hann".
overlap
Set window overlap. If set to 1, the recommended overlap for selected window function
will be picked. Default is 0.5.
treble, highshelf
Boost or cut treble (upper) frequencies of the audio using a two-pole shelving filter with
a response similar to that of a standard hi-fi's tone-controls. This is also known as
shelving equalisation (EQ).
The filter accepts the following options:
gain, g
Give the gain at whichever is the lower of ~22 kHz and the Nyquist frequency. Its
useful range is about -20 (for a large cut) to +20 (for a large boost). Beware of
clipping when using a positive gain.
frequency, f
Set the filter's central frequency and so can be used to extend or reduce the
frequency range to be boosted or cut. The default value is 3000 Hz.
width_type, t
Set method to specify band-width of filter.
h Hz
q Q-Factor
o octave
s slope
k kHz
width, w
Determine how steep is the filter's shelf transition.
mix, m
How much to use filtered signal in output. Default is 1. Range is between 0 and 1.
channels, c
Specify which channels to filter, by default all available are filtered.
Commands
This filter supports the following commands:
frequency, f
Change treble frequency. Syntax for the command is : "frequency"
width_type, t
Change treble width_type. Syntax for the command is : "width_type"
width, w
Change treble width. Syntax for the command is : "width"
gain, g
Change treble gain. Syntax for the command is : "gain"
mix, m
Change treble mix. Syntax for the command is : "mix"
tremolo
Sinusoidal amplitude modulation.
The filter accepts the following options:
f Modulation frequency in Hertz. Modulation frequencies in the subharmonic range (20 Hz
or lower) will result in a tremolo effect. This filter may also be used as a ring
modulator by specifying a modulation frequency higher than 20 Hz. Range is 0.1 -
20000.0. Default value is 5.0 Hz.
d Depth of modulation as a percentage. Range is 0.0 - 1.0. Default value is 0.5.
vibrato
Sinusoidal phase modulation.
The filter accepts the following options:
f Modulation frequency in Hertz. Range is 0.1 - 20000.0. Default value is 5.0 Hz.
d Depth of modulation as a percentage. Range is 0.0 - 1.0. Default value is 0.5.
volume
Adjust the input audio volume.
It accepts the following parameters:
volume
Set audio volume expression.
Output values are clipped to the maximum value.
The output audio volume is given by the relation:
<output_volume> = <volume> * <input_volume>
The default value for volume is "1.0".
precision
This parameter represents the mathematical precision.
It determines which input sample formats will be allowed, which affects the precision
of the volume scaling.
fixed
8-bit fixed-point; this limits input sample format to U8, S16, and S32.
float
32-bit floating-point; this limits input sample format to FLT. (default)
double
64-bit floating-point; this limits input sample format to DBL.
replaygain
Choose the behaviour on encountering ReplayGain side data in input frames.
drop
Remove ReplayGain side data, ignoring its contents (the default).
ignore
Ignore ReplayGain side data, but leave it in the frame.
track
Prefer the track gain, if present.
album
Prefer the album gain, if present.
replaygain_preamp
Pre-amplification gain in dB to apply to the selected replaygain gain.
Default value for replaygain_preamp is 0.0.
eval
Set when the volume expression is evaluated.
It accepts the following values:
once
only evaluate expression once during the filter initialization, or when the volume
command is sent
frame
evaluate expression for each incoming frame
Default value is once.
The volume expression can contain the following parameters.
n frame number (starting at zero)
nb_channels
number of channels
nb_consumed_samples
number of samples consumed by the filter
nb_samples
number of samples in the current frame
pos original frame position in the file
pts frame PTS
sample_rate
sample rate
startpts
PTS at start of stream
startt
time at start of stream
t frame time
tb timestamp timebase
volume
last set volume value
Note that when eval is set to once only the sample_rate and tb variables are available,
all other variables will evaluate to NAN.
Commands
This filter supports the following commands:
volume
Modify the volume expression. The command accepts the same syntax of the
corresponding option.
If the specified expression is not valid, it is kept at its current value.
replaygain_noclip
Prevent clipping by limiting the gain applied.
Default value for replaygain_noclip is 1.
Examples
• Halve the input audio volume:
volume=volume=0.5
volume=volume=1/2
volume=volume=-6.0206dB
In all the above example the named key for volume can be omitted, for example like in:
volume=0.5
• Increase input audio power by 6 decibels using fixed-point precision:
volume=volume=6dB:precision=fixed
• Fade volume after time 10 with an annihilation period of 5 seconds:
volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame
volumedetect
Detect the volume of the input video.
The filter has no parameters. The input is not modified. Statistics about the volume will
be printed in the log when the input stream end is reached.
In particular it will show the mean volume (root mean square), maximum volume (on a per-
sample basis), and the beginning of a histogram of the registered volume values (from the
maximum value to a cumulated 1/1000 of the samples).
All volumes are in decibels relative to the maximum PCM value.
Examples
Here is an excerpt of the output:
[Parsed_volumedetect_0 0xa23120] mean_volume: -27 dB
[Parsed_volumedetect_0 0xa23120] max_volume: -4 dB
[Parsed_volumedetect_0 0xa23120] histogram_4db: 6
[Parsed_volumedetect_0 0xa23120] histogram_5db: 62
[Parsed_volumedetect_0 0xa23120] histogram_6db: 286
[Parsed_volumedetect_0 0xa23120] histogram_7db: 1042
[Parsed_volumedetect_0 0xa23120] histogram_8db: 2551
[Parsed_volumedetect_0 0xa23120] histogram_9db: 4609
[Parsed_volumedetect_0 0xa23120] histogram_10db: 8409
It means that:
• The mean square energy is approximately -27 dB, or 10^-2.7.
• The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB.
• There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc.
In other words, raising the volume by +4 dB does not cause any clipping, raising it by +5
dB causes clipping for 6 samples, etc.
AUDIO SOURCES
Below is a description of the currently available audio sources.
abuffer
Buffer audio frames, and make them available to the filter chain.
This source is mainly intended for a programmatic use, in particular through the interface
defined in libavfilter/asrc_abuffer.h.
It accepts the following parameters:
time_base
The timebase which will be used for timestamps of submitted frames. It must be either
a floating-point number or in numerator/denominator form.
sample_rate
The sample rate of the incoming audio buffers.
sample_fmt
The sample format of the incoming audio buffers. Either a sample format name or its
corresponding integer representation from the enum AVSampleFormat in
libavutil/samplefmt.h
channel_layout
The channel layout of the incoming audio buffers. Either a channel layout name from
channel_layout_map in libavutil/channel_layout.c or its corresponding integer
representation from the AV_CH_LAYOUT_* macros in libavutil/channel_layout.h
channels
The number of channels of the incoming audio buffers. If both channels and
channel_layout are specified, then they must be consistent.
Examples
abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo
will instruct the source to accept planar 16bit signed stereo at 44100Hz. Since the
sample format with name "s16p" corresponds to the number 6 and the "stereo" channel layout
corresponds to the value 0x3, this is equivalent to:
abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3
aevalsrc
Generate an audio signal specified by an expression.
This source accepts in input one or more expressions (one for each channel), which are
evaluated and used to generate a corresponding audio signal.
This source accepts the following options:
exprs
Set the '|'-separated expressions list for each separate channel. In case the
channel_layout option is not specified, the selected channel layout depends on the
number of provided expressions. Otherwise the last specified expression is applied to
the remaining output channels.
channel_layout, c
Set the channel layout. The number of channels in the specified layout must be equal
to the number of specified expressions.
duration, d
Set the minimum duration of the sourced audio. See the Time duration section in the
ffmpeg-utils(1) manual for the accepted syntax. Note that the resulting duration may
be greater than the specified duration, as the generated audio is always cut at the
end of a complete frame.
If not specified, or the expressed duration is negative, the audio is supposed to be
generated forever.
nb_samples, n
Set the number of samples per channel per each output frame, default to 1024.
sample_rate, s
Specify the sample rate, default to 44100.
Each expression in exprs can contain the following constants:
n number of the evaluated sample, starting from 0
t time of the evaluated sample expressed in seconds, starting from 0
s sample rate
Examples
• Generate silence:
aevalsrc=0
• Generate a sin signal with frequency of 440 Hz, set sample rate to 8000 Hz:
aevalsrc="sin(440*2*PI*t):s=8000"
• Generate a two channels signal, specify the channel layout (Front Center + Back
Center) explicitly:
aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC"
• Generate white noise:
aevalsrc="-2+random(0)"
• Generate an amplitude modulated signal:
aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)"
• Generate 2.5 Hz binaural beats on a 360 Hz carrier:
aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)"
anullsrc
The null audio source, return unprocessed audio frames. It is mainly useful as a template
and to be employed in analysis / debugging tools, or as the source for filters which
ignore the input data (for example the sox synth filter).
This source accepts the following options:
channel_layout, cl
Specifies the channel layout, and can be either an integer or a string representing a
channel layout. The default value of channel_layout is "stereo".
Check the channel_layout_map definition in libavutil/channel_layout.c for the mapping
between strings and channel layout values.
sample_rate, r
Specifies the sample rate, and defaults to 44100.
nb_samples, n
Set the number of samples per requested frames.
Examples
• Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO.
anullsrc=r=48000:cl=4
• Do the same operation with a more obvious syntax:
anullsrc=r=48000:cl=mono
All the parameters need to be explicitly defined.
flite
Synthesize a voice utterance using the libflite library.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-libflite".
Note that versions of the flite library prior to 2.0 are not thread-safe.
The filter accepts the following options:
list_voices
If set to 1, list the names of the available voices and exit immediately. Default
value is 0.
nb_samples, n
Set the maximum number of samples per frame. Default value is 512.
textfile
Set the filename containing the text to speak.
text
Set the text to speak.
voice, v
Set the voice to use for the speech synthesis. Default value is "kal". See also the
list_voices option.
Examples
• Read from file speech.txt, and synthesize the text using the standard flite voice:
flite=textfile=speech.txt
• Read the specified text selecting the "slt" voice:
flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
• Input text to ffmpeg:
ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt
• Make ffplay speak the specified text, using "flite" and the "lavfi" device:
ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.'
For more information about libflite, check: <http://www.festvox.org/flite/>
anoisesrc
Generate a noise audio signal.
The filter accepts the following options:
sample_rate, r
Specify the sample rate. Default value is 48000 Hz.
amplitude, a
Specify the amplitude (0.0 - 1.0) of the generated audio stream. Default value is 1.0.
duration, d
Specify the duration of the generated audio stream. Not specifying this option results
in noise with an infinite length.
color, colour, c
Specify the color of noise. Available noise colors are white, pink, brown, blue and
violet. Default color is white.
seed, s
Specify a value used to seed the PRNG.
nb_samples, n
Set the number of samples per each output frame, default is 1024.
Examples
• Generate 60 seconds of pink noise, with a 44.1 kHz sampling rate and an amplitude of
0.5:
anoisesrc=d=60:c=pink:r=44100:a=0.5
hilbert
Generate odd-tap Hilbert transform FIR coefficients.
The resulting stream can be used with afir filter for phase-shifting the signal by 90
degrees.
This is used in many matrix coding schemes and for analytic signal generation. The
process is often written as a multiplication by i (or j), the imaginary unit.
The filter accepts the following options:
sample_rate, s
Set sample rate, default is 44100.
taps, t
Set length of FIR filter, default is 22051.
nb_samples, n
Set number of samples per each frame.
win_func, w
Set window function to be used when generating FIR coefficients.
sinc
Generate a sinc kaiser-windowed low-pass, high-pass, band-pass, or band-reject FIR
coefficients.
The resulting stream can be used with afir filter for filtering the audio signal.
The filter accepts the following options:
sample_rate, r
Set sample rate, default is 44100.
nb_samples, n
Set number of samples per each frame. Default is 1024.
hp Set high-pass frequency. Default is 0.
lp Set low-pass frequency. Default is 0. If high-pass frequency is lower than low-pass
frequency and low-pass frequency is higher than 0 then filter will create band-pass
filter coefficients, otherwise band-reject filter coefficients.
phase
Set filter phase response. Default is 50. Allowed range is from 0 to 100.
beta
Set Kaiser window beta.
att Set stop-band attenuation. Default is 120dB, allowed range is from 40 to 180 dB.
round
Enable rounding, by default is disabled.
hptaps
Set number of taps for high-pass filter.
lptaps
Set number of taps for low-pass filter.
sine
Generate an audio signal made of a sine wave with amplitude 1/8.
The audio signal is bit-exact.
The filter accepts the following options:
frequency, f
Set the carrier frequency. Default is 440 Hz.
beep_factor, b
Enable a periodic beep every second with frequency beep_factor times the carrier
frequency. Default is 0, meaning the beep is disabled.
sample_rate, r
Specify the sample rate, default is 44100.
duration, d
Specify the duration of the generated audio stream.
samples_per_frame
Set the number of samples per output frame.
The expression can contain the following constants:
n The (sequential) number of the output audio frame, starting from 0.
pts The PTS (Presentation TimeStamp) of the output audio frame, expressed in TB units.
t The PTS of the output audio frame, expressed in seconds.
TB The timebase of the output audio frames.
Default is 1024.
Examples
• Generate a simple 440 Hz sine wave:
sine
• Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds:
sine=220:4:d=5
sine=f=220:b=4:d=5
sine=frequency=220:beep_factor=4:duration=5
• Generate a 1 kHz sine wave following "1602,1601,1602,1601,1602" NTSC pattern:
sine=1000:samples_per_frame='st(0,mod(n,5)); 1602-not(not(eq(ld(0),1)+eq(ld(0),3)))'
AUDIO SINKS
Below is a description of the currently available audio sinks.
abuffersink
Buffer audio frames, and make them available to the end of filter chain.
This sink is mainly intended for programmatic use, in particular through the interface
defined in libavfilter/buffersink.h or the options system.
It accepts a pointer to an AVABufferSinkContext structure, which defines the incoming
buffers' formats, to be passed as the opaque parameter to "avfilter_init_filter" for
initialization.
anullsink
Null audio sink; do absolutely nothing with the input audio. It is mainly useful as a
template and for use in analysis / debugging tools.
VIDEO FILTERS
When you configure your FFmpeg build, you can disable any of the existing filters using
"--disable-filters". The configure output will show the video filters included in your
build.
Below is a description of the currently available video filters.
alphaextract
Extract the alpha component from the input as a grayscale video. This is especially useful
with the alphamerge filter.
alphamerge
Add or replace the alpha component of the primary input with the grayscale value of a
second input. This is intended for use with alphaextract to allow the transmission or
storage of frame sequences that have alpha in a format that doesn't support an alpha
channel.
For example, to reconstruct full frames from a normal YUV-encoded video and a separate
video created with alphaextract, you might use:
movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out]
Since this filter is designed for reconstruction, it operates on frame sequences without
considering timestamps, and terminates when either input reaches end of stream. This will
cause problems if your encoding pipeline drops frames. If you're trying to apply an image
as an overlay to a video stream, consider the overlay filter instead.
amplify
Amplify differences between current pixel and pixels of adjacent frames in same pixel
location.
This filter accepts the following options:
radius
Set frame radius. Default is 2. Allowed range is from 1 to 63. For example radius of
3 will instruct filter to calculate average of 7 frames.
factor
Set factor to amplify difference. Default is 2. Allowed range is from 0 to 65535.
threshold
Set threshold for difference amplification. Any difference greater or equal to this
value will not alter source pixel. Default is 10. Allowed range is from 0 to 65535.
tolerance
Set tolerance for difference amplification. Any difference lower to this value will
not alter source pixel. Default is 0. Allowed range is from 0 to 65535.
low Set lower limit for changing source pixel. Default is 65535. Allowed range is from 0
to 65535. This option controls maximum possible value that will decrease source pixel
value.
high
Set high limit for changing source pixel. Default is 65535. Allowed range is from 0 to
65535. This option controls maximum possible value that will increase source pixel
value.
planes
Set which planes to filter. Default is all. Allowed range is from 0 to 15.
ass
Same as the subtitles filter, except that it doesn't require libavcodec and libavformat to
work. On the other hand, it is limited to ASS (Advanced Substation Alpha) subtitles files.
This filter accepts the following option in addition to the common options from the
subtitles filter:
shaping
Set the shaping engine
Available values are:
auto
The default libass shaping engine, which is the best available.
simple
Fast, font-agnostic shaper that can do only substitutions
complex
Slower shaper using OpenType for substitutions and positioning
The default is "auto".
atadenoise
Apply an Adaptive Temporal Averaging Denoiser to the video input.
The filter accepts the following options:
0a Set threshold A for 1st plane. Default is 0.02. Valid range is 0 to 0.3.
0b Set threshold B for 1st plane. Default is 0.04. Valid range is 0 to 5.
1a Set threshold A for 2nd plane. Default is 0.02. Valid range is 0 to 0.3.
1b Set threshold B for 2nd plane. Default is 0.04. Valid range is 0 to 5.
2a Set threshold A for 3rd plane. Default is 0.02. Valid range is 0 to 0.3.
2b Set threshold B for 3rd plane. Default is 0.04. Valid range is 0 to 5.
Threshold A is designed to react on abrupt changes in the input signal and threshold B
is designed to react on continuous changes in the input signal.
s Set number of frames filter will use for averaging. Default is 9. Must be odd number
in range [5, 129].
p Set what planes of frame filter will use for averaging. Default is all.
avgblur
Apply average blur filter.
The filter accepts the following options:
sizeX
Set horizontal radius size.
planes
Set which planes to filter. By default all planes are filtered.
sizeY
Set vertical radius size, if zero it will be same as "sizeX". Default is 0.
bbox
Compute the bounding box for the non-black pixels in the input frame luminance plane.
This filter computes the bounding box containing all the pixels with a luminance value
greater than the minimum allowed value. The parameters describing the bounding box are
printed on the filter log.
The filter accepts the following option:
min_val
Set the minimal luminance value. Default is 16.
bitplanenoise
Show and measure bit plane noise.
The filter accepts the following options:
bitplane
Set which plane to analyze. Default is 1.
filter
Filter out noisy pixels from "bitplane" set above. Default is disabled.
blackdetect
Detect video intervals that are (almost) completely black. Can be useful to detect chapter
transitions, commercials, or invalid recordings. Output lines contains the time for the
start, end and duration of the detected black interval expressed in seconds.
In order to display the output lines, you need to set the loglevel at least to the
AV_LOG_INFO value.
The filter accepts the following options:
black_min_duration, d
Set the minimum detected black duration expressed in seconds. It must be a non-
negative floating point number.
Default value is 2.0.
picture_black_ratio_th, pic_th
Set the threshold for considering a picture "black". Express the minimum value for
the ratio:
<nb_black_pixels> / <nb_pixels>
for which a picture is considered black. Default value is 0.98.
pixel_black_th, pix_th
Set the threshold for considering a pixel "black".
The threshold expresses the maximum pixel luminance value for which a pixel is
considered "black". The provided value is scaled according to the following equation:
<absolute_threshold> = <luminance_minimum_value> + <pixel_black_th> * <luminance_range_size>
luminance_range_size and luminance_minimum_value depend on the input video format, the
range is [0-255] for YUV full-range formats and [16-235] for YUV non full-range
formats.
Default value is 0.10.
The following example sets the maximum pixel threshold to the minimum value, and detects
only black intervals of 2 or more seconds:
blackdetect=d=2:pix_th=0.00
blackframe
Detect frames that are (almost) completely black. Can be useful to detect chapter
transitions or commercials. Output lines consist of the frame number of the detected
frame, the percentage of blackness, the position in the file if known or -1 and the
timestamp in seconds.
In order to display the output lines, you need to set the loglevel at least to the
AV_LOG_INFO value.
This filter exports frame metadata "lavfi.blackframe.pblack". The value represents the
percentage of pixels in the picture that are below the threshold value.
It accepts the following parameters:
amount
The percentage of the pixels that have to be below the threshold; it defaults to 98.
threshold, thresh
The threshold below which a pixel value is considered black; it defaults to 32.
blend, tblend
Blend two video frames into each other.
The "blend" filter takes two input streams and outputs one stream, the first input is the
"top" layer and second input is "bottom" layer. By default, the output terminates when
the longest input terminates.
The "tblend" (time blend) filter takes two consecutive frames from one single stream, and
outputs the result obtained by blending the new frame on top of the old frame.
A description of the accepted options follows.
c0_mode
c1_mode
c2_mode
c3_mode
all_mode
Set blend mode for specific pixel component or all pixel components in case of
all_mode. Default value is "normal".
Available values for component modes are:
addition
grainmerge
and
average
burn
darken
difference
grainextract
divide
dodge
freeze
exclusion
extremity
glow
hardlight
hardmix
heat
lighten
linearlight
multiply
multiply128
negation
normal
or
overlay
phoenix
pinlight
reflect
screen
softlight
subtract
vividlight
xor
c0_opacity
c1_opacity
c2_opacity
c3_opacity
all_opacity
Set blend opacity for specific pixel component or all pixel components in case of
all_opacity. Only used in combination with pixel component blend modes.
c0_expr
c1_expr
c2_expr
c3_expr
all_expr
Set blend expression for specific pixel component or all pixel components in case of
all_expr. Note that related mode options will be ignored if those are set.
The expressions can use the following variables:
N The sequential number of the filtered frame, starting from 0.
X
Y the coordinates of the current sample
W
H the width and height of currently filtered plane
SW
SH Width and height scale for the plane being filtered. It is the ratio between the
dimensions of the current plane to the luma plane, e.g. for a "yuv420p" frame, the
values are "1,1" for the luma plane and "0.5,0.5" for the chroma planes.
T Time of the current frame, expressed in seconds.
TOP, A
Value of pixel component at current location for first video frame (top layer).
BOTTOM, B
Value of pixel component at current location for second video frame (bottom
layer).
The "blend" filter also supports the framesync options.
Examples
• Apply transition from bottom layer to top layer in first 10 seconds:
blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))'
• Apply linear horizontal transition from top layer to bottom layer:
blend=all_expr='A*(X/W)+B*(1-X/W)'
• Apply 1x1 checkerboard effect:
blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)'
• Apply uncover left effect:
blend=all_expr='if(gte(N*SW+X,W),A,B)'
• Apply uncover down effect:
blend=all_expr='if(gte(Y-N*SH,0),A,B)'
• Apply uncover up-left effect:
blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)'
• Split diagonally video and shows top and bottom layer on each side:
blend=all_expr='if(gt(X,Y*(W/H)),A,B)'
• Display differences between the current and the previous frame:
tblend=all_mode=grainextract
bm3d
Denoise frames using Block-Matching 3D algorithm.
The filter accepts the following options.
sigma
Set denoising strength. Default value is 1. Allowed range is from 0 to 999.9. The
denoising algorithm is very sensitive to sigma, so adjust it according to the source.
block
Set local patch size. This sets dimensions in 2D.
bstep
Set sliding step for processing blocks. Default value is 4. Allowed range is from 1
to 64. Smaller values allows processing more reference blocks and is slower.
group
Set maximal number of similar blocks for 3rd dimension. Default value is 1. When set
to 1, no block matching is done. Larger values allows more blocks in single group.
Allowed range is from 1 to 256.
range
Set radius for search block matching. Default is 9. Allowed range is from 1 to
INT32_MAX.
mstep
Set step between two search locations for block matching. Default is 1. Allowed range
is from 1 to 64. Smaller is slower.
thmse
Set threshold of mean square error for block matching. Valid range is 0 to INT32_MAX.
hdthr
Set thresholding parameter for hard thresholding in 3D transformed domain. Larger
values results in stronger hard-thresholding filtering in frequency domain.
estim
Set filtering estimation mode. Can be "basic" or "final". Default is "basic".
ref If enabled, filter will use 2nd stream for block matching. Default is disabled for
"basic" value of estim option, and always enabled if value of estim is "final".
planes
Set planes to filter. Default is all available except alpha.
Examples
• Basic filtering with bm3d:
bm3d=sigma=3:block=4:bstep=2:group=1:estim=basic
• Same as above, but filtering only luma:
bm3d=sigma=3:block=4:bstep=2:group=1:estim=basic:planes=1
• Same as above, but with both estimation modes:
split[a][b],[a]bm3d=sigma=3:block=4:bstep=2:group=1:estim=basic[a],[b][a]bm3d=sigma=3:block=4:bstep=2:group=16:estim=final:ref=1
• Same as above, but prefilter with nlmeans filter instead:
split[a][b],[a]nlmeans=s=3:r=7:p=3[a],[b][a]bm3d=sigma=3:block=4:bstep=2:group=16:estim=final:ref=1
boxblur
Apply a boxblur algorithm to the input video.
It accepts the following parameters:
luma_radius, lr
luma_power, lp
chroma_radius, cr
chroma_power, cp
alpha_radius, ar
alpha_power, ap
A description of the accepted options follows.
luma_radius, lr
chroma_radius, cr
alpha_radius, ar
Set an expression for the box radius in pixels used for blurring the corresponding
input plane.
The radius value must be a non-negative number, and must not be greater than the value
of the expression "min(w,h)/2" for the luma and alpha planes, and of "min(cw,ch)/2"
for the chroma planes.
Default value for luma_radius is "2". If not specified, chroma_radius and alpha_radius
default to the corresponding value set for luma_radius.
The expressions can contain the following constants:
w
h The input width and height in pixels.
cw
ch The input chroma image width and height in pixels.
hsub
vsub
The horizontal and vertical chroma subsample values. For example, for the pixel
format "yuv422p", hsub is 2 and vsub is 1.
luma_power, lp
chroma_power, cp
alpha_power, ap
Specify how many times the boxblur filter is applied to the corresponding plane.
Default value for luma_power is 2. If not specified, chroma_power and alpha_power
default to the corresponding value set for luma_power.
A value of 0 will disable the effect.
Examples
• Apply a boxblur filter with the luma, chroma, and alpha radii set to 2:
boxblur=luma_radius=2:luma_power=1
boxblur=2:1
• Set the luma radius to 2, and alpha and chroma radius to 0:
boxblur=2:1:cr=0:ar=0
• Set the luma and chroma radii to a fraction of the video dimension:
boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1
bwdif
Deinterlace the input video ("bwdif" stands for "Bob Weaver Deinterlacing Filter").
Motion adaptive deinterlacing based on yadif with the use of w3fdif and cubic
interpolation algorithms. It accepts the following parameters:
mode
The interlacing mode to adopt. It accepts one of the following values:
0, send_frame
Output one frame for each frame.
1, send_field
Output one frame for each field.
The default value is "send_field".
parity
The picture field parity assumed for the input interlaced video. It accepts one of the
following values:
0, tff
Assume the top field is first.
1, bff
Assume the bottom field is first.
-1, auto
Enable automatic detection of field parity.
The default value is "auto". If the interlacing is unknown or the decoder does not
export this information, top field first will be assumed.
deint
Specify which frames to deinterlace. Accept one of the following values:
0, all
Deinterlace all frames.
1, interlaced
Only deinterlace frames marked as interlaced.
The default value is "all".
chromahold
Remove all color information for all colors except for certain one.
The filter accepts the following options:
color
The color which will not be replaced with neutral chroma.
similarity
Similarity percentage with the above color. 0.01 matches only the exact key color,
while 1.0 matches everything.
blend
Blend percentage. 0.0 makes pixels either fully gray, or not gray at all. Higher
values result in more preserved color.
yuv Signals that the color passed is already in YUV instead of RGB.
Literal colors like "green" or "red" don't make sense with this enabled anymore. This
can be used to pass exact YUV values as hexadecimal numbers.
chromakey
YUV colorspace color/chroma keying.
The filter accepts the following options:
color
The color which will be replaced with transparency.
similarity
Similarity percentage with the key color.
0.01 matches only the exact key color, while 1.0 matches everything.
blend
Blend percentage.
0.0 makes pixels either fully transparent, or not transparent at all.
Higher values result in semi-transparent pixels, with a higher transparency the more
similar the pixels color is to the key color.
yuv Signals that the color passed is already in YUV instead of RGB.
Literal colors like "green" or "red" don't make sense with this enabled anymore. This
can be used to pass exact YUV values as hexadecimal numbers.
Examples
• Make every green pixel in the input image transparent:
ffmpeg -i input.png -vf chromakey=green out.png
• Overlay a greenscreen-video on top of a static black background.
ffmpeg -f lavfi -i color=c=black:s=1280x720 -i video.mp4 -shortest -filter_complex "[1:v]chromakey=0x70de77:0.1:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.mkv
chromashift
Shift chroma pixels horizontally and/or vertically.
The filter accepts the following options:
cbh Set amount to shift chroma-blue horizontally.
cbv Set amount to shift chroma-blue vertically.
crh Set amount to shift chroma-red horizontally.
crv Set amount to shift chroma-red vertically.
edge
Set edge mode, can be smear, default, or warp.
ciescope
Display CIE color diagram with pixels overlaid onto it.
The filter accepts the following options:
system
Set color system.
ntsc, 470m
ebu, 470bg
smpte
240m
apple
widergb
cie1931
rec709, hdtv
uhdtv, rec2020
cie Set CIE system.
xyy
ucs
luv
gamuts
Set what gamuts to draw.
See "system" option for available values.
size, s
Set ciescope size, by default set to 512.
intensity, i
Set intensity used to map input pixel values to CIE diagram.
contrast
Set contrast used to draw tongue colors that are out of active color system gamut.
corrgamma
Correct gamma displayed on scope, by default enabled.
showwhite
Show white point on CIE diagram, by default disabled.
gamma
Set input gamma. Used only with XYZ input color space.
codecview
Visualize information exported by some codecs.
Some codecs can export information through frames using side-data or other means. For
example, some MPEG based codecs export motion vectors through the export_mvs flag in the
codec flags2 option.
The filter accepts the following option:
mv Set motion vectors to visualize.
Available flags for mv are:
pf forward predicted MVs of P-frames
bf forward predicted MVs of B-frames
bb backward predicted MVs of B-frames
qp Display quantization parameters using the chroma planes.
mv_type, mvt
Set motion vectors type to visualize. Includes MVs from all frames unless specified by
frame_type option.
Available flags for mv_type are:
fp forward predicted MVs
bp backward predicted MVs
frame_type, ft
Set frame type to visualize motion vectors of.
Available flags for frame_type are:
if intra-coded frames (I-frames)
pf predicted frames (P-frames)
bf bi-directionally predicted frames (B-frames)
Examples
• Visualize forward predicted MVs of all frames using ffplay:
ffplay -flags2 +export_mvs input.mp4 -vf codecview=mv_type=fp
• Visualize multi-directionals MVs of P and B-Frames using ffplay:
ffplay -flags2 +export_mvs input.mp4 -vf codecview=mv=pf+bf+bb
colorbalance
Modify intensity of primary colors (red, green and blue) of input frames.
The filter allows an input frame to be adjusted in the shadows, midtones or highlights
regions for the red-cyan, green-magenta or blue-yellow balance.
A positive adjustment value shifts the balance towards the primary color, a negative value
towards the complementary color.
The filter accepts the following options:
rs
gs
bs Adjust red, green and blue shadows (darkest pixels).
rm
gm
bm Adjust red, green and blue midtones (medium pixels).
rh
gh
bh Adjust red, green and blue highlights (brightest pixels).
Allowed ranges for options are "[-1.0, 1.0]". Defaults are 0.
Examples
• Add red color cast to shadows:
colorbalance=rs=.3
colorkey
RGB colorspace color keying.
The filter accepts the following options:
color
The color which will be replaced with transparency.
similarity
Similarity percentage with the key color.
0.01 matches only the exact key color, while 1.0 matches everything.
blend
Blend percentage.
0.0 makes pixels either fully transparent, or not transparent at all.
Higher values result in semi-transparent pixels, with a higher transparency the more
similar the pixels color is to the key color.
Examples
• Make every green pixel in the input image transparent:
ffmpeg -i input.png -vf colorkey=green out.png
• Overlay a greenscreen-video on top of a static background image.
ffmpeg -i background.png -i video.mp4 -filter_complex "[1:v]colorkey=0x3BBD1E:0.3:0.2[ckout];[0:v][ckout]overlay[out]" -map "[out]" output.flv
colorhold
Remove all color information for all RGB colors except for certain one.
The filter accepts the following options:
color
The color which will not be replaced with neutral gray.
similarity
Similarity percentage with the above color. 0.01 matches only the exact key color,
while 1.0 matches everything.
blend
Blend percentage. 0.0 makes pixels fully gray. Higher values result in more preserved
color.
colorlevels
Adjust video input frames using levels.
The filter accepts the following options:
rimin
gimin
bimin
aimin
Adjust red, green, blue and alpha input black point. Allowed ranges for options are
"[-1.0, 1.0]". Defaults are 0.
rimax
gimax
bimax
aimax
Adjust red, green, blue and alpha input white point. Allowed ranges for options are
"[-1.0, 1.0]". Defaults are 1.
Input levels are used to lighten highlights (bright tones), darken shadows (dark
tones), change the balance of bright and dark tones.
romin
gomin
bomin
aomin
Adjust red, green, blue and alpha output black point. Allowed ranges for options are
"[0, 1.0]". Defaults are 0.
romax
gomax
bomax
aomax
Adjust red, green, blue and alpha output white point. Allowed ranges for options are
"[0, 1.0]". Defaults are 1.
Output levels allows manual selection of a constrained output level range.
Examples
• Make video output darker:
colorlevels=rimin=0.058:gimin=0.058:bimin=0.058
• Increase contrast:
colorlevels=rimin=0.039:gimin=0.039:bimin=0.039:rimax=0.96:gimax=0.96:bimax=0.96
• Make video output lighter:
colorlevels=rimax=0.902:gimax=0.902:bimax=0.902
• Increase brightness:
colorlevels=romin=0.5:gomin=0.5:bomin=0.5
colorchannelmixer
Adjust video input frames by re-mixing color channels.
This filter modifies a color channel by adding the values associated to the other channels
of the same pixels. For example if the value to modify is red, the output value will be:
<red>=<red>*<rr> + <blue>*<rb> + <green>*<rg> + <alpha>*<ra>
The filter accepts the following options:
rr
rg
rb
ra Adjust contribution of input red, green, blue and alpha channels for output red
channel. Default is 1 for rr, and 0 for rg, rb and ra.
gr
gg
gb
ga Adjust contribution of input red, green, blue and alpha channels for output green
channel. Default is 1 for gg, and 0 for gr, gb and ga.
br
bg
bb
ba Adjust contribution of input red, green, blue and alpha channels for output blue
channel. Default is 1 for bb, and 0 for br, bg and ba.
ar
ag
ab
aa Adjust contribution of input red, green, blue and alpha channels for output alpha
channel. Default is 1 for aa, and 0 for ar, ag and ab.
Allowed ranges for options are "[-2.0, 2.0]".
Examples
• Convert source to grayscale:
colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3
• Simulate sepia tones:
colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131
colormatrix
Convert color matrix.
The filter accepts the following options:
src
dst Specify the source and destination color matrix. Both values must be specified.
The accepted values are:
bt709
BT.709
fcc FCC
bt601
BT.601
bt470
BT.470
bt470bg
BT.470BG
smpte170m
SMPTE-170M
smpte240m
SMPTE-240M
bt2020
BT.2020
For example to convert from BT.601 to SMPTE-240M, use the command:
colormatrix=bt601:smpte240m
colorspace
Convert colorspace, transfer characteristics or color primaries. Input video needs to
have an even size.
The filter accepts the following options:
all Specify all color properties at once.
The accepted values are:
bt470m
BT.470M
bt470bg
BT.470BG
bt601-6-525
BT.601-6 525
bt601-6-625
BT.601-6 625
bt709
BT.709
smpte170m
SMPTE-170M
smpte240m
SMPTE-240M
bt2020
BT.2020
space
Specify output colorspace.
The accepted values are:
bt709
BT.709
fcc FCC
bt470bg
BT.470BG or BT.601-6 625
smpte170m
SMPTE-170M or BT.601-6 525
smpte240m
SMPTE-240M
ycgco
YCgCo
bt2020ncl
BT.2020 with non-constant luminance
trc Specify output transfer characteristics.
The accepted values are:
bt709
BT.709
bt470m
BT.470M
bt470bg
BT.470BG
gamma22
Constant gamma of 2.2
gamma28
Constant gamma of 2.8
smpte170m
SMPTE-170M, BT.601-6 625 or BT.601-6 525
smpte240m
SMPTE-240M
srgb
SRGB
iec61966-2-1
iec61966-2-1
iec61966-2-4
iec61966-2-4
xvycc
xvycc
bt2020-10
BT.2020 for 10-bits content
bt2020-12
BT.2020 for 12-bits content
primaries
Specify output color primaries.
The accepted values are:
bt709
BT.709
bt470m
BT.470M
bt470bg
BT.470BG or BT.601-6 625
smpte170m
SMPTE-170M or BT.601-6 525
smpte240m
SMPTE-240M
film
film
smpte431
SMPTE-431
smpte432
SMPTE-432
bt2020
BT.2020
jedec-p22
JEDEC P22 phosphors
range
Specify output color range.
The accepted values are:
tv TV (restricted) range
mpeg
MPEG (restricted) range
pc PC (full) range
jpeg
JPEG (full) range
format
Specify output color format.
The accepted values are:
yuv420p
YUV 4:2:0 planar 8-bits
yuv420p10
YUV 4:2:0 planar 10-bits
yuv420p12
YUV 4:2:0 planar 12-bits
yuv422p
YUV 4:2:2 planar 8-bits
yuv422p10
YUV 4:2:2 planar 10-bits
yuv422p12
YUV 4:2:2 planar 12-bits
yuv444p
YUV 4:4:4 planar 8-bits
yuv444p10
YUV 4:4:4 planar 10-bits
yuv444p12
YUV 4:4:4 planar 12-bits
fast
Do a fast conversion, which skips gamma/primary correction. This will take
significantly less CPU, but will be mathematically incorrect. To get output compatible
with that produced by the colormatrix filter, use fast=1.
dither
Specify dithering mode.
The accepted values are:
none
No dithering
fsb Floyd-Steinberg dithering
wpadapt
Whitepoint adaptation mode.
The accepted values are:
bradford
Bradford whitepoint adaptation
vonkries
von Kries whitepoint adaptation
identity
identity whitepoint adaptation (i.e. no whitepoint adaptation)
iall
Override all input properties at once. Same accepted values as all.
ispace
Override input colorspace. Same accepted values as space.
iprimaries
Override input color primaries. Same accepted values as primaries.
itrc
Override input transfer characteristics. Same accepted values as trc.
irange
Override input color range. Same accepted values as range.
The filter converts the transfer characteristics, color space and color primaries to the
specified user values. The output value, if not specified, is set to a default value based
on the "all" property. If that property is also not specified, the filter will log an
error. The output color range and format default to the same value as the input color
range and format. The input transfer characteristics, color space, color primaries and
color range should be set on the input data. If any of these are missing, the filter will
log an error and no conversion will take place.
For example to convert the input to SMPTE-240M, use the command:
colorspace=smpte240m
convolution
Apply convolution of 3x3, 5x5, 7x7 or horizontal/vertical up to 49 elements.
The filter accepts the following options:
0m
1m
2m
3m Set matrix for each plane. Matrix is sequence of 9, 25 or 49 signed integers in
square mode, and from 1 to 49 odd number of signed integers in row mode.
0rdiv
1rdiv
2rdiv
3rdiv
Set multiplier for calculated value for each plane. If unset or 0, it will be sum of
all matrix elements.
0bias
1bias
2bias
3bias
Set bias for each plane. This value is added to the result of the multiplication.
Useful for making the overall image brighter or darker. Default is 0.0.
0mode
1mode
2mode
3mode
Set matrix mode for each plane. Can be square, row or column. Default is square.
Examples
• Apply sharpen:
convolution="0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0"
• Apply blur:
convolution="1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1/9:1/9:1/9:1/9"
• Apply edge enhance:
convolution="0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:5:1:1:1:0:128:128:128"
• Apply edge detect:
convolution="0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:5:5:5:1:0:128:128:128"
• Apply laplacian edge detector which includes diagonals:
convolution="1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:5:5:5:1:0:128:128:0"
• Apply emboss:
convolution="-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2"
convolve
Apply 2D convolution of video stream in frequency domain using second stream as impulse.
The filter accepts the following options:
planes
Set which planes to process.
impulse
Set which impulse video frames will be processed, can be first or all. Default is all.
The "convolve" filter also supports the framesync options.
copy
Copy the input video source unchanged to the output. This is mainly useful for testing
purposes.
coreimage
Video filtering on GPU using Apple's CoreImage API on OSX.
Hardware acceleration is based on an OpenGL context. Usually, this means it is processed
by video hardware. However, software-based OpenGL implementations exist which means there
is no guarantee for hardware processing. It depends on the respective OSX.
There are many filters and image generators provided by Apple that come with a large
variety of options. The filter has to be referenced by its name along with its options.
The coreimage filter accepts the following options:
list_filters
List all available filters and generators along with all their respective options as
well as possible minimum and maximum values along with the default values.
list_filters=true
filter
Specify all filters by their respective name and options. Use list_filters to
determine all valid filter names and options. Numerical options are specified by a
float value and are automatically clamped to their respective value range. Vector and
color options have to be specified by a list of space separated float values.
Character escaping has to be done. A special option name "default" is available to
use default options for a filter.
It is required to specify either "default" or at least one of the filter options. All
omitted options are used with their default values. The syntax of the filter string
is as follows:
filter=<NAME>@<OPTION>=<VALUE>[@<OPTION>=<VALUE>][@...][#<NAME>@<OPTION>=<VALUE>[@<OPTION>=<VALUE>][@...]][#...]
output_rect
Specify a rectangle where the output of the filter chain is copied into the input
image. It is given by a list of space separated float values:
output_rect=x\ y\ width\ height
If not given, the output rectangle equals the dimensions of the input image. The
output rectangle is automatically cropped at the borders of the input image. Negative
values are valid for each component.
output_rect=25\ 25\ 100\ 100
Several filters can be chained for successive processing without GPU-HOST transfers
allowing for fast processing of complex filter chains. Currently, only filters with zero
(generators) or exactly one (filters) input image and one output image are supported.
Also, transition filters are not yet usable as intended.
Some filters generate output images with additional padding depending on the respective
filter kernel. The padding is automatically removed to ensure the filter output has the
same size as the input image.
For image generators, the size of the output image is determined by the previous output
image of the filter chain or the input image of the whole filterchain, respectively. The
generators do not use the pixel information of this image to generate their output.
However, the generated output is blended onto this image, resulting in partial or complete
coverage of the output image.
The coreimagesrc video source can be used for generating input images which are directly
fed into the filter chain. By using it, providing input images by another video source or
an input video is not required.
Examples
• List all filters available:
coreimage=list_filters=true
• Use the CIBoxBlur filter with default options to blur an image:
coreimage=filter=CIBoxBlur@default
• Use a filter chain with CISepiaTone at default values and CIVignetteEffect with its
center at 100x100 and a radius of 50 pixels:
coreimage=filter=CIBoxBlur@default#CIVignetteEffect@inputCenter=100\ 100@inputRadius=50
• Use nullsrc and CIQRCodeGenerator to create a QR code for the FFmpeg homepage, given
as complete and escaped command-line for Apple's standard bash shell:
ffmpeg -f lavfi -i nullsrc=s=100x100,coreimage=filter=CIQRCodeGenerator@inputMessage=https\\\\\://FFmpeg.org/@inputCorrectionLevel=H -frames:v 1 QRCode.png
crop
Crop the input video to given dimensions.
It accepts the following parameters:
w, out_w
The width of the output video. It defaults to "iw". This expression is evaluated only
once during the filter configuration, or when the w or out_w command is sent.
h, out_h
The height of the output video. It defaults to "ih". This expression is evaluated
only once during the filter configuration, or when the h or out_h command is sent.
x The horizontal position, in the input video, of the left edge of the output video. It
defaults to "(in_w-out_w)/2". This expression is evaluated per-frame.
y The vertical position, in the input video, of the top edge of the output video. It
defaults to "(in_h-out_h)/2". This expression is evaluated per-frame.
keep_aspect
If set to 1 will force the output display aspect ratio to be the same of the input, by
changing the output sample aspect ratio. It defaults to 0.
exact
Enable exact cropping. If enabled, subsampled videos will be cropped at exact
width/height/x/y as specified and will not be rounded to nearest smaller value. It
defaults to 0.
The out_w, out_h, x, y parameters are expressions containing the following constants:
x
y The computed values for x and y. They are evaluated for each new frame.
in_w
in_h
The input width and height.
iw
ih These are the same as in_w and in_h.
out_w
out_h
The output (cropped) width and height.
ow
oh These are the same as out_w and out_h.
a same as iw / ih
sar input sample aspect ratio
dar input display aspect ratio, it is the same as (iw / ih) * sar
hsub
vsub
horizontal and vertical chroma subsample values. For example for the pixel format
"yuv422p" hsub is 2 and vsub is 1.
n The number of the input frame, starting from 0.
pos the position in the file of the input frame, NAN if unknown
t The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
The expression for out_w may depend on the value of out_h, and the expression for out_h
may depend on out_w, but they cannot depend on x and y, as x and y are evaluated after
out_w and out_h.
The x and y parameters specify the expressions for the position of the top-left corner of
the output (non-cropped) area. They are evaluated for each frame. If the evaluated value
is not valid, it is approximated to the nearest valid value.
The expression for x may depend on y, and the expression for y may depend on x.
Examples
• Crop area with size 100x100 at position (12,34).
crop=100:100:12:34
Using named options, the example above becomes:
crop=w=100:h=100:x=12:y=34
• Crop the central input area with size 100x100:
crop=100:100
• Crop the central input area with size 2/3 of the input video:
crop=2/3*in_w:2/3*in_h
• Crop the input video central square:
crop=out_w=in_h
crop=in_h
• Delimit the rectangle with the top-left corner placed at position 100:100 and the
right-bottom corner corresponding to the right-bottom corner of the input image.
crop=in_w-100:in_h-100:100:100
• Crop 10 pixels from the left and right borders, and 20 pixels from the top and bottom
borders
crop=in_w-2*10:in_h-2*20
• Keep only the bottom right quarter of the input image:
crop=in_w/2:in_h/2:in_w/2:in_h/2
• Crop height for getting Greek harmony:
crop=in_w:1/PHI*in_w
• Apply trembling effect:
crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)
• Apply erratic camera effect depending on timestamp:
crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"
• Set x depending on the value of y:
crop=in_w/2:in_h/2:y:10+10*sin(n/10)
Commands
This filter supports the following commands:
w, out_w
h, out_h
x
y Set width/height of the output video and the horizontal/vertical position in the input
video. The command accepts the same syntax of the corresponding option.
If the specified expression is not valid, it is kept at its current value.
cropdetect
Auto-detect the crop size.
It calculates the necessary cropping parameters and prints the recommended parameters via
the logging system. The detected dimensions correspond to the non-black area of the input
video.
It accepts the following parameters:
limit
Set higher black value threshold, which can be optionally specified from nothing (0)
to everything (255 for 8-bit based formats). An intensity value greater to the set
value is considered non-black. It defaults to 24. You can also specify a value
between 0.0 and 1.0 which will be scaled depending on the bitdepth of the pixel
format.
round
The value which the width/height should be divisible by. It defaults to 16. The offset
is automatically adjusted to center the video. Use 2 to get only even dimensions
(needed for 4:2:2 video). 16 is best when encoding to most video codecs.
reset_count, reset
Set the counter that determines after how many frames cropdetect will reset the
previously detected largest video area and start over to detect the current optimal
crop area. Default value is 0.
This can be useful when channel logos distort the video area. 0 indicates 'never
reset', and returns the largest area encountered during playback.
cue
Delay video filtering until a given wallclock timestamp. The filter first passes on
preroll amount of frames, then it buffers at most buffer amount of frames and waits for
the cue. After reaching the cue it forwards the buffered frames and also any subsequent
frames coming in its input.
The filter can be used synchronize the output of multiple ffmpeg processes for realtime
output devices like decklink. By putting the delay in the filtering chain and pre-
buffering frames the process can pass on data to output almost immediately after the
target wallclock timestamp is reached.
Perfect frame accuracy cannot be guaranteed, but the result is good enough for some use
cases.
cue The cue timestamp expressed in a UNIX timestamp in microseconds. Default is 0.
preroll
The duration of content to pass on as preroll expressed in seconds. Default is 0.
buffer
The maximum duration of content to buffer before waiting for the cue expressed in
seconds. Default is 0.
curves
Apply color adjustments using curves.
This filter is similar to the Adobe Photoshop and GIMP curves tools. Each component (red,
green and blue) has its values defined by N key points tied from each other using a smooth
curve. The x-axis represents the pixel values from the input frame, and the y-axis the new
pixel values to be set for the output frame.
By default, a component curve is defined by the two points (0;0) and (1;1). This creates a
straight line where each original pixel value is "adjusted" to its own value, which means
no change to the image.
The filter allows you to redefine these two points and add some more. A new curve (using a
natural cubic spline interpolation) will be define to pass smoothly through all these new
coordinates. The new defined points needs to be strictly increasing over the x-axis, and
their x and y values must be in the [0;1] interval. If the computed curves happened to go
outside the vector spaces, the values will be clipped accordingly.
The filter accepts the following options:
preset
Select one of the available color presets. This option can be used in addition to the
r, g, b parameters; in this case, the later options takes priority on the preset
values. Available presets are:
none
color_negative
cross_process
darker
increase_contrast
lighter
linear_contrast
medium_contrast
negative
strong_contrast
vintage
Default is "none".
master, m
Set the master key points. These points will define a second pass mapping. It is
sometimes called a "luminance" or "value" mapping. It can be used with r, g, b or all
since it acts like a post-processing LUT.
red, r
Set the key points for the red component.
green, g
Set the key points for the green component.
blue, b
Set the key points for the blue component.
all Set the key points for all components (not including master). Can be used in addition
to the other key points component options. In this case, the unset component(s) will
fallback on this all setting.
psfile
Specify a Photoshop curves file (".acv") to import the settings from.
plot
Save Gnuplot script of the curves in specified file.
To avoid some filtergraph syntax conflicts, each key points list need to be defined using
the following syntax: "x0/y0 x1/y1 x2/y2 ...".
Examples
• Increase slightly the middle level of blue:
curves=blue='0/0 0.5/0.58 1/1'
• Vintage effect:
curves=r='0/0.11 .42/.51 1/0.95':g='0/0 0.50/0.48 1/1':b='0/0.22 .49/.44 1/0.8'
Here we obtain the following coordinates for each components:
red "(0;0.11) (0.42;0.51) (1;0.95)"
green
"(0;0) (0.50;0.48) (1;1)"
blue
"(0;0.22) (0.49;0.44) (1;0.80)"
• The previous example can also be achieved with the associated built-in preset:
curves=preset=vintage
• Or simply:
curves=vintage
• Use a Photoshop preset and redefine the points of the green component:
curves=psfile='MyCurvesPresets/purple.acv':green='0/0 0.45/0.53 1/1'
• Check out the curves of the "cross_process" profile using ffmpeg and gnuplot:
ffmpeg -f lavfi -i color -vf curves=cross_process:plot=/tmp/curves.plt -frames:v 1 -f null -
gnuplot -p /tmp/curves.plt
datascope
Video data analysis filter.
This filter shows hexadecimal pixel values of part of video.
The filter accepts the following options:
size, s
Set output video size.
x Set x offset from where to pick pixels.
y Set y offset from where to pick pixels.
mode
Set scope mode, can be one of the following:
mono
Draw hexadecimal pixel values with white color on black background.
color
Draw hexadecimal pixel values with input video pixel color on black background.
color2
Draw hexadecimal pixel values on color background picked from input video, the
text color is picked in such way so its always visible.
axis
Draw rows and columns numbers on left and top of video.
opacity
Set background opacity.
dctdnoiz
Denoise frames using 2D DCT (frequency domain filtering).
This filter is not designed for real time.
The filter accepts the following options:
sigma, s
Set the noise sigma constant.
This sigma defines a hard threshold of "3 * sigma"; every DCT coefficient (absolute
value) below this threshold with be dropped.
If you need a more advanced filtering, see expr.
Default is 0.
overlap
Set number overlapping pixels for each block. Since the filter can be slow, you may
want to reduce this value, at the cost of a less effective filter and the risk of
various artefacts.
If the overlapping value doesn't permit processing the whole input width or height, a
warning will be displayed and according borders won't be denoised.
Default value is blocksize-1, which is the best possible setting.
expr, e
Set the coefficient factor expression.
For each coefficient of a DCT block, this expression will be evaluated as a multiplier
value for the coefficient.
If this is option is set, the sigma option will be ignored.
The absolute value of the coefficient can be accessed through the c variable.
n Set the blocksize using the number of bits. "1<<n" defines the blocksize, which is the
width and height of the processed blocks.
The default value is 3 (8x8) and can be raised to 4 for a blocksize of 16x16. Note
that changing this setting has huge consequences on the speed processing. Also, a
larger block size does not necessarily means a better de-noising.
Examples
Apply a denoise with a sigma of 4.5:
dctdnoiz=4.5
The same operation can be achieved using the expression system:
dctdnoiz=e='gte(c, 4.5*3)'
Violent denoise using a block size of "16x16":
dctdnoiz=15:n=4
deband
Remove banding artifacts from input video. It works by replacing banded pixels with
average value of referenced pixels.
The filter accepts the following options:
1thr
2thr
3thr
4thr
Set banding detection threshold for each plane. Default is 0.02. Valid range is
0.00003 to 0.5. If difference between current pixel and reference pixel is less than
threshold, it will be considered as banded.
range, r
Banding detection range in pixels. Default is 16. If positive, random number in range
0 to set value will be used. If negative, exact absolute value will be used. The
range defines square of four pixels around current pixel.
direction, d
Set direction in radians from which four pixel will be compared. If positive, random
direction from 0 to set direction will be picked. If negative, exact of absolute value
will be picked. For example direction 0, -PI or -2*PI radians will pick only pixels on
same row and -PI/2 will pick only pixels on same column.
blur, b
If enabled, current pixel is compared with average value of all four surrounding
pixels. The default is enabled. If disabled current pixel is compared with all four
surrounding pixels. The pixel is considered banded if only all four differences with
surrounding pixels are less than threshold.
coupling, c
If enabled, current pixel is changed if and only if all pixel components are banded,
e.g. banding detection threshold is triggered for all color components. The default
is disabled.
deblock
Remove blocking artifacts from input video.
The filter accepts the following options:
filter
Set filter type, can be weak or strong. Default is strong. This controls what kind of
deblocking is applied.
block
Set size of block, allowed range is from 4 to 512. Default is 8.
alpha
beta
gamma
delta
Set blocking detection thresholds. Allowed range is 0 to 1. Defaults are: 0.098 for
alpha and 0.05 for the rest. Using higher threshold gives more deblocking strength.
Setting alpha controls threshold detection at exact edge of block. Remaining options
controls threshold detection near the edge. Each one for below/above or left/right.
Setting any of those to 0 disables deblocking.
planes
Set planes to filter. Default is to filter all available planes.
Examples
• Deblock using weak filter and block size of 4 pixels.
deblock=filter=weak:block=4
• Deblock using strong filter, block size of 4 pixels and custom thresholds for
deblocking more edges.
deblock=filter=strong:block=4:alpha=0.12:beta=0.07:gamma=0.06:delta=0.05
• Similar as above, but filter only first plane.
deblock=filter=strong:block=4:alpha=0.12:beta=0.07:gamma=0.06:delta=0.05:planes=1
• Similar as above, but filter only second and third plane.
deblock=filter=strong:block=4:alpha=0.12:beta=0.07:gamma=0.06:delta=0.05:planes=6
decimate
Drop duplicated frames at regular intervals.
The filter accepts the following options:
cycle
Set the number of frames from which one will be dropped. Setting this to N means one
frame in every batch of N frames will be dropped. Default is 5.
dupthresh
Set the threshold for duplicate detection. If the difference metric for a frame is
less than or equal to this value, then it is declared as duplicate. Default is 1.1
scthresh
Set scene change threshold. Default is 15.
blockx
blocky
Set the size of the x and y-axis blocks used during metric calculations. Larger
blocks give better noise suppression, but also give worse detection of small
movements. Must be a power of two. Default is 32.
ppsrc
Mark main input as a pre-processed input and activate clean source input stream. This
allows the input to be pre-processed with various filters to help the metrics
calculation while keeping the frame selection lossless. When set to 1, the first
stream is for the pre-processed input, and the second stream is the clean source from
where the kept frames are chosen. Default is 0.
chroma
Set whether or not chroma is considered in the metric calculations. Default is 1.
deconvolve
Apply 2D deconvolution of video stream in frequency domain using second stream as impulse.
The filter accepts the following options:
planes
Set which planes to process.
impulse
Set which impulse video frames will be processed, can be first or all. Default is all.
noise
Set noise when doing divisions. Default is 0.0000001. Useful when width and height are
not same and not power of 2 or if stream prior to convolving had noise.
The "deconvolve" filter also supports the framesync options.
dedot
Reduce cross-luminance (dot-crawl) and cross-color (rainbows) from video.
It accepts the following options:
m Set mode of operation. Can be combination of dotcrawl for cross-luminance reduction
and/or rainbows for cross-color reduction.
lt Set spatial luma threshold. Lower values increases reduction of cross-luminance.
tl Set tolerance for temporal luma. Higher values increases reduction of cross-luminance.
tc Set tolerance for chroma temporal variation. Higher values increases reduction of
cross-color.
ct Set temporal chroma threshold. Lower values increases reduction of cross-color.
deflate
Apply deflate effect to the video.
This filter replaces the pixel by the local(3x3) average by taking into account only
values lower than the pixel.
It accepts the following options:
threshold0
threshold1
threshold2
threshold3
Limit the maximum change for each plane, default is 65535. If 0, plane will remain
unchanged.
deflicker
Remove temporal frame luminance variations.
It accepts the following options:
size, s
Set moving-average filter size in frames. Default is 5. Allowed range is 2 - 129.
mode, m
Set averaging mode to smooth temporal luminance variations.
Available values are:
am Arithmetic mean
gm Geometric mean
hm Harmonic mean
qm Quadratic mean
cm Cubic mean
pm Power mean
median
Median
bypass
Do not actually modify frame. Useful when one only wants metadata.
dejudder
Remove judder produced by partially interlaced telecined content.
Judder can be introduced, for instance, by pullup filter. If the original source was
partially telecined content then the output of "pullup,dejudder" will have a variable
frame rate. May change the recorded frame rate of the container. Aside from that change,
this filter will not affect constant frame rate video.
The option available in this filter is:
cycle
Specify the length of the window over which the judder repeats.
Accepts any integer greater than 1. Useful values are:
4 If the original was telecined from 24 to 30 fps (Film to NTSC).
5 If the original was telecined from 25 to 30 fps (PAL to NTSC).
20 If a mixture of the two.
The default is 4.
delogo
Suppress a TV station logo by a simple interpolation of the surrounding pixels. Just set a
rectangle covering the logo and watch it disappear (and sometimes something even uglier
appear - your mileage may vary).
It accepts the following parameters:
x
y Specify the top left corner coordinates of the logo. They must be specified.
w
h Specify the width and height of the logo to clear. They must be specified.
band, t
Specify the thickness of the fuzzy edge of the rectangle (added to w and h). The
default value is 1. This option is deprecated, setting higher values should no longer
be necessary and is not recommended.
show
When set to 1, a green rectangle is drawn on the screen to simplify finding the right
x, y, w, and h parameters. The default value is 0.
The rectangle is drawn on the outermost pixels which will be (partly) replaced with
interpolated values. The values of the next pixels immediately outside this rectangle
in each direction will be used to compute the interpolated pixel values inside the
rectangle.
Examples
• Set a rectangle covering the area with top left corner coordinates 0,0 and size
100x77, and a band of size 10:
delogo=x=0:y=0:w=100:h=77:band=10
derain
Remove the rain in the input image/video by applying the derain methods based on
convolutional neural networks. Supported models:
• Recurrent Squeeze-and-Excitation Context Aggregation Net (RESCAN). See
<http://openaccess.thecvf.com/content_ECCV_2018/papers/Xia_Li_Recurrent_Squeeze-and-Excitation_Context_ECCV_2018_paper.pdf>.
Training scripts as well as scripts for model generation are provided in the repository at
<https://github.com/XueweiMeng/derain_filter.git>.
The filter accepts the following options:
dnn_backend
Specify which DNN backend to use for model loading and execution. This option accepts
the following values:
native
Native implementation of DNN loading and execution.
Default value is native.
model
Set path to model file specifying network architecture and its parameters. Note that
different backends use different file formats. TensorFlow backend can load files for
both formats, while native backend can load files for only its format.
deshake
Attempt to fix small changes in horizontal and/or vertical shift. This filter helps remove
camera shake from hand-holding a camera, bumping a tripod, moving on a vehicle, etc.
The filter accepts the following options:
x
y
w
h Specify a rectangular area where to limit the search for motion vectors. If desired
the search for motion vectors can be limited to a rectangular area of the frame
defined by its top left corner, width and height. These parameters have the same
meaning as the drawbox filter which can be used to visualise the position of the
bounding box.
This is useful when simultaneous movement of subjects within the frame might be
confused for camera motion by the motion vector search.
If any or all of x, y, w and h are set to -1 then the full frame is used. This allows
later options to be set without specifying the bounding box for the motion vector
search.
Default - search the whole frame.
rx
ry Specify the maximum extent of movement in x and y directions in the range 0-64 pixels.
Default 16.
edge
Specify how to generate pixels to fill blanks at the edge of the frame. Available
values are:
blank, 0
Fill zeroes at blank locations
original, 1
Original image at blank locations
clamp, 2
Extruded edge value at blank locations
mirror, 3
Mirrored edge at blank locations
Default value is mirror.
blocksize
Specify the blocksize to use for motion search. Range 4-128 pixels, default 8.
contrast
Specify the contrast threshold for blocks. Only blocks with more than the specified
contrast (difference between darkest and lightest pixels) will be considered. Range
1-255, default 125.
search
Specify the search strategy. Available values are:
exhaustive, 0
Set exhaustive search
less, 1
Set less exhaustive search.
Default value is exhaustive.
filename
If set then a detailed log of the motion search is written to the specified file.
despill
Remove unwanted contamination of foreground colors, caused by reflected color of
greenscreen or bluescreen.
This filter accepts the following options:
type
Set what type of despill to use.
mix Set how spillmap will be generated.
expand
Set how much to get rid of still remaining spill.
red Controls amount of red in spill area.
green
Controls amount of green in spill area. Should be -1 for greenscreen.
blue
Controls amount of blue in spill area. Should be -1 for bluescreen.
brightness
Controls brightness of spill area, preserving colors.
alpha
Modify alpha from generated spillmap.
detelecine
Apply an exact inverse of the telecine operation. It requires a predefined pattern
specified using the pattern option which must be the same as that passed to the telecine
filter.
This filter accepts the following options:
first_field
top, t
top field first
bottom, b
bottom field first The default value is "top".
pattern
A string of numbers representing the pulldown pattern you wish to apply. The default
value is 23.
start_frame
A number representing position of the first frame with respect to the telecine
pattern. This is to be used if the stream is cut. The default value is 0.
dilation
Apply dilation effect to the video.
This filter replaces the pixel by the local(3x3) maximum.
It accepts the following options:
threshold0
threshold1
threshold2
threshold3
Limit the maximum change for each plane, default is 65535. If 0, plane will remain
unchanged.
coordinates
Flag which specifies the pixel to refer to. Default is 255 i.e. all eight pixels are
used.
Flags to local 3x3 coordinates maps like this:
1 2 3
4 5
6 7 8
displace
Displace pixels as indicated by second and third input stream.
It takes three input streams and outputs one stream, the first input is the source, and
second and third input are displacement maps.
The second input specifies how much to displace pixels along the x-axis, while the third
input specifies how much to displace pixels along the y-axis. If one of displacement map
streams terminates, last frame from that displacement map will be used.
Note that once generated, displacements maps can be reused over and over again.
A description of the accepted options follows.
edge
Set displace behavior for pixels that are out of range.
Available values are:
blank
Missing pixels are replaced by black pixels.
smear
Adjacent pixels will spread out to replace missing pixels.
wrap
Out of range pixels are wrapped so they point to pixels of other side.
mirror
Out of range pixels will be replaced with mirrored pixels.
Default is smear.
Examples
• Add ripple effect to rgb input of video size hd720:
ffmpeg -i INPUT -f lavfi -i nullsrc=s=hd720,lutrgb=128:128:128 -f lavfi -i nullsrc=s=hd720,geq='r=128+30*sin(2*PI*X/400+T):g=128+30*sin(2*PI*X/400+T):b=128+30*sin(2*PI*X/400+T)' -lavfi '[0][1][2]displace' OUTPUT
• Add wave effect to rgb input of video size hd720:
ffmpeg -i INPUT -f lavfi -i nullsrc=hd720,geq='r=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T)):g=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T)):b=128+80*(sin(sqrt((X-W/2)*(X-W/2)+(Y-H/2)*(Y-H/2))/220*2*PI+T))' -lavfi '[1]split[x][y],[0][x][y]displace' OUTPUT
drawbox
Draw a colored box on the input image.
It accepts the following parameters:
x
y The expressions which specify the top left corner coordinates of the box. It defaults
to 0.
width, w
height, h
The expressions which specify the width and height of the box; if 0 they are
interpreted as the input width and height. It defaults to 0.
color, c
Specify the color of the box to write. For the general syntax of this option, check
the "Color" section in the ffmpeg-utils manual. If the special value "invert" is used,
the box edge color is the same as the video with inverted luma.
thickness, t
The expression which sets the thickness of the box edge. A value of "fill" will
create a filled box. Default value is 3.
See below for the list of accepted constants.
replace
Applicable if the input has alpha. With value 1, the pixels of the painted box will
overwrite the video's color and alpha pixels. Default is 0, which composites the box
onto the input, leaving the video's alpha intact.
The parameters for x, y, w and h and t are expressions containing the following constants:
dar The input display aspect ratio, it is the same as (w / h) * sar.
hsub
vsub
horizontal and vertical chroma subsample values. For example for the pixel format
"yuv422p" hsub is 2 and vsub is 1.
in_h, ih
in_w, iw
The input width and height.
sar The input sample aspect ratio.
x
y The x and y offset coordinates where the box is drawn.
w
h The width and height of the drawn box.
t The thickness of the drawn box.
These constants allow the x, y, w, h and t expressions to refer to each other, so you
may for example specify "y=x/dar" or "h=w/dar".
Examples
• Draw a black box around the edge of the input image:
drawbox
• Draw a box with color red and an opacity of 50%:
drawbox=10:20:200:60:red@0.5
The previous example can be specified as:
drawbox=x=10:y=20:w=200:h=60:color=red@0.5
• Fill the box with pink color:
drawbox=x=10:y=10:w=100:h=100:color=pink@0.5:t=fill
• Draw a 2-pixel red 2.40:1 mask:
drawbox=x=-t:y=0.5*(ih-iw/2.4)-t:w=iw+t*2:h=iw/2.4+t*2:t=2:c=red
drawgrid
Draw a grid on the input image.
It accepts the following parameters:
x
y The expressions which specify the coordinates of some point of grid intersection
(meant to configure offset). Both default to 0.
width, w
height, h
The expressions which specify the width and height of the grid cell, if 0 they are
interpreted as the input width and height, respectively, minus "thickness", so image
gets framed. Default to 0.
color, c
Specify the color of the grid. For the general syntax of this option, check the
"Color" section in the ffmpeg-utils manual. If the special value "invert" is used, the
grid color is the same as the video with inverted luma.
thickness, t
The expression which sets the thickness of the grid line. Default value is 1.
See below for the list of accepted constants.
replace
Applicable if the input has alpha. With 1 the pixels of the painted grid will
overwrite the video's color and alpha pixels. Default is 0, which composites the grid
onto the input, leaving the video's alpha intact.
The parameters for x, y, w and h and t are expressions containing the following constants:
dar The input display aspect ratio, it is the same as (w / h) * sar.
hsub
vsub
horizontal and vertical chroma subsample values. For example for the pixel format
"yuv422p" hsub is 2 and vsub is 1.
in_h, ih
in_w, iw
The input grid cell width and height.
sar The input sample aspect ratio.
x
y The x and y coordinates of some point of grid intersection (meant to configure
offset).
w
h The width and height of the drawn cell.
t The thickness of the drawn cell.
These constants allow the x, y, w, h and t expressions to refer to each other, so you
may for example specify "y=x/dar" or "h=w/dar".
Examples
• Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an
opacity of 50%:
drawgrid=width=100:height=100:thickness=2:color=red@0.5
• Draw a white 3x3 grid with an opacity of 50%:
drawgrid=w=iw/3:h=ih/3:t=2:c=white@0.5
drawtext
Draw a text string or text from a specified file on top of a video, using the libfreetype
library.
To enable compilation of this filter, you need to configure FFmpeg with
"--enable-libfreetype". To enable default font fallback and the font option you need to
configure FFmpeg with "--enable-libfontconfig". To enable the text_shaping option, you
need to configure FFmpeg with "--enable-libfribidi".
Syntax
It accepts the following parameters:
box Used to draw a box around text using the background color. The value must be either 1
(enable) or 0 (disable). The default value of box is 0.
boxborderw
Set the width of the border to be drawn around the box using boxcolor. The default
value of boxborderw is 0.
boxcolor
The color to be used for drawing box around text. For the syntax of this option, check
the "Color" section in the ffmpeg-utils manual.
The default value of boxcolor is "white".
line_spacing
Set the line spacing in pixels of the border to be drawn around the box using box.
The default value of line_spacing is 0.
borderw
Set the width of the border to be drawn around the text using bordercolor. The
default value of borderw is 0.
bordercolor
Set the color to be used for drawing border around text. For the syntax of this
option, check the "Color" section in the ffmpeg-utils manual.
The default value of bordercolor is "black".
expansion
Select how the text is expanded. Can be either "none", "strftime" (deprecated) or
"normal" (default). See the drawtext_expansion, Text expansion section below for
details.
basetime
Set a start time for the count. Value is in microseconds. Only applied in the
deprecated strftime expansion mode. To emulate in normal expansion mode use the "pts"
function, supplying the start time (in seconds) as the second argument.
fix_bounds
If true, check and fix text coords to avoid clipping.
fontcolor
The color to be used for drawing fonts. For the syntax of this option, check the
"Color" section in the ffmpeg-utils manual.
The default value of fontcolor is "black".
fontcolor_expr
String which is expanded the same way as text to obtain dynamic fontcolor value. By
default this option has empty value and is not processed. When this option is set, it
overrides fontcolor option.
font
The font family to be used for drawing text. By default Sans.
fontfile
The font file to be used for drawing text. The path must be included. This parameter
is mandatory if the fontconfig support is disabled.
alpha
Draw the text applying alpha blending. The value can be a number between 0.0 and 1.0.
The expression accepts the same variables x, y as well. The default value is 1.
Please see fontcolor_expr.
fontsize
The font size to be used for drawing text. The default value of fontsize is 16.
text_shaping
If set to 1, attempt to shape the text (for example, reverse the order of right-to-
left text and join Arabic characters) before drawing it. Otherwise, just draw the
text exactly as given. By default 1 (if supported).
ft_load_flags
The flags to be used for loading the fonts.
The flags map the corresponding flags supported by libfreetype, and are a combination
of the following values:
default
no_scale
no_hinting
render
no_bitmap
vertical_layout
force_autohint
crop_bitmap
pedantic
ignore_global_advance_width
no_recurse
ignore_transform
monochrome
linear_design
no_autohint
Default value is "default".
For more information consult the documentation for the FT_LOAD_* libfreetype flags.
shadowcolor
The color to be used for drawing a shadow behind the drawn text. For the syntax of
this option, check the "Color" section in the ffmpeg-utils manual.
The default value of shadowcolor is "black".
shadowx
shadowy
The x and y offsets for the text shadow position with respect to the position of the
text. They can be either positive or negative values. The default value for both is
"0".
start_number
The starting frame number for the n/frame_num variable. The default value is "0".
tabsize
The size in number of spaces to use for rendering the tab. Default value is 4.
timecode
Set the initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used
with or without text parameter. timecode_rate option must be specified.
timecode_rate, rate, r
Set the timecode frame rate (timecode only). Value will be rounded to nearest integer.
Minimum value is "1". Drop-frame timecode is supported for frame rates 30 & 60.
tc24hmax
If set to 1, the output of the timecode option will wrap around at 24 hours. Default
is 0 (disabled).
text
The text string to be drawn. The text must be a sequence of UTF-8 encoded characters.
This parameter is mandatory if no file is specified with the parameter textfile.
textfile
A text file containing text to be drawn. The text must be a sequence of UTF-8 encoded
characters.
This parameter is mandatory if no text string is specified with the parameter text.
If both text and textfile are specified, an error is thrown.
reload
If set to 1, the textfile will be reloaded before each frame. Be sure to update it
atomically, or it may be read partially, or even fail.
x
y The expressions which specify the offsets where text will be drawn within the video
frame. They are relative to the top/left border of the output image.
The default value of x and y is "0".
See below for the list of accepted constants and functions.
The parameters for x and y are expressions containing the following constants and
functions:
dar input display aspect ratio, it is the same as (w / h) * sar
hsub
vsub
horizontal and vertical chroma subsample values. For example for the pixel format
"yuv422p" hsub is 2 and vsub is 1.
line_h, lh
the height of each text line
main_h, h, H
the input height
main_w, w, W
the input width
max_glyph_a, ascent
the maximum distance from the baseline to the highest/upper grid coordinate used to
place a glyph outline point, for all the rendered glyphs. It is a positive value, due
to the grid's orientation with the Y axis upwards.
max_glyph_d, descent
the maximum distance from the baseline to the lowest grid coordinate used to place a
glyph outline point, for all the rendered glyphs. This is a negative value, due to
the grid's orientation, with the Y axis upwards.
max_glyph_h
maximum glyph height, that is the maximum height for all the glyphs contained in the
rendered text, it is equivalent to ascent - descent.
max_glyph_w
maximum glyph width, that is the maximum width for all the glyphs contained in the
rendered text
n the number of input frame, starting from 0
rand(min, max)
return a random number included between min and max
sar The input sample aspect ratio.
t timestamp expressed in seconds, NAN if the input timestamp is unknown
text_h, th
the height of the rendered text
text_w, tw
the width of the rendered text
x
y the x and y offset coordinates where the text is drawn.
These parameters allow the x and y expressions to refer to each other, so you can for
example specify "y=x/dar".
pict_type
A one character description of the current frame's picture type.
pkt_pos
The current packet's position in the input file or stream (in bytes, from the start of
the input). A value of -1 indicates this info is not available.
pkt_duration
The current packet's duration, in seconds.
pkt_size
The current packet's size (in bytes).
Text expansion
If expansion is set to "strftime", the filter recognizes strftime() sequences in the
provided text and expands them accordingly. Check the documentation of strftime(). This
feature is deprecated.
If expansion is set to "none", the text is printed verbatim.
If expansion is set to "normal" (which is the default), the following expansion mechanism
is used.
The backslash character \, followed by any character, always expands to the second
character.
Sequences of the form "%{...}" are expanded. The text between the braces is a function
name, possibly followed by arguments separated by ':'. If the arguments contain special
characters or delimiters (':' or '}'), they should be escaped.
Note that they probably must also be escaped as the value for the text option in the
filter argument string and as the filter argument in the filtergraph description, and
possibly also for the shell, that makes up to four levels of escaping; using a text file
avoids these problems.
The following functions are available:
expr, e
The expression evaluation result.
It must take one argument specifying the expression to be evaluated, which accepts the
same constants and functions as the x and y values. Note that not all constants should
be used, for example the text size is not known when evaluating the expression, so the
constants text_w and text_h will have an undefined value.
expr_int_format, eif
Evaluate the expression's value and output as formatted integer.
The first argument is the expression to be evaluated, just as for the expr function.
The second argument specifies the output format. Allowed values are x, X, d and u.
They are treated exactly as in the "printf" function. The third parameter is optional
and sets the number of positions taken by the output. It can be used to add padding
with zeros from the left.
gmtime
The time at which the filter is running, expressed in UTC. It can accept an argument:
a strftime() format string.
localtime
The time at which the filter is running, expressed in the local time zone. It can
accept an argument: a strftime() format string.
metadata
Frame metadata. Takes one or two arguments.
The first argument is mandatory and specifies the metadata key.
The second argument is optional and specifies a default value, used when the metadata
key is not found or empty.
Available metadata can be identified by inspecting entries starting with TAG included
within each frame section printed by running "ffprobe -show_frames".
String metadata generated in filters leading to the drawtext filter are also
available.
n, frame_num
The frame number, starting from 0.
pict_type
A one character description of the current picture type.
pts The timestamp of the current frame. It can take up to three arguments.
The first argument is the format of the timestamp; it defaults to "flt" for seconds as
a decimal number with microsecond accuracy; "hms" stands for a formatted
[-]HH:MM:SS.mmm timestamp with millisecond accuracy. "gmtime" stands for the
timestamp of the frame formatted as UTC time; "localtime" stands for the timestamp of
the frame formatted as local time zone time.
The second argument is an offset added to the timestamp.
If the format is set to "hms", a third argument "24HH" may be supplied to present the
hour part of the formatted timestamp in 24h format (00-23).
If the format is set to "localtime" or "gmtime", a third argument may be supplied: a
strftime() format string. By default, YYYY-MM-DD HH:MM:SS format will be used.
Commands
This filter supports altering parameters via commands:
reinit
Alter existing filter parameters.
Syntax for the argument is the same as for filter invocation, e.g.
fontsize=56:fontcolor=green:text='Hello World'
Full filter invocation with sendcmd would look like this:
sendcmd=c='56.0 drawtext reinit fontsize=56\:fontcolor=green\:text=Hello\\ World'
If the entire argument can't be parsed or applied as valid values then the filter will
continue with its existing parameters.
Examples
• Draw "Test Text" with font FreeSerif, using the default values for the optional
parameters.
drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"
• Draw 'Test Text' with font FreeSerif of size 24 at position x=100 and y=50 (counting
from the top-left corner of the screen), text is yellow with a red box around it. Both
the text and the box have an opacity of 20%.
drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
x=100: y=50: fontsize=24: fontcolor=yellow@0.2: box=1: boxcolor=red@0.2"
Note that the double quotes are not necessary if spaces are not used within the
parameter list.
• Show the text at the center of the video frame:
drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h)/2"
• Show the text at a random position, switching to a new position every 30 seconds:
drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=if(eq(mod(t\,30)\,0)\,rand(0\,(w-text_w))\,x):y=if(eq(mod(t\,30)\,0)\,rand(0\,(h-text_h))\,y)"
• Show a text line sliding from right to left in the last row of the video frame. The
file LONG_LINE is assumed to contain a single line with no newlines.
drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t"
• Show the content of file CREDITS off the bottom of the frame and scroll up.
drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t"
• Draw a single green letter "g", at the center of the input video. The glyph baseline
is placed at half screen height.
drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent"
• Show text for 1 second every 3 seconds:
drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'"
• Use fontconfig to set the font. Note that the colons need to be escaped.
drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg'
• Print the date of a real-time encoding (see strftime(3)):
drawtext='fontfile=FreeSans.ttf:text=%{localtime\:%a %b %d %Y}'
• Show text fading in and out (appearing/disappearing):
#!/bin/sh
DS=1.0 # display start
DE=10.0 # display end
FID=1.5 # fade in duration
FOD=5 # fade out duration
ffplay -f lavfi "color,drawtext=text=TEST:fontsize=50:fontfile=FreeSerif.ttf:fontcolor_expr=ff0000%{eif\\\\: clip(255*(1*between(t\\, $DS + $FID\\, $DE - $FOD) + ((t - $DS)/$FID)*between(t\\, $DS\\, $DS + $FID) + (-(t - $DE)/$FOD)*between(t\\, $DE - $FOD\\, $DE) )\\, 0\\, 255) \\\\: x\\\\: 2 }"
• Horizontally align multiple separate texts. Note that max_glyph_a and the fontsize
value are included in the y offset.
drawtext=fontfile=FreeSans.ttf:text=DOG:fontsize=24:x=10:y=20+24-max_glyph_a,
drawtext=fontfile=FreeSans.ttf:text=cow:fontsize=24:x=80:y=20+24-max_glyph_a
For more information about libfreetype, check: <http://www.freetype.org/>.
For more information about fontconfig, check:
<http://freedesktop.org/software/fontconfig/fontconfig-user.html>.
For more information about libfribidi, check: <http://fribidi.org/>.
edgedetect
Detect and draw edges. The filter uses the Canny Edge Detection algorithm.
The filter accepts the following options:
low
high
Set low and high threshold values used by the Canny thresholding algorithm.
The high threshold selects the "strong" edge pixels, which are then connected through
8-connectivity with the "weak" edge pixels selected by the low threshold.
low and high threshold values must be chosen in the range [0,1], and low should be
lesser or equal to high.
Default value for low is "20/255", and default value for high is "50/255".
mode
Define the drawing mode.
wires
Draw white/gray wires on black background.
colormix
Mix the colors to create a paint/cartoon effect.
canny
Apply Canny edge detector on all selected planes.
Default value is wires.
planes
Select planes for filtering. By default all available planes are filtered.
Examples
• Standard edge detection with custom values for the hysteresis thresholding:
edgedetect=low=0.1:high=0.4
• Painting effect without thresholding:
edgedetect=mode=colormix:high=0
eq
Set brightness, contrast, saturation and approximate gamma adjustment.
The filter accepts the following options:
contrast
Set the contrast expression. The value must be a float value in range "-2.0" to 2.0.
The default value is "1".
brightness
Set the brightness expression. The value must be a float value in range "-1.0" to 1.0.
The default value is "0".
saturation
Set the saturation expression. The value must be a float in range 0.0 to 3.0. The
default value is "1".
gamma
Set the gamma expression. The value must be a float in range 0.1 to 10.0. The default
value is "1".
gamma_r
Set the gamma expression for red. The value must be a float in range 0.1 to 10.0. The
default value is "1".
gamma_g
Set the gamma expression for green. The value must be a float in range 0.1 to 10.0.
The default value is "1".
gamma_b
Set the gamma expression for blue. The value must be a float in range 0.1 to 10.0. The
default value is "1".
gamma_weight
Set the gamma weight expression. It can be used to reduce the effect of a high gamma
value on bright image areas, e.g. keep them from getting overamplified and just plain
white. The value must be a float in range 0.0 to 1.0. A value of 0.0 turns the gamma
correction all the way down while 1.0 leaves it at its full strength. Default is "1".
eval
Set when the expressions for brightness, contrast, saturation and gamma expressions
are evaluated.
It accepts the following values:
init
only evaluate expressions once during the filter initialization or when a command
is processed
frame
evaluate expressions for each incoming frame
Default value is init.
The expressions accept the following parameters:
n frame count of the input frame starting from 0
pos byte position of the corresponding packet in the input file, NAN if unspecified
r frame rate of the input video, NAN if the input frame rate is unknown
t timestamp expressed in seconds, NAN if the input timestamp is unknown
Commands
The filter supports the following commands:
contrast
Set the contrast expression.
brightness
Set the brightness expression.
saturation
Set the saturation expression.
gamma
Set the gamma expression.
gamma_r
Set the gamma_r expression.
gamma_g
Set gamma_g expression.
gamma_b
Set gamma_b expression.
gamma_weight
Set gamma_weight expression.
The command accepts the same syntax of the corresponding option.
If the specified expression is not valid, it is kept at its current value.
erosion
Apply erosion effect to the video.
This filter replaces the pixel by the local(3x3) minimum.
It accepts the following options:
threshold0
threshold1
threshold2
threshold3
Limit the maximum change for each plane, default is 65535. If 0, plane will remain
unchanged.
coordinates
Flag which specifies the pixel to refer to. Default is 255 i.e. all eight pixels are
used.
Flags to local 3x3 coordinates maps like this:
1 2 3
4 5
6 7 8
extractplanes
Extract color channel components from input video stream into separate grayscale video
streams.
The filter accepts the following option:
planes
Set plane(s) to extract.
Available values for planes are:
y
u
v
a
r
g
b
Choosing planes not available in the input will result in an error. That means you
cannot select "r", "g", "b" planes with "y", "u", "v" planes at same time.
Examples
• Extract luma, u and v color channel component from input video frame into 3 grayscale
outputs:
ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi
elbg
Apply a posterize effect using the ELBG (Enhanced LBG) algorithm.
For each input image, the filter will compute the optimal mapping from the input to the
output given the codebook length, that is the number of distinct output colors.
This filter accepts the following options.
codebook_length, l
Set codebook length. The value must be a positive integer, and represents the number
of distinct output colors. Default value is 256.
nb_steps, n
Set the maximum number of iterations to apply for computing the optimal mapping. The
higher the value the better the result and the higher the computation time. Default
value is 1.
seed, s
Set a random seed, must be an integer included between 0 and UINT32_MAX. If not
specified, or if explicitly set to -1, the filter will try to use a good random seed
on a best effort basis.
pal8
Set pal8 output pixel format. This option does not work with codebook length greater
than 256.
entropy
Measure graylevel entropy in histogram of color channels of video frames.
It accepts the following parameters:
mode
Can be either normal or diff. Default is normal.
diff mode measures entropy of histogram delta values, absolute differences between
neighbour histogram values.
fade
Apply a fade-in/out effect to the input video.
It accepts the following parameters:
type, t
The effect type can be either "in" for a fade-in, or "out" for a fade-out effect.
Default is "in".
start_frame, s
Specify the number of the frame to start applying the fade effect at. Default is 0.
nb_frames, n
The number of frames that the fade effect lasts. At the end of the fade-in effect, the
output video will have the same intensity as the input video. At the end of the fade-
out transition, the output video will be filled with the selected color. Default is
25.
alpha
If set to 1, fade only alpha channel, if one exists on the input. Default value is 0.
start_time, st
Specify the timestamp (in seconds) of the frame to start to apply the fade effect. If
both start_frame and start_time are specified, the fade will start at whichever comes
last. Default is 0.
duration, d
The number of seconds for which the fade effect has to last. At the end of the fade-in
effect the output video will have the same intensity as the input video, at the end of
the fade-out transition the output video will be filled with the selected color. If
both duration and nb_frames are specified, duration is used. Default is 0 (nb_frames
is used by default).
color, c
Specify the color of the fade. Default is "black".
Examples
• Fade in the first 30 frames of video:
fade=in:0:30
The command above is equivalent to:
fade=t=in:s=0:n=30
• Fade out the last 45 frames of a 200-frame video:
fade=out:155:45
fade=type=out:start_frame=155:nb_frames=45
• Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video:
fade=in:0:25, fade=out:975:25
• Make the first 5 frames yellow, then fade in from frame 5-24:
fade=in:5:20:color=yellow
• Fade in alpha over first 25 frames of video:
fade=in:0:25:alpha=1
• Make the first 5.5 seconds black, then fade in for 0.5 seconds:
fade=t=in:st=5.5:d=0.5
fftfilt
Apply arbitrary expressions to samples in frequency domain
dc_Y
Adjust the dc value (gain) of the luma plane of the image. The filter accepts an
integer value in range 0 to 1000. The default value is set to 0.
dc_U
Adjust the dc value (gain) of the 1st chroma plane of the image. The filter accepts an
integer value in range 0 to 1000. The default value is set to 0.
dc_V
Adjust the dc value (gain) of the 2nd chroma plane of the image. The filter accepts an
integer value in range 0 to 1000. The default value is set to 0.
weight_Y
Set the frequency domain weight expression for the luma plane.
weight_U
Set the frequency domain weight expression for the 1st chroma plane.
weight_V
Set the frequency domain weight expression for the 2nd chroma plane.
eval
Set when the expressions are evaluated.
It accepts the following values:
init
Only evaluate expressions once during the filter initialization.
frame
Evaluate expressions for each incoming frame.
Default value is init.
The filter accepts the following variables:
X
Y The coordinates of the current sample.
W
H The width and height of the image.
N The number of input frame, starting from 0.
Examples
• High-pass:
fftfilt=dc_Y=128:weight_Y='squish(1-(Y+X)/100)'
• Low-pass:
fftfilt=dc_Y=0:weight_Y='squish((Y+X)/100-1)'
• Sharpen:
fftfilt=dc_Y=0:weight_Y='1+squish(1-(Y+X)/100)'
• Blur:
fftfilt=dc_Y=0:weight_Y='exp(-4 * ((Y+X)/(W+H)))'
fftdnoiz
Denoise frames using 3D FFT (frequency domain filtering).
The filter accepts the following options:
sigma
Set the noise sigma constant. This sets denoising strength. Default value is 1.
Allowed range is from 0 to 30. Using very high sigma with low overlap may give
blocking artifacts.
amount
Set amount of denoising. By default all detected noise is reduced. Default value is
1. Allowed range is from 0 to 1.
block
Set size of block, Default is 4, can be 3, 4, 5 or 6. Actual size of block in pixels
is 2 to power of block, so by default block size in pixels is 2^4 which is 16.
overlap
Set block overlap. Default is 0.5. Allowed range is from 0.2 to 0.8.
prev
Set number of previous frames to use for denoising. By default is set to 0.
next
Set number of next frames to to use for denoising. By default is set to 0.
planes
Set planes which will be filtered, by default are all available filtered except alpha.
field
Extract a single field from an interlaced image using stride arithmetic to avoid wasting
CPU time. The output frames are marked as non-interlaced.
The filter accepts the following options:
type
Specify whether to extract the top (if the value is 0 or "top") or the bottom field
(if the value is 1 or "bottom").
fieldhint
Create new frames by copying the top and bottom fields from surrounding frames supplied as
numbers by the hint file.
hint
Set file containing hints: absolute/relative frame numbers.
There must be one line for each frame in a clip. Each line must contain two numbers
separated by the comma, optionally followed by "-" or "+". Numbers supplied on each
line of file can not be out of [N-1,N+1] where N is current frame number for
"absolute" mode or out of [-1, 1] range for "relative" mode. First number tells from
which frame to pick up top field and second number tells from which frame to pick up
bottom field.
If optionally followed by "+" output frame will be marked as interlaced, else if
followed by "-" output frame will be marked as progressive, else it will be marked
same as input frame. If line starts with "#" or ";" that line is skipped.
mode
Can be item "absolute" or "relative". Default is "absolute".
Example of first several lines of "hint" file for "relative" mode:
0,0 - # first frame
1,0 - # second frame, use third's frame top field and second's frame bottom field
1,0 - # third frame, use fourth's frame top field and third's frame bottom field
1,0 -
0,0 -
0,0 -
1,0 -
1,0 -
1,0 -
0,0 -
0,0 -
1,0 -
1,0 -
1,0 -
0,0 -
fieldmatch
Field matching filter for inverse telecine. It is meant to reconstruct the progressive
frames from a telecined stream. The filter does not drop duplicated frames, so to achieve
a complete inverse telecine "fieldmatch" needs to be followed by a decimation filter such
as decimate in the filtergraph.
The separation of the field matching and the decimation is notably motivated by the
possibility of inserting a de-interlacing filter fallback between the two. If the source
has mixed telecined and real interlaced content, "fieldmatch" will not be able to match
fields for the interlaced parts. But these remaining combed frames will be marked as
interlaced, and thus can be de-interlaced by a later filter such as yadif before
decimation.
In addition to the various configuration options, "fieldmatch" can take an optional second
stream, activated through the ppsrc option. If enabled, the frames reconstruction will be
based on the fields and frames from this second stream. This allows the first input to be
pre-processed in order to help the various algorithms of the filter, while keeping the
output lossless (assuming the fields are matched properly). Typically, a field-aware
denoiser, or brightness/contrast adjustments can help.
Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project) and
VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from which "fieldmatch"
is based on. While the semantic and usage are very close, some behaviour and options names
can differ.
The decimate filter currently only works for constant frame rate input. If your input has
mixed telecined (30fps) and progressive content with a lower framerate like 24fps use the
following filterchain to produce the necessary cfr stream:
"dejudder,fps=30000/1001,fieldmatch,decimate".
The filter accepts the following options:
order
Specify the assumed field order of the input stream. Available values are:
auto
Auto detect parity (use FFmpeg's internal parity value).
bff Assume bottom field first.
tff Assume top field first.
Note that it is sometimes recommended not to trust the parity announced by the stream.
Default value is auto.
mode
Set the matching mode or strategy to use. pc mode is the safest in the sense that it
won't risk creating jerkiness due to duplicate frames when possible, but if there are
bad edits or blended fields it will end up outputting combed frames when a good match
might actually exist. On the other hand, pcn_ub mode is the most risky in terms of
creating jerkiness, but will almost always find a good frame if there is one. The
other values are all somewhere in between pc and pcn_ub in terms of risking jerkiness
and creating duplicate frames versus finding good matches in sections with bad edits,
orphaned fields, blended fields, etc.
More details about p/c/n/u/b are available in p/c/n/u/b meaning section.
Available values are:
pc 2-way matching (p/c)
pc_n
2-way matching, and trying 3rd match if still combed (p/c + n)
pc_u
2-way matching, and trying 3rd match (same order) if still combed (p/c + u)
pc_n_ub
2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if
still combed (p/c + n + u/b)
pcn 3-way matching (p/c/n)
pcn_ub
3-way matching, and trying 4th/5th matches if all 3 of the original matches are
detected as combed (p/c/n + u/b)
The parenthesis at the end indicate the matches that would be used for that mode
assuming order=tff (and field on auto or top).
In terms of speed pc mode is by far the fastest and pcn_ub is the slowest.
Default value is pc_n.
ppsrc
Mark the main input stream as a pre-processed input, and enable the secondary input
stream as the clean source to pick the fields from. See the filter introduction for
more details. It is similar to the clip2 feature from VFM/TFM.
Default value is 0 (disabled).
field
Set the field to match from. It is recommended to set this to the same value as order
unless you experience matching failures with that setting. In certain circumstances
changing the field that is used to match from can have a large impact on matching
performance. Available values are:
auto
Automatic (same value as order).
bottom
Match from the bottom field.
top Match from the top field.
Default value is auto.
mchroma
Set whether or not chroma is included during the match comparisons. In most cases it
is recommended to leave this enabled. You should set this to 0 only if your clip has
bad chroma problems such as heavy rainbowing or other artifacts. Setting this to 0
could also be used to speed things up at the cost of some accuracy.
Default value is 1.
y0
y1 These define an exclusion band which excludes the lines between y0 and y1 from being
included in the field matching decision. An exclusion band can be used to ignore
subtitles, a logo, or other things that may interfere with the matching. y0 sets the
starting scan line and y1 sets the ending line; all lines in between y0 and y1
(including y0 and y1) will be ignored. Setting y0 and y1 to the same value will
disable the feature. y0 and y1 defaults to 0.
scthresh
Set the scene change detection threshold as a percentage of maximum change on the luma
plane. Good values are in the "[8.0, 14.0]" range. Scene change detection is only
relevant in case combmatch=sc. The range for scthresh is "[0.0, 100.0]".
Default value is 12.0.
combmatch
When combatch is not none, "fieldmatch" will take into account the combed scores of
matches when deciding what match to use as the final match. Available values are:
none
No final matching based on combed scores.
sc Combed scores are only used when a scene change is detected.
full
Use combed scores all the time.
Default is sc.
combdbg
Force "fieldmatch" to calculate the combed metrics for certain matches and print them.
This setting is known as micout in TFM/VFM vocabulary. Available values are:
none
No forced calculation.
pcn Force p/c/n calculations.
pcnub
Force p/c/n/u/b calculations.
Default value is none.
cthresh
This is the area combing threshold used for combed frame detection. This essentially
controls how "strong" or "visible" combing must be to be detected. Larger values mean
combing must be more visible and smaller values mean combing can be less visible or
strong and still be detected. Valid settings are from "-1" (every pixel will be
detected as combed) to 255 (no pixel will be detected as combed). This is basically a
pixel difference value. A good range is "[8, 12]".
Default value is 9.
chroma
Sets whether or not chroma is considered in the combed frame decision. Only disable
this if your source has chroma problems (rainbowing, etc.) that are causing problems
for the combed frame detection with chroma enabled. Actually, using chroma=0 is
usually more reliable, except for the case where there is chroma only combing in the
source.
Default value is 0.
blockx
blocky
Respectively set the x-axis and y-axis size of the window used during combed frame
detection. This has to do with the size of the area in which combpel pixels are
required to be detected as combed for a frame to be declared combed. See the combpel
parameter description for more info. Possible values are any number that is a power
of 2 starting at 4 and going up to 512.
Default value is 16.
combpel
The number of combed pixels inside any of the blocky by blockx size blocks on the
frame for the frame to be detected as combed. While cthresh controls how "visible" the
combing must be, this setting controls "how much" combing there must be in any
localized area (a window defined by the blockx and blocky settings) on the frame.
Minimum value is 0 and maximum is "blocky x blockx" (at which point no frames will
ever be detected as combed). This setting is known as MI in TFM/VFM vocabulary.
Default value is 80.
p/c/n/u/b meaning
p/c/n
We assume the following telecined stream:
Top fields: 1 2 2 3 4
Bottom fields: 1 2 3 4 4
The numbers correspond to the progressive frame the fields relate to. Here, the first two
frames are progressive, the 3rd and 4th are combed, and so on.
When "fieldmatch" is configured to run a matching from bottom (field=bottom) this is how
this input stream get transformed:
Input stream:
T 1 2 2 3 4
B 1 2 3 4 4 <-- matching reference
Matches: c c n n c
Output stream:
T 1 2 3 4 4
B 1 2 3 4 4
As a result of the field matching, we can see that some frames get duplicated. To perform
a complete inverse telecine, you need to rely on a decimation filter after this operation.
See for instance the decimate filter.
The same operation now matching from top fields (field=top) looks like this:
Input stream:
T 1 2 2 3 4 <-- matching reference
B 1 2 3 4 4
Matches: c c p p c
Output stream:
T 1 2 2 3 4
B 1 2 2 3 4
In these examples, we can see what p, c and n mean; basically, they refer to the frame and
field of the opposite parity:
*<p matches the field of the opposite parity in the previous frame>
*<c matches the field of the opposite parity in the current frame>
*<n matches the field of the opposite parity in the next frame>
u/b
The u and b matching are a bit special in the sense that they match from the opposite
parity flag. In the following examples, we assume that we are currently matching the 2nd
frame (Top:2, bottom:2). According to the match, a 'x' is placed above and below each
matched fields.
With bottom matching (field=bottom):
Match: c p n b u
x x x x x
Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
x x x x x
Output frames:
2 1 2 2 2
2 2 2 1 3
With top matching (field=top):
Match: c p n b u
x x x x x
Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2
Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
x x x x x
Output frames:
2 2 2 1 2
2 1 3 2 2
Examples
Simple IVTC of a top field first telecined stream:
fieldmatch=order=tff:combmatch=none, decimate
Advanced IVTC, with fallback on yadif for still combed frames:
fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate
fieldorder
Transform the field order of the input video.
It accepts the following parameters:
order
The output field order. Valid values are tff for top field first or bff for bottom
field first.
The default value is tff.
The transformation is done by shifting the picture content up or down by one line, and
filling the remaining line with appropriate picture content. This method is consistent
with most broadcast field order converters.
If the input video is not flagged as being interlaced, or it is already flagged as being
of the required output field order, then this filter does not alter the incoming video.
It is very useful when converting to or from PAL DV material, which is bottom field first.
For example:
ffmpeg -i in.vob -vf "fieldorder=bff" out.dv
fifo, afifo
Buffer input images and send them when they are requested.
It is mainly useful when auto-inserted by the libavfilter framework.
It does not take parameters.
fillborders
Fill borders of the input video, without changing video stream dimensions. Sometimes
video can have garbage at the four edges and you may not want to crop video input to keep
size multiple of some number.
This filter accepts the following options:
left
Number of pixels to fill from left border.
right
Number of pixels to fill from right border.
top Number of pixels to fill from top border.
bottom
Number of pixels to fill from bottom border.
mode
Set fill mode.
It accepts the following values:
smear
fill pixels using outermost pixels
mirror
fill pixels using mirroring
fixed
fill pixels with constant value
Default is smear.
color
Set color for pixels in fixed mode. Default is black.
find_rect
Find a rectangular object
It accepts the following options:
object
Filepath of the object image, needs to be in gray8.
threshold
Detection threshold, default is 0.5.
mipmaps
Number of mipmaps, default is 3.
xmin, ymin, xmax, ymax
Specifies the rectangle in which to search.
Examples
• Cover a rectangular object by the supplied image of a given video using ffmpeg:
ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
cover_rect
Cover a rectangular object
It accepts the following options:
cover
Filepath of the optional cover image, needs to be in yuv420.
mode
Set covering mode.
It accepts the following values:
cover
cover it by the supplied image
blur
cover it by interpolating the surrounding pixels
Default value is blur.
Examples
• Cover a rectangular object by the supplied image of a given video using ffmpeg:
ffmpeg -i file.ts -vf find_rect=newref.pgm,cover_rect=cover.jpg:mode=cover new.mkv
floodfill
Flood area with values of same pixel components with another values.
It accepts the following options:
x Set pixel x coordinate.
y Set pixel y coordinate.
s0 Set source #0 component value.
s1 Set source #1 component value.
s2 Set source #2 component value.
s3 Set source #3 component value.
d0 Set destination #0 component value.
d1 Set destination #1 component value.
d2 Set destination #2 component value.
d3 Set destination #3 component value.
format
Convert the input video to one of the specified pixel formats. Libavfilter will try to
pick one that is suitable as input to the next filter.
It accepts the following parameters:
pix_fmts
A '|'-separated list of pixel format names, such as "pix_fmts=yuv420p|monow|rgb24".
Examples
• Convert the input video to the yuv420p format
format=pix_fmts=yuv420p
Convert the input video to any of the formats in the list
format=pix_fmts=yuv420p|yuv444p|yuv410p
fps
Convert the video to specified constant frame rate by duplicating or dropping frames as
necessary.
It accepts the following parameters:
fps The desired output frame rate. The default is 25.
start_time
Assume the first PTS should be the given value, in seconds. This allows for
padding/trimming at the start of stream. By default, no assumption is made about the
first frame's expected PTS, so no padding or trimming is done. For example, this
could be set to 0 to pad the beginning with duplicates of the first frame if a video
stream starts after the audio stream or to trim any frames with a negative PTS.
round
Timestamp (PTS) rounding method.
Possible values are:
zero
round towards 0
inf round away from 0
down
round towards -infinity
up round towards +infinity
near
round to nearest
The default is "near".
eof_action
Action performed when reading the last frame.
Possible values are:
round
Use same timestamp rounding method as used for other frames.
pass
Pass through last frame if input duration has not been reached yet.
The default is "round".
Alternatively, the options can be specified as a flat string: fps[:start_time[:round]].
See also the setpts filter.
Examples
• A typical usage in order to set the fps to 25:
fps=fps=25
• Sets the fps to 24, using abbreviation and rounding method to round to nearest:
fps=fps=film:round=near
framepack
Pack two different video streams into a stereoscopic video, setting proper metadata on
supported codecs. The two views should have the same size and framerate and processing
will stop when the shorter video ends. Please note that you may conveniently adjust view
properties with the scale and fps filters.
It accepts the following parameters:
format
The desired packing format. Supported values are:
sbs The views are next to each other (default).
tab The views are on top of each other.
lines
The views are packed by line.
columns
The views are packed by column.
frameseq
The views are temporally interleaved.
Some examples:
# Convert left and right views into a frame-sequential video
ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT
# Convert views into a side-by-side video with the same output resolution as the input
ffmpeg -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT
framerate
Change the frame rate by interpolating new video output frames from the source frames.
This filter is not designed to function correctly with interlaced media. If you wish to
change the frame rate of interlaced media then you are required to deinterlace before this
filter and re-interlace after this filter.
A description of the accepted options follows.
fps Specify the output frames per second. This option can also be specified as a value
alone. The default is 50.
interp_start
Specify the start of a range where the output frame will be created as a linear
interpolation of two frames. The range is [0-255], the default is 15.
interp_end
Specify the end of a range where the output frame will be created as a linear
interpolation of two frames. The range is [0-255], the default is 240.
scene
Specify the level at which a scene change is detected as a value between 0 and 100 to
indicate a new scene; a low value reflects a low probability for the current frame to
introduce a new scene, while a higher value means the current frame is more likely to
be one. The default is 8.2.
flags
Specify flags influencing the filter process.
Available value for flags is:
scene_change_detect, scd
Enable scene change detection using the value of the option scene. This flag is
enabled by default.
framestep
Select one frame every N-th frame.
This filter accepts the following option:
step
Select frame after every "step" frames. Allowed values are positive integers higher
than 0. Default value is 1.
freezedetect
Detect frozen video.
This filter logs a message and sets frame metadata when it detects that the input video
has no significant change in content during a specified duration. Video freeze detection
calculates the mean average absolute difference of all the components of video frames and
compares it to a noise floor.
The printed times and duration are expressed in seconds. The
"lavfi.freezedetect.freeze_start" metadata key is set on the first frame whose timestamp
equals or exceeds the detection duration and it contains the timestamp of the first frame
of the freeze. The "lavfi.freezedetect.freeze_duration" and
"lavfi.freezedetect.freeze_end" metadata keys are set on the first frame after the freeze.
The filter accepts the following options:
noise, n
Set noise tolerance. Can be specified in dB (in case "dB" is appended to the specified
value) or as a difference ratio between 0 and 1. Default is -60dB, or 0.001.
duration, d
Set freeze duration until notification (default is 2 seconds).
frei0r
Apply a frei0r effect to the input video.
To enable the compilation of this filter, you need to install the frei0r header and
configure FFmpeg with "--enable-frei0r".
It accepts the following parameters:
filter_name
The name of the frei0r effect to load. If the environment variable FREI0R_PATH is
defined, the frei0r effect is searched for in each of the directories specified by the
colon-separated list in FREI0R_PATH. Otherwise, the standard frei0r paths are
searched, in this order: HOME/.frei0r-1/lib/, /usr/local/lib/frei0r-1/,
/usr/lib/frei0r-1/.
filter_params
A '|'-separated list of parameters to pass to the frei0r effect.
A frei0r effect parameter can be a boolean (its value is either "y" or "n"), a double, a
color (specified as R/G/B, where R, G, and B are floating point numbers between 0.0 and
1.0, inclusive) or a color description as specified in the "Color" section in the ffmpeg-
utils manual, a position (specified as X/Y, where X and Y are floating point numbers)
and/or a string.
The number and types of parameters depend on the loaded effect. If an effect parameter is
not specified, the default value is set.
Examples
• Apply the distort0r effect, setting the first two double parameters:
frei0r=filter_name=distort0r:filter_params=0.5|0.01
• Apply the colordistance effect, taking a color as the first parameter:
frei0r=colordistance:0.2/0.3/0.4
frei0r=colordistance:violet
frei0r=colordistance:0x112233
• Apply the perspective effect, specifying the top left and top right image positions:
frei0r=perspective:0.2/0.2|0.8/0.2
For more information, see <http://frei0r.dyne.org>
fspp
Apply fast and simple postprocessing. It is a faster version of spp.
It splits (I)DCT into horizontal/vertical passes. Unlike the simple post- processing
filter, one of them is performed once per block, not per pixel. This allows for much
higher speed.
The filter accepts the following options:
quality
Set quality. This option defines the number of levels for averaging. It accepts an
integer in the range 4-5. Default value is 4.
qp Force a constant quantization parameter. It accepts an integer in range 0-63. If not
set, the filter will use the QP from the video stream (if available).
strength
Set filter strength. It accepts an integer in range -15 to 32. Lower values mean more
details but also more artifacts, while higher values make the image smoother but also
blurrier. Default value is 0 X PSNR optimal.
use_bframe_qp
Enable the use of the QP from the B-Frames if set to 1. Using this option may cause
flicker since the B-Frames have often larger QP. Default is 0 (not enabled).
gblur
Apply Gaussian blur filter.
The filter accepts the following options:
sigma
Set horizontal sigma, standard deviation of Gaussian blur. Default is 0.5.
steps
Set number of steps for Gaussian approximation. Default is 1.
planes
Set which planes to filter. By default all planes are filtered.
sigmaV
Set vertical sigma, if negative it will be same as "sigma". Default is "-1".
geq
Apply generic equation to each pixel.
The filter accepts the following options:
lum_expr, lum
Set the luminance expression.
cb_expr, cb
Set the chrominance blue expression.
cr_expr, cr
Set the chrominance red expression.
alpha_expr, a
Set the alpha expression.
red_expr, r
Set the red expression.
green_expr, g
Set the green expression.
blue_expr, b
Set the blue expression.
The colorspace is selected according to the specified options. If one of the lum_expr,
cb_expr, or cr_expr options is specified, the filter will automatically select a YCbCr
colorspace. If one of the red_expr, green_expr, or blue_expr options is specified, it will
select an RGB colorspace.
If one of the chrominance expression is not defined, it falls back on the other one. If no
alpha expression is specified it will evaluate to opaque value. If none of chrominance
expressions are specified, they will evaluate to the luminance expression.
The expressions can use the following variables and functions:
N The sequential number of the filtered frame, starting from 0.
X
Y The coordinates of the current sample.
W
H The width and height of the image.
SW
SH Width and height scale depending on the currently filtered plane. It is the ratio
between the corresponding luma plane number of pixels and the current plane ones. E.g.
for YUV4:2:0 the values are "1,1" for the luma plane, and "0.5,0.5" for chroma planes.
T Time of the current frame, expressed in seconds.
p(x, y)
Return the value of the pixel at location (x,y) of the current plane.
lum(x, y)
Return the value of the pixel at location (x,y) of the luminance plane.
cb(x, y)
Return the value of the pixel at location (x,y) of the blue-difference chroma plane.
Return 0 if there is no such plane.
cr(x, y)
Return the value of the pixel at location (x,y) of the red-difference chroma plane.
Return 0 if there is no such plane.
r(x, y)
g(x, y)
b(x, y)
Return the value of the pixel at location (x,y) of the red/green/blue component.
Return 0 if there is no such component.
alpha(x, y)
Return the value of the pixel at location (x,y) of the alpha plane. Return 0 if there
is no such plane.
For functions, if x and y are outside the area, the value will be automatically clipped to
the closer edge.
Examples
• Flip the image horizontally:
geq=p(W-X\,Y)
• Generate a bidimensional sine wave, with angle "PI/3" and a wavelength of 100 pixels:
geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128
• Generate a fancy enigmatic moving light:
nullsrc=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128
• Generate a quick emboss effect:
format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2'
• Modify RGB components depending on pixel position:
geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)'
• Create a radial gradient that is the same size as the input (also see the vignette
filter):
geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray
gradfun
Fix the banding artifacts that are sometimes introduced into nearly flat regions by
truncation to 8-bit color depth. Interpolate the gradients that should go where the bands
are, and dither them.
It is designed for playback only. Do not use it prior to lossy compression, because
compression tends to lose the dither and bring back the bands.
It accepts the following parameters:
strength
The maximum amount by which the filter will change any one pixel. This is also the
threshold for detecting nearly flat regions. Acceptable values range from .51 to 64;
the default value is 1.2. Out-of-range values will be clipped to the valid range.
radius
The neighborhood to fit the gradient to. A larger radius makes for smoother gradients,
but also prevents the filter from modifying the pixels near detailed regions.
Acceptable values are 8-32; the default value is 16. Out-of-range values will be
clipped to the valid range.
Alternatively, the options can be specified as a flat string: strength[:radius]
Examples
• Apply the filter with a 3.5 strength and radius of 8:
gradfun=3.5:8
• Specify radius, omitting the strength (which will fall-back to the default value):
gradfun=radius=8
graphmonitor, agraphmonitor
Show various filtergraph stats.
With this filter one can debug complete filtergraph. Especially issues with links filling
with queued frames.
The filter accepts the following options:
size, s
Set video output size. Default is hd720.
opacity, o
Set video opacity. Default is 0.9. Allowed range is from 0 to 1.
mode, m
Set output mode, can be fulll or compact. In compact mode only filters with some
queued frames have displayed stats.
flags, f
Set flags which enable which stats are shown in video.
Available values for flags are:
queue
Display number of queued frames in each link.
frame_count_in
Display number of frames taken from filter.
frame_count_out
Display number of frames given out from filter.
pts Display current filtered frame pts.
time
Display current filtered frame time.
timebase
Display time base for filter link.
format
Display used format for filter link.
size
Display video size or number of audio channels in case of audio used by filter
link.
rate
Display video frame rate or sample rate in case of audio used by filter link.
rate, r
Set upper limit for video rate of output stream, Default value is 25. This guarantee
that output video frame rate will not be higher than this value.
greyedge
A color constancy variation filter which estimates scene illumination via grey edge
algorithm and corrects the scene colors accordingly.
See: <https://staff.science.uva.nl/th.gevers/pub/GeversTIP07.pdf>
The filter accepts the following options:
difford
The order of differentiation to be applied on the scene. Must be chosen in the range
[0,2] and default value is 1.
minknorm
The Minkowski parameter to be used for calculating the Minkowski distance. Must be
chosen in the range [0,20] and default value is 1. Set to 0 for getting max value
instead of calculating Minkowski distance.
sigma
The standard deviation of Gaussian blur to be applied on the scene. Must be chosen in
the range [0,1024.0] and default value = 1. floor( sigma * break_off_sigma(3) ) can't
be equal to 0 if difford is greater than 0.
Examples
• Grey Edge:
greyedge=difford=1:minknorm=5:sigma=2
• Max Edge:
greyedge=difford=1:minknorm=0:sigma=2
haldclut
Apply a Hald CLUT to a video stream.
First input is the video stream to process, and second one is the Hald CLUT. The Hald
CLUT input can be a simple picture or a complete video stream.
The filter accepts the following options:
shortest
Force termination when the shortest input terminates. Default is 0.
repeatlast
Continue applying the last CLUT after the end of the stream. A value of 0 disable the
filter after the last frame of the CLUT is reached. Default is 1.
"haldclut" also has the same interpolation options as lut3d (both filters share the same
internals).
This filter also supports the framesync options.
More information about the Hald CLUT can be found on Eskil Steenberg's website (Hald CLUT
author) at <http://www.quelsolaar.com/technology/clut.html>.
Workflow examples
Hald CLUT video stream
Generate an identity Hald CLUT stream altered with various effects:
ffmpeg -f lavfi -i B<haldclutsrc>=8 -vf "hue=H=2*PI*t:s=sin(2*PI*t)+1, curves=cross_process" -t 10 -c:v ffv1 clut.nut
Note: make sure you use a lossless codec.
Then use it with "haldclut" to apply it on some random stream:
ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv
The Hald CLUT will be applied to the 10 first seconds (duration of clut.nut), then the
latest picture of that CLUT stream will be applied to the remaining frames of the
"mandelbrot" stream.
Hald CLUT with preview
A Hald CLUT is supposed to be a squared image of "Level*Level*Level" by
"Level*Level*Level" pixels. For a given Hald CLUT, FFmpeg will select the biggest possible
square starting at the top left of the picture. The remaining padding pixels (bottom or
right) will be ignored. This area can be used to add a preview of the Hald CLUT.
Typically, the following generated Hald CLUT will be supported by the "haldclut" filter:
ffmpeg -f lavfi -i B<haldclutsrc>=8 -vf "
pad=iw+320 [padded_clut];
smptebars=s=320x256, split [a][b];
[padded_clut][a] overlay=W-320:h, curves=color_negative [main];
[main][b] overlay=W-320" -frames:v 1 clut.png
It contains the original and a preview of the effect of the CLUT: SMPTE color bars are
displayed on the right-top, and below the same color bars processed by the color changes.
Then, the effect of this Hald CLUT can be visualized with:
ffplay input.mkv -vf "movie=clut.png, [in] haldclut"
hflip
Flip the input video horizontally.
For example, to horizontally flip the input video with ffmpeg:
ffmpeg -i in.avi -vf "hflip" out.avi
histeq
This filter applies a global color histogram equalization on a per-frame basis.
It can be used to correct video that has a compressed range of pixel intensities. The
filter redistributes the pixel intensities to equalize their distribution across the
intensity range. It may be viewed as an "automatically adjusting contrast filter". This
filter is useful only for correcting degraded or poorly captured source video.
The filter accepts the following options:
strength
Determine the amount of equalization to be applied. As the strength is reduced, the
distribution of pixel intensities more-and-more approaches that of the input frame.
The value must be a float number in the range [0,1] and defaults to 0.200.
intensity
Set the maximum intensity that can generated and scale the output values
appropriately. The strength should be set as desired and then the intensity can be
limited if needed to avoid washing-out. The value must be a float number in the range
[0,1] and defaults to 0.210.
antibanding
Set the antibanding level. If enabled the filter will randomly vary the luminance of
output pixels by a small amount to avoid banding of the histogram. Possible values are
"none", "weak" or "strong". It defaults to "none".
histogram
Compute and draw a color distribution histogram for the input video.
The computed histogram is a representation of the color component distribution in an
image.
Standard histogram displays the color components distribution in an image. Displays color
graph for each color component. Shows distribution of the Y, U, V, A or R, G, B
components, depending on input format, in the current frame. Below each graph a color
component scale meter is shown.
The filter accepts the following options:
level_height
Set height of level. Default value is 200. Allowed range is [50, 2048].
scale_height
Set height of color scale. Default value is 12. Allowed range is [0, 40].
display_mode
Set display mode. It accepts the following values:
stack
Per color component graphs are placed below each other.
parade
Per color component graphs are placed side by side.
overlay
Presents information identical to that in the "parade", except that the graphs
representing color components are superimposed directly over one another.
Default is "stack".
levels_mode
Set mode. Can be either "linear", or "logarithmic". Default is "linear".
components
Set what color components to display. Default is 7.
fgopacity
Set foreground opacity. Default is 0.7.
bgopacity
Set background opacity. Default is 0.5.
Examples
• Calculate and draw histogram:
ffplay -i input -vf histogram
hqdn3d
This is a high precision/quality 3d denoise filter. It aims to reduce image noise,
producing smooth images and making still images really still. It should enhance
compressibility.
It accepts the following optional parameters:
luma_spatial
A non-negative floating point number which specifies spatial luma strength. It
defaults to 4.0.
chroma_spatial
A non-negative floating point number which specifies spatial chroma strength. It
defaults to 3.0*luma_spatial/4.0.
luma_tmp
A floating point number which specifies luma temporal strength. It defaults to
6.0*luma_spatial/4.0.
chroma_tmp
A floating point number which specifies chroma temporal strength. It defaults to
luma_tmp*chroma_spatial/luma_spatial.
hwdownload
Download hardware frames to system memory.
The input must be in hardware frames, and the output a non-hardware format. Not all
formats will be supported on the output - it may be necessary to insert an additional
format filter immediately following in the graph to get the output in a supported format.
hwmap
Map hardware frames to system memory or to another device.
This filter has several different modes of operation; which one is used depends on the
input and output formats:
• Hardware frame input, normal frame output
Map the input frames to system memory and pass them to the output. If the original
hardware frame is later required (for example, after overlaying something else on part
of it), the hwmap filter can be used again in the next mode to retrieve it.
• Normal frame input, hardware frame output
If the input is actually a software-mapped hardware frame, then unmap it - that is,
return the original hardware frame.
Otherwise, a device must be provided. Create new hardware surfaces on that device for
the output, then map them back to the software format at the input and give those
frames to the preceding filter. This will then act like the hwupload filter, but may
be able to avoid an additional copy when the input is already in a compatible format.
• Hardware frame input and output
A device must be supplied for the output, either directly or with the derive_device
option. The input and output devices must be of different types and compatible - the
exact meaning of this is system-dependent, but typically it means that they must refer
to the same underlying hardware context (for example, refer to the same graphics
card).
If the input frames were originally created on the output device, then unmap to
retrieve the original frames.
Otherwise, map the frames to the output device - create new hardware frames on the
output corresponding to the frames on the input.
The following additional parameters are accepted:
mode
Set the frame mapping mode. Some combination of:
read
The mapped frame should be readable.
write
The mapped frame should be writeable.
overwrite
The mapping will always overwrite the entire frame.
This may improve performance in some cases, as the original contents of the frame
need not be loaded.
direct
The mapping must not involve any copying.
Indirect mappings to copies of frames are created in some cases where either
direct mapping is not possible or it would have unexpected properties. Setting
this flag ensures that the mapping is direct and will fail if that is not
possible.
Defaults to read+write if not specified.
derive_device type
Rather than using the device supplied at initialisation, instead derive a new device
of type type from the device the input frames exist on.
reverse
In a hardware to hardware mapping, map in reverse - create frames in the sink and map
them back to the source. This may be necessary in some cases where a mapping in one
direction is required but only the opposite direction is supported by the devices
being used.
This option is dangerous - it may break the preceding filter in undefined ways if
there are any additional constraints on that filter's output. Do not use it without
fully understanding the implications of its use.
hwupload
Upload system memory frames to hardware surfaces.
The device to upload to must be supplied when the filter is initialised. If using ffmpeg,
select the appropriate device with the -filter_hw_device option.
hwupload_cuda
Upload system memory frames to a CUDA device.
It accepts the following optional parameters:
device
The number of the CUDA device to use
hqx
Apply a high-quality magnification filter designed for pixel art. This filter was
originally created by Maxim Stepin.
It accepts the following option:
n Set the scaling dimension: 2 for "hq2x", 3 for "hq3x" and 4 for "hq4x". Default is 3.
hstack
Stack input videos horizontally.
All streams must be of same pixel format and of same height.
Note that this filter is faster than using overlay and pad filter to create same output.
The filter accept the following option:
inputs
Set number of input streams. Default is 2.
shortest
If set to 1, force the output to terminate when the shortest input terminates. Default
value is 0.
hue
Modify the hue and/or the saturation of the input.
It accepts the following parameters:
h Specify the hue angle as a number of degrees. It accepts an expression, and defaults
to "0".
s Specify the saturation in the [-10,10] range. It accepts an expression and defaults to
"1".
H Specify the hue angle as a number of radians. It accepts an expression, and defaults
to "0".
b Specify the brightness in the [-10,10] range. It accepts an expression and defaults to
"0".
h and H are mutually exclusive, and can't be specified at the same time.
The b, h, H and s option values are expressions containing the following constants:
n frame count of the input frame starting from 0
pts presentation timestamp of the input frame expressed in time base units
r frame rate of the input video, NAN if the input frame rate is unknown
t timestamp expressed in seconds, NAN if the input timestamp is unknown
tb time base of the input video
Examples
• Set the hue to 90 degrees and the saturation to 1.0:
hue=h=90:s=1
• Same command but expressing the hue in radians:
hue=H=PI/2:s=1
• Rotate hue and make the saturation swing between 0 and 2 over a period of 1 second:
hue="H=2*PI*t: s=sin(2*PI*t)+1"
• Apply a 3 seconds saturation fade-in effect starting at 0:
hue="s=min(t/3\,1)"
The general fade-in expression can be written as:
hue="s=min(0\, max((t-START)/DURATION\, 1))"
• Apply a 3 seconds saturation fade-out effect starting at 5 seconds:
hue="s=max(0\, min(1\, (8-t)/3))"
The general fade-out expression can be written as:
hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))"
Commands
This filter supports the following commands:
b
s
h
H Modify the hue and/or the saturation and/or brightness of the input video. The
command accepts the same syntax of the corresponding option.
If the specified expression is not valid, it is kept at its current value.
hysteresis
Grow first stream into second stream by connecting components. This makes it possible to
build more robust edge masks.
This filter accepts the following options:
planes
Set which planes will be processed as bitmap, unprocessed planes will be copied from
first stream. By default value 0xf, all planes will be processed.
threshold
Set threshold which is used in filtering. If pixel component value is higher than this
value filter algorithm for connecting components is activated. By default value is 0.
idet
Detect video interlacing type.
This filter tries to detect if the input frames are interlaced, progressive, top or bottom
field first. It will also try to detect fields that are repeated between adjacent frames
(a sign of telecine).
Single frame detection considers only immediately adjacent frames when classifying each
frame. Multiple frame detection incorporates the classification history of previous
frames.
The filter will log these metadata values:
single.current_frame
Detected type of current frame using single-frame detection. One of: ``tff'' (top
field first), ``bff'' (bottom field first), ``progressive'', or ``undetermined''
single.tff
Cumulative number of frames detected as top field first using single-frame detection.
multiple.tff
Cumulative number of frames detected as top field first using multiple-frame
detection.
single.bff
Cumulative number of frames detected as bottom field first using single-frame
detection.
multiple.current_frame
Detected type of current frame using multiple-frame detection. One of: ``tff'' (top
field first), ``bff'' (bottom field first), ``progressive'', or ``undetermined''
multiple.bff
Cumulative number of frames detected as bottom field first using multiple-frame
detection.
single.progressive
Cumulative number of frames detected as progressive using single-frame detection.
multiple.progressive
Cumulative number of frames detected as progressive using multiple-frame detection.
single.undetermined
Cumulative number of frames that could not be classified using single-frame detection.
multiple.undetermined
Cumulative number of frames that could not be classified using multiple-frame
detection.
repeated.current_frame
Which field in the current frame is repeated from the last. One of ``neither'',
``top'', or ``bottom''.
repeated.neither
Cumulative number of frames with no repeated field.
repeated.top
Cumulative number of frames with the top field repeated from the previous frame's top
field.
repeated.bottom
Cumulative number of frames with the bottom field repeated from the previous frame's
bottom field.
The filter accepts the following options:
intl_thres
Set interlacing threshold.
prog_thres
Set progressive threshold.
rep_thres
Threshold for repeated field detection.
half_life
Number of frames after which a given frame's contribution to the statistics is halved
(i.e., it contributes only 0.5 to its classification). The default of 0 means that all
frames seen are given full weight of 1.0 forever.
analyze_interlaced_flag
When this is not 0 then idet will use the specified number of frames to determine if
the interlaced flag is accurate, it will not count undetermined frames. If the flag
is found to be accurate it will be used without any further computations, if it is
found to be inaccurate it will be cleared without any further computations. This
allows inserting the idet filter as a low computational method to clean up the
interlaced flag
il
Deinterleave or interleave fields.
This filter allows one to process interlaced images fields without deinterlacing them.
Deinterleaving splits the input frame into 2 fields (so called half pictures). Odd lines
are moved to the top half of the output image, even lines to the bottom half. You can
process (filter) them independently and then re-interleave them.
The filter accepts the following options:
luma_mode, l
chroma_mode, c
alpha_mode, a
Available values for luma_mode, chroma_mode and alpha_mode are:
none
Do nothing.
deinterleave, d
Deinterleave fields, placing one above the other.
interleave, i
Interleave fields. Reverse the effect of deinterleaving.
Default value is "none".
luma_swap, ls
chroma_swap, cs
alpha_swap, as
Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is 0.
inflate
Apply inflate effect to the video.
This filter replaces the pixel by the local(3x3) average by taking into account only
values higher than the pixel.
It accepts the following options:
threshold0
threshold1
threshold2
threshold3
Limit the maximum change for each plane, default is 65535. If 0, plane will remain
unchanged.
interlace
Simple interlacing filter from progressive contents. This interleaves upper (or lower)
lines from odd frames with lower (or upper) lines from even frames, halving the frame rate
and preserving image height.
Original Original New Frame
Frame 'j' Frame 'j+1' (tff)
========== =========== ==================
Line 0 --------------------> Frame 'j' Line 0
Line 1 Line 1 ----> Frame 'j+1' Line 1
Line 2 ---------------------> Frame 'j' Line 2
Line 3 Line 3 ----> Frame 'j+1' Line 3
... ... ...
New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on
It accepts the following optional parameters:
scan
This determines whether the interlaced frame is taken from the even (tff - default) or
odd (bff) lines of the progressive frame.
lowpass
Vertical lowpass filter to avoid twitter interlacing and reduce moire patterns.
0, off
Disable vertical lowpass filter
1, linear
Enable linear filter (default)
2, complex
Enable complex filter. This will slightly less reduce twitter and moire but better
retain detail and subjective sharpness impression.
kerndeint
Deinterlace input video by applying Donald Graft's adaptive kernel deinterling. Work on
interlaced parts of a video to produce progressive frames.
The description of the accepted parameters follows.
thresh
Set the threshold which affects the filter's tolerance when determining if a pixel
line must be processed. It must be an integer in the range [0,255] and defaults to 10.
A value of 0 will result in applying the process on every pixels.
map Paint pixels exceeding the threshold value to white if set to 1. Default is 0.
order
Set the fields order. Swap fields if set to 1, leave fields alone if 0. Default is 0.
sharp
Enable additional sharpening if set to 1. Default is 0.
twoway
Enable twoway sharpening if set to 1. Default is 0.
Examples
• Apply default values:
kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0
• Enable additional sharpening:
kerndeint=sharp=1
• Paint processed pixels in white:
kerndeint=map=1
lagfun
Slowly update darker pixels.
This filter makes short flashes of light appear longer. This filter accepts the following
options:
decay
Set factor for decaying. Default is .95. Allowed range is from 0 to 1.
planes
Set which planes to filter. Default is all. Allowed range is from 0 to 15.
lenscorrection
Correct radial lens distortion
This filter can be used to correct for radial distortion as can result from the use of
wide angle lenses, and thereby re-rectify the image. To find the right parameters one can
use tools available for example as part of opencv or simply trial-and-error. To use
opencv use the calibration sample (under samples/cpp) from the opencv sources and extract
the k1 and k2 coefficients from the resulting matrix.
Note that effectively the same filter is available in the open-source tools Krita and
Digikam from the KDE project.
In contrast to the vignette filter, which can also be used to compensate lens errors, this
filter corrects the distortion of the image, whereas vignette corrects the brightness
distribution, so you may want to use both filters together in certain cases, though you
will have to take care of ordering, i.e. whether vignetting should be applied before or
after lens correction.
Options
The filter accepts the following options:
cx Relative x-coordinate of the focal point of the image, and thereby the center of the
distortion. This value has a range [0,1] and is expressed as fractions of the image
width. Default is 0.5.
cy Relative y-coordinate of the focal point of the image, and thereby the center of the
distortion. This value has a range [0,1] and is expressed as fractions of the image
height. Default is 0.5.
k1 Coefficient of the quadratic correction term. This value has a range [-1,1]. 0 means
no correction. Default is 0.
k2 Coefficient of the double quadratic correction term. This value has a range [-1,1]. 0
means no correction. Default is 0.
The formula that generates the correction is:
r_src = r_tgt * (1 + k1 * (r_tgt / r_0)^2 + k2 * (r_tgt / r_0)^4)
where r_0 is halve of the image diagonal and r_src and r_tgt are the distances from the
focal point in the source and target images, respectively.
lensfun
Apply lens correction via the lensfun library (<http://lensfun.sourceforge.net/>).
The "lensfun" filter requires the camera make, camera model, and lens model to apply the
lens correction. The filter will load the lensfun database and query it to find the
corresponding camera and lens entries in the database. As long as these entries can be
found with the given options, the filter can perform corrections on frames. Note that
incomplete strings will result in the filter choosing the best match with the given
options, and the filter will output the chosen camera and lens models (logged with level
"info"). You must provide the make, camera model, and lens model as they are required.
The filter accepts the following options:
make
The make of the camera (for example, "Canon"). This option is required.
model
The model of the camera (for example, "Canon EOS 100D"). This option is required.
lens_model
The model of the lens (for example, "Canon EF-S 18-55mm f/3.5-5.6 IS STM"). This
option is required.
mode
The type of correction to apply. The following values are valid options:
vignetting
Enables fixing lens vignetting.
geometry
Enables fixing lens geometry. This is the default.
subpixel
Enables fixing chromatic aberrations.
vig_geo
Enables fixing lens vignetting and lens geometry.
vig_subpixel
Enables fixing lens vignetting and chromatic aberrations.
distortion
Enables fixing both lens geometry and chromatic aberrations.
all Enables all possible corrections.
focal_length
The focal length of the image/video (zoom; expected constant for video). For example,
a 18--55mm lens has focal length range of [18--55], so a value in that range should be
chosen when using that lens. Default 18.
aperture
The aperture of the image/video (expected constant for video). Note that aperture is
only used for vignetting correction. Default 3.5.
focus_distance
The focus distance of the image/video (expected constant for video). Note that focus
distance is only used for vignetting and only slightly affects the vignetting
correction process. If unknown, leave it at the default value (which is 1000).
scale
The scale factor which is applied after transformation. After correction the video is
no longer necessarily rectangular. This parameter controls how much of the resulting
image is visible. The value 0 means that a value will be chosen automatically such
that there is little or no unmapped area in the output image. 1.0 means that no
additional scaling is done. Lower values may result in more of the corrected image
being visible, while higher values may avoid unmapped areas in the output.
target_geometry
The target geometry of the output image/video. The following values are valid options:
rectilinear (default)
fisheye
panoramic
equirectangular
fisheye_orthographic
fisheye_stereographic
fisheye_equisolid
fisheye_thoby
reverse
Apply the reverse of image correction (instead of correcting distortion, apply it).
interpolation
The type of interpolation used when correcting distortion. The following values are
valid options:
nearest
linear (default)
lanczos
Examples
• Apply lens correction with make "Canon", camera model "Canon EOS 100D", and lens model
"Canon EF-S 18-55mm f/3.5-5.6 IS STM" with focal length of "18" and aperture of "8.0".
ffmpeg -i input.mov -vf lensfun=make=Canon:model="Canon EOS 100D":lens_model="Canon EF-S 18-55mm f/3.5-5.6 IS STM":focal_length=18:aperture=8 -c:v h264 -b:v 8000k output.mov
• Apply the same as before, but only for the first 5 seconds of video.
ffmpeg -i input.mov -vf lensfun=make=Canon:model="Canon EOS 100D":lens_model="Canon EF-S 18-55mm f/3.5-5.6 IS STM":focal_length=18:aperture=8:enable='lte(t\,5)' -c:v h264 -b:v 8000k output.mov
libvmaf
Obtain the VMAF (Video Multi-Method Assessment Fusion) score between two input videos.
The obtained VMAF score is printed through the logging system.
It requires Netflix's vmaf library (libvmaf) as a pre-requisite. After installing the
library it can be enabled using: "./configure --enable-libvmaf --enable-version3". If no
model path is specified it uses the default model: "vmaf_v0.6.1.pkl".
The filter has following options:
model_path
Set the model path which is to be used for SVM. Default value: "vmaf_v0.6.1.pkl"
log_path
Set the file path to be used to store logs.
log_fmt
Set the format of the log file (xml or json).
enable_transform
This option can enable/disable the "score_transform" applied to the final predicted
VMAF score, if you have specified score_transform option in the input parameter file
passed to "run_vmaf_training.py" Default value: "false"
phone_model
Invokes the phone model which will generate VMAF scores higher than in the regular
model, which is more suitable for laptop, TV, etc. viewing conditions.
psnr
Enables computing psnr along with vmaf.
ssim
Enables computing ssim along with vmaf.
ms_ssim
Enables computing ms_ssim along with vmaf.
pool
Set the pool method (mean, min or harmonic mean) to be used for computing vmaf.
n_threads
Set number of threads to be used when computing vmaf.
n_subsample
Set interval for frame subsampling used when computing vmaf.
enable_conf_interval
Enables confidence interval.
This filter also supports the framesync options.
On the below examples the input file main.mpg being processed is compared with the
reference file ref.mpg.
ffmpeg -i main.mpg -i ref.mpg -lavfi libvmaf -f null -
Example with options:
ffmpeg -i main.mpg -i ref.mpg -lavfi libvmaf="psnr=1:log_fmt=json" -f null -
limiter
Limits the pixel components values to the specified range [min, max].
The filter accepts the following options:
min Lower bound. Defaults to the lowest allowed value for the input.
max Upper bound. Defaults to the highest allowed value for the input.
planes
Specify which planes will be processed. Defaults to all available.
loop
Loop video frames.
The filter accepts the following options:
loop
Set the number of loops. Setting this value to -1 will result in infinite loops.
Default is 0.
size
Set maximal size in number of frames. Default is 0.
start
Set first frame of loop. Default is 0.
Examples
• Loop single first frame infinitely:
loop=loop=-1:size=1:start=0
• Loop single first frame 10 times:
loop=loop=10:size=1:start=0
• Loop 10 first frames 5 times:
loop=loop=5:size=10:start=0
lut1d
Apply a 1D LUT to an input video.
The filter accepts the following options:
file
Set the 1D LUT file name.
Currently supported formats:
cube
Iridas
csp cineSpace
interp
Select interpolation mode.
Available values are:
nearest
Use values from the nearest defined point.
linear
Interpolate values using the linear interpolation.
cosine
Interpolate values using the cosine interpolation.
cubic
Interpolate values using the cubic interpolation.
spline
Interpolate values using the spline interpolation.
lut3d
Apply a 3D LUT to an input video.
The filter accepts the following options:
file
Set the 3D LUT file name.
Currently supported formats:
3dl AfterEffects
cube
Iridas
dat DaVinci
m3d Pandora
csp cineSpace
interp
Select interpolation mode.
Available values are:
nearest
Use values from the nearest defined point.
trilinear
Interpolate values using the 8 points defining a cube.
tetrahedral
Interpolate values using a tetrahedron.
lumakey
Turn certain luma values into transparency.
The filter accepts the following options:
threshold
Set the luma which will be used as base for transparency. Default value is 0.
tolerance
Set the range of luma values to be keyed out. Default value is 0.
softness
Set the range of softness. Default value is 0. Use this to control gradual transition
from zero to full transparency.
lut, lutrgb, lutyuv
Compute a look-up table for binding each pixel component input value to an output value,
and apply it to the input video.
lutyuv applies a lookup table to a YUV input video, lutrgb to an RGB input video.
These filters accept the following parameters:
c0 set first pixel component expression
c1 set second pixel component expression
c2 set third pixel component expression
c3 set fourth pixel component expression, corresponds to the alpha component
r set red component expression
g set green component expression
b set blue component expression
a alpha component expression
y set Y/luminance component expression
u set U/Cb component expression
v set V/Cr component expression
Each of them specifies the expression to use for computing the lookup table for the
corresponding pixel component values.
The exact component associated to each of the c* options depends on the format in input.
The lut filter requires either YUV or RGB pixel formats in input, lutrgb requires RGB
pixel formats in input, and lutyuv requires YUV.
The expressions can contain the following constants and functions:
w
h The input width and height.
val The input value for the pixel component.
clipval
The input value, clipped to the minval-maxval range.
maxval
The maximum value for the pixel component.
minval
The minimum value for the pixel component.
negval
The negated value for the pixel component value, clipped to the minval-maxval range;
it corresponds to the expression "maxval-clipval+minval".
clip(val)
The computed value in val, clipped to the minval-maxval range.
gammaval(gamma)
The computed gamma correction value of the pixel component value, clipped to the
minval-maxval range. It corresponds to the expression
"pow((clipval-minval)/(maxval-minval)\,gamma)*(maxval-minval)+minval"
All expressions default to "val".
Examples
• Negate input video:
lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"
The above is the same as:
lutrgb="r=negval:g=negval:b=negval"
lutyuv="y=negval:u=negval:v=negval"
• Negate luminance:
lutyuv=y=negval
• Remove chroma components, turning the video into a graytone image:
lutyuv="u=128:v=128"
• Apply a luma burning effect:
lutyuv="y=2*val"
• Remove green and blue components:
lutrgb="g=0:b=0"
• Set a constant alpha channel value on input:
format=rgba,lutrgb=a="maxval-minval/2"
• Correct luminance gamma by a factor of 0.5:
lutyuv=y=gammaval(0.5)
• Discard least significant bits of luma:
lutyuv=y='bitand(val, 128+64+32)'
• Technicolor like effect:
lutyuv=u='(val-maxval/2)*2+maxval/2':v='(val-maxval/2)*2+maxval/2'
lut2, tlut2
The "lut2" filter takes two input streams and outputs one stream.
The "tlut2" (time lut2) filter takes two consecutive frames from one single stream.
This filter accepts the following parameters:
c0 set first pixel component expression
c1 set second pixel component expression
c2 set third pixel component expression
c3 set fourth pixel component expression, corresponds to the alpha component
d set output bit depth, only available for "lut2" filter. By default is 0, which means
bit depth is automatically picked from first input format.
Each of them specifies the expression to use for computing the lookup table for the
corresponding pixel component values.
The exact component associated to each of the c* options depends on the format in inputs.
The expressions can contain the following constants:
w
h The input width and height.
x The first input value for the pixel component.
y The second input value for the pixel component.
bdx The first input video bit depth.
bdy The second input video bit depth.
All expressions default to "x".
Examples
• Highlight differences between two RGB video streams:
lut2='ifnot(x-y,0,pow(2,bdx)-1):ifnot(x-y,0,pow(2,bdx)-1):ifnot(x-y,0,pow(2,bdx)-1)'
• Highlight differences between two YUV video streams:
lut2='ifnot(x-y,0,pow(2,bdx)-1):ifnot(x-y,pow(2,bdx-1),pow(2,bdx)-1):ifnot(x-y,pow(2,bdx-1),pow(2,bdx)-1)'
• Show max difference between two video streams:
lut2='if(lt(x,y),0,if(gt(x,y),pow(2,bdx)-1,pow(2,bdx-1))):if(lt(x,y),0,if(gt(x,y),pow(2,bdx)-1,pow(2,bdx-1))):if(lt(x,y),0,if(gt(x,y),pow(2,bdx)-1,pow(2,bdx-1)))'
maskedclamp
Clamp the first input stream with the second input and third input stream.
Returns the value of first stream to be between second input stream - "undershoot" and
third input stream + "overshoot".
This filter accepts the following options:
undershoot
Default value is 0.
overshoot
Default value is 0.
planes
Set which planes will be processed as bitmap, unprocessed planes will be copied from
first stream. By default value 0xf, all planes will be processed.
maskedmerge
Merge the first input stream with the second input stream using per pixel weights in the
third input stream.
A value of 0 in the third stream pixel component means that pixel component from first
stream is returned unchanged, while maximum value (eg. 255 for 8-bit videos) means that
pixel component from second stream is returned unchanged. Intermediate values define the
amount of merging between both input stream's pixel components.
This filter accepts the following options:
planes
Set which planes will be processed as bitmap, unprocessed planes will be copied from
first stream. By default value 0xf, all planes will be processed.
maskfun
Create mask from input video.
For example it is useful to create motion masks after "tblend" filter.
This filter accepts the following options:
low Set low threshold. Any pixel component lower or exact than this value will be set to
0.
high
Set high threshold. Any pixel component higher than this value will be set to max
value allowed for current pixel format.
planes
Set planes to filter, by default all available planes are filtered.
fill
Fill all frame pixels with this value.
sum Set max average pixel value for frame. If sum of all pixel components is higher that
this average, output frame will be completely filled with value set by fill option.
Typically useful for scene changes when used in combination with "tblend" filter.
mcdeint
Apply motion-compensation deinterlacing.
It needs one field per frame as input and must thus be used together with yadif=1/3 or
equivalent.
This filter accepts the following options:
mode
Set the deinterlacing mode.
It accepts one of the following values:
fast
medium
slow
use iterative motion estimation
extra_slow
like slow, but use multiple reference frames.
Default value is fast.
parity
Set the picture field parity assumed for the input video. It must be one of the
following values:
0, tff
assume top field first
1, bff
assume bottom field first
Default value is bff.
qp Set per-block quantization parameter (QP) used by the internal encoder.
Higher values should result in a smoother motion vector field but less optimal
individual vectors. Default value is 1.
mergeplanes
Merge color channel components from several video streams.
The filter accepts up to 4 input streams, and merge selected input planes to the output
video.
This filter accepts the following options:
mapping
Set input to output plane mapping. Default is 0.
The mappings is specified as a bitmap. It should be specified as a hexadecimal number
in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the mapping for the first plane of the
output stream. 'A' sets the number of the input stream to use (from 0 to 3), and 'a'
the plane number of the corresponding input to use (from 0 to 3). The rest of the
mappings is similar, 'Bb' describes the mapping for the output stream second plane,
'Cc' describes the mapping for the output stream third plane and 'Dd' describes the
mapping for the output stream fourth plane.
format
Set output pixel format. Default is "yuva444p".
Examples
• Merge three gray video streams of same width and height into single video stream:
[a0][a1][a2]mergeplanes=0x001020:yuv444p
• Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream:
[a0][a1]mergeplanes=0x00010210:yuva444p
• Swap Y and A plane in yuva444p stream:
format=yuva444p,mergeplanes=0x03010200:yuva444p
• Swap U and V plane in yuv420p stream:
format=yuv420p,mergeplanes=0x000201:yuv420p
• Cast a rgb24 clip to yuv444p:
format=rgb24,mergeplanes=0x000102:yuv444p
mestimate
Estimate and export motion vectors using block matching algorithms. Motion vectors are
stored in frame side data to be used by other filters.
This filter accepts the following options:
method
Specify the motion estimation method. Accepts one of the following values:
esa Exhaustive search algorithm.
tss Three step search algorithm.
tdls
Two dimensional logarithmic search algorithm.
ntss
New three step search algorithm.
fss Four step search algorithm.
ds Diamond search algorithm.
hexbs
Hexagon-based search algorithm.
epzs
Enhanced predictive zonal search algorithm.
umh Uneven multi-hexagon search algorithm.
Default value is esa.
mb_size
Macroblock size. Default 16.
search_param
Search parameter. Default 7.
midequalizer
Apply Midway Image Equalization effect using two video streams.
Midway Image Equalization adjusts a pair of images to have the same histogram, while
maintaining their dynamics as much as possible. It's useful for e.g. matching exposures
from a pair of stereo cameras.
This filter has two inputs and one output, which must be of same pixel format, but may be
of different sizes. The output of filter is first input adjusted with midway histogram of
both inputs.
This filter accepts the following option:
planes
Set which planes to process. Default is 15, which is all available planes.
minterpolate
Convert the video to specified frame rate using motion interpolation.
This filter accepts the following options:
fps Specify the output frame rate. This can be rational e.g. "60000/1001". Frames are
dropped if fps is lower than source fps. Default 60.
mi_mode
Motion interpolation mode. Following values are accepted:
dup Duplicate previous or next frame for interpolating new ones.
blend
Blend source frames. Interpolated frame is mean of previous and next frames.
mci Motion compensated interpolation. Following options are effective when this mode
is selected:
mc_mode
Motion compensation mode. Following values are accepted:
obmc
Overlapped block motion compensation.
aobmc
Adaptive overlapped block motion compensation. Window weighting
coefficients are controlled adaptively according to the reliabilities of
the neighboring motion vectors to reduce oversmoothing.
Default mode is obmc.
me_mode
Motion estimation mode. Following values are accepted:
bidir
Bidirectional motion estimation. Motion vectors are estimated for each
source frame in both forward and backward directions.
bilat
Bilateral motion estimation. Motion vectors are estimated directly for
interpolated frame.
Default mode is bilat.
me The algorithm to be used for motion estimation. Following values are accepted:
esa Exhaustive search algorithm.
tss Three step search algorithm.
tdls
Two dimensional logarithmic search algorithm.
ntss
New three step search algorithm.
fss Four step search algorithm.
ds Diamond search algorithm.
hexbs
Hexagon-based search algorithm.
epzs
Enhanced predictive zonal search algorithm.
umh Uneven multi-hexagon search algorithm.
Default algorithm is epzs.
mb_size
Macroblock size. Default 16.
search_param
Motion estimation search parameter. Default 32.
vsbmc
Enable variable-size block motion compensation. Motion estimation is applied
with smaller block sizes at object boundaries in order to make the them less
blur. Default is 0 (disabled).
scd Scene change detection method. Scene change leads motion vectors to be in random
direction. Scene change detection replace interpolated frames by duplicate ones. May
not be needed for other modes. Following values are accepted:
none
Disable scene change detection.
fdiff
Frame difference. Corresponding pixel values are compared and if it satisfies
scd_threshold scene change is detected.
Default method is fdiff.
scd_threshold
Scene change detection threshold. Default is 5.0.
mix
Mix several video input streams into one video stream.
A description of the accepted options follows.
nb_inputs
The number of inputs. If unspecified, it defaults to 2.
weights
Specify weight of each input video stream as sequence. Each weight is separated by
space. If number of weights is smaller than number of frames last specified weight
will be used for all remaining unset weights.
scale
Specify scale, if it is set it will be multiplied with sum of each weight multiplied
with pixel values to give final destination pixel value. By default scale is auto
scaled to sum of weights.
duration
Specify how end of stream is determined.
longest
The duration of the longest input. (default)
shortest
The duration of the shortest input.
first
The duration of the first input.
mpdecimate
Drop frames that do not differ greatly from the previous frame in order to reduce frame
rate.
The main use of this filter is for very-low-bitrate encoding (e.g. streaming over dialup
modem), but it could in theory be used for fixing movies that were inverse-telecined
incorrectly.
A description of the accepted options follows.
max Set the maximum number of consecutive frames which can be dropped (if positive), or
the minimum interval between dropped frames (if negative). If the value is 0, the
frame is dropped disregarding the number of previous sequentially dropped frames.
Default value is 0.
hi
lo
frac
Set the dropping threshold values.
Values for hi and lo are for 8x8 pixel blocks and represent actual pixel value
differences, so a threshold of 64 corresponds to 1 unit of difference for each pixel,
or the same spread out differently over the block.
A frame is a candidate for dropping if no 8x8 blocks differ by more than a threshold
of hi, and if no more than frac blocks (1 meaning the whole image) differ by more than
a threshold of lo.
Default value for hi is 64*12, default value for lo is 64*5, and default value for
frac is 0.33.
negate
Negate (invert) the input video.
It accepts the following option:
negate_alpha
With value 1, it negates the alpha component, if present. Default value is 0.
nlmeans
Denoise frames using Non-Local Means algorithm.
Each pixel is adjusted by looking for other pixels with similar contexts. This context
similarity is defined by comparing their surrounding patches of size pxp. Patches are
searched in an area of rxr around the pixel.
Note that the research area defines centers for patches, which means some patches will be
made of pixels outside that research area.
The filter accepts the following options.
s Set denoising strength. Default is 1.0. Must be in range [1.0, 30.0].
p Set patch size. Default is 7. Must be odd number in range [0, 99].
pc Same as p but for chroma planes.
The default value is 0 and means automatic.
r Set research size. Default is 15. Must be odd number in range [0, 99].
rc Same as r but for chroma planes.
The default value is 0 and means automatic.
nnedi
Deinterlace video using neural network edge directed interpolation.
This filter accepts the following options:
weights
Mandatory option, without binary file filter can not work. Currently file can be
found here:
https://github.com/dubhater/vapoursynth-nnedi3/blob/master/src/nnedi3_weights.bin
deint
Set which frames to deinterlace, by default it is "all". Can be "all" or
"interlaced".
field
Set mode of operation.
Can be one of the following:
af Use frame flags, both fields.
a Use frame flags, single field.
t Use top field only.
b Use bottom field only.
tf Use both fields, top first.
bf Use both fields, bottom first.
planes
Set which planes to process, by default filter process all frames.
nsize
Set size of local neighborhood around each pixel, used by the predictor neural
network.
Can be one of the following:
s8x6
s16x6
s32x6
s48x6
s8x4
s16x4
s32x4
nns Set the number of neurons in predictor neural network. Can be one of the following:
n16
n32
n64
n128
n256
qual
Controls the number of different neural network predictions that are blended together
to compute the final output value. Can be "fast", default or "slow".
etype
Set which set of weights to use in the predictor. Can be one of the following:
a weights trained to minimize absolute error
s weights trained to minimize squared error
pscrn
Controls whether or not the prescreener neural network is used to decide which pixels
should be processed by the predictor neural network and which can be handled by simple
cubic interpolation. The prescreener is trained to know whether cubic interpolation
will be sufficient for a pixel or whether it should be predicted by the predictor nn.
The computational complexity of the prescreener nn is much less than that of the
predictor nn. Since most pixels can be handled by cubic interpolation, using the
prescreener generally results in much faster processing. The prescreener is pretty
accurate, so the difference between using it and not using it is almost always
unnoticeable.
Can be one of the following:
none
original
new
Default is "new".
fapprox
Set various debugging flags.
noformat
Force libavfilter not to use any of the specified pixel formats for the input to the next
filter.
It accepts the following parameters:
pix_fmts
A '|'-separated list of pixel format names, such as pix_fmts=yuv420p|monow|rgb24".
Examples
• Force libavfilter to use a format different from yuv420p for the input to the vflip
filter:
noformat=pix_fmts=yuv420p,vflip
• Convert the input video to any of the formats not contained in the list:
noformat=yuv420p|yuv444p|yuv410p
noise
Add noise on video input frame.
The filter accepts the following options:
all_seed
c0_seed
c1_seed
c2_seed
c3_seed
Set noise seed for specific pixel component or all pixel components in case of
all_seed. Default value is 123457.
all_strength, alls
c0_strength, c0s
c1_strength, c1s
c2_strength, c2s
c3_strength, c3s
Set noise strength for specific pixel component or all pixel components in case
all_strength. Default value is 0. Allowed range is [0, 100].
all_flags, allf
c0_flags, c0f
c1_flags, c1f
c2_flags, c2f
c3_flags, c3f
Set pixel component flags or set flags for all components if all_flags. Available
values for component flags are:
a averaged temporal noise (smoother)
p mix random noise with a (semi)regular pattern
t temporal noise (noise pattern changes between frames)
u uniform noise (gaussian otherwise)
Examples
Add temporal and uniform noise to input video:
noise=alls=20:allf=t+u
normalize
Normalize RGB video (aka histogram stretching, contrast stretching). See:
https://en.wikipedia.org/wiki/Normalization_(image_processing)
For each channel of each frame, the filter computes the input range and maps it linearly
to the user-specified output range. The output range defaults to the full dynamic range
from pure black to pure white.
Temporal smoothing can be used on the input range to reduce flickering (rapid changes in
brightness) caused when small dark or bright objects enter or leave the scene. This is
similar to the auto-exposure (automatic gain control) on a video camera, and, like a video
camera, it may cause a period of over- or under-exposure of the video.
The R,G,B channels can be normalized independently, which may cause some color shifting,
or linked together as a single channel, which prevents color shifting. Linked
normalization preserves hue. Independent normalization does not, so it can be used to
remove some color casts. Independent and linked normalization can be combined in any
ratio.
The normalize filter accepts the following options:
blackpt
whitept
Colors which define the output range. The minimum input value is mapped to the
blackpt. The maximum input value is mapped to the whitept. The defaults are black and
white respectively. Specifying white for blackpt and black for whitept will give
color-inverted, normalized video. Shades of grey can be used to reduce the dynamic
range (contrast). Specifying saturated colors here can create some interesting
effects.
smoothing
The number of previous frames to use for temporal smoothing. The input range of each
channel is smoothed using a rolling average over the current frame and the smoothing
previous frames. The default is 0 (no temporal smoothing).
independence
Controls the ratio of independent (color shifting) channel normalization to linked
(color preserving) normalization. 0.0 is fully linked, 1.0 is fully independent.
Defaults to 1.0 (fully independent).
strength
Overall strength of the filter. 1.0 is full strength. 0.0 is a rather expensive no-op.
Defaults to 1.0 (full strength).
Examples
Stretch video contrast to use the full dynamic range, with no temporal smoothing; may
flicker depending on the source content:
normalize=blackpt=black:whitept=white:smoothing=0
As above, but with 50 frames of temporal smoothing; flicker should be reduced, depending
on the source content:
normalize=blackpt=black:whitept=white:smoothing=50
As above, but with hue-preserving linked channel normalization:
normalize=blackpt=black:whitept=white:smoothing=50:independence=0
As above, but with half strength:
normalize=blackpt=black:whitept=white:smoothing=50:independence=0:strength=0.5
Map the darkest input color to red, the brightest input color to cyan:
normalize=blackpt=red:whitept=cyan
null
Pass the video source unchanged to the output.
ocr
Optical Character Recognition
This filter uses Tesseract for optical character recognition. To enable compilation of
this filter, you need to configure FFmpeg with "--enable-libtesseract".
It accepts the following options:
datapath
Set datapath to tesseract data. Default is to use whatever was set at installation.
language
Set language, default is "eng".
whitelist
Set character whitelist.
blacklist
Set character blacklist.
The filter exports recognized text as the frame metadata "lavfi.ocr.text". The filter
exports confidence of recognized words as the frame metadata "lavfi.ocr.confidence".
ocv
Apply a video transform using libopencv.
To enable this filter, install the libopencv library and headers and configure FFmpeg with
"--enable-libopencv".
It accepts the following parameters:
filter_name
The name of the libopencv filter to apply.
filter_params
The parameters to pass to the libopencv filter. If not specified, the default values
are assumed.
Refer to the official libopencv documentation for more precise information:
<http://docs.opencv.org/master/modules/imgproc/doc/filtering.html>
Several libopencv filters are supported; see the following subsections.
dilate
Dilate an image by using a specific structuring element. It corresponds to the libopencv
function "cvDilate".
It accepts the parameters: struct_el|nb_iterations.
struct_el represents a structuring element, and has the syntax:
colsxrows+anchor_xxanchor_y/shape
cols and rows represent the number of columns and rows of the structuring element,
anchor_x and anchor_y the anchor point, and shape the shape for the structuring element.
shape must be "rect", "cross", "ellipse", or "custom".
If the value for shape is "custom", it must be followed by a string of the form
"=filename". The file with name filename is assumed to represent a binary image, with each
printable character corresponding to a bright pixel. When a custom shape is used, cols and
rows are ignored, the number or columns and rows of the read file are assumed instead.
The default value for struct_el is "3x3+0x0/rect".
nb_iterations specifies the number of times the transform is applied to the image, and
defaults to 1.
Some examples:
# Use the default values
ocv=dilate
# Dilate using a structuring element with a 5x5 cross, iterating two times
ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2
# Read the shape from the file diamond.shape, iterating two times.
# The file diamond.shape may contain a pattern of characters like this
# *
# ***
# *****
# ***
# *
# The specified columns and rows are ignored
# but the anchor point coordinates are not
ocv=dilate:0x0+2x2/custom=diamond.shape|2
erode
Erode an image by using a specific structuring element. It corresponds to the libopencv
function "cvErode".
It accepts the parameters: struct_el:nb_iterations, with the same syntax and semantics as
the dilate filter.
smooth
Smooth the input video.
The filter takes the following parameters: type|param1|param2|param3|param4.
type is the type of smooth filter to apply, and must be one of the following values:
"blur", "blur_no_scale", "median", "gaussian", or "bilateral". The default value is
"gaussian".
The meaning of param1, param2, param3, and param4 depend on the smooth type. param1 and
param2 accept integer positive values or 0. param3 and param4 accept floating point
values.
The default value for param1 is 3. The default value for the other parameters is 0.
These parameters correspond to the parameters assigned to the libopencv function
"cvSmooth".
oscilloscope
2D Video Oscilloscope.
Useful to measure spatial impulse, step responses, chroma delays, etc.
It accepts the following parameters:
x Set scope center x position.
y Set scope center y position.
s Set scope size, relative to frame diagonal.
t Set scope tilt/rotation.
o Set trace opacity.
tx Set trace center x position.
ty Set trace center y position.
tw Set trace width, relative to width of frame.
th Set trace height, relative to height of frame.
c Set which components to trace. By default it traces first three components.
g Draw trace grid. By default is enabled.
st Draw some statistics. By default is enabled.
sc Draw scope. By default is enabled.
Examples
• Inspect full first row of video frame.
oscilloscope=x=0.5:y=0:s=1
• Inspect full last row of video frame.
oscilloscope=x=0.5:y=1:s=1
• Inspect full 5th line of video frame of height 1080.
oscilloscope=x=0.5:y=5/1080:s=1
• Inspect full last column of video frame.
oscilloscope=x=1:y=0.5:s=1:t=1
overlay
Overlay one video on top of another.
It takes two inputs and has one output. The first input is the "main" video on which the
second input is overlaid.
It accepts the following parameters:
A description of the accepted options follows.
x
y Set the expression for the x and y coordinates of the overlaid video on the main
video. Default value is "0" for both expressions. In case the expression is invalid,
it is set to a huge value (meaning that the overlay will not be displayed within the
output visible area).
eof_action
See framesync.
eval
Set when the expressions for x, and y are evaluated.
It accepts the following values:
init
only evaluate expressions once during the filter initialization or when a command
is processed
frame
evaluate expressions for each incoming frame
Default value is frame.
shortest
See framesync.
format
Set the format for the output video.
It accepts the following values:
yuv420
force YUV420 output
yuv422
force YUV422 output
yuv444
force YUV444 output
rgb force packed RGB output
gbrp
force planar RGB output
auto
automatically pick format
Default value is yuv420.
repeatlast
See framesync.
alpha
Set format of alpha of the overlaid video, it can be straight or premultiplied.
Default is straight.
The x, and y expressions can contain the following parameters.
main_w, W
main_h, H
The main input width and height.
overlay_w, w
overlay_h, h
The overlay input width and height.
x
y The computed values for x and y. They are evaluated for each new frame.
hsub
vsub
horizontal and vertical chroma subsample values of the output format. For example for
the pixel format "yuv422p" hsub is 2 and vsub is 1.
n the number of input frame, starting from 0
pos the position in the file of the input frame, NAN if unknown
t The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown.
This filter also supports the framesync options.
Note that the n, pos, t variables are available only when evaluation is done per frame,
and will evaluate to NAN when eval is set to init.
Be aware that frames are taken from each input video in timestamp order, hence, if their
initial timestamps differ, it is a good idea to pass the two inputs through a
setpts=PTS-STARTPTS filter to have them begin in the same zero timestamp, as the example
for the movie filter does.
You can chain together more overlays but you should test the efficiency of such approach.
Commands
This filter supports the following commands:
x
y Modify the x and y of the overlay input. The command accepts the same syntax of the
corresponding option.
If the specified expression is not valid, it is kept at its current value.
Examples
• Draw the overlay at 10 pixels from the bottom right corner of the main video:
overlay=main_w-overlay_w-10:main_h-overlay_h-10
Using named options the example above becomes:
overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
• Insert a transparent PNG logo in the bottom left corner of the input, using the ffmpeg
tool with the "-filter_complex" option:
ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
• Insert 2 different transparent PNG logos (second logo on bottom right corner) using
the ffmpeg tool:
ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
• Add a transparent color layer on top of the main video; "WxH" must specify the size of
the main input to the overlay filter:
color=color=red@.3:size=WxH [over]; [in][over] overlay [out]
• Play an original video and a filtered version (here with the deshake filter) side by
side using the ffplay tool:
ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w'
The above command is the same as:
ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w'
• Make a sliding overlay appearing from the left to the right top part of the screen
starting since time 2:
overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0
• Compose output by putting two input videos side to side:
ffmpeg -i left.avi -i right.avi -filter_complex "
nullsrc=size=200x100 [background];
[0:v] setpts=PTS-STARTPTS, scale=100x100 [left];
[1:v] setpts=PTS-STARTPTS, scale=100x100 [right];
[background][left] overlay=shortest=1 [background+left];
[background+left][right] overlay=shortest=1:x=100 [left+right]
"
• Mask 10-20 seconds of a video by applying the delogo filter to a section
ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k
-vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]'
masked.avi
• Chain several overlays in cascade:
nullsrc=s=200x200 [bg];
testsrc=s=100x100, split=4 [in0][in1][in2][in3];
[in0] lutrgb=r=0, [bg] overlay=0:0 [mid0];
[in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1];
[in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2];
[in3] null, [mid2] overlay=100:100 [out0]
owdenoise
Apply Overcomplete Wavelet denoiser.
The filter accepts the following options:
depth
Set depth.
Larger depth values will denoise lower frequency components more, but slow down
filtering.
Must be an int in the range 8-16, default is 8.
luma_strength, ls
Set luma strength.
Must be a double value in the range 0-1000, default is 1.0.
chroma_strength, cs
Set chroma strength.
Must be a double value in the range 0-1000, default is 1.0.
pad
Add paddings to the input image, and place the original input at the provided x, y
coordinates.
It accepts the following parameters:
width, w
height, h
Specify an expression for the size of the output image with the paddings added. If the
value for width or height is 0, the corresponding input size is used for the output.
The width expression can reference the value set by the height expression, and vice
versa.
The default value of width and height is 0.
x
y Specify the offsets to place the input image at within the padded area, with respect
to the top/left border of the output image.
The x expression can reference the value set by the y expression, and vice versa.
The default value of x and y is 0.
If x or y evaluate to a negative number, they'll be changed so the input image is
centered on the padded area.
color
Specify the color of the padded area. For the syntax of this option, check the "Color"
section in the ffmpeg-utils manual.
The default value of color is "black".
eval
Specify when to evaluate width, height, x and y expression.
It accepts the following values:
init
Only evaluate expressions once during the filter initialization or when a command
is processed.
frame
Evaluate expressions for each incoming frame.
Default value is init.
aspect
Pad to aspect instead to a resolution.
The value for the width, height, x, and y options are expressions containing the following
constants:
in_w
in_h
The input video width and height.
iw
ih These are the same as in_w and in_h.
out_w
out_h
The output width and height (the size of the padded area), as specified by the width
and height expressions.
ow
oh These are the same as out_w and out_h.
x
y The x and y offsets as specified by the x and y expressions, or NAN if not yet
specified.
a same as iw / ih
sar input sample aspect ratio
dar input display aspect ratio, it is the same as (iw / ih) * sar
hsub
vsub
The horizontal and vertical chroma subsample values. For example for the pixel format
"yuv422p" hsub is 2 and vsub is 1.
Examples
• Add paddings with the color "violet" to the input video. The output video size is
640x480, and the top-left corner of the input video is placed at column 0, row 40
pad=640:480:0:40:violet
The example above is equivalent to the following command:
pad=width=640:height=480:x=0:y=40:color=violet
• Pad the input to get an output with dimensions increased by 3/2, and put the input
video at the center of the padded area:
pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"
• Pad the input to get a squared output with size equal to the maximum value between the
input width and height, and put the input video at the center of the padded area:
pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2"
• Pad the input to get a final w/h ratio of 16:9:
pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"
• In case of anamorphic video, in order to set the output display aspect correctly, it
is necessary to use sar in the expression, according to the relation:
(ih * X / ih) * sar = output_dar
X = output_dar / sar
Thus the previous example needs to be modified to:
pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2"
• Double the output size and put the input video in the bottom-right corner of the
output padded area:
pad="2*iw:2*ih:ow-iw:oh-ih"
palettegen
Generate one palette for a whole video stream.
It accepts the following options:
max_colors
Set the maximum number of colors to quantize in the palette. Note: the palette will
still contain 256 colors; the unused palette entries will be black.
reserve_transparent
Create a palette of 255 colors maximum and reserve the last one for transparency.
Reserving the transparency color is useful for GIF optimization. If not set, the
maximum of colors in the palette will be 256. You probably want to disable this option
for a standalone image. Set by default.
transparency_color
Set the color that will be used as background for transparency.
stats_mode
Set statistics mode.
It accepts the following values:
full
Compute full frame histograms.
diff
Compute histograms only for the part that differs from previous frame. This might
be relevant to give more importance to the moving part of your input if the
background is static.
single
Compute new histogram for each frame.
Default value is full.
The filter also exports the frame metadata "lavfi.color_quant_ratio" ("nb_color_in /
nb_color_out") which you can use to evaluate the degree of color quantization of the
palette. This information is also visible at info logging level.
Examples
• Generate a representative palette of a given video using ffmpeg:
ffmpeg -i input.mkv -vf palettegen palette.png
paletteuse
Use a palette to downsample an input video stream.
The filter takes two inputs: one video stream and a palette. The palette must be a 256
pixels image.
It accepts the following options:
dither
Select dithering mode. Available algorithms are:
bayer
Ordered 8x8 bayer dithering (deterministic)
heckbert
Dithering as defined by Paul Heckbert in 1982 (simple error diffusion). Note:
this dithering is sometimes considered "wrong" and is included as a reference.
floyd_steinberg
Floyd and Steingberg dithering (error diffusion)
sierra2
Frankie Sierra dithering v2 (error diffusion)
sierra2_4a
Frankie Sierra dithering v2 "Lite" (error diffusion)
Default is sierra2_4a.
bayer_scale
When bayer dithering is selected, this option defines the scale of the pattern (how
much the crosshatch pattern is visible). A low value means more visible pattern for
less banding, and higher value means less visible pattern at the cost of more banding.
The option must be an integer value in the range [0,5]. Default is 2.
diff_mode
If set, define the zone to process
rectangle
Only the changing rectangle will be reprocessed. This is similar to GIF
cropping/offsetting compression mechanism. This option can be useful for speed if
only a part of the image is changing, and has use cases such as limiting the scope
of the error diffusal dither to the rectangle that bounds the moving scene (it
leads to more deterministic output if the scene doesn't change much, and as a
result less moving noise and better GIF compression).
Default is none.
new Take new palette for each output frame.
alpha_threshold
Sets the alpha threshold for transparency. Alpha values above this threshold will be
treated as completely opaque, and values below this threshold will be treated as
completely transparent.
The option must be an integer value in the range [0,255]. Default is 128.
Examples
• Use a palette (generated for example with palettegen) to encode a GIF using ffmpeg:
ffmpeg -i input.mkv -i palette.png -lavfi paletteuse output.gif
perspective
Correct perspective of video not recorded perpendicular to the screen.
A description of the accepted parameters follows.
x0
y0
x1
y1
x2
y2
x3
y3 Set coordinates expression for top left, top right, bottom left and bottom right
corners. Default values are "0:0:W:0:0:H:W:H" with which perspective will remain
unchanged. If the "sense" option is set to "source", then the specified points will
be sent to the corners of the destination. If the "sense" option is set to
"destination", then the corners of the source will be sent to the specified
coordinates.
The expressions can use the following variables:
W
H the width and height of video frame.
in Input frame count.
on Output frame count.
interpolation
Set interpolation for perspective correction.
It accepts the following values:
linear
cubic
Default value is linear.
sense
Set interpretation of coordinate options.
It accepts the following values:
0, source
Send point in the source specified by the given coordinates to the corners of the
destination.
1, destination
Send the corners of the source to the point in the destination specified by the
given coordinates.
Default value is source.
eval
Set when the expressions for coordinates x0,y0,...x3,y3 are evaluated.
It accepts the following values:
init
only evaluate expressions once during the filter initialization or when a command
is processed
frame
evaluate expressions for each incoming frame
Default value is init.
phase
Delay interlaced video by one field time so that the field order changes.
The intended use is to fix PAL movies that have been captured with the opposite field
order to the film-to-video transfer.
A description of the accepted parameters follows.
mode
Set phase mode.
It accepts the following values:
t Capture field order top-first, transfer bottom-first. Filter will delay the
bottom field.
b Capture field order bottom-first, transfer top-first. Filter will delay the top
field.
p Capture and transfer with the same field order. This mode only exists for the
documentation of the other options to refer to, but if you actually select it, the
filter will faithfully do nothing.
a Capture field order determined automatically by field flags, transfer opposite.
Filter selects among t and b modes on a frame by frame basis using field flags. If
no field information is available, then this works just like u.
u Capture unknown or varying, transfer opposite. Filter selects among t and b on a
frame by frame basis by analyzing the images and selecting the alternative that
produces best match between the fields.
T Capture top-first, transfer unknown or varying. Filter selects among t and p
using image analysis.
B Capture bottom-first, transfer unknown or varying. Filter selects among b and p
using image analysis.
A Capture determined by field flags, transfer unknown or varying. Filter selects
among t, b and p using field flags and image analysis. If no field information is
available, then this works just like U. This is the default mode.
U Both capture and transfer unknown or varying. Filter selects among t, b and p
using image analysis only.
pixdesctest
Pixel format descriptor test filter, mainly useful for internal testing. The output video
should be equal to the input video.
For example:
format=monow, pixdesctest
can be used to test the monowhite pixel format descriptor definition.
pixscope
Display sample values of color channels. Mainly useful for checking color and levels.
Minimum supported resolution is 640x480.
The filters accept the following options:
x Set scope X position, relative offset on X axis.
y Set scope Y position, relative offset on Y axis.
w Set scope width.
h Set scope height.
o Set window opacity. This window also holds statistics about pixel area.
wx Set window X position, relative offset on X axis.
wy Set window Y position, relative offset on Y axis.
pp
Enable the specified chain of postprocessing subfilters using libpostproc. This library
should be automatically selected with a GPL build ("--enable-gpl"). Subfilters must be
separated by '/' and can be disabled by prepending a '-'. Each subfilter and some options
have a short and a long name that can be used interchangeably, i.e. dr/dering are the
same.
The filters accept the following options:
subfilters
Set postprocessing subfilters string.
All subfilters share common options to determine their scope:
a/autoq
Honor the quality commands for this subfilter.
c/chrom
Do chrominance filtering, too (default).
y/nochrom
Do luminance filtering only (no chrominance).
n/noluma
Do chrominance filtering only (no luminance).
These options can be appended after the subfilter name, separated by a '|'.
Available subfilters are:
hb/hdeblock[|difference[|flatness]]
Horizontal deblocking filter
difference
Difference factor where higher values mean more deblocking (default: 32).
flatness
Flatness threshold where lower values mean more deblocking (default: 39).
vb/vdeblock[|difference[|flatness]]
Vertical deblocking filter
difference
Difference factor where higher values mean more deblocking (default: 32).
flatness
Flatness threshold where lower values mean more deblocking (default: 39).
ha/hadeblock[|difference[|flatness]]
Accurate horizontal deblocking filter
difference
Difference factor where higher values mean more deblocking (default: 32).
flatness
Flatness threshold where lower values mean more deblocking (default: 39).
va/vadeblock[|difference[|flatness]]
Accurate vertical deblocking filter
difference
Difference factor where higher values mean more deblocking (default: 32).
flatness
Flatness threshold where lower values mean more deblocking (default: 39).
The horizontal and vertical deblocking filters share the difference and flatness values so
you cannot set different horizontal and vertical thresholds.
h1/x1hdeblock
Experimental horizontal deblocking filter
v1/x1vdeblock
Experimental vertical deblocking filter
dr/dering
Deringing filter
tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer
threshold1
larger -> stronger filtering
threshold2
larger -> stronger filtering
threshold3
larger -> stronger filtering
al/autolevels[:f/fullyrange], automatic brightness / contrast correction
f/fullyrange
Stretch luminance to "0-255".
lb/linblenddeint
Linear blend deinterlacing filter that deinterlaces the given block by filtering all
lines with a "(1 2 1)" filter.
li/linipoldeint
Linear interpolating deinterlacing filter that deinterlaces the given block by
linearly interpolating every second line.
ci/cubicipoldeint
Cubic interpolating deinterlacing filter deinterlaces the given block by cubically
interpolating every second line.
md/mediandeint
Median deinterlacing filter that deinterlaces the given block by applying a median
filter to every second line.
fd/ffmpegdeint
FFmpeg deinterlacing filter that deinterlaces the given block by filtering every
second line with a "(-1 4 2 4 -1)" filter.
l5/lowpass5
Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given block
by filtering all lines with a "(-1 2 6 2 -1)" filter.
fq/forceQuant[|quantizer]
Overrides the quantizer table from the input with the constant quantizer you specify.
quantizer
Quantizer to use
de/default
Default pp filter combination ("hb|a,vb|a,dr|a")
fa/fast
Fast pp filter combination ("h1|a,v1|a,dr|a")
ac High quality pp filter combination ("ha|a|128|7,va|a,dr|a")
Examples
• Apply horizontal and vertical deblocking, deringing and automatic brightness/contrast:
pp=hb/vb/dr/al
• Apply default filters without brightness/contrast correction:
pp=de/-al
• Apply default filters and temporal denoiser:
pp=default/tmpnoise|1|2|3
• Apply deblocking on luminance only, and switch vertical deblocking on or off
automatically depending on available CPU time:
pp=hb|y/vb|a
pp7
Apply Postprocessing filter 7. It is variant of the spp filter, similar to spp = 6 with 7
point DCT, where only the center sample is used after IDCT.
The filter accepts the following options:
qp Force a constant quantization parameter. It accepts an integer in range 0 to 63. If
not set, the filter will use the QP from the video stream (if available).
mode
Set thresholding mode. Available modes are:
hard
Set hard thresholding.
soft
Set soft thresholding (better de-ringing effect, but likely blurrier).
medium
Set medium thresholding (good results, default).
premultiply
Apply alpha premultiply effect to input video stream using first plane of second stream as
alpha.
Both streams must have same dimensions and same pixel format.
The filter accepts the following option:
planes
Set which planes will be processed, unprocessed planes will be copied. By default
value 0xf, all planes will be processed.
inplace
Do not require 2nd input for processing, instead use alpha plane from input stream.
prewitt
Apply prewitt operator to input video stream.
The filter accepts the following option:
planes
Set which planes will be processed, unprocessed planes will be copied. By default
value 0xf, all planes will be processed.
scale
Set value which will be multiplied with filtered result.
delta
Set value which will be added to filtered result.
program_opencl
Filter video using an OpenCL program.
source
OpenCL program source file.
kernel
Kernel name in program.
inputs
Number of inputs to the filter. Defaults to 1.
size, s
Size of output frames. Defaults to the same as the first input.
The program source file must contain a kernel function with the given name, which will be
run once for each plane of the output. Each run on a plane gets enqueued as a separate 2D
global NDRange with one work-item for each pixel to be generated. The global ID offset
for each work-item is therefore the coordinates of a pixel in the destination image.
The kernel function needs to take the following arguments:
• Destination image, __write_only image2d_t.
This image will become the output; the kernel should write all of it.
• Frame index, unsigned int.
This is a counter starting from zero and increasing by one for each frame.
• Source images, __read_only image2d_t.
These are the most recent images on each input. The kernel may read from them to
generate the output, but they can't be written to.
Example programs:
• Copy the input to the output (output must be the same size as the input).
__kernel void copy(__write_only image2d_t destination,
unsigned int index,
__read_only image2d_t source)
{
const sampler_t sampler = CLK_NORMALIZED_COORDS_FALSE;
int2 location = (int2)(get_global_id(0), get_global_id(1));
float4 value = read_imagef(source, sampler, location);
write_imagef(destination, location, value);
}
• Apply a simple transformation, rotating the input by an amount increasing with the
index counter. Pixel values are linearly interpolated by the sampler, and the output
need not have the same dimensions as the input.
__kernel void rotate_image(__write_only image2d_t dst,
unsigned int index,
__read_only image2d_t src)
{
const sampler_t sampler = (CLK_NORMALIZED_COORDS_FALSE |
CLK_FILTER_LINEAR);
float angle = (float)index / 100.0f;
float2 dst_dim = convert_float2(get_image_dim(dst));
float2 src_dim = convert_float2(get_image_dim(src));
float2 dst_cen = dst_dim / 2.0f;
float2 src_cen = src_dim / 2.0f;
int2 dst_loc = (int2)(get_global_id(0), get_global_id(1));
float2 dst_pos = convert_float2(dst_loc) - dst_cen;
float2 src_pos = {
cos(angle) * dst_pos.x - sin(angle) * dst_pos.y,
sin(angle) * dst_pos.x + cos(angle) * dst_pos.y
};
src_pos = src_pos * src_dim / dst_dim;
float2 src_loc = src_pos + src_cen;
if (src_loc.x < 0.0f || src_loc.y < 0.0f ||
src_loc.x > src_dim.x || src_loc.y > src_dim.y)
write_imagef(dst, dst_loc, 0.5f);
else
write_imagef(dst, dst_loc, read_imagef(src, sampler, src_loc));
}
• Blend two inputs together, with the amount of each input used varying with the index
counter.
__kernel void blend_images(__write_only image2d_t dst,
unsigned int index,
__read_only image2d_t src1,
__read_only image2d_t src2)
{
const sampler_t sampler = (CLK_NORMALIZED_COORDS_FALSE |
CLK_FILTER_LINEAR);
float blend = (cos((float)index / 50.0f) + 1.0f) / 2.0f;
int2 dst_loc = (int2)(get_global_id(0), get_global_id(1));
int2 src1_loc = dst_loc * get_image_dim(src1) / get_image_dim(dst);
int2 src2_loc = dst_loc * get_image_dim(src2) / get_image_dim(dst);
float4 val1 = read_imagef(src1, sampler, src1_loc);
float4 val2 = read_imagef(src2, sampler, src2_loc);
write_imagef(dst, dst_loc, val1 * blend + val2 * (1.0f - blend));
}
pseudocolor
Alter frame colors in video with pseudocolors.
This filter accept the following options:
c0 set pixel first component expression
c1 set pixel second component expression
c2 set pixel third component expression
c3 set pixel fourth component expression, corresponds to the alpha component
i set component to use as base for altering colors
Each of them specifies the expression to use for computing the lookup table for the
corresponding pixel component values.
The expressions can contain the following constants and functions:
w
h The input width and height.
val The input value for the pixel component.
ymin, umin, vmin, amin
The minimum allowed component value.
ymax, umax, vmax, amax
The maximum allowed component value.
All expressions default to "val".
Examples
• Change too high luma values to gradient:
pseudocolor="'if(between(val,ymax,amax),lerp(ymin,ymax,(val-ymax)/(amax-ymax)),-1):if(between(val,ymax,amax),lerp(umax,umin,(val-ymax)/(amax-ymax)),-1):if(between(val,ymax,amax),lerp(vmin,vmax,(val-ymax)/(amax-ymax)),-1):-1'"
psnr
Obtain the average, maximum and minimum PSNR (Peak Signal to Noise Ratio) between two
input videos.
This filter takes in input two input videos, the first input is considered the "main"
source and is passed unchanged to the output. The second input is used as a "reference"
video for computing the PSNR.
Both video inputs must have the same resolution and pixel format for this filter to work
correctly. Also it assumes that both inputs have the same number of frames, which are
compared one by one.
The obtained average PSNR is printed through the logging system.
The filter stores the accumulated MSE (mean squared error) of each frame, and at the end
of the processing it is averaged across all frames equally, and the following formula is
applied to obtain the PSNR:
PSNR = 10*log10(MAX^2/MSE)
Where MAX is the average of the maximum values of each component of the image.
The description of the accepted parameters follows.
stats_file, f
If specified the filter will use the named file to save the PSNR of each individual
frame. When filename equals "-" the data is sent to standard output.
stats_version
Specifies which version of the stats file format to use. Details of each format are
written below. Default value is 1.
stats_add_max
Determines whether the max value is output to the stats log. Default value is 0.
Requires stats_version >= 2. If this is set and stats_version < 2, the filter will
return an error.
This filter also supports the framesync options.
The file printed if stats_file is selected, contains a sequence of key/value pairs of the
form key:value for each compared couple of frames.
If a stats_version greater than 1 is specified, a header line precedes the list of per-
frame-pair stats, with key value pairs following the frame format with the following
parameters:
psnr_log_version
The version of the log file format. Will match stats_version.
fields
A comma separated list of the per-frame-pair parameters included in the log.
A description of each shown per-frame-pair parameter follows:
n sequential number of the input frame, starting from 1
mse_avg
Mean Square Error pixel-by-pixel average difference of the compared frames, averaged
over all the image components.
mse_y, mse_u, mse_v, mse_r, mse_g, mse_b, mse_a
Mean Square Error pixel-by-pixel average difference of the compared frames for the
component specified by the suffix.
psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a
Peak Signal to Noise ratio of the compared frames for the component specified by the
suffix.
max_avg, max_y, max_u, max_v
Maximum allowed value for each channel, and average over all channels.
For example:
movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
[main][ref] psnr="stats_file=stats.log" [out]
On this example the input file being processed is compared with the reference file
ref_movie.mpg. The PSNR of each individual frame is stored in stats.log.
pullup
Pulldown reversal (inverse telecine) filter, capable of handling mixed hard-telecine,
24000/1001 fps progressive, and 30000/1001 fps progressive content.
The pullup filter is designed to take advantage of future context in making its decisions.
This filter is stateless in the sense that it does not lock onto a pattern to follow, but
it instead looks forward to the following fields in order to identify matches and rebuild
progressive frames.
To produce content with an even framerate, insert the fps filter after pullup, use
"fps=24000/1001" if the input frame rate is 29.97fps, "fps=24" for 30fps and the (rare)
telecined 25fps input.
The filter accepts the following options:
jl
jr
jt
jb These options set the amount of "junk" to ignore at the left, right, top, and bottom
of the image, respectively. Left and right are in units of 8 pixels, while top and
bottom are in units of 2 lines. The default is 8 pixels on each side.
sb Set the strict breaks. Setting this option to 1 will reduce the chances of filter
generating an occasional mismatched frame, but it may also cause an excessive number
of frames to be dropped during high motion sequences. Conversely, setting it to -1
will make filter match fields more easily. This may help processing of video where
there is slight blurring between the fields, but may also cause there to be interlaced
frames in the output. Default value is 0.
mp Set the metric plane to use. It accepts the following values:
l Use luma plane.
u Use chroma blue plane.
v Use chroma red plane.
This option may be set to use chroma plane instead of the default luma plane for doing
filter's computations. This may improve accuracy on very clean source material, but
more likely will decrease accuracy, especially if there is chroma noise (rainbow
effect) or any grayscale video. The main purpose of setting mp to a chroma plane is
to reduce CPU load and make pullup usable in realtime on slow machines.
For best results (without duplicated frames in the output file) it is necessary to change
the output frame rate. For example, to inverse telecine NTSC input:
ffmpeg -i input -vf pullup -r 24000/1001 ...
qp
Change video quantization parameters (QP).
The filter accepts the following option:
qp Set expression for quantization parameter.
The expression is evaluated through the eval API and can contain, among others, the
following constants:
known
1 if index is not 129, 0 otherwise.
qp Sequential index starting from -129 to 128.
Examples
• Some equation like:
qp=2+2*sin(PI*qp)
random
Flush video frames from internal cache of frames into a random order. No frame is
discarded. Inspired by frei0r nervous filter.
frames
Set size in number of frames of internal cache, in range from 2 to 512. Default is 30.
seed
Set seed for random number generator, must be an integer included between 0 and
"UINT32_MAX". If not specified, or if explicitly set to less than 0, the filter will
try to use a good random seed on a best effort basis.
readeia608
Read closed captioning (EIA-608) information from the top lines of a video frame.
This filter adds frame metadata for "lavfi.readeia608.X.cc" and "lavfi.readeia608.X.line",
where "X" is the number of the identified line with EIA-608 data (starting from 0). A
description of each metadata value follows:
lavfi.readeia608.X.cc
The two bytes stored as EIA-608 data (printed in hexadecimal).
lavfi.readeia608.X.line
The number of the line on which the EIA-608 data was identified and read.
This filter accepts the following options:
scan_min
Set the line to start scanning for EIA-608 data. Default is 0.
scan_max
Set the line to end scanning for EIA-608 data. Default is 29.
mac Set minimal acceptable amplitude change for sync codes detection. Default is 0.2.
Allowed range is "[0.001 - 1]".
spw Set the ratio of width reserved for sync code detection. Default is 0.27. Allowed
range is "[0.01 - 0.7]".
mhd Set the max peaks height difference for sync code detection. Default is 0.1. Allowed
range is "[0.0 - 0.5]".
mpd Set max peaks period difference for sync code detection. Default is 0.1. Allowed
range is "[0.0 - 0.5]".
msd Set the first two max start code bits differences. Default is 0.02. Allowed range is
"[0.0 - 0.5]".
bhd Set the minimum ratio of bits height compared to 3rd start code bit. Default is 0.75.
Allowed range is "[0.01 - 1]".
th_w
Set the white color threshold. Default is 0.35. Allowed range is "[0.1 - 1]".
th_b
Set the black color threshold. Default is 0.15. Allowed range is "[0.0 - 0.5]".
chp Enable checking the parity bit. In the event of a parity error, the filter will output
0x00 for that character. Default is false.
lp Lowpass lines prior further proccessing. Default is disabled.
Examples
• Output a csv with presentation time and the first two lines of identified EIA-608
captioning data.
ffprobe -f lavfi -i movie=captioned_video.mov,readeia608 -show_entries frame=pkt_pts_time:frame_tags=lavfi.readeia608.0.cc,lavfi.readeia608.1.cc -of csv
readvitc
Read vertical interval timecode (VITC) information from the top lines of a video frame.
The filter adds frame metadata key "lavfi.readvitc.tc_str" with the timecode value, if a
valid timecode has been detected. Further metadata key "lavfi.readvitc.found" is set to
0/1 depending on whether timecode data has been found or not.
This filter accepts the following options:
scan_max
Set the maximum number of lines to scan for VITC data. If the value is set to "-1" the
full video frame is scanned. Default is 45.
thr_b
Set the luma threshold for black. Accepts float numbers in the range [0.0,1.0],
default value is 0.2. The value must be equal or less than "thr_w".
thr_w
Set the luma threshold for white. Accepts float numbers in the range [0.0,1.0],
default value is 0.6. The value must be equal or greater than "thr_b".
Examples
• Detect and draw VITC data onto the video frame; if no valid VITC is detected, draw
"--:--:--:--" as a placeholder:
ffmpeg -i input.avi -filter:v 'readvitc,drawtext=fontfile=FreeMono.ttf:text=%{metadata\\:lavfi.readvitc.tc_str\\:--\\\\\\:--\\\\\\:--\\\\\\:--}:x=(w-tw)/2:y=400-ascent'
remap
Remap pixels using 2nd: Xmap and 3rd: Ymap input video stream.
Destination pixel at position (X, Y) will be picked from source (x, y) position where x =
Xmap(X, Y) and y = Ymap(X, Y). If mapping values are out of range, zero value for pixel
will be used for destination pixel.
Xmap and Ymap input video streams must be of same dimensions. Output video stream will
have Xmap/Ymap video stream dimensions. Xmap and Ymap input video streams are 16bit
depth, single channel.
format
Specify pixel format of output from this filter. Can be "color" or "gray". Default is
"color".
removegrain
The removegrain filter is a spatial denoiser for progressive video.
m0 Set mode for the first plane.
m1 Set mode for the second plane.
m2 Set mode for the third plane.
m3 Set mode for the fourth plane.
Range of mode is from 0 to 24. Description of each mode follows:
0 Leave input plane unchanged. Default.
1 Clips the pixel with the minimum and maximum of the 8 neighbour pixels.
2 Clips the pixel with the second minimum and maximum of the 8 neighbour pixels.
3 Clips the pixel with the third minimum and maximum of the 8 neighbour pixels.
4 Clips the pixel with the fourth minimum and maximum of the 8 neighbour pixels. This
is equivalent to a median filter.
5 Line-sensitive clipping giving the minimal change.
6 Line-sensitive clipping, intermediate.
7 Line-sensitive clipping, intermediate.
8 Line-sensitive clipping, intermediate.
9 Line-sensitive clipping on a line where the neighbours pixels are the closest.
10 Replaces the target pixel with the closest neighbour.
11 [1 2 1] horizontal and vertical kernel blur.
12 Same as mode 11.
13 Bob mode, interpolates top field from the line where the neighbours pixels are the
closest.
14 Bob mode, interpolates bottom field from the line where the neighbours pixels are the
closest.
15 Bob mode, interpolates top field. Same as 13 but with a more complicated interpolation
formula.
16 Bob mode, interpolates bottom field. Same as 14 but with a more complicated
interpolation formula.
17 Clips the pixel with the minimum and maximum of respectively the maximum and minimum
of each pair of opposite neighbour pixels.
18 Line-sensitive clipping using opposite neighbours whose greatest distance from the
current pixel is minimal.
19 Replaces the pixel with the average of its 8 neighbours.
20 Averages the 9 pixels ([1 1 1] horizontal and vertical blur).
21 Clips pixels using the averages of opposite neighbour.
22 Same as mode 21 but simpler and faster.
23 Small edge and halo removal, but reputed useless.
24 Similar as 23.
removelogo
Suppress a TV station logo, using an image file to determine which pixels comprise the
logo. It works by filling in the pixels that comprise the logo with neighboring pixels.
The filter accepts the following options:
filename, f
Set the filter bitmap file, which can be any image format supported by libavformat.
The width and height of the image file must match those of the video stream being
processed.
Pixels in the provided bitmap image with a value of zero are not considered part of the
logo, non-zero pixels are considered part of the logo. If you use white (255) for the logo
and black (0) for the rest, you will be safe. For making the filter bitmap, it is
recommended to take a screen capture of a black frame with the logo visible, and then
using a threshold filter followed by the erode filter once or twice.
If needed, little splotches can be fixed manually. Remember that if logo pixels are not
covered, the filter quality will be much reduced. Marking too many pixels as part of the
logo does not hurt as much, but it will increase the amount of blurring needed to cover
over the image and will destroy more information than necessary, and extra pixels will
slow things down on a large logo.
repeatfields
This filter uses the repeat_field flag from the Video ES headers and hard repeats fields
based on its value.
reverse
Reverse a video clip.
Warning: This filter requires memory to buffer the entire clip, so trimming is suggested.
Examples
• Take the first 5 seconds of a clip, and reverse it.
trim=end=5,reverse
rgbashift
Shift R/G/B/A pixels horizontally and/or vertically.
The filter accepts the following options:
rh Set amount to shift red horizontally.
rv Set amount to shift red vertically.
gh Set amount to shift green horizontally.
gv Set amount to shift green vertically.
bh Set amount to shift blue horizontally.
bv Set amount to shift blue vertically.
ah Set amount to shift alpha horizontally.
av Set amount to shift alpha vertically.
edge
Set edge mode, can be smear, default, or warp.
roberts
Apply roberts cross operator to input video stream.
The filter accepts the following option:
planes
Set which planes will be processed, unprocessed planes will be copied. By default
value 0xf, all planes will be processed.
scale
Set value which will be multiplied with filtered result.
delta
Set value which will be added to filtered result.
rotate
Rotate video by an arbitrary angle expressed in radians.
The filter accepts the following options:
A description of the optional parameters follows.
angle, a
Set an expression for the angle by which to rotate the input video clockwise,
expressed as a number of radians. A negative value will result in a counter-clockwise
rotation. By default it is set to "0".
This expression is evaluated for each frame.
out_w, ow
Set the output width expression, default value is "iw". This expression is evaluated
just once during configuration.
out_h, oh
Set the output height expression, default value is "ih". This expression is evaluated
just once during configuration.
bilinear
Enable bilinear interpolation if set to 1, a value of 0 disables it. Default value is
1.
fillcolor, c
Set the color used to fill the output area not covered by the rotated image. For the
general syntax of this option, check the "Color" section in the ffmpeg-utils manual.
If the special value "none" is selected then no background is printed (useful for
example if the background is never shown).
Default value is "black".
The expressions for the angle and the output size can contain the following constants and
functions:
n sequential number of the input frame, starting from 0. It is always NAN before the
first frame is filtered.
t time in seconds of the input frame, it is set to 0 when the filter is configured. It
is always NAN before the first frame is filtered.
hsub
vsub
horizontal and vertical chroma subsample values. For example for the pixel format
"yuv422p" hsub is 2 and vsub is 1.
in_w, iw
in_h, ih
the input video width and height
out_w, ow
out_h, oh
the output width and height, that is the size of the padded area as specified by the
width and height expressions
rotw(a)
roth(a)
the minimal width/height required for completely containing the input video rotated by
a radians.
These are only available when computing the out_w and out_h expressions.
Examples
• Rotate the input by PI/6 radians clockwise:
rotate=PI/6
• Rotate the input by PI/6 radians counter-clockwise:
rotate=-PI/6
• Rotate the input by 45 degrees clockwise:
rotate=45*PI/180
• Apply a constant rotation with period T, starting from an angle of PI/3:
rotate=PI/3+2*PI*t/T
• Make the input video rotation oscillating with a period of T seconds and an amplitude
of A radians:
rotate=A*sin(2*PI/T*t)
• Rotate the video, output size is chosen so that the whole rotating input video is
always completely contained in the output:
rotate='2*PI*t:ow=hypot(iw,ih):oh=ow'
• Rotate the video, reduce the output size so that no background is ever shown:
rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none
Commands
The filter supports the following commands:
a, angle
Set the angle expression. The command accepts the same syntax of the corresponding
option.
If the specified expression is not valid, it is kept at its current value.
sab
Apply Shape Adaptive Blur.
The filter accepts the following options:
luma_radius, lr
Set luma blur filter strength, must be a value in range 0.1-4.0, default value is 1.0.
A greater value will result in a more blurred image, and in slower processing.
luma_pre_filter_radius, lpfr
Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default value is
1.0.
luma_strength, ls
Set luma maximum difference between pixels to still be considered, must be a value in
the 0.1-100.0 range, default value is 1.0.
chroma_radius, cr
Set chroma blur filter strength, must be a value in range -0.9-4.0. A greater value
will result in a more blurred image, and in slower processing.
chroma_pre_filter_radius, cpfr
Set chroma pre-filter radius, must be a value in the -0.9-2.0 range.
chroma_strength, cs
Set chroma maximum difference between pixels to still be considered, must be a value
in the -0.9-100.0 range.
Each chroma option value, if not explicitly specified, is set to the corresponding luma
option value.
scale
Scale (resize) the input video, using the libswscale library.
The scale filter forces the output display aspect ratio to be the same of the input, by
changing the output sample aspect ratio.
If the input image format is different from the format requested by the next filter, the
scale filter will convert the input to the requested format.
Options
The filter accepts the following options, or any of the options supported by the
libswscale scaler.
See the ffmpeg-scaler manual for the complete list of scaler options.
width, w
height, h
Set the output video dimension expression. Default value is the input dimension.
If the width or w value is 0, the input width is used for the output. If the height or
h value is 0, the input height is used for the output.
If one and only one of the values is -n with n >= 1, the scale filter will use a value
that maintains the aspect ratio of the input image, calculated from the other
specified dimension. After that it will, however, make sure that the calculated
dimension is divisible by n and adjust the value if necessary.
If both values are -n with n >= 1, the behavior will be identical to both values being
set to 0 as previously detailed.
See below for the list of accepted constants for use in the dimension expression.
eval
Specify when to evaluate width and height expression. It accepts the following values:
init
Only evaluate expressions once during the filter initialization or when a command
is processed.
frame
Evaluate expressions for each incoming frame.
Default value is init.
interl
Set the interlacing mode. It accepts the following values:
1 Force interlaced aware scaling.
0 Do not apply interlaced scaling.
-1 Select interlaced aware scaling depending on whether the source frames are flagged
as interlaced or not.
Default value is 0.
flags
Set libswscale scaling flags. See the ffmpeg-scaler manual for the complete list of
values. If not explicitly specified the filter applies the default flags.
param0, param1
Set libswscale input parameters for scaling algorithms that need them. See the ffmpeg-
scaler manual for the complete documentation. If not explicitly specified the filter
applies empty parameters.
size, s
Set the video size. For the syntax of this option, check the "Video size" section in
the ffmpeg-utils manual.
in_color_matrix
out_color_matrix
Set in/output YCbCr color space type.
This allows the autodetected value to be overridden as well as allows forcing a
specific value used for the output and encoder.
If not specified, the color space type depends on the pixel format.
Possible values:
auto
Choose automatically.
bt709
Format conforming to International Telecommunication Union (ITU) Recommendation
BT.709.
fcc Set color space conforming to the United States Federal Communications Commission
(FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a).
bt601
bt470
smpte170m
Set color space conforming to:
• ITU Radiocommunication Sector (ITU-R) Recommendation BT.601
• ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G
• Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004
smpte240m
Set color space conforming to SMPTE ST 240:1999.
bt2020
Set color space conforming to ITU-R BT.2020 non-constant luminance system.
in_range
out_range
Set in/output YCbCr sample range.
This allows the autodetected value to be overridden as well as allows forcing a
specific value used for the output and encoder. If not specified, the range depends on
the pixel format. Possible values:
auto/unknown
Choose automatically.
jpeg/full/pc
Set full range (0-255 in case of 8-bit luma).
mpeg/limited/tv
Set "MPEG" range (16-235 in case of 8-bit luma).
force_original_aspect_ratio
Enable decreasing or increasing output video width or height if necessary to keep the
original aspect ratio. Possible values:
disable
Scale the video as specified and disable this feature.
decrease
The output video dimensions will automatically be decreased if needed.
increase
The output video dimensions will automatically be increased if needed.
One useful instance of this option is that when you know a specific device's maximum
allowed resolution, you can use this to limit the output video to that, while
retaining the aspect ratio. For example, device A allows 1280x720 playback, and your
video is 1920x800. Using this option (set it to decrease) and specifying 1280x720 to
the command line makes the output 1280x533.
Please note that this is a different thing than specifying -1 for w or h, you still
need to specify the output resolution for this option to work.
The values of the w and h options are expressions containing the following constants:
in_w
in_h
The input width and height
iw
ih These are the same as in_w and in_h.
out_w
out_h
The output (scaled) width and height
ow
oh These are the same as out_w and out_h
a The same as iw / ih
sar input sample aspect ratio
dar The input display aspect ratio. Calculated from "(iw / ih) * sar".
hsub
vsub
horizontal and vertical input chroma subsample values. For example for the pixel
format "yuv422p" hsub is 2 and vsub is 1.
ohsub
ovsub
horizontal and vertical output chroma subsample values. For example for the pixel
format "yuv422p" hsub is 2 and vsub is 1.
Examples
• Scale the input video to a size of 200x100
scale=w=200:h=100
This is equivalent to:
scale=200:100
or:
scale=200x100
• Specify a size abbreviation for the output size:
scale=qcif
which can also be written as:
scale=size=qcif
• Scale the input to 2x:
scale=w=2*iw:h=2*ih
• The above is the same as:
scale=2*in_w:2*in_h
• Scale the input to 2x with forced interlaced scaling:
scale=2*iw:2*ih:interl=1
• Scale the input to half size:
scale=w=iw/2:h=ih/2
• Increase the width, and set the height to the same size:
scale=3/2*iw:ow
• Seek Greek harmony:
scale=iw:1/PHI*iw
scale=ih*PHI:ih
• Increase the height, and set the width to 3/2 of the height:
scale=w=3/2*oh:h=3/5*ih
• Increase the size, making the size a multiple of the chroma subsample values:
scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"
• Increase the width to a maximum of 500 pixels, keeping the same aspect ratio as the
input:
scale=w='min(500\, iw*3/2):h=-1'
• Make pixels square by combining scale and setsar:
scale='trunc(ih*dar):ih',setsar=1/1
• Make pixels square by combining scale and setsar, making sure the resulting resolution
is even (required by some codecs):
scale='trunc(ih*dar/2)*2:trunc(ih/2)*2',setsar=1/1
Commands
This filter supports the following commands:
width, w
height, h
Set the output video dimension expression. The command accepts the same syntax of the
corresponding option.
If the specified expression is not valid, it is kept at its current value.
scale_npp
Use the NVIDIA Performance Primitives (libnpp) to perform scaling and/or pixel format
conversion on CUDA video frames. Setting the output width and height works in the same way
as for the scale filter.
The following additional options are accepted:
format
The pixel format of the output CUDA frames. If set to the string "same" (the default),
the input format will be kept. Note that automatic format negotiation and conversion
is not yet supported for hardware frames
interp_algo
The interpolation algorithm used for resizing. One of the following:
nn Nearest neighbour.
linear
cubic
cubic2p_bspline
2-parameter cubic (B=1, C=0)
cubic2p_catmullrom
2-parameter cubic (B=0, C=1/2)
cubic2p_b05c03
2-parameter cubic (B=1/2, C=3/10)
super
Supersampling
lanczos
scale2ref
Scale (resize) the input video, based on a reference video.
See the scale filter for available options, scale2ref supports the same but uses the
reference video instead of the main input as basis. scale2ref also supports the following
additional constants for the w and h options:
main_w
main_h
The main input video's width and height
main_a
The same as main_w / main_h
main_sar
The main input video's sample aspect ratio
main_dar, mdar
The main input video's display aspect ratio. Calculated from "(main_w / main_h) *
main_sar".
main_hsub
main_vsub
The main input video's horizontal and vertical chroma subsample values. For example
for the pixel format "yuv422p" hsub is 2 and vsub is 1.
Examples
• Scale a subtitle stream (b) to match the main video (a) in size before overlaying
'scale2ref[b][a];[a][b]overlay'
• Scale a logo to 1/10th the height of a video, while preserving its display aspect
ratio.
[logo-in][video-in]scale2ref=w=oh*mdar:h=ih/10[logo-out][video-out]
selectivecolor
Adjust cyan, magenta, yellow and black (CMYK) to certain ranges of colors (such as "reds",
"yellows", "greens", "cyans", ...). The adjustment range is defined by the "purity" of the
color (that is, how saturated it already is).
This filter is similar to the Adobe Photoshop Selective Color tool.
The filter accepts the following options:
correction_method
Select color correction method.
Available values are:
absolute
Specified adjustments are applied "as-is" (added/subtracted to original pixel
component value).
relative
Specified adjustments are relative to the original component value.
Default is "absolute".
reds
Adjustments for red pixels (pixels where the red component is the maximum)
yellows
Adjustments for yellow pixels (pixels where the blue component is the minimum)
greens
Adjustments for green pixels (pixels where the green component is the maximum)
cyans
Adjustments for cyan pixels (pixels where the red component is the minimum)
blues
Adjustments for blue pixels (pixels where the blue component is the maximum)
magentas
Adjustments for magenta pixels (pixels where the green component is the minimum)
whites
Adjustments for white pixels (pixels where all components are greater than 128)
neutrals
Adjustments for all pixels except pure black and pure white
blacks
Adjustments for black pixels (pixels where all components are lesser than 128)
psfile
Specify a Photoshop selective color file (".asv") to import the settings from.
All the adjustment settings (reds, yellows, ...) accept up to 4 space separated floating
point adjustment values in the [-1,1] range, respectively to adjust the amount of cyan,
magenta, yellow and black for the pixels of its range.
Examples
• Increase cyan by 50% and reduce yellow by 33% in every green areas, and increase
magenta by 27% in blue areas:
selectivecolor=greens=.5 0 -.33 0:blues=0 .27
• Use a Photoshop selective color preset:
selectivecolor=psfile=MySelectiveColorPresets/Misty.asv
separatefields
The "separatefields" takes a frame-based video input and splits each frame into its
components fields, producing a new half height clip with twice the frame rate and twice
the frame count.
This filter use field-dominance information in frame to decide which of each pair of
fields to place first in the output. If it gets it wrong use setfield filter before
"separatefields" filter.
setdar, setsar
The "setdar" filter sets the Display Aspect Ratio for the filter output video.
This is done by changing the specified Sample (aka Pixel) Aspect Ratio, according to the
following equation:
<DAR> = <HORIZONTAL_RESOLUTION> / <VERTICAL_RESOLUTION> * <SAR>
Keep in mind that the "setdar" filter does not modify the pixel dimensions of the video
frame. Also, the display aspect ratio set by this filter may be changed by later filters
in the filterchain, e.g. in case of scaling or if another "setdar" or a "setsar" filter is
applied.
The "setsar" filter sets the Sample (aka Pixel) Aspect Ratio for the filter output video.
Note that as a consequence of the application of this filter, the output display aspect
ratio will change according to the equation above.
Keep in mind that the sample aspect ratio set by the "setsar" filter may be changed by
later filters in the filterchain, e.g. if another "setsar" or a "setdar" filter is
applied.
It accepts the following parameters:
r, ratio, dar ("setdar" only), sar ("setsar" only)
Set the aspect ratio used by the filter.
The parameter can be a floating point number string, an expression, or a string of the
form num:den, where num and den are the numerator and denominator of the aspect ratio.
If the parameter is not specified, it is assumed the value "0". In case the form
"num:den" is used, the ":" character should be escaped.
max Set the maximum integer value to use for expressing numerator and denominator when
reducing the expressed aspect ratio to a rational. Default value is 100.
The parameter sar is an expression containing the following constants:
E, PI, PHI
These are approximated values for the mathematical constants e (Euler's number), pi
(Greek pi), and phi (the golden ratio).
w, h
The input width and height.
a These are the same as w / h.
sar The input sample aspect ratio.
dar The input display aspect ratio. It is the same as (w / h) * sar.
hsub, vsub
Horizontal and vertical chroma subsample values. For example, for the pixel format
"yuv422p" hsub is 2 and vsub is 1.
Examples
• To change the display aspect ratio to 16:9, specify one of the following:
setdar=dar=1.77777
setdar=dar=16/9
• To change the sample aspect ratio to 10:11, specify:
setsar=sar=10/11
• To set a display aspect ratio of 16:9, and specify a maximum integer value of 1000 in
the aspect ratio reduction, use the command:
setdar=ratio=16/9:max=1000
setfield
Force field for the output video frame.
The "setfield" filter marks the interlace type field for the output frames. It does not
change the input frame, but only sets the corresponding property, which affects how the
frame is treated by following filters (e.g. "fieldorder" or "yadif").
The filter accepts the following options:
mode
Available values are:
auto
Keep the same field property.
bff Mark the frame as bottom-field-first.
tff Mark the frame as top-field-first.
prog
Mark the frame as progressive.
setparams
Force frame parameter for the output video frame.
The "setparams" filter marks interlace and color range for the output frames. It does not
change the input frame, but only sets the corresponding property, which affects how the
frame is treated by filters/encoders.
field_mode
Available values are:
auto
Keep the same field property (default).
bff Mark the frame as bottom-field-first.
tff Mark the frame as top-field-first.
prog
Mark the frame as progressive.
range
Available values are:
auto
Keep the same color range property (default).
unspecified, unknown
Mark the frame as unspecified color range.
limited, tv, mpeg
Mark the frame as limited range.
full, pc, jpeg
Mark the frame as full range.
color_primaries
Set the color primaries. Available values are:
auto
Keep the same color primaries property (default).
bt709
unknown
bt470m
bt470bg
smpte170m
smpte240m
film
bt2020
smpte428
smpte431
smpte432
jedec-p22
color_trc
Set the color transfer. Available values are:
auto
Keep the same color trc property (default).
bt709
unknown
bt470m
bt470bg
smpte170m
smpte240m
linear
log100
log316
iec61966-2-4
bt1361e
iec61966-2-1
bt2020-10
bt2020-12
smpte2084
smpte428
arib-std-b67
colorspace
Set the colorspace. Available values are:
auto
Keep the same colorspace property (default).
gbr
bt709
unknown
fcc
bt470bg
smpte170m
smpte240m
ycgco
bt2020nc
bt2020c
smpte2085
chroma-derived-nc
chroma-derived-c
ictcp
showinfo
Show a line containing various information for each input video frame. The input video is
not modified.
This filter supports the following options:
checksum
Calculate checksums of each plane. By default enabled.
The shown line contains a sequence of key/value pairs of the form key:value.
The following values are shown in the output:
n The (sequential) number of the input frame, starting from 0.
pts The Presentation TimeStamp of the input frame, expressed as a number of time base
units. The time base unit depends on the filter input pad.
pts_time
The Presentation TimeStamp of the input frame, expressed as a number of seconds.
pos The position of the frame in the input stream, or -1 if this information is
unavailable and/or meaningless (for example in case of synthetic video).
fmt The pixel format name.
sar The sample aspect ratio of the input frame, expressed in the form num/den.
s The size of the input frame. For the syntax of this option, check the "Video size"
section in the ffmpeg-utils manual.
i The type of interlaced mode ("P" for "progressive", "T" for top field first, "B" for
bottom field first).
iskey
This is 1 if the frame is a key frame, 0 otherwise.
type
The picture type of the input frame ("I" for an I-frame, "P" for a P-frame, "B" for a
B-frame, or "?" for an unknown type). Also refer to the documentation of the
"AVPictureType" enum and of the "av_get_picture_type_char" function defined in
libavutil/avutil.h.
checksum
The Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame.
plane_checksum
The Adler-32 checksum (printed in hexadecimal) of each plane of the input frame,
expressed in the form "[c0 c1 c2 c3]".
showpalette
Displays the 256 colors palette of each frame. This filter is only relevant for pal8 pixel
format frames.
It accepts the following option:
s Set the size of the box used to represent one palette color entry. Default is 30 (for
a "30x30" pixel box).
shuffleframes
Reorder and/or duplicate and/or drop video frames.
It accepts the following parameters:
mapping
Set the destination indexes of input frames. This is space or '|' separated list of
indexes that maps input frames to output frames. Number of indexes also sets maximal
value that each index may have. '-1' index have special meaning and that is to drop
frame.
The first frame has the index 0. The default is to keep the input unchanged.
Examples
• Swap second and third frame of every three frames of the input:
ffmpeg -i INPUT -vf "shuffleframes=0 2 1" OUTPUT
• Swap 10th and 1st frame of every ten frames of the input:
ffmpeg -i INPUT -vf "shuffleframes=9 1 2 3 4 5 6 7 8 0" OUTPUT
shuffleplanes
Reorder and/or duplicate video planes.
It accepts the following parameters:
map0
The index of the input plane to be used as the first output plane.
map1
The index of the input plane to be used as the second output plane.
map2
The index of the input plane to be used as the third output plane.
map3
The index of the input plane to be used as the fourth output plane.
The first plane has the index 0. The default is to keep the input unchanged.
Examples
• Swap the second and third planes of the input:
ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
signalstats
Evaluate various visual metrics that assist in determining issues associated with the
digitization of analog video media.
By default the filter will log these metadata values:
YMIN
Display the minimal Y value contained within the input frame. Expressed in range of
[0-255].
YLOW
Display the Y value at the 10% percentile within the input frame. Expressed in range
of [0-255].
YAVG
Display the average Y value within the input frame. Expressed in range of [0-255].
YHIGH
Display the Y value at the 90% percentile within the input frame. Expressed in range
of [0-255].
YMAX
Display the maximum Y value contained within the input frame. Expressed in range of
[0-255].
UMIN
Display the minimal U value contained within the input frame. Expressed in range of
[0-255].
ULOW
Display the U value at the 10% percentile within the input frame. Expressed in range
of [0-255].
UAVG
Display the average U value within the input frame. Expressed in range of [0-255].
UHIGH
Display the U value at the 90% percentile within the input frame. Expressed in range
of [0-255].
UMAX
Display the maximum U value contained within the input frame. Expressed in range of
[0-255].
VMIN
Display the minimal V value contained within the input frame. Expressed in range of
[0-255].
VLOW
Display the V value at the 10% percentile within the input frame. Expressed in range
of [0-255].
VAVG
Display the average V value within the input frame. Expressed in range of [0-255].
VHIGH
Display the V value at the 90% percentile within the input frame. Expressed in range
of [0-255].
VMAX
Display the maximum V value contained within the input frame. Expressed in range of
[0-255].
SATMIN
Display the minimal saturation value contained within the input frame. Expressed in
range of [0-~181.02].
SATLOW
Display the saturation value at the 10% percentile within the input frame. Expressed
in range of [0-~181.02].
SATAVG
Display the average saturation value within the input frame. Expressed in range of
[0-~181.02].
SATHIGH
Display the saturation value at the 90% percentile within the input frame. Expressed
in range of [0-~181.02].
SATMAX
Display the maximum saturation value contained within the input frame. Expressed in
range of [0-~181.02].
HUEMED
Display the median value for hue within the input frame. Expressed in range of
[0-360].
HUEAVG
Display the average value for hue within the input frame. Expressed in range of
[0-360].
YDIF
Display the average of sample value difference between all values of the Y plane in
the current frame and corresponding values of the previous input frame. Expressed in
range of [0-255].
UDIF
Display the average of sample value difference between all values of the U plane in
the current frame and corresponding values of the previous input frame. Expressed in
range of [0-255].
VDIF
Display the average of sample value difference between all values of the V plane in
the current frame and corresponding values of the previous input frame. Expressed in
range of [0-255].
YBITDEPTH
Display bit depth of Y plane in current frame. Expressed in range of [0-16].
UBITDEPTH
Display bit depth of U plane in current frame. Expressed in range of [0-16].
VBITDEPTH
Display bit depth of V plane in current frame. Expressed in range of [0-16].
The filter accepts the following options:
stat
out stat specify an additional form of image analysis. out output video with the
specified type of pixel highlighted.
Both options accept the following values:
tout
Identify temporal outliers pixels. A temporal outlier is a pixel unlike the
neighboring pixels of the same field. Examples of temporal outliers include the
results of video dropouts, head clogs, or tape tracking issues.
vrep
Identify vertical line repetition. Vertical line repetition includes similar rows
of pixels within a frame. In born-digital video vertical line repetition is
common, but this pattern is uncommon in video digitized from an analog source.
When it occurs in video that results from the digitization of an analog source it
can indicate concealment from a dropout compensator.
brng
Identify pixels that fall outside of legal broadcast range.
color, c
Set the highlight color for the out option. The default color is yellow.
Examples
• Output data of various video metrics:
ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames
• Output specific data about the minimum and maximum values of the Y plane per frame:
ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN
• Playback video while highlighting pixels that are outside of broadcast range in red.
ffplay example.mov -vf signalstats="out=brng:color=red"
• Playback video with signalstats metadata drawn over the frame.
ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt
The contents of signalstat_drawtext.txt used in the command are:
time %{pts:hms}
Y (%{metadata:lavfi.signalstats.YMIN}-%{metadata:lavfi.signalstats.YMAX})
U (%{metadata:lavfi.signalstats.UMIN}-%{metadata:lavfi.signalstats.UMAX})
V (%{metadata:lavfi.signalstats.VMIN}-%{metadata:lavfi.signalstats.VMAX})
saturation maximum: %{metadata:lavfi.signalstats.SATMAX}
signature
Calculates the MPEG-7 Video Signature. The filter can handle more than one input. In this
case the matching between the inputs can be calculated additionally. The filter always
passes through the first input. The signature of each stream can be written into a file.
It accepts the following options:
detectmode
Enable or disable the matching process.
Available values are:
off Disable the calculation of a matching (default).
full
Calculate the matching for the whole video and output whether the whole video
matches or only parts.
fast
Calculate only until a matching is found or the video ends. Should be faster in
some cases.
nb_inputs
Set the number of inputs. The option value must be a non negative integer. Default
value is 1.
filename
Set the path to which the output is written. If there is more than one input, the path
must be a prototype, i.e. must contain %d or %0nd (where n is a positive integer),
that will be replaced with the input number. If no filename is specified, no output
will be written. This is the default.
format
Choose the output format.
Available values are:
binary
Use the specified binary representation (default).
xml Use the specified xml representation.
th_d
Set threshold to detect one word as similar. The option value must be an integer
greater than zero. The default value is 9000.
th_dc
Set threshold to detect all words as similar. The option value must be an integer
greater than zero. The default value is 60000.
th_xh
Set threshold to detect frames as similar. The option value must be an integer greater
than zero. The default value is 116.
th_di
Set the minimum length of a sequence in frames to recognize it as matching sequence.
The option value must be a non negative integer value. The default value is 0.
th_it
Set the minimum relation, that matching frames to all frames must have. The option
value must be a double value between 0 and 1. The default value is 0.5.
Examples
• To calculate the signature of an input video and store it in signature.bin:
ffmpeg -i input.mkv -vf signature=filename=signature.bin -map 0:v -f null -
• To detect whether two videos match and store the signatures in XML format in
signature0.xml and signature1.xml:
ffmpeg -i input1.mkv -i input2.mkv -filter_complex "[0:v][1:v] signature=nb_inputs=2:detectmode=full:format=xml:filename=signature%d.xml" -map :v -f null -
smartblur
Blur the input video without impacting the outlines.
It accepts the following options:
luma_radius, lr
Set the luma radius. The option value must be a float number in the range [0.1,5.0]
that specifies the variance of the gaussian filter used to blur the image (slower if
larger). Default value is 1.0.
luma_strength, ls
Set the luma strength. The option value must be a float number in the range [-1.0,1.0]
that configures the blurring. A value included in [0.0,1.0] will blur the image
whereas a value included in [-1.0,0.0] will sharpen the image. Default value is 1.0.
luma_threshold, lt
Set the luma threshold used as a coefficient to determine whether a pixel should be
blurred or not. The option value must be an integer in the range [-30,30]. A value of
0 will filter all the image, a value included in [0,30] will filter flat areas and a
value included in [-30,0] will filter edges. Default value is 0.
chroma_radius, cr
Set the chroma radius. The option value must be a float number in the range [0.1,5.0]
that specifies the variance of the gaussian filter used to blur the image (slower if
larger). Default value is luma_radius.
chroma_strength, cs
Set the chroma strength. The option value must be a float number in the range
[-1.0,1.0] that configures the blurring. A value included in [0.0,1.0] will blur the
image whereas a value included in [-1.0,0.0] will sharpen the image. Default value is
luma_strength.
chroma_threshold, ct
Set the chroma threshold used as a coefficient to determine whether a pixel should be
blurred or not. The option value must be an integer in the range [-30,30]. A value of
0 will filter all the image, a value included in [0,30] will filter flat areas and a
value included in [-30,0] will filter edges. Default value is luma_threshold.
If a chroma option is not explicitly set, the corresponding luma value is set.
ssim
Obtain the SSIM (Structural SImilarity Metric) between two input videos.
This filter takes in input two input videos, the first input is considered the "main"
source and is passed unchanged to the output. The second input is used as a "reference"
video for computing the SSIM.
Both video inputs must have the same resolution and pixel format for this filter to work
correctly. Also it assumes that both inputs have the same number of frames, which are
compared one by one.
The filter stores the calculated SSIM of each frame.
The description of the accepted parameters follows.
stats_file, f
If specified the filter will use the named file to save the SSIM of each individual
frame. When filename equals "-" the data is sent to standard output.
The file printed if stats_file is selected, contains a sequence of key/value pairs of the
form key:value for each compared couple of frames.
A description of each shown parameter follows:
n sequential number of the input frame, starting from 1
Y, U, V, R, G, B
SSIM of the compared frames for the component specified by the suffix.
All SSIM of the compared frames for the whole frame.
dB Same as above but in dB representation.
This filter also supports the framesync options.
For example:
movie=ref_movie.mpg, setpts=PTS-STARTPTS [main];
[main][ref] ssim="stats_file=stats.log" [out]
On this example the input file being processed is compared with the reference file
ref_movie.mpg. The SSIM of each individual frame is stored in stats.log.
Another example with both psnr and ssim at same time:
ffmpeg -i main.mpg -i ref.mpg -lavfi "ssim;[0:v][1:v]psnr" -f null -
stereo3d
Convert between different stereoscopic image formats.
The filters accept the following options:
in Set stereoscopic image format of input.
Available values for input image formats are:
sbsl
side by side parallel (left eye left, right eye right)
sbsr
side by side crosseye (right eye left, left eye right)
sbs2l
side by side parallel with half width resolution (left eye left, right eye right)
sbs2r
side by side crosseye with half width resolution (right eye left, left eye right)
abl above-below (left eye above, right eye below)
abr above-below (right eye above, left eye below)
ab2l
above-below with half height resolution (left eye above, right eye below)
ab2r
above-below with half height resolution (right eye above, left eye below)
al alternating frames (left eye first, right eye second)
ar alternating frames (right eye first, left eye second)
irl interleaved rows (left eye has top row, right eye starts on next row)
irr interleaved rows (right eye has top row, left eye starts on next row)
icl interleaved columns, left eye first
icr interleaved columns, right eye first
Default value is sbsl.
out Set stereoscopic image format of output.
sbsl
side by side parallel (left eye left, right eye right)
sbsr
side by side crosseye (right eye left, left eye right)
sbs2l
side by side parallel with half width resolution (left eye left, right eye right)
sbs2r
side by side crosseye with half width resolution (right eye left, left eye right)
abl above-below (left eye above, right eye below)
abr above-below (right eye above, left eye below)
ab2l
above-below with half height resolution (left eye above, right eye below)
ab2r
above-below with half height resolution (right eye above, left eye below)
al alternating frames (left eye first, right eye second)
ar alternating frames (right eye first, left eye second)
irl interleaved rows (left eye has top row, right eye starts on next row)
irr interleaved rows (right eye has top row, left eye starts on next row)
arbg
anaglyph red/blue gray (red filter on left eye, blue filter on right eye)
argg
anaglyph red/green gray (red filter on left eye, green filter on right eye)
arcg
anaglyph red/cyan gray (red filter on left eye, cyan filter on right eye)
arch
anaglyph red/cyan half colored (red filter on left eye, cyan filter on right eye)
arcc
anaglyph red/cyan color (red filter on left eye, cyan filter on right eye)
arcd
anaglyph red/cyan color optimized with the least squares projection of dubois (red
filter on left eye, cyan filter on right eye)
agmg
anaglyph green/magenta gray (green filter on left eye, magenta filter on right
eye)
agmh
anaglyph green/magenta half colored (green filter on left eye, magenta filter on
right eye)
agmc
anaglyph green/magenta colored (green filter on left eye, magenta filter on right
eye)
agmd
anaglyph green/magenta color optimized with the least squares projection of dubois
(green filter on left eye, magenta filter on right eye)
aybg
anaglyph yellow/blue gray (yellow filter on left eye, blue filter on right eye)
aybh
anaglyph yellow/blue half colored (yellow filter on left eye, blue filter on right
eye)
aybc
anaglyph yellow/blue colored (yellow filter on left eye, blue filter on right eye)
aybd
anaglyph yellow/blue color optimized with the least squares projection of dubois
(yellow filter on left eye, blue filter on right eye)
ml mono output (left eye only)
mr mono output (right eye only)
chl checkerboard, left eye first
chr checkerboard, right eye first
icl interleaved columns, left eye first
icr interleaved columns, right eye first
hdmi
HDMI frame pack
Default value is arcd.
Examples
• Convert input video from side by side parallel to anaglyph yellow/blue dubois:
stereo3d=sbsl:aybd
• Convert input video from above below (left eye above, right eye below) to side by side
crosseye.
stereo3d=abl:sbsr
streamselect, astreamselect
Select video or audio streams.
The filter accepts the following options:
inputs
Set number of inputs. Default is 2.
map Set input indexes to remap to outputs.
Commands
The "streamselect" and "astreamselect" filter supports the following commands:
map Set input indexes to remap to outputs.
Examples
• Select first 5 seconds 1st stream and rest of time 2nd stream:
sendcmd='5.0 streamselect map 1',streamselect=inputs=2:map=0
• Same as above, but for audio:
asendcmd='5.0 astreamselect map 1',astreamselect=inputs=2:map=0
sobel
Apply sobel operator to input video stream.
The filter accepts the following option:
planes
Set which planes will be processed, unprocessed planes will be copied. By default
value 0xf, all planes will be processed.
scale
Set value which will be multiplied with filtered result.
delta
Set value which will be added to filtered result.
spp
Apply a simple postprocessing filter that compresses and decompresses the image at several
(or - in the case of quality level 6 - all) shifts and average the results.
The filter accepts the following options:
quality
Set quality. This option defines the number of levels for averaging. It accepts an
integer in the range 0-6. If set to 0, the filter will have no effect. A value of 6
means the higher quality. For each increment of that value the speed drops by a factor
of approximately 2. Default value is 3.
qp Force a constant quantization parameter. If not set, the filter will use the QP from
the video stream (if available).
mode
Set thresholding mode. Available modes are:
hard
Set hard thresholding (default).
soft
Set soft thresholding (better de-ringing effect, but likely blurrier).
use_bframe_qp
Enable the use of the QP from the B-Frames if set to 1. Using this option may cause
flicker since the B-Frames have often larger QP. Default is 0 (not enabled).
sr
Scale the input by applying one of the super-resolution methods based on convolutional
neural networks. Supported models:
• Super-Resolution Convolutional Neural Network model (SRCNN). See
<https://arxiv.org/abs/1501.00092>.
• Efficient Sub-Pixel Convolutional Neural Network model (ESPCN). See
<https://arxiv.org/abs/1609.05158>.
Training scripts as well as scripts for model file (.pb) saving can be found at
<https://github.com/XueweiMeng/sr/tree/sr_dnn_native>. Original repository is at
<https://github.com/HighVoltageRocknRoll/sr.git>.
Native model files (.model) can be generated from TensorFlow model files (.pb) by using
tools/python/convert.py
The filter accepts the following options:
dnn_backend
Specify which DNN backend to use for model loading and execution. This option accepts
the following values:
native
Native implementation of DNN loading and execution.
tensorflow
TensorFlow backend. To enable this backend you need to install the TensorFlow for
C library (see <https://www.tensorflow.org/install/install_c>) and configure
FFmpeg with "--enable-libtensorflow"
Default value is native.
model
Set path to model file specifying network architecture and its parameters. Note that
different backends use different file formats. TensorFlow backend can load files for
both formats, while native backend can load files for only its format.
scale_factor
Set scale factor for SRCNN model. Allowed values are 2, 3 and 4. Default value is 2.
Scale factor is necessary for SRCNN model, because it accepts input upscaled using
bicubic upscaling with proper scale factor.
subtitles
Draw subtitles on top of input video using the libass library.
To enable compilation of this filter you need to configure FFmpeg with "--enable-libass".
This filter also requires a build with libavcodec and libavformat to convert the passed
subtitles file to ASS (Advanced Substation Alpha) subtitles format.
The filter accepts the following options:
filename, f
Set the filename of the subtitle file to read. It must be specified.
original_size
Specify the size of the original video, the video for which the ASS file was composed.
For the syntax of this option, check the "Video size" section in the ffmpeg-utils
manual. Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to
correctly scale the fonts if the aspect ratio has been changed.
fontsdir
Set a directory path containing fonts that can be used by the filter. These fonts
will be used in addition to whatever the font provider uses.
alpha
Process alpha channel, by default alpha channel is untouched.
charenc
Set subtitles input character encoding. "subtitles" filter only. Only useful if not
UTF-8.
stream_index, si
Set subtitles stream index. "subtitles" filter only.
force_style
Override default style or script info parameters of the subtitles. It accepts a string
containing ASS style format "KEY=VALUE" couples separated by ",".
If the first key is not specified, it is assumed that the first value specifies the
filename.
For example, to render the file sub.srt on top of the input video, use the command:
subtitles=sub.srt
which is equivalent to:
subtitles=filename=sub.srt
To render the default subtitles stream from file video.mkv, use:
subtitles=video.mkv
To render the second subtitles stream from that file, use:
subtitles=video.mkv:si=1
To make the subtitles stream from sub.srt appear in 80% transparent blue "DejaVu Serif",
use:
subtitles=sub.srt:force_style='FontName=DejaVu Serif,PrimaryColour=&HCCFF0000'
super2xsai
Scale the input by 2x and smooth using the Super2xSaI (Scale and Interpolate) pixel art
scaling algorithm.
Useful for enlarging pixel art images without reducing sharpness.
swaprect
Swap two rectangular objects in video.
This filter accepts the following options:
w Set object width.
h Set object height.
x1 Set 1st rect x coordinate.
y1 Set 1st rect y coordinate.
x2 Set 2nd rect x coordinate.
y2 Set 2nd rect y coordinate.
All expressions are evaluated once for each frame.
The all options are expressions containing the following constants:
w
h The input width and height.
a same as w / h
sar input sample aspect ratio
dar input display aspect ratio, it is the same as (w / h) * sar
n The number of the input frame, starting from 0.
t The timestamp expressed in seconds. It's NAN if the input timestamp is unknown.
pos the position in the file of the input frame, NAN if unknown
swapuv
Swap U & V plane.
telecine
Apply telecine process to the video.
This filter accepts the following options:
first_field
top, t
top field first
bottom, b
bottom field first The default value is "top".
pattern
A string of numbers representing the pulldown pattern you wish to apply. The default
value is 23.
Some typical patterns:
NTSC output (30i):
27.5p: 32222
24p: 23 (classic)
24p: 2332 (preferred)
20p: 33
18p: 334
16p: 3444
PAL output (25i):
27.5p: 12222
24p: 222222222223 ("Euro pulldown")
16.67p: 33
16p: 33333334
threshold
Apply threshold effect to video stream.
This filter needs four video streams to perform thresholding. First stream is stream we
are filtering. Second stream is holding threshold values, third stream is holding min
values, and last, fourth stream is holding max values.
The filter accepts the following option:
planes
Set which planes will be processed, unprocessed planes will be copied. By default
value 0xf, all planes will be processed.
For example if first stream pixel's component value is less then threshold value of pixel
component from 2nd threshold stream, third stream value will picked, otherwise fourth
stream pixel component value will be picked.
Using color source filter one can perform various types of thresholding:
Examples
• Binary threshold, using gray color as threshold:
ffmpeg -i 320x240.avi -f lavfi -i color=gray -f lavfi -i color=black -f lavfi -i color=white -lavfi threshold output.avi
• Inverted binary threshold, using gray color as threshold:
ffmpeg -i 320x240.avi -f lavfi -i color=gray -f lavfi -i color=white -f lavfi -i color=black -lavfi threshold output.avi
• Truncate binary threshold, using gray color as threshold:
ffmpeg -i 320x240.avi -f lavfi -i color=gray -i 320x240.avi -f lavfi -i color=gray -lavfi threshold output.avi
• Threshold to zero, using gray color as threshold:
ffmpeg -i 320x240.avi -f lavfi -i color=gray -f lavfi -i color=white -i 320x240.avi -lavfi threshold output.avi
• Inverted threshold to zero, using gray color as threshold:
ffmpeg -i 320x240.avi -f lavfi -i color=gray -i 320x240.avi -f lavfi -i color=white -lavfi threshold output.avi
thumbnail
Select the most representative frame in a given sequence of consecutive frames.
The filter accepts the following options:
n Set the frames batch size to analyze; in a set of n frames, the filter will pick one
of them, and then handle the next batch of n frames until the end. Default is 100.
Since the filter keeps track of the whole frames sequence, a bigger n value will result in
a higher memory usage, so a high value is not recommended.
Examples
• Extract one picture each 50 frames:
thumbnail=50
• Complete example of a thumbnail creation with ffmpeg:
ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
tile
Tile several successive frames together.
The filter accepts the following options:
layout
Set the grid size (i.e. the number of lines and columns). For the syntax of this
option, check the "Video size" section in the ffmpeg-utils manual.
nb_frames
Set the maximum number of frames to render in the given area. It must be less than or
equal to wxh. The default value is 0, meaning all the area will be used.
margin
Set the outer border margin in pixels.
padding
Set the inner border thickness (i.e. the number of pixels between frames). For more
advanced padding options (such as having different values for the edges), refer to the
pad video filter.
color
Specify the color of the unused area. For the syntax of this option, check the "Color"
section in the ffmpeg-utils manual. The default value of color is "black".
overlap
Set the number of frames to overlap when tiling several successive frames together.
The value must be between 0 and nb_frames - 1.
init_padding
Set the number of frames to initially be empty before displaying first output frame.
This controls how soon will one get first output frame. The value must be between 0
and nb_frames - 1.
Examples
• Produce 8x8 PNG tiles of all keyframes (-skip_frame nokey) in a movie:
ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png
The -vsync 0 is necessary to prevent ffmpeg from duplicating each output frame to
accommodate the originally detected frame rate.
• Display 5 pictures in an area of "3x2" frames, with 7 pixels between them, and 2
pixels of initial margin, using mixed flat and named options:
tile=3x2:nb_frames=5:padding=7:margin=2
tinterlace
Perform various types of temporal field interlacing.
Frames are counted starting from 1, so the first input frame is considered odd.
The filter accepts the following options:
mode
Specify the mode of the interlacing. This option can also be specified as a value
alone. See below for a list of values for this option.
Available values are:
merge, 0
Move odd frames into the upper field, even into the lower field, generating a
double height frame at half frame rate.
------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
11111 33333
22222 44444
11111 33333
22222 44444
11111 33333
22222 44444
11111 33333
22222 44444
drop_even, 1
Only output odd frames, even frames are dropped, generating a frame with unchanged
height at half frame rate.
------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
11111 33333
11111 33333
11111 33333
11111 33333
drop_odd, 2
Only output even frames, odd frames are dropped, generating a frame with unchanged
height at half frame rate.
------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
22222 44444
22222 44444
22222 44444
22222 44444
pad, 3
Expand each frame to full height, but pad alternate lines with black, generating a
frame with double height at the same input frame rate.
------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
11111 ..... 33333 .....
..... 22222 ..... 44444
11111 ..... 33333 .....
..... 22222 ..... 44444
11111 ..... 33333 .....
..... 22222 ..... 44444
11111 ..... 33333 .....
..... 22222 ..... 44444
interleave_top, 4
Interleave the upper field from odd frames with the lower field from even frames,
generating a frame with unchanged height at half frame rate.
------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111<- 22222 33333<- 44444
11111 22222<- 33333 44444<-
11111<- 22222 33333<- 44444
11111 22222<- 33333 44444<-
Output:
11111 33333
22222 44444
11111 33333
22222 44444
interleave_bottom, 5
Interleave the lower field from odd frames with the upper field from even frames,
generating a frame with unchanged height at half frame rate.
------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222<- 33333 44444<-
11111<- 22222 33333<- 44444
11111 22222<- 33333 44444<-
11111<- 22222 33333<- 44444
Output:
22222 44444
11111 33333
22222 44444
11111 33333
interlacex2, 6
Double frame rate with unchanged height. Frames are inserted each containing the
second temporal field from the previous input frame and the first temporal field
from the next input frame. This mode relies on the top_field_first flag. Useful
for interlaced video displays with no field synchronisation.
------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
11111 22222 22222 33333 33333 44444 44444
11111 11111 22222 22222 33333 33333 44444
11111 22222 22222 33333 33333 44444 44444
11111 11111 22222 22222 33333 33333 44444
mergex2, 7
Move odd frames into the upper field, even into the lower field, generating a
double height frame at same frame rate.
------> time
Input:
Frame 1 Frame 2 Frame 3 Frame 4
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
11111 22222 33333 44444
Output:
11111 33333 33333 55555
22222 22222 44444 44444
11111 33333 33333 55555
22222 22222 44444 44444
11111 33333 33333 55555
22222 22222 44444 44444
11111 33333 33333 55555
22222 22222 44444 44444
Numeric values are deprecated but are accepted for backward compatibility reasons.
Default mode is "merge".
flags
Specify flags influencing the filter process.
Available value for flags is:
low_pass_filter, vlpf
Enable linear vertical low-pass filtering in the filter. Vertical low-pass
filtering is required when creating an interlaced destination from a progressive
source which contains high-frequency vertical detail. Filtering will reduce
interlace 'twitter' and Moire patterning.
complex_filter, cvlpf
Enable complex vertical low-pass filtering. This will slightly less reduce
interlace 'twitter' and Moire patterning but better retain detail and subjective
sharpness impression.
Vertical low-pass filtering can only be enabled for mode interleave_top and
interleave_bottom.
tmix
Mix successive video frames.
A description of the accepted options follows.
frames
The number of successive frames to mix. If unspecified, it defaults to 3.
weights
Specify weight of each input video frame. Each weight is separated by space. If
number of weights is smaller than number of frames last specified weight will be used
for all remaining unset weights.
scale
Specify scale, if it is set it will be multiplied with sum of each weight multiplied
with pixel values to give final destination pixel value. By default scale is auto
scaled to sum of weights.
Examples
• Average 7 successive frames:
tmix=frames=7:weights="1 1 1 1 1 1 1"
• Apply simple temporal convolution:
tmix=frames=3:weights="-1 3 -1"
• Similar as above but only showing temporal differences:
tmix=frames=3:weights="-1 2 -1":scale=1
tonemap
Tone map colors from different dynamic ranges.
This filter expects data in single precision floating point, as it needs to operate on
(and can output) out-of-range values. Another filter, such as zscale, is needed to convert
the resulting frame to a usable format.
The tonemapping algorithms implemented only work on linear light, so input data should be
linearized beforehand (and possibly correctly tagged).
ffmpeg -i INPUT -vf zscale=transfer=linear,tonemap=clip,zscale=transfer=bt709,format=yuv420p OUTPUT
Options
The filter accepts the following options.
tonemap
Set the tone map algorithm to use.
Possible values are:
none
Do not apply any tone map, only desaturate overbright pixels.
clip
Hard-clip any out-of-range values. Use it for perfect color accuracy for in-range
values, while distorting out-of-range values.
linear
Stretch the entire reference gamut to a linear multiple of the display.
gamma
Fit a logarithmic transfer between the tone curves.
reinhard
Preserve overall image brightness with a simple curve, using nonlinear contrast,
which results in flattening details and degrading color accuracy.
hable
Preserve both dark and bright details better than reinhard, at the cost of
slightly darkening everything. Use it when detail preservation is more important
than color and brightness accuracy.
mobius
Smoothly map out-of-range values, while retaining contrast and colors for in-range
material as much as possible. Use it when color accuracy is more important than
detail preservation.
Default is none.
param
Tune the tone mapping algorithm.
This affects the following algorithms:
none
Ignored.
linear
Specifies the scale factor to use while stretching. Default to 1.0.
gamma
Specifies the exponent of the function. Default to 1.8.
clip
Specify an extra linear coefficient to multiply into the signal before clipping.
Default to 1.0.
reinhard
Specify the local contrast coefficient at the display peak. Default to 0.5, which
means that in-gamut values will be about half as bright as when clipping.
hable
Ignored.
mobius
Specify the transition point from linear to mobius transform. Every value below
this point is guaranteed to be mapped 1:1. The higher the value, the more accurate
the result will be, at the cost of losing bright details. Default to 0.3, which
due to the steep initial slope still preserves in-range colors fairly accurately.
desat
Apply desaturation for highlights that exceed this level of brightness. The higher the
parameter, the more color information will be preserved. This setting helps prevent
unnaturally blown-out colors for super-highlights, by (smoothly) turning into white
instead. This makes images feel more natural, at the cost of reducing information
about out-of-range colors.
The default of 2.0 is somewhat conservative and will mostly just apply to skies or
directly sunlit surfaces. A setting of 0.0 disables this option.
This option works only if the input frame has a supported color tag.
peak
Override signal/nominal/reference peak with this value. Useful when the embedded peak
information in display metadata is not reliable or when tone mapping from a lower
range to a higher range.
tpad
Temporarily pad video frames.
The filter accepts the following options:
start
Specify number of delay frames before input video stream.
stop
Specify number of padding frames after input video stream. Set to -1 to pad
indefinitely.
start_mode
Set kind of frames added to beginning of stream. Can be either add or clone. With
add frames of solid-color are added. With clone frames are clones of first frame.
stop_mode
Set kind of frames added to end of stream. Can be either add or clone. With add
frames of solid-color are added. With clone frames are clones of last frame.
start_duration, stop_duration
Specify the duration of the start/stop delay. See the Time duration section in the
ffmpeg-utils(1) manual for the accepted syntax. These options override start and
stop.
color
Specify the color of the padded area. For the syntax of this option, check the "Color"
section in the ffmpeg-utils manual.
The default value of color is "black".
transpose
Transpose rows with columns in the input video and optionally flip it.
It accepts the following parameters:
dir Specify the transposition direction.
Can assume the following values:
0, 4, cclock_flip
Rotate by 90 degrees counterclockwise and vertically flip (default), that is:
L.R L.l
. . -> . .
l.r R.r
1, 5, clock
Rotate by 90 degrees clockwise, that is:
L.R l.L
. . -> . .
l.r r.R
2, 6, cclock
Rotate by 90 degrees counterclockwise, that is:
L.R R.r
. . -> . .
l.r L.l
3, 7, clock_flip
Rotate by 90 degrees clockwise and vertically flip, that is:
L.R r.R
. . -> . .
l.r l.L
For values between 4-7, the transposition is only done if the input video geometry is
portrait and not landscape. These values are deprecated, the "passthrough" option
should be used instead.
Numerical values are deprecated, and should be dropped in favor of symbolic constants.
passthrough
Do not apply the transposition if the input geometry matches the one specified by the
specified value. It accepts the following values:
none
Always apply transposition.
portrait
Preserve portrait geometry (when height >= width).
landscape
Preserve landscape geometry (when width >= height).
Default value is "none".
For example to rotate by 90 degrees clockwise and preserve portrait layout:
transpose=dir=1:passthrough=portrait
The command above can also be specified as:
transpose=1:portrait
transpose_npp
Transpose rows with columns in the input video and optionally flip it. For more in depth
examples see the transpose video filter, which shares mostly the same options.
It accepts the following parameters:
dir Specify the transposition direction.
Can assume the following values:
cclock_flip
Rotate by 90 degrees counterclockwise and vertically flip. (default)
clock
Rotate by 90 degrees clockwise.
cclock
Rotate by 90 degrees counterclockwise.
clock_flip
Rotate by 90 degrees clockwise and vertically flip.
passthrough
Do not apply the transposition if the input geometry matches the one specified by the
specified value. It accepts the following values:
none
Always apply transposition. (default)
portrait
Preserve portrait geometry (when height >= width).
landscape
Preserve landscape geometry (when width >= height).
trim
Trim the input so that the output contains one continuous subpart of the input.
It accepts the following parameters:
start
Specify the time of the start of the kept section, i.e. the frame with the timestamp
start will be the first frame in the output.
end Specify the time of the first frame that will be dropped, i.e. the frame immediately
preceding the one with the timestamp end will be the last frame in the output.
start_pts
This is the same as start, except this option sets the start timestamp in timebase
units instead of seconds.
end_pts
This is the same as end, except this option sets the end timestamp in timebase units
instead of seconds.
duration
The maximum duration of the output in seconds.
start_frame
The number of the first frame that should be passed to the output.
end_frame
The number of the first frame that should be dropped.
start, end, and duration are expressed as time duration specifications; see the Time
duration section in the ffmpeg-utils(1) manual for the accepted syntax.
Note that the first two sets of the start/end options and the duration option look at the
frame timestamp, while the _frame variants simply count the frames that pass through the
filter. Also note that this filter does not modify the timestamps. If you wish for the
output timestamps to start at zero, insert a setpts filter after the trim filter.
If multiple start or end options are set, this filter tries to be greedy and keep all the
frames that match at least one of the specified constraints. To keep only the part that
matches all the constraints at once, chain multiple trim filters.
The defaults are such that all the input is kept. So it is possible to set e.g. just the
end values to keep everything before the specified time.
Examples:
• Drop everything except the second minute of input:
ffmpeg -i INPUT -vf trim=60:120
• Keep only the first second:
ffmpeg -i INPUT -vf trim=duration=1
unpremultiply
Apply alpha unpremultiply effect to input video stream using first plane of second stream
as alpha.
Both streams must have same dimensions and same pixel format.
The filter accepts the following option:
planes
Set which planes will be processed, unprocessed planes will be copied. By default
value 0xf, all planes will be processed.
If the format has 1 or 2 components, then luma is bit 0. If the format has 3 or 4
components: for RGB formats bit 0 is green, bit 1 is blue and bit 2 is red; for YUV
formats bit 0 is luma, bit 1 is chroma-U and bit 2 is chroma-V. If present, the alpha
channel is always the last bit.
inplace
Do not require 2nd input for processing, instead use alpha plane from input stream.
unsharp
Sharpen or blur the input video.
It accepts the following parameters:
luma_msize_x, lx
Set the luma matrix horizontal size. It must be an odd integer between 3 and 23. The
default value is 5.
luma_msize_y, ly
Set the luma matrix vertical size. It must be an odd integer between 3 and 23. The
default value is 5.
luma_amount, la
Set the luma effect strength. It must be a floating point number, reasonable values
lay between -1.5 and 1.5.
Negative values will blur the input video, while positive values will sharpen it, a
value of zero will disable the effect.
Default value is 1.0.
chroma_msize_x, cx
Set the chroma matrix horizontal size. It must be an odd integer between 3 and 23. The
default value is 5.
chroma_msize_y, cy
Set the chroma matrix vertical size. It must be an odd integer between 3 and 23. The
default value is 5.
chroma_amount, ca
Set the chroma effect strength. It must be a floating point number, reasonable values
lay between -1.5 and 1.5.
Negative values will blur the input video, while positive values will sharpen it, a
value of zero will disable the effect.
Default value is 0.0.
All parameters are optional and default to the equivalent of the string '5:5:1.0:5:5:0.0'.
Examples
• Apply strong luma sharpen effect:
unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5
• Apply a strong blur of both luma and chroma parameters:
unsharp=7:7:-2:7:7:-2
uspp
Apply ultra slow/simple postprocessing filter that compresses and decompresses the image
at several (or - in the case of quality level 8 - all) shifts and average the results.
The way this differs from the behavior of spp is that uspp actually encodes & decodes each
case with libavcodec Snow, whereas spp uses a simplified intra only 8x8 DCT similar to
MJPEG.
The filter accepts the following options:
quality
Set quality. This option defines the number of levels for averaging. It accepts an
integer in the range 0-8. If set to 0, the filter will have no effect. A value of 8
means the higher quality. For each increment of that value the speed drops by a factor
of approximately 2. Default value is 3.
qp Force a constant quantization parameter. If not set, the filter will use the QP from
the video stream (if available).
vaguedenoiser
Apply a wavelet based denoiser.
It transforms each frame from the video input into the wavelet domain, using Cohen-
Daubechies-Feauveau 9/7. Then it applies some filtering to the obtained coefficients. It
does an inverse wavelet transform after. Due to wavelet properties, it should give a nice
smoothed result, and reduced noise, without blurring picture features.
This filter accepts the following options:
threshold
The filtering strength. The higher, the more filtered the video will be. Hard
thresholding can use a higher threshold than soft thresholding before the video looks
overfiltered. Default value is 2.
method
The filtering method the filter will use.
It accepts the following values:
hard
All values under the threshold will be zeroed.
soft
All values under the threshold will be zeroed. All values above will be reduced by
the threshold.
garrote
Scales or nullifies coefficients - intermediary between (more) soft and (less)
hard thresholding.
Default is garrote.
nsteps
Number of times, the wavelet will decompose the picture. Picture can't be decomposed
beyond a particular point (typically, 8 for a 640x480 frame - as 2^9 = 512 > 480).
Valid values are integers between 1 and 32. Default value is 6.
percent
Partial of full denoising (limited coefficients shrinking), from 0 to 100. Default
value is 85.
planes
A list of the planes to process. By default all planes are processed.
vectorscope
Display 2 color component values in the two dimensional graph (which is called a
vectorscope).
This filter accepts the following options:
mode, m
Set vectorscope mode.
It accepts the following values:
gray
Gray values are displayed on graph, higher brightness means more pixels have same
component color value on location in graph. This is the default mode.
color
Gray values are displayed on graph. Surrounding pixels values which are not
present in video frame are drawn in gradient of 2 color components which are set
by option "x" and "y". The 3rd color component is static.
color2
Actual color components values present in video frame are displayed on graph.
color3
Similar as color2 but higher frequency of same values "x" and "y" on graph
increases value of another color component, which is luminance by default values
of "x" and "y".
color4
Actual colors present in video frame are displayed on graph. If two different
colors map to same position on graph then color with higher value of component not
present in graph is picked.
color5
Gray values are displayed on graph. Similar to "color" but with 3rd color
component picked from radial gradient.
x Set which color component will be represented on X-axis. Default is 1.
y Set which color component will be represented on Y-axis. Default is 2.
intensity, i
Set intensity, used by modes: gray, color, color3 and color5 for increasing brightness
of color component which represents frequency of (X, Y) location in graph.
envelope, e
none
No envelope, this is default.
instant
Instant envelope, even darkest single pixel will be clearly highlighted.
peak
Hold maximum and minimum values presented in graph over time. This way you can
still spot out of range values without constantly looking at vectorscope.
peak+instant
Peak and instant envelope combined together.
graticule, g
Set what kind of graticule to draw.
none
green
color
opacity, o
Set graticule opacity.
flags, f
Set graticule flags.
white
Draw graticule for white point.
black
Draw graticule for black point.
name
Draw color points short names.
bgopacity, b
Set background opacity.
lthreshold, l
Set low threshold for color component not represented on X or Y axis. Values lower
than this value will be ignored. Default is 0. Note this value is multiplied with
actual max possible value one pixel component can have. So for 8-bit input and low
threshold value of 0.1 actual threshold is 0.1 * 255 = 25.
hthreshold, h
Set high threshold for color component not represented on X or Y axis. Values higher
than this value will be ignored. Default is 1. Note this value is multiplied with
actual max possible value one pixel component can have. So for 8-bit input and high
threshold value of 0.9 actual threshold is 0.9 * 255 = 230.
colorspace, c
Set what kind of colorspace to use when drawing graticule.
auto
601
709
Default is auto.
vidstabdetect
Analyze video stabilization/deshaking. Perform pass 1 of 2, see vidstabtransform for pass
2.
This filter generates a file with relative translation and rotation transform information
about subsequent frames, which is then used by the vidstabtransform filter.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-libvidstab".
This filter accepts the following options:
result
Set the path to the file used to write the transforms information. Default value is
transforms.trf.
shakiness
Set how shaky the video is and how quick the camera is. It accepts an integer in the
range 1-10, a value of 1 means little shakiness, a value of 10 means strong shakiness.
Default value is 5.
accuracy
Set the accuracy of the detection process. It must be a value in the range 1-15. A
value of 1 means low accuracy, a value of 15 means high accuracy. Default value is 15.
stepsize
Set stepsize of the search process. The region around minimum is scanned with 1 pixel
resolution. Default value is 6.
mincontrast
Set minimum contrast. Below this value a local measurement field is discarded. Must be
a floating point value in the range 0-1. Default value is 0.3.
tripod
Set reference frame number for tripod mode.
If enabled, the motion of the frames is compared to a reference frame in the filtered
stream, identified by the specified number. The idea is to compensate all movements in
a more-or-less static scene and keep the camera view absolutely still.
If set to 0, it is disabled. The frames are counted starting from 1.
show
Show fields and transforms in the resulting frames. It accepts an integer in the range
0-2. Default value is 0, which disables any visualization.
Examples
• Use default values:
vidstabdetect
• Analyze strongly shaky movie and put the results in file mytransforms.trf:
vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf"
• Visualize the result of internal transformations in the resulting video:
vidstabdetect=show=1
• Analyze a video with medium shakiness using ffmpeg:
ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi
vidstabtransform
Video stabilization/deshaking: pass 2 of 2, see vidstabdetect for pass 1.
Read a file with transform information for each frame and apply/compensate them. Together
with the vidstabdetect filter this can be used to deshake videos. See also
<http://public.hronopik.de/vid.stab>. It is important to also use the unsharp filter, see
below.
To enable compilation of this filter you need to configure FFmpeg with
"--enable-libvidstab".
Options
input
Set path to the file used to read the transforms. Default value is transforms.trf.
smoothing
Set the number of frames (value*2 + 1) used for lowpass filtering the camera
movements. Default value is 10.
For example a number of 10 means that 21 frames are used (10 in the past and 10 in the
future) to smoothen the motion in the video. A larger value leads to a smoother video,
but limits the acceleration of the camera (pan/tilt movements). 0 is a special case
where a static camera is simulated.
optalgo
Set the camera path optimization algorithm.
Accepted values are:
gauss
gaussian kernel low-pass filter on camera motion (default)
avg averaging on transformations
maxshift
Set maximal number of pixels to translate frames. Default value is -1, meaning no
limit.
maxangle
Set maximal angle in radians (degree*PI/180) to rotate frames. Default value is -1,
meaning no limit.
crop
Specify how to deal with borders that may be visible due to movement compensation.
Available values are:
keep
keep image information from previous frame (default)
black
fill the border black
invert
Invert transforms if set to 1. Default value is 0.
relative
Consider transforms as relative to previous frame if set to 1, absolute if set to 0.
Default value is 0.
zoom
Set percentage to zoom. A positive value will result in a zoom-in effect, a negative
value in a zoom-out effect. Default value is 0 (no zoom).
optzoom
Set optimal zooming to avoid borders.
Accepted values are:
0 disabled
1 optimal static zoom value is determined (only very strong movements will lead to
visible borders) (default)
2 optimal adaptive zoom value is determined (no borders will be visible), see
zoomspeed
Note that the value given at zoom is added to the one calculated here.
zoomspeed
Set percent to zoom maximally each frame (enabled when optzoom is set to 2). Range is
from 0 to 5, default value is 0.25.
interpol
Specify type of interpolation.
Available values are:
no no interpolation
linear
linear only horizontal
bilinear
linear in both directions (default)
bicubic
cubic in both directions (slow)
tripod
Enable virtual tripod mode if set to 1, which is equivalent to
"relative=0:smoothing=0". Default value is 0.
Use also "tripod" option of vidstabdetect.
debug
Increase log verbosity if set to 1. Also the detected global motions are written to
the temporary file global_motions.trf. Default value is 0.
Examples
• Use ffmpeg for a typical stabilization with default values:
ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg
Note the use of the unsharp filter which is always recommended.
• Zoom in a bit more and load transform data from a given file:
vidstabtransform=zoom=5:input="mytransforms.trf"
• Smoothen the video even more:
vidstabtransform=smoothing=30
vflip
Flip the input video vertically.
For example, to vertically flip a video with ffmpeg:
ffmpeg -i in.avi -vf "vflip" out.avi
vfrdet
Detect variable frame rate video.
This filter tries to detect if the input is variable or constant frame rate.
At end it will output number of frames detected as having variable delta pts, and ones
with constant delta pts. If there was frames with variable delta, than it will also show
min and max delta encountered.
vibrance
Boost or alter saturation.
The filter accepts the following options:
intensity
Set strength of boost if positive value or strength of alter if negative value.
Default is 0. Allowed range is from -2 to 2.
rbal
Set the red balance. Default is 1. Allowed range is from -10 to 10.
gbal
Set the green balance. Default is 1. Allowed range is from -10 to 10.
bbal
Set the blue balance. Default is 1. Allowed range is from -10 to 10.
rlum
Set the red luma coefficient.
glum
Set the green luma coefficient.
blum
Set the blue luma coefficient.
alternate
If "intensity" is negative and this is set to 1, colors will change, otherwise colors
will be less saturated, more towards gray.
vignette
Make or reverse a natural vignetting effect.
The filter accepts the following options:
angle, a
Set lens angle expression as a number of radians.
The value is clipped in the "[0,PI/2]" range.
Default value: "PI/5"
x0
y0 Set center coordinates expressions. Respectively "w/2" and "h/2" by default.
mode
Set forward/backward mode.
Available modes are:
forward
The larger the distance from the central point, the darker the image becomes.
backward
The larger the distance from the central point, the brighter the image becomes.
This can be used to reverse a vignette effect, though there is no automatic
detection to extract the lens angle and other settings (yet). It can also be used
to create a burning effect.
Default value is forward.
eval
Set evaluation mode for the expressions (angle, x0, y0).
It accepts the following values:
init
Evaluate expressions only once during the filter initialization.
frame
Evaluate expressions for each incoming frame. This is way slower than the init
mode since it requires all the scalers to be re-computed, but it allows advanced
dynamic expressions.
Default value is init.
dither
Set dithering to reduce the circular banding effects. Default is 1 (enabled).
aspect
Set vignette aspect. This setting allows one to adjust the shape of the vignette.
Setting this value to the SAR of the input will make a rectangular vignetting
following the dimensions of the video.
Default is "1/1".
Expressions
The alpha, x0 and y0 expressions can contain the following parameters.
w
h input width and height
n the number of input frame, starting from 0
pts the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in TB
units, NAN if undefined
r frame rate of the input video, NAN if the input frame rate is unknown
t the PTS (Presentation TimeStamp) of the filtered video frame, expressed in seconds,
NAN if undefined
tb time base of the input video
Examples
• Apply simple strong vignetting effect:
vignette=PI/4
• Make a flickering vignetting:
vignette='PI/4+random(1)*PI/50':eval=frame
vmafmotion
Obtain the average vmaf motion score of a video. It is one of the component filters of
VMAF.
The obtained average motion score is printed through the logging system.
In the below example the input file ref.mpg is being processed and score is computed.
ffmpeg -i ref.mpg -lavfi vmafmotion -f null -
vstack
Stack input videos vertically.
All streams must be of same pixel format and of same width.
Note that this filter is faster than using overlay and pad filter to create same output.
The filter accept the following option:
inputs
Set number of input streams. Default is 2.
shortest
If set to 1, force the output to terminate when the shortest input terminates. Default
value is 0.
w3fdif
Deinterlace the input video ("w3fdif" stands for "Weston 3 Field Deinterlacing Filter").
Based on the process described by Martin Weston for BBC R&D, and implemented based on the
de-interlace algorithm written by Jim Easterbrook for BBC R&D, the Weston 3 field
deinterlacing filter uses filter coefficients calculated by BBC R&D.
This filter use field-dominance information in frame to decide which of each pair of
fields to place first in the output. If it gets it wrong use setfield filter before
"w3fdif" filter.
There are two sets of filter coefficients, so called "simple": and "complex". Which set of
filter coefficients is used can be set by passing an optional parameter:
filter
Set the interlacing filter coefficients. Accepts one of the following values:
simple
Simple filter coefficient set.
complex
More-complex filter coefficient set.
Default value is complex.
deint
Specify which frames to deinterlace. Accept one of the following values:
all Deinterlace all frames,
interlaced
Only deinterlace frames marked as interlaced.
Default value is all.
waveform
Video waveform monitor.
The waveform monitor plots color component intensity. By default luminance only. Each
column of the waveform corresponds to a column of pixels in the source video.
It accepts the following options:
mode, m
Can be either "row", or "column". Default is "column". In row mode, the graph on the
left side represents color component value 0 and the right side represents value =
255. In column mode, the top side represents color component value = 0 and bottom side
represents value = 255.
intensity, i
Set intensity. Smaller values are useful to find out how many values of the same
luminance are distributed across input rows/columns. Default value is 0.04. Allowed
range is [0, 1].
mirror, r
Set mirroring mode. 0 means unmirrored, 1 means mirrored. In mirrored mode, higher
values will be represented on the left side for "row" mode and at the top for "column"
mode. Default is 1 (mirrored).
display, d
Set display mode. It accepts the following values:
overlay
Presents information identical to that in the "parade", except that the graphs
representing color components are superimposed directly over one another.
This display mode makes it easier to spot relative differences or similarities in
overlapping areas of the color components that are supposed to be identical, such
as neutral whites, grays, or blacks.
stack
Display separate graph for the color components side by side in "row" mode or one
below the other in "column" mode.
parade
Display separate graph for the color components side by side in "column" mode or
one below the other in "row" mode.
Using this display mode makes it easy to spot color casts in the highlights and
shadows of an image, by comparing the contours of the top and the bottom graphs of
each waveform. Since whites, grays, and blacks are characterized by exactly equal
amounts of red, green, and blue, neutral areas of the picture should display three
waveforms of roughly equal width/height. If not, the correction is easy to perform
by making level adjustments the three waveforms.
Default is "stack".
components, c
Set which color components to display. Default is 1, which means only luminance or red
color component if input is in RGB colorspace. If is set for example to 7 it will
display all 3 (if) available color components.
envelope, e
none
No envelope, this is default.
instant
Instant envelope, minimum and maximum values presented in graph will be easily
visible even with small "step" value.
peak
Hold minimum and maximum values presented in graph across time. This way you can
still spot out of range values without constantly looking at waveforms.
peak+instant
Peak and instant envelope combined together.
filter, f
lowpass
No filtering, this is default.
flat
Luma and chroma combined together.
aflat
Similar as above, but shows difference between blue and red chroma.
xflat
Similar as above, but use different colors.
chroma
Displays only chroma.
color
Displays actual color value on waveform.
acolor
Similar as above, but with luma showing frequency of chroma values.
graticule, g
Set which graticule to display.
none
Do not display graticule.
green
Display green graticule showing legal broadcast ranges.
orange
Display orange graticule showing legal broadcast ranges.
opacity, o
Set graticule opacity.
flags, fl
Set graticule flags.
numbers
Draw numbers above lines. By default enabled.
dots
Draw dots instead of lines.
scale, s
Set scale used for displaying graticule.
digital
millivolts
ire
Default is digital.
bgopacity, b
Set background opacity.
weave, doubleweave
The "weave" takes a field-based video input and join each two sequential fields into
single frame, producing a new double height clip with half the frame rate and half the
frame count.
The "doubleweave" works same as "weave" but without halving frame rate and frame count.
It accepts the following option:
first_field
Set first field. Available values are:
top, t
Set the frame as top-field-first.
bottom, b
Set the frame as bottom-field-first.
Examples
• Interlace video using select and separatefields filter:
separatefields,select=eq(mod(n,4),0)+eq(mod(n,4),3),weave
xbr
Apply the xBR high-quality magnification filter which is designed for pixel art. It
follows a set of edge-detection rules, see
<https://forums.libretro.com/t/xbr-algorithm-tutorial/123>.
It accepts the following option:
n Set the scaling dimension: 2 for "2xBR", 3 for "3xBR" and 4 for "4xBR". Default is 3.
xmedian
Pick median pixels from several input videos.
The filter accept the following options:
inputs
Set number of inputs. Default is 3. Allowed range is from 3 to 255. If number of
inputs is even number, than result will be mean value between two median values.
planes
Set which planes to filter. Default value is 15, by which all planes are processed.
xstack
Stack video inputs into custom layout.
All streams must be of same pixel format.
The filter accept the following option:
inputs
Set number of input streams. Default is 2.
layout
Specify layout of inputs. This option requires the desired layout configuration to be
explicitly set by the user. This sets position of each video input in output. Each
input is separated by '|'. The first number represents the column, and the second
number represents the row. Numbers start at 0 and are separated by '_'. Optionally
one can use wX and hX, where X is video input from which to take width or height.
Multiple values can be used when separated by '+'. In such case values are summed
together.
For 2 inputs, a default layout of "0_0|w0_0" is set. In all other cases, a layout must
be set by the user.
shortest
If set to 1, force the output to terminate when the shortest input terminates. Default
value is 0.
Examples
• Display 4 inputs into 2x2 grid, note that if inputs are of different sizes unused gaps
might appear, as not all of output video is used.
xstack=inputs=4:layout=0_0|0_h0|w0_0|w0_h0
• Display 4 inputs into 1x4 grid, note that if inputs are of different sizes unused gaps
might appear, as not all of output video is used.
xstack=inputs=4:layout=0_0|0_h0|0_h0+h1|0_h0+h1+h2
• Display 9 inputs into 3x3 grid, note that if inputs are of different sizes unused gaps
might appear, as not all of output video is used.
xstack=inputs=9:layout=w3_0|w3_h0+h2|w3_h0|0_h4|0_0|w3+w1_0|0_h1+h2|w3+w1_h0|w3+w1_h1+h2
yadif
Deinterlace the input video ("yadif" means "yet another deinterlacing filter").
It accepts the following parameters:
mode
The interlacing mode to adopt. It accepts one of the following values:
0, send_frame
Output one frame for each frame.
1, send_field
Output one frame for each field.
2, send_frame_nospatial
Like "send_frame", but it skips the spatial interlacing check.
3, send_field_nospatial
Like "send_field", but it skips the spatial interlacing check.
The default value is "send_frame".
parity
The picture field parity assumed for the input interlaced video. It accepts one of the
following values:
0, tff
Assume the top field is first.
1, bff
Assume the bottom field is first.
-1, auto
Enable automatic detection of field parity.
The default value is "auto". If the interlacing is unknown or the decoder does not
export this information, top field first will be assumed.
deint
Specify which frames to deinterlace. Accept one of the following values:
0, all
Deinterlace all frames.
1, interlaced
Only deinterlace frames marked as interlaced.
The default value is "all".
yadif_cuda
Deinterlace the input video using the yadif algorithm, but implemented in CUDA so that it
can work as part of a GPU accelerated pipeline with nvdec and/or nvenc.
It accepts the following parameters:
mode
The interlacing mode to adopt. It accepts one of the following values:
0, send_frame
Output one frame for each frame.
1, send_field
Output one frame for each field.
2, send_frame_nospatial
Like "send_frame", but it skips the spatial interlacing check.
3, send_field_nospatial
Like "send_field", but it skips the spatial interlacing check.
The default value is "send_frame".
parity
The picture field parity assumed for the input interlaced video. It accepts one of the
following values:
0, tff
Assume the top field is first.
1, bff
Assume the bottom field is first.
-1, auto
Enable automatic detection of field parity.
The default value is "auto". If the interlacing is unknown or the decoder does not
export this information, top field first will be assumed.
deint
Specify which frames to deinterlace. Accept one of the following values:
0, all
Deinterlace all frames.
1, interlaced
Only deinterlace frames marked as interlaced.
The default value is "all".
zoompan
Apply Zoom & Pan effect.
This filter accepts the following options:
zoom, z
Set the zoom expression. Range is 1-10. Default is 1.
x
y Set the x and y expression. Default is 0.
d Set the duration expression in number of frames. This sets for how many number of
frames effect will last for single input image.
s Set the output image size, default is 'hd720'.
fps Set the output frame rate, default is '25'.
Each expression can contain the following constants:
in_w, iw
Input width.
in_h, ih
Input height.
out_w, ow
Output width.
out_h, oh
Output height.
in Input frame count.
on Output frame count.
x
y Last calculated 'x' and 'y' position from 'x' and 'y' expression for current input
frame.
px
py 'x' and 'y' of last output frame of previous input frame or 0 when there was not yet
such frame (first input frame).
zoom
Last calculated zoom from 'z' expression for current input frame.
pzoom
Last calculated zoom of last output frame of previous input frame.
duration
Number of output frames for current input frame. Calculated from 'd' expression for
each input frame.
pduration
number of output frames created for previous input frame
a Rational number: input width / input height
sar sample aspect ratio
dar display aspect ratio
Examples
• Zoom-in up to 1.5 and pan at same time to some spot near center of picture:
zoompan=z='min(zoom+0.0015,1.5)':d=700:x='if(gte(zoom,1.5),x,x+1/a)':y='if(gte(zoom,1.5),y,y+1)':s=640x360
• Zoom-in up to 1.5 and pan always at center of picture:
zoompan=z='min(zoom+0.0015,1.5)':d=700:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
• Same as above but without pausing:
zoompan=z='min(max(zoom,pzoom)+0.0015,1.5)':d=1:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)'
zscale
Scale (resize) the input video, using the z.lib library:
<https://github.com/sekrit-twc/zimg>. To enable compilation of this filter, you need to
configure FFmpeg with "--enable-libzimg".
The zscale filter forces the output display aspect ratio to be the same as the input, by
changing the output sample aspect ratio.
If the input image format is different from the format requested by the next filter, the
zscale filter will convert the input to the requested format.
Options
The filter accepts the following options.
width, w
height, h
Set the output video dimension expression. Default value is the input dimension.
If the width or w value is 0, the input width is used for the output. If the height or
h value is 0, the input height is used for the output.
If one and only one of the values is -n with n >= 1, the zscale filter will use a
value that maintains the aspect ratio of the input image, calculated from the other
specified dimension. After that it will, however, make sure that the calculated
dimension is divisible by n and adjust the value if necessary.
If both values are -n with n >= 1, the behavior will be identical to both values being
set to 0 as previously detailed.
See below for the list of accepted constants for use in the dimension expression.
size, s
Set the video size. For the syntax of this option, check the "Video size" section in
the ffmpeg-utils manual.
dither, d
Set the dither type.
Possible values are:
none
ordered
random
error_diffusion
Default is none.
filter, f
Set the resize filter type.
Possible values are:
point
bilinear
bicubic
spline16
spline36
lanczos
Default is bilinear.
range, r
Set the color range.
Possible values are:
input
limited
full
Default is same as input.
primaries, p
Set the color primaries.
Possible values are:
input
709
unspecified
170m
240m
2020
Default is same as input.
transfer, t
Set the transfer characteristics.
Possible values are:
input
709
unspecified
601
linear
2020_10
2020_12
smpte2084
iec61966-2-1
arib-std-b67
Default is same as input.
matrix, m
Set the colorspace matrix.
Possible value are:
input
709
unspecified
470bg
170m
2020_ncl
2020_cl
Default is same as input.
rangein, rin
Set the input color range.
Possible values are:
input
limited
full
Default is same as input.
primariesin, pin
Set the input color primaries.
Possible values are:
input
709
unspecified
170m
240m
2020
Default is same as input.
transferin, tin
Set the input transfer characteristics.
Possible values are:
input
709
unspecified
601
linear
2020_10
2020_12
Default is same as input.
matrixin, min
Set the input colorspace matrix.
Possible value are:
input
709
unspecified
470bg
170m
2020_ncl
2020_cl
chromal, c
Set the output chroma location.
Possible values are:
input
left
center
topleft
top
bottomleft
bottom
chromalin, cin
Set the input chroma location.
Possible values are:
input
left
center
topleft
top
bottomleft
bottom
npl Set the nominal peak luminance.
The values of the w and h options are expressions containing the following constants:
in_w
in_h
The input width and height
iw
ih These are the same as in_w and in_h.
out_w
out_h
The output (scaled) width and height
ow
oh These are the same as out_w and out_h
a The same as iw / ih
sar input sample aspect ratio
dar The input display aspect ratio. Calculated from "(iw / ih) * sar".
hsub
vsub
horizontal and vertical input chroma subsample values. For example for the pixel
format "yuv422p" hsub is 2 and vsub is 1.
ohsub
ovsub
horizontal and vertical output chroma subsample values. For example for the pixel
format "yuv422p" hsub is 2 and vsub is 1.
OPENCL VIDEO FILTERS
Below is a description of the currently available OpenCL video filters.
To enable compilation of these filters you need to configure FFmpeg with
"--enable-opencl".
Running OpenCL filters requires you to initialize a hardware device and to pass that
device to all filters in any filter graph.
-init_hw_device opencl[=name][:device[,key=value...]]
Initialise a new hardware device of type opencl called name, using the given device
parameters.
-filter_hw_device name
Pass the hardware device called name to all filters in any filter graph.
For more detailed information see
<https://www.ffmpeg.org/ffmpeg.html#Advanced-Video-options>
• Example of choosing the first device on the second platform and running avgblur_opencl
filter with default parameters on it.
-init_hw_device opencl=gpu:1.0 -filter_hw_device gpu -i INPUT -vf "hwupload, avgblur_opencl, hwdownload" OUTPUT
Since OpenCL filters are not able to access frame data in normal memory, all frame data
needs to be uploaded(hwupload) to hardware surfaces connected to the appropriate device
before being used and then downloaded(hwdownload) back to normal memory. Note that
hwupload will upload to a surface with the same layout as the software frame, so it may be
necessary to add a format filter immediately before to get the input into the right format
and hwdownload does not support all formats on the output - it may be necessary to insert
an additional format filter immediately following in the graph to get the output in a
supported format.
avgblur_opencl
Apply average blur filter.
The filter accepts the following options:
sizeX
Set horizontal radius size. Range is "[1, 1024]" and default value is 1.
planes
Set which planes to filter. Default value is 0xf, by which all planes are processed.
sizeY
Set vertical radius size. Range is "[1, 1024]" and default value is 0. If zero,
"sizeX" value will be used.
Example
• Apply average blur filter with horizontal and vertical size of 3, setting each pixel
of the output to the average value of the 7x7 region centered on it in the input. For
pixels on the edges of the image, the region does not extend beyond the image
boundaries, and so out-of-range coordinates are not used in the calculations.
-i INPUT -vf "hwupload, avgblur_opencl=3, hwdownload" OUTPUT
boxblur_opencl
Apply a boxblur algorithm to the input video.
It accepts the following parameters:
luma_radius, lr
luma_power, lp
chroma_radius, cr
chroma_power, cp
alpha_radius, ar
alpha_power, ap
A description of the accepted options follows.
luma_radius, lr
chroma_radius, cr
alpha_radius, ar
Set an expression for the box radius in pixels used for blurring the corresponding
input plane.
The radius value must be a non-negative number, and must not be greater than the value
of the expression "min(w,h)/2" for the luma and alpha planes, and of "min(cw,ch)/2"
for the chroma planes.
Default value for luma_radius is "2". If not specified, chroma_radius and alpha_radius
default to the corresponding value set for luma_radius.
The expressions can contain the following constants:
w
h The input width and height in pixels.
cw
ch The input chroma image width and height in pixels.
hsub
vsub
The horizontal and vertical chroma subsample values. For example, for the pixel
format "yuv422p", hsub is 2 and vsub is 1.
luma_power, lp
chroma_power, cp
alpha_power, ap
Specify how many times the boxblur filter is applied to the corresponding plane.
Default value for luma_power is 2. If not specified, chroma_power and alpha_power
default to the corresponding value set for luma_power.
A value of 0 will disable the effect.
Examples
Apply boxblur filter, setting each pixel of the output to the average value of box-
radiuses luma_radius, chroma_radius, alpha_radius for each plane respectively. The filter
will apply luma_power, chroma_power, alpha_power times onto the corresponding plane. For
pixels on the edges of the image, the radius does not extend beyond the image boundaries,
and so out-of-range coordinates are not used in the calculations.
• Apply a boxblur filter with the luma, chroma, and alpha radius set to 2 and luma,
chroma, and alpha power set to 3. The filter will run 3 times with box-radius set to 2
for every plane of the image.
-i INPUT -vf "hwupload, boxblur_opencl=luma_radius=2:luma_power=3, hwdownload" OUTPUT
-i INPUT -vf "hwupload, boxblur_opencl=2:3, hwdownload" OUTPUT
• Apply a boxblur filter with luma radius set to 2, luma_power to 1, chroma_radius to 4,
chroma_power to 5, alpha_radius to 3 and alpha_power to 7.
For the luma plane, a 2x2 box radius will be run once.
For the chroma plane, a 4x4 box radius will be run 5 times.
For the alpha plane, a 3x3 box radius will be run 7 times.
-i INPUT -vf "hwupload, boxblur_opencl=2:1:4:5:3:7, hwdownload" OUTPUT
convolution_opencl
Apply convolution of 3x3, 5x5, 7x7 matrix.
The filter accepts the following options:
0m
1m
2m
3m Set matrix for each plane. Matrix is sequence of 9, 25 or 49 signed numbers. Default
value for each plane is "0 0 0 0 1 0 0 0 0".
0rdiv
1rdiv
2rdiv
3rdiv
Set multiplier for calculated value for each plane. If unset or 0, it will be sum of
all matrix elements. The option value must be a float number greater or equal to 0.0.
Default value is 1.0.
0bias
1bias
2bias
3bias
Set bias for each plane. This value is added to the result of the multiplication.
Useful for making the overall image brighter or darker. The option value must be a
float number greater or equal to 0.0. Default value is 0.0.
Examples
• Apply sharpen:
-i INPUT -vf "hwupload, convolution_opencl=0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0:0 -1 0 -1 5 -1 0 -1 0, hwdownload" OUTPUT
• Apply blur:
-i INPUT -vf "hwupload, convolution_opencl=1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1 1 1 1 1 1 1 1 1:1/9:1/9:1/9:1/9, hwdownload" OUTPUT
• Apply edge enhance:
-i INPUT -vf "hwupload, convolution_opencl=0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:0 0 0 -1 1 0 0 0 0:5:1:1:1:0:128:128:128, hwdownload" OUTPUT
• Apply edge detect:
-i INPUT -vf "hwupload, convolution_opencl=0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:0 1 0 1 -4 1 0 1 0:5:5:5:1:0:128:128:128, hwdownload" OUTPUT
• Apply laplacian edge detector which includes diagonals:
-i INPUT -vf "hwupload, convolution_opencl=1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:1 1 1 1 -8 1 1 1 1:5:5:5:1:0:128:128:0, hwdownload" OUTPUT
• Apply emboss:
-i INPUT -vf "hwupload, convolution_opencl=-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2:-2 -1 0 -1 1 1 0 1 2, hwdownload" OUTPUT
dilation_opencl
Apply dilation effect to the video.
This filter replaces the pixel by the local(3x3) maximum.
It accepts the following options:
threshold0
threshold1
threshold2
threshold3
Limit the maximum change for each plane. Range is "[0, 65535]" and default value is
65535. If 0, plane will remain unchanged.
coordinates
Flag which specifies the pixel to refer to. Range is "[0, 255]" and default value is
255, i.e. all eight pixels are used.
Flags to local 3x3 coordinates region centered on "x":
1 2 3
4 x 5
6 7 8
Example
• Apply dilation filter with threshold0 set to 30, threshold1 set 40, threshold2 set to
50 and coordinates set to 231, setting each pixel of the output to the local maximum
between pixels: 1, 2, 3, 6, 7, 8 of the 3x3 region centered on it in the input. If the
difference between input pixel and local maximum is more then threshold of the
corresponding plane, output pixel will be set to input pixel + threshold of
corresponding plane.
-i INPUT -vf "hwupload, dilation_opencl=30:40:50:coordinates=231, hwdownload" OUTPUT
erosion_opencl
Apply erosion effect to the video.
This filter replaces the pixel by the local(3x3) minimum.
It accepts the following options:
threshold0
threshold1
threshold2
threshold3
Limit the maximum change for each plane. Range is "[0, 65535]" and default value is
65535. If 0, plane will remain unchanged.
coordinates
Flag which specifies the pixel to refer to. Range is "[0, 255]" and default value is
255, i.e. all eight pixels are used.
Flags to local 3x3 coordinates region centered on "x":
1 2 3
4 x 5
6 7 8
Example
• Apply erosion filter with threshold0 set to 30, threshold1 set 40, threshold2 set to
50 and coordinates set to 231, setting each pixel of the output to the local minimum
between pixels: 1, 2, 3, 6, 7, 8 of the 3x3 region centered on it in the input. If the
difference between input pixel and local minimum is more then threshold of the
corresponding plane, output pixel will be set to input pixel - threshold of
corresponding plane.
-i INPUT -vf "hwupload, erosion_opencl=30:40:50:coordinates=231, hwdownload" OUTPUT
colorkey_opencl
RGB colorspace color keying.
The filter accepts the following options:
color
The color which will be replaced with transparency.
similarity
Similarity percentage with the key color.
0.01 matches only the exact key color, while 1.0 matches everything.
blend
Blend percentage.
0.0 makes pixels either fully transparent, or not transparent at all.
Higher values result in semi-transparent pixels, with a higher transparency the more
similar the pixels color is to the key color.
Examples
• Make every semi-green pixel in the input transparent with some slight blending:
-i INPUT -vf "hwupload, colorkey_opencl=green:0.3:0.1, hwdownload" OUTPUT
nlmeans_opencl
Non-local Means denoise filter through OpenCL, this filter accepts same options as
nlmeans.
overlay_opencl
Overlay one video on top of another.
It takes two inputs and has one output. The first input is the "main" video on which the
second input is overlaid. This filter requires same memory layout for all the inputs. So,
format conversion may be needed.
The filter accepts the following options:
x Set the x coordinate of the overlaid video on the main video. Default value is 0.
y Set the x coordinate of the overlaid video on the main video. Default value is 0.
Examples
• Overlay an image LOGO at the top-left corner of the INPUT video. Both inputs are
yuv420p format.
-i INPUT -i LOGO -filter_complex "[0:v]hwupload[a], [1:v]format=yuv420p, hwupload[b], [a][b]overlay_opencl, hwdownload" OUTPUT
• The inputs have same memory layout for color channels , the overlay has additional
alpha plane, like INPUT is yuv420p, and the LOGO is yuva420p.
-i INPUT -i LOGO -filter_complex "[0:v]hwupload[a], [1:v]format=yuva420p, hwupload[b], [a][b]overlay_opencl, hwdownload" OUTPUT
prewitt_opencl
Apply the Prewitt operator (<https://en.wikipedia.org/wiki/Prewitt_operator>) to input
video stream.
The filter accepts the following option:
planes
Set which planes to filter. Default value is 0xf, by which all planes are processed.
scale
Set value which will be multiplied with filtered result. Range is "[0.0, 65535]" and
default value is 1.0.
delta
Set value which will be added to filtered result. Range is "[-65535, 65535]" and
default value is 0.0.
Example
• Apply the Prewitt operator with scale set to 2 and delta set to 10.
-i INPUT -vf "hwupload, prewitt_opencl=scale=2:delta=10, hwdownload" OUTPUT
roberts_opencl
Apply the Roberts cross operator (<https://en.wikipedia.org/wiki/Roberts_cross>) to input
video stream.
The filter accepts the following option:
planes
Set which planes to filter. Default value is 0xf, by which all planes are processed.
scale
Set value which will be multiplied with filtered result. Range is "[0.0, 65535]" and
default value is 1.0.
delta
Set value which will be added to filtered result. Range is "[-65535, 65535]" and
default value is 0.0.
Example
• Apply the Roberts cross operator with scale set to 2 and delta set to 10
-i INPUT -vf "hwupload, roberts_opencl=scale=2:delta=10, hwdownload" OUTPUT
sobel_opencl
Apply the Sobel operator (<https://en.wikipedia.org/wiki/Sobel_operator>) to input video
stream.
The filter accepts the following option:
planes
Set which planes to filter. Default value is 0xf, by which all planes are processed.
scale
Set value which will be multiplied with filtered result. Range is "[0.0, 65535]" and
default value is 1.0.
delta
Set value which will be added to filtered result. Range is "[-65535, 65535]" and
default value is 0.0.
Example
• Apply sobel operator with scale set to 2 and delta set to 10
-i INPUT -vf "hwupload, sobel_opencl=scale=2:delta=10, hwdownload" OUTPUT
tonemap_opencl
Perform HDR(PQ/HLG) to SDR conversion with tone-mapping.
It accepts the following parameters:
tonemap
Specify the tone-mapping operator to be used. Same as tonemap option in tonemap.
param
Tune the tone mapping algorithm. same as param option in tonemap.
desat
Apply desaturation for highlights that exceed this level of brightness. The higher the
parameter, the more color information will be preserved. This setting helps prevent
unnaturally blown-out colors for super-highlights, by (smoothly) turning into white
instead. This makes images feel more natural, at the cost of reducing information
about out-of-range colors.
The default value is 0.5, and the algorithm here is a little different from the cpu
version tonemap currently. A setting of 0.0 disables this option.
threshold
The tonemapping algorithm parameters is fine-tuned per each scene. And a threshold is
used to detect whether the scene has changed or not. If the distance between the
current frame average brightness and the current running average exceeds a threshold
value, we would re-calculate scene average and peak brightness. The default value is
0.2.
format
Specify the output pixel format.
Currently supported formats are:
p010
nv12
range, r
Set the output color range.
Possible values are:
tv/mpeg
pc/jpeg
Default is same as input.
primaries, p
Set the output color primaries.
Possible values are:
bt709
bt2020
Default is same as input.
transfer, t
Set the output transfer characteristics.
Possible values are:
bt709
bt2020
Default is bt709.
matrix, m
Set the output colorspace matrix.
Possible value are:
bt709
bt2020
Default is same as input.
Example
• Convert HDR(PQ/HLG) video to bt2020-transfer-characteristic p010 format using linear
operator.
-i INPUT -vf "format=p010,hwupload,tonemap_opencl=t=bt2020:tonemap=linear:format=p010,hwdownload,format=p010" OUTPUT
unsharp_opencl
Sharpen or blur the input video.
It accepts the following parameters:
luma_msize_x, lx
Set the luma matrix horizontal size. Range is "[1, 23]" and default value is 5.
luma_msize_y, ly
Set the luma matrix vertical size. Range is "[1, 23]" and default value is 5.
luma_amount, la
Set the luma effect strength. Range is "[-10, 10]" and default value is 1.0.
Negative values will blur the input video, while positive values will sharpen it, a
value of zero will disable the effect.
chroma_msize_x, cx
Set the chroma matrix horizontal size. Range is "[1, 23]" and default value is 5.
chroma_msize_y, cy
Set the chroma matrix vertical size. Range is "[1, 23]" and default value is 5.
chroma_amount, ca
Set the chroma effect strength. Range is "[-10, 10]" and default value is 0.0.
Negative values will blur the input video, while positive values will sharpen it, a
value of zero will disable the effect.
All parameters are optional and default to the equivalent of the string '5:5:1.0:5:5:0.0'.
Examples
• Apply strong luma sharpen effect:
-i INPUT -vf "hwupload, unsharp_opencl=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5, hwdownload" OUTPUT
• Apply a strong blur of both luma and chroma parameters:
-i INPUT -vf "hwupload, unsharp_opencl=7:7:-2:7:7:-2, hwdownload" OUTPUT
VIDEO SOURCES
Below is a description of the currently available video sources.
buffer
Buffer video frames, and make them available to the filter chain.
This source is mainly intended for a programmatic use, in particular through the interface
defined in libavfilter/vsrc_buffer.h.
It accepts the following parameters:
video_size
Specify the size (width and height) of the buffered video frames. For the syntax of
this option, check the "Video size" section in the ffmpeg-utils manual.
width
The input video width.
height
The input video height.
pix_fmt
A string representing the pixel format of the buffered video frames. It may be a
number corresponding to a pixel format, or a pixel format name.
time_base
Specify the timebase assumed by the timestamps of the buffered frames.
frame_rate
Specify the frame rate expected for the video stream.
pixel_aspect, sar
The sample (pixel) aspect ratio of the input video.
sws_param
Specify the optional parameters to be used for the scale filter which is automatically
inserted when an input change is detected in the input size or format.
hw_frames_ctx
When using a hardware pixel format, this should be a reference to an AVHWFramesContext
describing input frames.
For example:
buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1
will instruct the source to accept video frames with size 320x240 and with format
"yuv410p", assuming 1/24 as the timestamps timebase and square pixels (1:1 sample aspect
ratio). Since the pixel format with name "yuv410p" corresponds to the number 6 (check the
enum AVPixelFormat definition in libavutil/pixfmt.h), this example corresponds to:
buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1
Alternatively, the options can be specified as a flat string, but this syntax is
deprecated:
width:height:pix_fmt:time_base.num:time_base.den:pixel_aspect.num:pixel_aspect.den[:sws_param]
cellauto
Create a pattern generated by an elementary cellular automaton.
The initial state of the cellular automaton can be defined through the filename and
pattern options. If such options are not specified an initial state is created randomly.
At each new frame a new row in the video is filled with the result of the cellular
automaton next generation. The behavior when the whole frame is filled is defined by the
scroll option.
This source accepts the following options:
filename, f
Read the initial cellular automaton state, i.e. the starting row, from the specified
file. In the file, each non-whitespace character is considered an alive cell, a
newline will terminate the row, and further characters in the file will be ignored.
pattern, p
Read the initial cellular automaton state, i.e. the starting row, from the specified
string.
Each non-whitespace character in the string is considered an alive cell, a newline
will terminate the row, and further characters in the string will be ignored.
rate, r
Set the video rate, that is the number of frames generated per second. Default is 25.
random_fill_ratio, ratio
Set the random fill ratio for the initial cellular automaton row. It is a floating
point number value ranging from 0 to 1, defaults to 1/PHI.
This option is ignored when a file or a pattern is specified.
random_seed, seed
Set the seed for filling randomly the initial row, must be an integer included between
0 and UINT32_MAX. If not specified, or if explicitly set to -1, the filter will try to
use a good random seed on a best effort basis.
rule
Set the cellular automaton rule, it is a number ranging from 0 to 255. Default value
is 110.
size, s
Set the size of the output video. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual.
If filename or pattern is specified, the size is set by default to the width of the
specified initial state row, and the height is set to width * PHI.
If size is set, it must contain the width of the specified pattern string, and the
specified pattern will be centered in the larger row.
If a filename or a pattern string is not specified, the size value defaults to
"320x518" (used for a randomly generated initial state).
scroll
If set to 1, scroll the output upward when all the rows in the output have been
already filled. If set to 0, the new generated row will be written over the top row
just after the bottom row is filled. Defaults to 1.
start_full, full
If set to 1, completely fill the output with generated rows before outputting the
first frame. This is the default behavior, for disabling set the value to 0.
stitch
If set to 1, stitch the left and right row edges together. This is the default
behavior, for disabling set the value to 0.
Examples
• Read the initial state from pattern, and specify an output of size 200x400.
cellauto=f=pattern:s=200x400
• Generate a random initial row with a width of 200 cells, with a fill ratio of 2/3:
cellauto=ratio=2/3:s=200x200
• Create a pattern generated by rule 18 starting by a single alive cell centered on an
initial row with width 100:
cellauto=p=@s=100x400:full=0:rule=18
• Specify a more elaborated initial pattern:
cellauto=p='@@ @ @@':s=100x400:full=0:rule=18
coreimagesrc
Video source generated on GPU using Apple's CoreImage API on OSX.
This video source is a specialized version of the coreimage video filter. Use a core
image generator at the beginning of the applied filterchain to generate the content.
The coreimagesrc video source accepts the following options:
list_generators
List all available generators along with all their respective options as well as
possible minimum and maximum values along with the default values.
list_generators=true
size, s
Specify the size of the sourced video. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. The default value is "320x240".
rate, r
Specify the frame rate of the sourced video, as the number of frames generated per
second. It has to be a string in the format frame_rate_num/frame_rate_den, an integer
number, a floating point number or a valid video frame rate abbreviation. The default
value is "25".
sar Set the sample aspect ratio of the sourced video.
duration, d
Set the duration of the sourced video. See the Time duration section in the
ffmpeg-utils(1) manual for the accepted syntax.
If not specified, or the expressed duration is negative, the video is supposed to be
generated forever.
Additionally, all options of the coreimage video filter are accepted. A complete
filterchain can be used for further processing of the generated input without CPU-HOST
transfer. See coreimage documentation and examples for details.
Examples
• Use CIQRCodeGenerator to create a QR code for the FFmpeg homepage, given as complete
and escaped command-line for Apple's standard bash shell:
ffmpeg -f lavfi -i coreimagesrc=s=100x100:filter=CIQRCodeGenerator@inputMessage=https\\\\\://FFmpeg.org/@inputCorrectionLevel=H -frames:v 1 QRCode.png
This example is equivalent to the QRCode example of coreimage without the need for a
nullsrc video source.
mandelbrot
Generate a Mandelbrot set fractal, and progressively zoom towards the point specified with
start_x and start_y.
This source accepts the following options:
end_pts
Set the terminal pts value. Default value is 400.
end_scale
Set the terminal scale value. Must be a floating point value. Default value is 0.3.
inner
Set the inner coloring mode, that is the algorithm used to draw the Mandelbrot fractal
internal region.
It shall assume one of the following values:
black
Set black mode.
convergence
Show time until convergence.
mincol
Set color based on point closest to the origin of the iterations.
period
Set period mode.
Default value is mincol.
bailout
Set the bailout value. Default value is 10.0.
maxiter
Set the maximum of iterations performed by the rendering algorithm. Default value is
7189.
outer
Set outer coloring mode. It shall assume one of following values:
iteration_count
Set iteration count mode.
normalized_iteration_count
set normalized iteration count mode.
Default value is normalized_iteration_count.
rate, r
Set frame rate, expressed as number of frames per second. Default value is "25".
size, s
Set frame size. For the syntax of this option, check the "Video size" section in the
ffmpeg-utils manual. Default value is "640x480".
start_scale
Set the initial scale value. Default value is 3.0.
start_x
Set the initial x position. Must be a floating point value between -100 and 100.
Default value is -0.743643887037158704752191506114774.
start_y
Set the initial y position. Must be a floating point value between -100 and 100.
Default value is -0.131825904205311970493132056385139.
mptestsrc
Generate various test patterns, as generated by the MPlayer test filter.
The size of the generated video is fixed, and is 256x256. This source is useful in
particular for testing encoding features.
This source accepts the following options:
rate, r
Specify the frame rate of the sourced video, as the number of frames generated per
second. It has to be a string in the format frame_rate_num/frame_rate_den, an integer
number, a floating point number or a valid video frame rate abbreviation. The default
value is "25".
duration, d
Set the duration of the sourced video. See the Time duration section in the
ffmpeg-utils(1) manual for the accepted syntax.
If not specified, or the expressed duration is negative, the video is supposed to be
generated forever.
test, t
Set the number or the name of the test to perform. Supported tests are:
dc_luma
dc_chroma
freq_luma
freq_chroma
amp_luma
amp_chroma
cbp
mv
ring1
ring2
all
Default value is "all", which will cycle through the list of all tests.
Some examples:
mptestsrc=t=dc_luma
will generate a "dc_luma" test pattern.
frei0r_src
Provide a frei0r source.
To enable compilation of this filter you need to install the frei0r header and configure
FFmpeg with "--enable-frei0r".
This source accepts the following parameters:
size
The size of the video to generate. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual.
framerate
The framerate of the generated video. It may be a string of the form num/den or a
frame rate abbreviation.
filter_name
The name to the frei0r source to load. For more information regarding frei0r and how
to set the parameters, read the frei0r section in the video filters documentation.
filter_params
A '|'-separated list of parameters to pass to the frei0r source.
For example, to generate a frei0r partik0l source with size 200x200 and frame rate 10
which is overlaid on the overlay filter main input:
frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay
life
Generate a life pattern.
This source is based on a generalization of John Conway's life game.
The sourced input represents a life grid, each pixel represents a cell which can be in one
of two possible states, alive or dead. Every cell interacts with its eight neighbours,
which are the cells that are horizontally, vertically, or diagonally adjacent.
At each interaction the grid evolves according to the adopted rule, which specifies the
number of neighbor alive cells which will make a cell stay alive or born. The rule option
allows one to specify the rule to adopt.
This source accepts the following options:
filename, f
Set the file from which to read the initial grid state. In the file, each non-
whitespace character is considered an alive cell, and newline is used to delimit the
end of each row.
If this option is not specified, the initial grid is generated randomly.
rate, r
Set the video rate, that is the number of frames generated per second. Default is 25.
random_fill_ratio, ratio
Set the random fill ratio for the initial random grid. It is a floating point number
value ranging from 0 to 1, defaults to 1/PHI. It is ignored when a file is specified.
random_seed, seed
Set the seed for filling the initial random grid, must be an integer included between
0 and UINT32_MAX. If not specified, or if explicitly set to -1, the filter will try to
use a good random seed on a best effort basis.
rule
Set the life rule.
A rule can be specified with a code of the kind "SNS/BNB", where NS and NB are
sequences of numbers in the range 0-8, NS specifies the number of alive neighbor cells
which make a live cell stay alive, and NB the number of alive neighbor cells which
make a dead cell to become alive (i.e. to "born"). "s" and "b" can be used in place
of "S" and "B", respectively.
Alternatively a rule can be specified by an 18-bits integer. The 9 high order bits are
used to encode the next cell state if it is alive for each number of neighbor alive
cells, the low order bits specify the rule for "borning" new cells. Higher order bits
encode for an higher number of neighbor cells. For example the number 6153 =
"(12<<9)+9" specifies a stay alive rule of 12 and a born rule of 9, which corresponds
to "S23/B03".
Default value is "S23/B3", which is the original Conway's game of life rule, and will
keep a cell alive if it has 2 or 3 neighbor alive cells, and will born a new cell if
there are three alive cells around a dead cell.
size, s
Set the size of the output video. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual.
If filename is specified, the size is set by default to the same size of the input
file. If size is set, it must contain the size specified in the input file, and the
initial grid defined in that file is centered in the larger resulting area.
If a filename is not specified, the size value defaults to "320x240" (used for a
randomly generated initial grid).
stitch
If set to 1, stitch the left and right grid edges together, and the top and bottom
edges also. Defaults to 1.
mold
Set cell mold speed. If set, a dead cell will go from death_color to mold_color with a
step of mold. mold can have a value from 0 to 255.
life_color
Set the color of living (or new born) cells.
death_color
Set the color of dead cells. If mold is set, this is the first color used to represent
a dead cell.
mold_color
Set mold color, for definitely dead and moldy cells.
For the syntax of these 3 color options, check the "Color" section in the ffmpeg-utils
manual.
Examples
• Read a grid from pattern, and center it on a grid of size 300x300 pixels:
life=f=pattern:s=300x300
• Generate a random grid of size 200x200, with a fill ratio of 2/3:
life=ratio=2/3:s=200x200
• Specify a custom rule for evolving a randomly generated grid:
life=rule=S14/B34
• Full example with slow death effect (mold) using ffplay:
ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16
allrgb, allyuv, color, haldclutsrc, nullsrc, pal75bars, pal100bars, rgbtestsrc, smptebars,
smptehdbars, testsrc, testsrc2, yuvtestsrc
The "allrgb" source returns frames of size 4096x4096 of all rgb colors.
The "allyuv" source returns frames of size 4096x4096 of all yuv colors.
The "color" source provides an uniformly colored input.
The "haldclutsrc" source provides an identity Hald CLUT. See also haldclut filter.
The "nullsrc" source returns unprocessed video frames. It is mainly useful to be employed
in analysis / debugging tools, or as the source for filters which ignore the input data.
The "pal75bars" source generates a color bars pattern, based on EBU PAL recommendations
with 75% color levels.
The "pal100bars" source generates a color bars pattern, based on EBU PAL recommendations
with 100% color levels.
The "rgbtestsrc" source generates an RGB test pattern useful for detecting RGB vs BGR
issues. You should see a red, green and blue stripe from top to bottom.
The "smptebars" source generates a color bars pattern, based on the SMPTE Engineering
Guideline EG 1-1990.
The "smptehdbars" source generates a color bars pattern, based on the SMPTE RP 219-2002.
The "testsrc" source generates a test video pattern, showing a color pattern, a scrolling
gradient and a timestamp. This is mainly intended for testing purposes.
The "testsrc2" source is similar to testsrc, but supports more pixel formats instead of
just "rgb24". This allows using it as an input for other tests without requiring a format
conversion.
The "yuvtestsrc" source generates an YUV test pattern. You should see a y, cb and cr
stripe from top to bottom.
The sources accept the following parameters:
level
Specify the level of the Hald CLUT, only available in the "haldclutsrc" source. A
level of "N" generates a picture of "N*N*N" by "N*N*N" pixels to be used as identity
matrix for 3D lookup tables. Each component is coded on a "1/(N*N)" scale.
color, c
Specify the color of the source, only available in the "color" source. For the syntax
of this option, check the "Color" section in the ffmpeg-utils manual.
size, s
Specify the size of the sourced video. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. The default value is "320x240".
This option is not available with the "allrgb", "allyuv", and "haldclutsrc" filters.
rate, r
Specify the frame rate of the sourced video, as the number of frames generated per
second. It has to be a string in the format frame_rate_num/frame_rate_den, an integer
number, a floating point number or a valid video frame rate abbreviation. The default
value is "25".
duration, d
Set the duration of the sourced video. See the Time duration section in the
ffmpeg-utils(1) manual for the accepted syntax.
If not specified, or the expressed duration is negative, the video is supposed to be
generated forever.
sar Set the sample aspect ratio of the sourced video.
alpha
Specify the alpha (opacity) of the background, only available in the "testsrc2"
source. The value must be between 0 (fully transparent) and 255 (fully opaque, the
default).
decimals, n
Set the number of decimals to show in the timestamp, only available in the "testsrc"
source.
The displayed timestamp value will correspond to the original timestamp value
multiplied by the power of 10 of the specified value. Default value is 0.
Examples
• Generate a video with a duration of 5.3 seconds, with size 176x144 and a frame rate of
10 frames per second:
testsrc=duration=5.3:size=qcif:rate=10
• The following graph description will generate a red source with an opacity of 0.2,
with size "qcif" and a frame rate of 10 frames per second:
color=c=red@0.2:s=qcif:r=10
• If the input content is to be ignored, "nullsrc" can be used. The following command
generates noise in the luminance plane by employing the "geq" filter:
nullsrc=s=256x256, geq=random(1)*255:128:128
Commands
The "color" source supports the following commands:
c, color
Set the color of the created image. Accepts the same syntax of the corresponding color
option.
openclsrc
Generate video using an OpenCL program.
source
OpenCL program source file.
kernel
Kernel name in program.
size, s
Size of frames to generate. This must be set.
format
Pixel format to use for the generated frames. This must be set.
rate, r
Number of frames generated every second. Default value is '25'.
For details of how the program loading works, see the program_opencl filter.
Example programs:
• Generate a colour ramp by setting pixel values from the position of the pixel in the
output image. (Note that this will work with all pixel formats, but the generated
output will not be the same.)
__kernel void ramp(__write_only image2d_t dst,
unsigned int index)
{
int2 loc = (int2)(get_global_id(0), get_global_id(1));
float4 val;
val.xy = val.zw = convert_float2(loc) / convert_float2(get_image_dim(dst));
write_imagef(dst, loc, val);
}
• Generate a Sierpinski carpet pattern, panning by a single pixel each frame.
__kernel void sierpinski_carpet(__write_only image2d_t dst,
unsigned int index)
{
int2 loc = (int2)(get_global_id(0), get_global_id(1));
float4 value = 0.0f;
int x = loc.x + index;
int y = loc.y + index;
while (x > 0 || y > 0) {
if (x % 3 == 1 && y % 3 == 1) {
value = 1.0f;
break;
}
x /= 3;
y /= 3;
}
write_imagef(dst, loc, value);
}
VIDEO SINKS
Below is a description of the currently available video sinks.
buffersink
Buffer video frames, and make them available to the end of the filter graph.
This sink is mainly intended for programmatic use, in particular through the interface
defined in libavfilter/buffersink.h or the options system.
It accepts a pointer to an AVBufferSinkContext structure, which defines the incoming
buffers' formats, to be passed as the opaque parameter to "avfilter_init_filter" for
initialization.
nullsink
Null video sink: do absolutely nothing with the input video. It is mainly useful as a
template and for use in analysis / debugging tools.
MULTIMEDIA FILTERS
Below is a description of the currently available multimedia filters.
abitscope
Convert input audio to a video output, displaying the audio bit scope.
The filter accepts the following options:
rate, r
Set frame rate, expressed as number of frames per second. Default value is "25".
size, s
Specify the video size for the output. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "1024x256".
colors
Specify list of colors separated by space or by '|' which will be used to draw
channels. Unrecognized or missing colors will be replaced by white color.
ahistogram
Convert input audio to a video output, displaying the volume histogram.
The filter accepts the following options:
dmode
Specify how histogram is calculated.
It accepts the following values:
single
Use single histogram for all channels.
separate
Use separate histogram for each channel.
Default is "single".
rate, r
Set frame rate, expressed as number of frames per second. Default value is "25".
size, s
Specify the video size for the output. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "hd720".
scale
Set display scale.
It accepts the following values:
log logarithmic
sqrt
square root
cbrt
cubic root
lin linear
rlog
reverse logarithmic
Default is "log".
ascale
Set amplitude scale.
It accepts the following values:
log logarithmic
lin linear
Default is "log".
acount
Set how much frames to accumulate in histogram. Default is 1. Setting this to -1
accumulates all frames.
rheight
Set histogram ratio of window height.
slide
Set sonogram sliding.
It accepts the following values:
replace
replace old rows with new ones.
scroll
scroll from top to bottom.
Default is "replace".
aphasemeter
Measures phase of input audio, which is exported as metadata "lavfi.aphasemeter.phase",
representing mean phase of current audio frame. A video output can also be produced and is
enabled by default. The audio is passed through as first output.
Audio will be rematrixed to stereo if it has a different channel layout. Phase value is in
range "[-1, 1]" where "-1" means left and right channels are completely out of phase and 1
means channels are in phase.
The filter accepts the following options, all related to its video output:
rate, r
Set the output frame rate. Default value is 25.
size, s
Set the video size for the output. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "800x400".
rc
gc
bc Specify the red, green, blue contrast. Default values are 2, 7 and 1. Allowed range
is "[0, 255]".
mpc Set color which will be used for drawing median phase. If color is "none" which is
default, no median phase value will be drawn.
video
Enable video output. Default is enabled.
avectorscope
Convert input audio to a video output, representing the audio vector scope.
The filter is used to measure the difference between channels of stereo audio stream. A
monoaural signal, consisting of identical left and right signal, results in straight
vertical line. Any stereo separation is visible as a deviation from this line, creating a
Lissajous figure. If the straight (or deviation from it) but horizontal line appears this
indicates that the left and right channels are out of phase.
The filter accepts the following options:
mode, m
Set the vectorscope mode.
Available values are:
lissajous
Lissajous rotated by 45 degrees.
lissajous_xy
Same as above but not rotated.
polar
Shape resembling half of circle.
Default value is lissajous.
size, s
Set the video size for the output. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "400x400".
rate, r
Set the output frame rate. Default value is 25.
rc
gc
bc
ac Specify the red, green, blue and alpha contrast. Default values are 40, 160, 80 and
255. Allowed range is "[0, 255]".
rf
gf
bf
af Specify the red, green, blue and alpha fade. Default values are 15, 10, 5 and 5.
Allowed range is "[0, 255]".
zoom
Set the zoom factor. Default value is 1. Allowed range is "[0, 10]". Values lower
than 1 will auto adjust zoom factor to maximal possible value.
draw
Set the vectorscope drawing mode.
Available values are:
dot Draw dot for each sample.
line
Draw line between previous and current sample.
Default value is dot.
scale
Specify amplitude scale of audio samples.
Available values are:
lin Linear.
sqrt
Square root.
cbrt
Cubic root.
log Logarithmic.
swap
Swap left channel axis with right channel axis.
mirror
Mirror axis.
none
No mirror.
x Mirror only x axis.
y Mirror only y axis.
xy Mirror both axis.
Examples
• Complete example using ffplay:
ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
[a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]'
bench, abench
Benchmark part of a filtergraph.
The filter accepts the following options:
action
Start or stop a timer.
Available values are:
start
Get the current time, set it as frame metadata (using the key
"lavfi.bench.start_time"), and forward the frame to the next filter.
stop
Get the current time and fetch the "lavfi.bench.start_time" metadata from the
input frame metadata to get the time difference. Time difference, average, maximum
and minimum time (respectively "t", "avg", "max" and "min") are then printed. The
timestamps are expressed in seconds.
Examples
• Benchmark selectivecolor filter:
bench=start,selectivecolor=reds=-.2 .12 -.49,bench=stop
concat
Concatenate audio and video streams, joining them together one after the other.
The filter works on segments of synchronized video and audio streams. All segments must
have the same number of streams of each type, and that will also be the number of streams
at output.
The filter accepts the following options:
n Set the number of segments. Default is 2.
v Set the number of output video streams, that is also the number of video streams in
each segment. Default is 1.
a Set the number of output audio streams, that is also the number of audio streams in
each segment. Default is 0.
unsafe
Activate unsafe mode: do not fail if segments have a different format.
The filter has v+a outputs: first v video outputs, then a audio outputs.
There are nx(v+a) inputs: first the inputs for the first segment, in the same order as the
outputs, then the inputs for the second segment, etc.
Related streams do not always have exactly the same duration, for various reasons
including codec frame size or sloppy authoring. For that reason, related synchronized
streams (e.g. a video and its audio track) should be concatenated at once. The concat
filter will use the duration of the longest stream in each segment (except the last one),
and if necessary pad shorter audio streams with silence.
For this filter to work correctly, all segments must start at timestamp 0.
All corresponding streams must have the same parameters in all segments; the filtering
system will automatically select a common pixel format for video streams, and a common
sample format, sample rate and channel layout for audio streams, but other settings, such
as resolution, must be converted explicitly by the user.
Different frame rates are acceptable but will result in variable frame rate at output; be
sure to configure the output file to handle it.
Examples
• Concatenate an opening, an episode and an ending, all in bilingual version (video in
stream 0, audio in streams 1 and 2):
ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \
'[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2]
concat=n=3:v=1:a=2 [v] [a1] [a2]' \
-map '[v]' -map '[a1]' -map '[a2]' output.mkv
• Concatenate two parts, handling audio and video separately, using the (a)movie
sources, and adjusting the resolution:
movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ;
movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ;
[v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa]
Note that a desync will happen at the stitch if the audio and video streams do not
have exactly the same duration in the first file.
Commands
This filter supports the following commands:
next
Close the current segment and step to the next one
drawgraph, adrawgraph
Draw a graph using input video or audio metadata.
It accepts the following parameters:
m1 Set 1st frame metadata key from which metadata values will be used to draw a graph.
fg1 Set 1st foreground color expression.
m2 Set 2nd frame metadata key from which metadata values will be used to draw a graph.
fg2 Set 2nd foreground color expression.
m3 Set 3rd frame metadata key from which metadata values will be used to draw a graph.
fg3 Set 3rd foreground color expression.
m4 Set 4th frame metadata key from which metadata values will be used to draw a graph.
fg4 Set 4th foreground color expression.
min Set minimal value of metadata value.
max Set maximal value of metadata value.
bg Set graph background color. Default is white.
mode
Set graph mode.
Available values for mode is:
bar
dot
line
Default is "line".
slide
Set slide mode.
Available values for slide is:
frame
Draw new frame when right border is reached.
replace
Replace old columns with new ones.
scroll
Scroll from right to left.
rscroll
Scroll from left to right.
picture
Draw single picture.
Default is "frame".
size
Set size of graph video. For the syntax of this option, check the "Video size" section
in the ffmpeg-utils manual. The default value is "900x256".
The foreground color expressions can use the following variables:
MIN Minimal value of metadata value.
MAX Maximal value of metadata value.
VAL Current metadata key value.
The color is defined as 0xAABBGGRR.
Example using metadata from signalstats filter:
signalstats,drawgraph=lavfi.signalstats.YAVG:min=0:max=255
Example using metadata from ebur128 filter:
ebur128=metadata=1,adrawgraph=lavfi.r128.M:min=-120:max=5
ebur128
EBU R128 scanner filter. This filter takes an audio stream and analyzes its loudness
level. By default, it logs a message at a frequency of 10Hz with the Momentary loudness
(identified by "M"), Short-term loudness ("S"), Integrated loudness ("I") and Loudness
Range ("LRA").
The filter can only analyze streams which have a sampling rate of 48000 Hz and whose
sample format is double-precision floating point. The input stream will be converted to
this specification, if needed. Users may need to insert aformat and/or aresample filters
after this filter to obtain the original parameters.
The filter also has a video output (see the video option) with a real time graph to
observe the loudness evolution. The graphic contains the logged message mentioned above,
so it is not printed anymore when this option is set, unless the verbose logging is set.
The main graphing area contains the short-term loudness (3 seconds of analysis), and the
gauge on the right is for the momentary loudness (400 milliseconds), but can optionally be
configured to instead display short-term loudness (see gauge).
The green area marks a +/- 1LU target range around the target loudness (-23LUFS by
default, unless modified through target).
More information about the Loudness Recommendation EBU R128 on
<http://tech.ebu.ch/loudness>.
The filter accepts the following options:
video
Activate the video output. The audio stream is passed unchanged whether this option is
set or no. The video stream will be the first output stream if activated. Default is
0.
size
Set the video size. This option is for video only. For the syntax of this option,
check the "Video size" section in the ffmpeg-utils manual. Default and minimum
resolution is "640x480".
meter
Set the EBU scale meter. Default is 9. Common values are 9 and 18, respectively for
EBU scale meter +9 and EBU scale meter +18. Any other integer value between this range
is allowed.
metadata
Set metadata injection. If set to 1, the audio input will be segmented into 100ms
output frames, each of them containing various loudness information in metadata. All
the metadata keys are prefixed with "lavfi.r128.".
Default is 0.
framelog
Force the frame logging level.
Available values are:
info
information logging level
verbose
verbose logging level
By default, the logging level is set to info. If the video or the metadata options are
set, it switches to verbose.
peak
Set peak mode(s).
Available modes can be cumulated (the option is a "flag" type). Possible values are:
none
Disable any peak mode (default).
sample
Enable sample-peak mode.
Simple peak mode looking for the higher sample value. It logs a message for
sample-peak (identified by "SPK").
true
Enable true-peak mode.
If enabled, the peak lookup is done on an over-sampled version of the input stream
for better peak accuracy. It logs a message for true-peak. (identified by "TPK")
and true-peak per frame (identified by "FTPK"). This mode requires a build with
"libswresample".
dualmono
Treat mono input files as "dual mono". If a mono file is intended for playback on a
stereo system, its EBU R128 measurement will be perceptually incorrect. If set to
"true", this option will compensate for this effect. Multi-channel input files are
not affected by this option.
panlaw
Set a specific pan law to be used for the measurement of dual mono files. This
parameter is optional, and has a default value of -3.01dB.
target
Set a specific target level (in LUFS) used as relative zero in the visualization.
This parameter is optional and has a default value of -23LUFS as specified by EBU
R128. However, material published online may prefer a level of -16LUFS (e.g. for use
with podcasts or video platforms).
gauge
Set the value displayed by the gauge. Valid values are "momentary" and s "shortterm".
By default the momentary value will be used, but in certain scenarios it may be more
useful to observe the short term value instead (e.g. live mixing).
scale
Sets the display scale for the loudness. Valid parameters are "absolute" (in LUFS) or
"relative" (LU) relative to the target. This only affects the video output, not the
summary or continuous log output.
Examples
• Real-time graph using ffplay, with a EBU scale meter +18:
ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]"
• Run an analysis with ffmpeg:
ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null -
interleave, ainterleave
Temporally interleave frames from several inputs.
"interleave" works with video inputs, "ainterleave" with audio.
These filters read frames from several inputs and send the oldest queued frame to the
output.
Input streams must have well defined, monotonically increasing frame timestamp values.
In order to submit one frame to output, these filters need to enqueue at least one frame
for each input, so they cannot work in case one input is not yet terminated and will not
receive incoming frames.
For example consider the case when one input is a "select" filter which always drops input
frames. The "interleave" filter will keep reading from that input, but it will never be
able to send new frames to output until the input sends an end-of-stream signal.
Also, depending on inputs synchronization, the filters will drop frames in case one input
receives more frames than the other ones, and the queue is already filled.
These filters accept the following options:
nb_inputs, n
Set the number of different inputs, it is 2 by default.
Examples
• Interleave frames belonging to different streams using ffmpeg:
ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi
• Add flickering blur effect:
select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave
metadata, ametadata
Manipulate frame metadata.
This filter accepts the following options:
mode
Set mode of operation of the filter.
Can be one of the following:
select
If both "value" and "key" is set, select frames which have such metadata. If only
"key" is set, select every frame that has such key in metadata.
add Add new metadata "key" and "value". If key is already available do nothing.
modify
Modify value of already present key.
delete
If "value" is set, delete only keys that have such value. Otherwise, delete key.
If "key" is not set, delete all metadata values in the frame.
print
Print key and its value if metadata was found. If "key" is not set print all
metadata values available in frame.
key Set key used with all modes. Must be set for all modes except "print" and "delete".
value
Set metadata value which will be used. This option is mandatory for "modify" and "add"
mode.
function
Which function to use when comparing metadata value and "value".
Can be one of following:
same_str
Values are interpreted as strings, returns true if metadata value is same as
"value".
starts_with
Values are interpreted as strings, returns true if metadata value starts with the
"value" option string.
less
Values are interpreted as floats, returns true if metadata value is less than
"value".
equal
Values are interpreted as floats, returns true if "value" is equal with metadata
value.
greater
Values are interpreted as floats, returns true if metadata value is greater than
"value".
expr
Values are interpreted as floats, returns true if expression from option "expr"
evaluates to true.
expr
Set expression which is used when "function" is set to "expr". The expression is
evaluated through the eval API and can contain the following constants:
VALUE1
Float representation of "value" from metadata key.
VALUE2
Float representation of "value" as supplied by user in "value" option.
file
If specified in "print" mode, output is written to the named file. Instead of plain
filename any writable url can be specified. Filename ``-'' is a shorthand for standard
output. If "file" option is not set, output is written to the log with AV_LOG_INFO
loglevel.
Examples
• Print all metadata values for frames with key "lavfi.signalstats.YDIF" with values
between 0 and 1.
signalstats,metadata=print:key=lavfi.signalstats.YDIF:value=0:function=expr:expr='between(VALUE1,0,1)'
• Print silencedetect output to file metadata.txt.
silencedetect,ametadata=mode=print:file=metadata.txt
• Direct all metadata to a pipe with file descriptor 4.
metadata=mode=print:file='pipe\:4'
perms, aperms
Set read/write permissions for the output frames.
These filters are mainly aimed at developers to test direct path in the following filter
in the filtergraph.
The filters accept the following options:
mode
Select the permissions mode.
It accepts the following values:
none
Do nothing. This is the default.
ro Set all the output frames read-only.
rw Set all the output frames directly writable.
toggle
Make the frame read-only if writable, and writable if read-only.
random
Set each output frame read-only or writable randomly.
seed
Set the seed for the random mode, must be an integer included between 0 and
"UINT32_MAX". If not specified, or if explicitly set to "-1", the filter will try to
use a good random seed on a best effort basis.
Note: in case of auto-inserted filter between the permission filter and the following one,
the permission might not be received as expected in that following filter. Inserting a
format or aformat filter before the perms/aperms filter can avoid this problem.
realtime, arealtime
Slow down filtering to match real time approximately.
These filters will pause the filtering for a variable amount of time to match the output
rate with the input timestamps. They are similar to the re option to "ffmpeg".
They accept the following options:
limit
Time limit for the pauses. Any pause longer than that will be considered a timestamp
discontinuity and reset the timer. Default is 2 seconds.
speed
Speed factor for processing. The value must be a float larger than zero. Values
larger than 1.0 will result in faster than realtime processing, smaller will slow
processing down. The limit is automatically adapted accordingly. Default is 1.0.
A processing speed faster than what is possible without these filters cannot be
achieved.
select, aselect
Select frames to pass in output.
This filter accepts the following options:
expr, e
Set expression, which is evaluated for each input frame.
If the expression is evaluated to zero, the frame is discarded.
If the evaluation result is negative or NaN, the frame is sent to the first output;
otherwise it is sent to the output with index "ceil(val)-1", assuming that the input
index starts from 0.
For example a value of 1.2 corresponds to the output with index "ceil(1.2)-1 = 2-1 =
1", that is the second output.
outputs, n
Set the number of outputs. The output to which to send the selected frame is based on
the result of the evaluation. Default value is 1.
The expression can contain the following constants:
n The (sequential) number of the filtered frame, starting from 0.
selected_n
The (sequential) number of the selected frame, starting from 0.
prev_selected_n
The sequential number of the last selected frame. It's NAN if undefined.
TB The timebase of the input timestamps.
pts The PTS (Presentation TimeStamp) of the filtered video frame, expressed in TB units.
It's NAN if undefined.
t The PTS of the filtered video frame, expressed in seconds. It's NAN if undefined.
prev_pts
The PTS of the previously filtered video frame. It's NAN if undefined.
prev_selected_pts
The PTS of the last previously filtered video frame. It's NAN if undefined.
prev_selected_t
The PTS of the last previously selected video frame, expressed in seconds. It's NAN if
undefined.
start_pts
The PTS of the first video frame in the video. It's NAN if undefined.
start_t
The time of the first video frame in the video. It's NAN if undefined.
pict_type (video only)
The type of the filtered frame. It can assume one of the following values:
I
P
B
S
SI
SP
BI
interlace_type (video only)
The frame interlace type. It can assume one of the following values:
PROGRESSIVE
The frame is progressive (not interlaced).
TOPFIRST
The frame is top-field-first.
BOTTOMFIRST
The frame is bottom-field-first.
consumed_sample_n (audio only)
the number of selected samples before the current frame
samples_n (audio only)
the number of samples in the current frame
sample_rate (audio only)
the input sample rate
key This is 1 if the filtered frame is a key-frame, 0 otherwise.
pos the position in the file of the filtered frame, -1 if the information is not available
(e.g. for synthetic video)
scene (video only)
value between 0 and 1 to indicate a new scene; a low value reflects a low probability
for the current frame to introduce a new scene, while a higher value means the current
frame is more likely to be one (see the example below)
concatdec_select
The concat demuxer can select only part of a concat input file by setting an inpoint
and an outpoint, but the output packets may not be entirely contained in the selected
interval. By using this variable, it is possible to skip frames generated by the
concat demuxer which are not exactly contained in the selected interval.
This works by comparing the frame pts against the lavf.concat.start_time and the
lavf.concat.duration packet metadata values which are also present in the decoded
frames.
The concatdec_select variable is -1 if the frame pts is at least start_time and either
the duration metadata is missing or the frame pts is less than start_time + duration,
0 otherwise, and NaN if the start_time metadata is missing.
That basically means that an input frame is selected if its pts is within the interval
set by the concat demuxer.
The default value of the select expression is "1".
Examples
• Select all frames in input:
select
The example above is the same as:
select=1
• Skip all frames:
select=0
• Select only I-frames:
select='eq(pict_type\,I)'
• Select one frame every 100:
select='not(mod(n\,100))'
• Select only frames contained in the 10-20 time interval:
select=between(t\,10\,20)
• Select only I-frames contained in the 10-20 time interval:
select=between(t\,10\,20)*eq(pict_type\,I)
• Select frames with a minimum distance of 10 seconds:
select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)'
• Use aselect to select only audio frames with samples number > 100:
aselect='gt(samples_n\,100)'
• Create a mosaic of the first scenes:
ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png
Comparing scene against a value between 0.3 and 0.5 is generally a sane choice.
• Send even and odd frames to separate outputs, and compose them:
select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h
• Select useful frames from an ffconcat file which is using inpoints and outpoints but
where the source files are not intra frame only.
ffmpeg -copyts -vsync 0 -segment_time_metadata 1 -i input.ffconcat -vf select=concatdec_select -af aselect=concatdec_select output.avi
sendcmd, asendcmd
Send commands to filters in the filtergraph.
These filters read commands to be sent to other filters in the filtergraph.
"sendcmd" must be inserted between two video filters, "asendcmd" must be inserted between
two audio filters, but apart from that they act the same way.
The specification of commands can be provided in the filter arguments with the commands
option, or in a file specified by the filename option.
These filters accept the following options:
commands, c
Set the commands to be read and sent to the other filters.
filename, f
Set the filename of the commands to be read and sent to the other filters.
Commands syntax
A commands description consists of a sequence of interval specifications, comprising a
list of commands to be executed when a particular event related to that interval occurs.
The occurring event is typically the current frame time entering or leaving a given time
interval.
An interval is specified by the following syntax:
<START>[-<END>] <COMMANDS>;
The time interval is specified by the START and END times. END is optional and defaults
to the maximum time.
The current frame time is considered within the specified interval if it is included in
the interval [START, END), that is when the time is greater or equal to START and is
lesser than END.
COMMANDS consists of a sequence of one or more command specifications, separated by ",",
relating to that interval. The syntax of a command specification is given by:
[<FLAGS>] <TARGET> <COMMAND> <ARG>
FLAGS is optional and specifies the type of events relating to the time interval which
enable sending the specified command, and must be a non-null sequence of identifier flags
separated by "+" or "|" and enclosed between "[" and "]".
The following flags are recognized:
enter
The command is sent when the current frame timestamp enters the specified interval. In
other words, the command is sent when the previous frame timestamp was not in the
given interval, and the current is.
leave
The command is sent when the current frame timestamp leaves the specified interval. In
other words, the command is sent when the previous frame timestamp was in the given
interval, and the current is not.
If FLAGS is not specified, a default value of "[enter]" is assumed.
TARGET specifies the target of the command, usually the name of the filter class or a
specific filter instance name.
COMMAND specifies the name of the command for the target filter.
ARG is optional and specifies the optional list of argument for the given COMMAND.
Between one interval specification and another, whitespaces, or sequences of characters
starting with "#" until the end of line, are ignored and can be used to annotate comments.
A simplified BNF description of the commands specification syntax follows:
<COMMAND_FLAG> ::= "enter" | "leave"
<COMMAND_FLAGS> ::= <COMMAND_FLAG> [(+|"|")<COMMAND_FLAG>]
<COMMAND> ::= ["[" <COMMAND_FLAGS> "]"] <TARGET> <COMMAND> [<ARG>]
<COMMANDS> ::= <COMMAND> [,<COMMANDS>]
<INTERVAL> ::= <START>[-<END>] <COMMANDS>
<INTERVALS> ::= <INTERVAL>[;<INTERVALS>]
Examples
• Specify audio tempo change at second 4:
asendcmd=c='4.0 atempo tempo 1.5',atempo
• Target a specific filter instance:
asendcmd=c='4.0 atempo@my tempo 1.5',atempo@my
• Specify a list of drawtext and hue commands in a file.
# show text in the interval 5-10
5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world',
[leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=';
# desaturate the image in the interval 15-20
15.0-20.0 [enter] hue s 0,
[enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor',
[leave] hue s 1,
[leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color';
# apply an exponential saturation fade-out effect, starting from time 25
25 [enter] hue s exp(25-t)
A filtergraph allowing to read and process the above command list stored in a file
test.cmd, can be specified with:
sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue
setpts, asetpts
Change the PTS (presentation timestamp) of the input frames.
"setpts" works on video frames, "asetpts" on audio frames.
This filter accepts the following options:
expr
The expression which is evaluated for each frame to construct its timestamp.
The expression is evaluated through the eval API and can contain the following constants:
FRAME_RATE, FR
frame rate, only defined for constant frame-rate video
PTS The presentation timestamp in input
N The count of the input frame for video or the number of consumed samples, not
including the current frame for audio, starting from 0.
NB_CONSUMED_SAMPLES
The number of consumed samples, not including the current frame (only audio)
NB_SAMPLES, S
The number of samples in the current frame (only audio)
SAMPLE_RATE, SR
The audio sample rate.
STARTPTS
The PTS of the first frame.
STARTT
the time in seconds of the first frame
INTERLACED
State whether the current frame is interlaced.
T the time in seconds of the current frame
POS original position in the file of the frame, or undefined if undefined for the current
frame
PREV_INPTS
The previous input PTS.
PREV_INT
previous input time in seconds
PREV_OUTPTS
The previous output PTS.
PREV_OUTT
previous output time in seconds
RTCTIME
The wallclock (RTC) time in microseconds. This is deprecated, use time(0) instead.
RTCSTART
The wallclock (RTC) time at the start of the movie in microseconds.
TB The timebase of the input timestamps.
Examples
• Start counting PTS from zero
setpts=PTS-STARTPTS
• Apply fast motion effect:
setpts=0.5*PTS
• Apply slow motion effect:
setpts=2.0*PTS
• Set fixed rate of 25 frames per second:
setpts=N/(25*TB)
• Set fixed rate 25 fps with some jitter:
setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'
• Apply an offset of 10 seconds to the input PTS:
setpts=PTS+10/TB
• Generate timestamps from a "live source" and rebase onto the current timebase:
setpts='(RTCTIME - RTCSTART) / (TB * 1000000)'
• Generate timestamps by counting samples:
asetpts=N/SR/TB
setrange
Force color range for the output video frame.
The "setrange" filter marks the color range property for the output frames. It does not
change the input frame, but only sets the corresponding property, which affects how the
frame is treated by following filters.
The filter accepts the following options:
range
Available values are:
auto
Keep the same color range property.
unspecified, unknown
Set the color range as unspecified.
limited, tv, mpeg
Set the color range as limited.
full, pc, jpeg
Set the color range as full.
settb, asettb
Set the timebase to use for the output frames timestamps. It is mainly useful for testing
timebase configuration.
It accepts the following parameters:
expr, tb
The expression which is evaluated into the output timebase.
The value for tb is an arithmetic expression representing a rational. The expression can
contain the constants "AVTB" (the default timebase), "intb" (the input timebase) and "sr"
(the sample rate, audio only). Default value is "intb".
Examples
• Set the timebase to 1/25:
settb=expr=1/25
• Set the timebase to 1/10:
settb=expr=0.1
• Set the timebase to 1001/1000:
settb=1+0.001
• Set the timebase to 2*intb:
settb=2*intb
• Set the default timebase value:
settb=AVTB
showcqt
Convert input audio to a video output representing frequency spectrum logarithmically
using Brown-Puckette constant Q transform algorithm with direct frequency domain
coefficient calculation (but the transform itself is not really constant Q, instead the Q
factor is actually variable/clamped), with musical tone scale, from E0 to D#10.
The filter accepts the following options:
size, s
Specify the video size for the output. It must be even. For the syntax of this option,
check the "Video size" section in the ffmpeg-utils manual. Default value is
"1920x1080".
fps, rate, r
Set the output frame rate. Default value is 25.
bar_h
Set the bargraph height. It must be even. Default value is "-1" which computes the
bargraph height automatically.
axis_h
Set the axis height. It must be even. Default value is "-1" which computes the axis
height automatically.
sono_h
Set the sonogram height. It must be even. Default value is "-1" which computes the
sonogram height automatically.
fullhd
Set the fullhd resolution. This option is deprecated, use size, s instead. Default
value is 1.
sono_v, volume
Specify the sonogram volume expression. It can contain variables:
bar_v
the bar_v evaluated expression
frequency, freq, f
the frequency where it is evaluated
timeclamp, tc
the value of timeclamp option
and functions:
a_weighting(f)
A-weighting of equal loudness
b_weighting(f)
B-weighting of equal loudness
c_weighting(f)
C-weighting of equal loudness.
Default value is 16.
bar_v, volume2
Specify the bargraph volume expression. It can contain variables:
sono_v
the sono_v evaluated expression
frequency, freq, f
the frequency where it is evaluated
timeclamp, tc
the value of timeclamp option
and functions:
a_weighting(f)
A-weighting of equal loudness
b_weighting(f)
B-weighting of equal loudness
c_weighting(f)
C-weighting of equal loudness.
Default value is "sono_v".
sono_g, gamma
Specify the sonogram gamma. Lower gamma makes the spectrum more contrast, higher gamma
makes the spectrum having more range. Default value is 3. Acceptable range is "[1,
7]".
bar_g, gamma2
Specify the bargraph gamma. Default value is 1. Acceptable range is "[1, 7]".
bar_t
Specify the bargraph transparency level. Lower value makes the bargraph sharper.
Default value is 1. Acceptable range is "[0, 1]".
timeclamp, tc
Specify the transform timeclamp. At low frequency, there is trade-off between accuracy
in time domain and frequency domain. If timeclamp is lower, event in time domain is
represented more accurately (such as fast bass drum), otherwise event in frequency
domain is represented more accurately (such as bass guitar). Acceptable range is
"[0.002, 1]". Default value is 0.17.
attack
Set attack time in seconds. The default is 0 (disabled). Otherwise, it limits future
samples by applying asymmetric windowing in time domain, useful when low latency is
required. Accepted range is "[0, 1]".
basefreq
Specify the transform base frequency. Default value is 20.01523126408007475, which is
frequency 50 cents below E0. Acceptable range is "[10, 100000]".
endfreq
Specify the transform end frequency. Default value is 20495.59681441799654, which is
frequency 50 cents above D#10. Acceptable range is "[10, 100000]".
coeffclamp
This option is deprecated and ignored.
tlength
Specify the transform length in time domain. Use this option to control accuracy
trade-off between time domain and frequency domain at every frequency sample. It can
contain variables:
frequency, freq, f
the frequency where it is evaluated
timeclamp, tc
the value of timeclamp option.
Default value is "384*tc/(384+tc*f)".
count
Specify the transform count for every video frame. Default value is 6. Acceptable
range is "[1, 30]".
fcount
Specify the transform count for every single pixel. Default value is 0, which makes it
computed automatically. Acceptable range is "[0, 10]".
fontfile
Specify font file for use with freetype to draw the axis. If not specified, use
embedded font. Note that drawing with font file or embedded font is not implemented
with custom basefreq and endfreq, use axisfile option instead.
font
Specify fontconfig pattern. This has lower priority than fontfile. The : in the
pattern may be replaced by | to avoid unnecessary escaping.
fontcolor
Specify font color expression. This is arithmetic expression that should return
integer value 0xRRGGBB. It can contain variables:
frequency, freq, f
the frequency where it is evaluated
timeclamp, tc
the value of timeclamp option
and functions:
midi(f)
midi number of frequency f, some midi numbers: E0(16), C1(24), C2(36), A4(69)
r(x), g(x), b(x)
red, green, and blue value of intensity x.
Default value is "st(0, (midi(f)-59.5)/12); st(1, if(between(ld(0),0,1),
0.5-0.5*cos(2*PI*ld(0)), 0)); r(1-ld(1)) + b(ld(1))".
axisfile
Specify image file to draw the axis. This option override fontfile and fontcolor
option.
axis, text
Enable/disable drawing text to the axis. If it is set to 0, drawing to the axis is
disabled, ignoring fontfile and axisfile option. Default value is 1.
csp Set colorspace. The accepted values are:
unspecified
Unspecified (default)
bt709
BT.709
fcc FCC
bt470bg
BT.470BG or BT.601-6 625
smpte170m
SMPTE-170M or BT.601-6 525
smpte240m
SMPTE-240M
bt2020ncl
BT.2020 with non-constant luminance
cscheme
Set spectrogram color scheme. This is list of floating point values with format
"left_r|left_g|left_b|right_r|right_g|right_b". The default is "1|0.5|0|0|0.5|1".
Examples
• Playing audio while showing the spectrum:
ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]'
• Same as above, but with frame rate 30 fps:
ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]'
• Playing at 1280x720:
ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=s=1280x720:count=4 [out0]'
• Disable sonogram display:
sono_h=0
• A1 and its harmonics: A1, A2, (near)E3, A3:
ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
asplit[a][out1]; [a] showcqt [out0]'
• Same as above, but with more accuracy in frequency domain:
ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t),
asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]'
• Custom volume:
bar_v=10:sono_v=bar_v*a_weighting(f)
• Custom gamma, now spectrum is linear to the amplitude.
bar_g=2:sono_g=2
• Custom tlength equation:
tc=0.33:tlength='st(0,0.17); 384*tc / (384 / ld(0) + tc*f /(1-ld(0))) + 384*tc / (tc*f / ld(0) + 384 /(1-ld(0)))'
• Custom fontcolor and fontfile, C-note is colored green, others are colored blue:
fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))':fontfile=myfont.ttf
• Custom font using fontconfig:
font='Courier New,Monospace,mono|bold'
• Custom frequency range with custom axis using image file:
axisfile=myaxis.png:basefreq=40:endfreq=10000
showfreqs
Convert input audio to video output representing the audio power spectrum. Audio
amplitude is on Y-axis while frequency is on X-axis.
The filter accepts the following options:
size, s
Specify size of video. For the syntax of this option, check the "Video size" section
in the ffmpeg-utils manual. Default is "1024x512".
mode
Set display mode. This set how each frequency bin will be represented.
It accepts the following values:
line
bar
dot
Default is "bar".
ascale
Set amplitude scale.
It accepts the following values:
lin Linear scale.
sqrt
Square root scale.
cbrt
Cubic root scale.
log Logarithmic scale.
Default is "log".
fscale
Set frequency scale.
It accepts the following values:
lin Linear scale.
log Logarithmic scale.
rlog
Reverse logarithmic scale.
Default is "lin".
win_size
Set window size. Allowed range is from 16 to 65536.
Default is 2048
win_func
Set windowing function.
It accepts the following values:
rect
bartlett
hanning
hamming
blackman
welch
flattop
bharris
bnuttall
bhann
sine
nuttall
lanczos
gauss
tukey
dolph
cauchy
parzen
poisson
bohman
Default is "hanning".
overlap
Set window overlap. In range "[0, 1]". Default is 1, which means optimal overlap for
selected window function will be picked.
averaging
Set time averaging. Setting this to 0 will display current maximal peaks. Default is
1, which means time averaging is disabled.
colors
Specify list of colors separated by space or by '|' which will be used to draw channel
frequencies. Unrecognized or missing colors will be replaced by white color.
cmode
Set channel display mode.
It accepts the following values:
combined
separate
Default is "combined".
minamp
Set minimum amplitude used in "log" amplitude scaler.
showspatial
Convert stereo input audio to a video output, representing the spatial relationship
between two channels.
The filter accepts the following options:
size, s
Specify the video size for the output. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "512x512".
win_size
Set window size. Allowed range is from 1024 to 65536. Default size is 4096.
win_func
Set window function.
It accepts the following values:
rect
bartlett
hann
hanning
hamming
blackman
welch
flattop
bharris
bnuttall
bhann
sine
nuttall
lanczos
gauss
tukey
dolph
cauchy
parzen
poisson
bohman
Default value is "hann".
overlap
Set ratio of overlap window. Default value is 0.5. When value is 1 overlap is set to
recommended size for specific window function currently used.
showspectrum
Convert input audio to a video output, representing the audio frequency spectrum.
The filter accepts the following options:
size, s
Specify the video size for the output. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "640x512".
slide
Specify how the spectrum should slide along the window.
It accepts the following values:
replace
the samples start again on the left when they reach the right
scroll
the samples scroll from right to left
fullframe
frames are only produced when the samples reach the right
rscroll
the samples scroll from left to right
Default value is "replace".
mode
Specify display mode.
It accepts the following values:
combined
all channels are displayed in the same row
separate
all channels are displayed in separate rows
Default value is combined.
color
Specify display color mode.
It accepts the following values:
channel
each channel is displayed in a separate color
intensity
each channel is displayed using the same color scheme
rainbow
each channel is displayed using the rainbow color scheme
moreland
each channel is displayed using the moreland color scheme
nebulae
each channel is displayed using the nebulae color scheme
fire
each channel is displayed using the fire color scheme
fiery
each channel is displayed using the fiery color scheme
fruit
each channel is displayed using the fruit color scheme
cool
each channel is displayed using the cool color scheme
magma
each channel is displayed using the magma color scheme
green
each channel is displayed using the green color scheme
viridis
each channel is displayed using the viridis color scheme
plasma
each channel is displayed using the plasma color scheme
cividis
each channel is displayed using the cividis color scheme
terrain
each channel is displayed using the terrain color scheme
Default value is channel.
scale
Specify scale used for calculating intensity color values.
It accepts the following values:
lin linear
sqrt
square root, default
cbrt
cubic root
log logarithmic
4thrt
4th root
5thrt
5th root
Default value is sqrt.
fscale
Specify frequency scale.
It accepts the following values:
lin linear
log logarithmic
Default value is lin.
saturation
Set saturation modifier for displayed colors. Negative values provide alternative
color scheme. 0 is no saturation at all. Saturation must be in [-10.0, 10.0] range.
Default value is 1.
win_func
Set window function.
It accepts the following values:
rect
bartlett
hann
hanning
hamming
blackman
welch
flattop
bharris
bnuttall
bhann
sine
nuttall
lanczos
gauss
tukey
dolph
cauchy
parzen
poisson
bohman
Default value is "hann".
orientation
Set orientation of time vs frequency axis. Can be "vertical" or "horizontal". Default
is "vertical".
overlap
Set ratio of overlap window. Default value is 0. When value is 1 overlap is set to
recommended size for specific window function currently used.
gain
Set scale gain for calculating intensity color values. Default value is 1.
data
Set which data to display. Can be "magnitude", default or "phase".
rotation
Set color rotation, must be in [-1.0, 1.0] range. Default value is 0.
start
Set start frequency from which to display spectrogram. Default is 0.
stop
Set stop frequency to which to display spectrogram. Default is 0.
fps Set upper frame rate limit. Default is "auto", unlimited.
legend
Draw time and frequency axes and legends. Default is disabled.
The usage is very similar to the showwaves filter; see the examples in that section.
Examples
• Large window with logarithmic color scaling:
showspectrum=s=1280x480:scale=log
• Complete example for a colored and sliding spectrum per channel using ffplay:
ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1];
[a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]'
showspectrumpic
Convert input audio to a single video frame, representing the audio frequency spectrum.
The filter accepts the following options:
size, s
Specify the video size for the output. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "4096x2048".
mode
Specify display mode.
It accepts the following values:
combined
all channels are displayed in the same row
separate
all channels are displayed in separate rows
Default value is combined.
color
Specify display color mode.
It accepts the following values:
channel
each channel is displayed in a separate color
intensity
each channel is displayed using the same color scheme
rainbow
each channel is displayed using the rainbow color scheme
moreland
each channel is displayed using the moreland color scheme
nebulae
each channel is displayed using the nebulae color scheme
fire
each channel is displayed using the fire color scheme
fiery
each channel is displayed using the fiery color scheme
fruit
each channel is displayed using the fruit color scheme
cool
each channel is displayed using the cool color scheme
magma
each channel is displayed using the magma color scheme
green
each channel is displayed using the green color scheme
viridis
each channel is displayed using the viridis color scheme
plasma
each channel is displayed using the plasma color scheme
cividis
each channel is displayed using the cividis color scheme
terrain
each channel is displayed using the terrain color scheme
Default value is intensity.
scale
Specify scale used for calculating intensity color values.
It accepts the following values:
lin linear
sqrt
square root, default
cbrt
cubic root
log logarithmic
4thrt
4th root
5thrt
5th root
Default value is log.
fscale
Specify frequency scale.
It accepts the following values:
lin linear
log logarithmic
Default value is lin.
saturation
Set saturation modifier for displayed colors. Negative values provide alternative
color scheme. 0 is no saturation at all. Saturation must be in [-10.0, 10.0] range.
Default value is 1.
win_func
Set window function.
It accepts the following values:
rect
bartlett
hann
hanning
hamming
blackman
welch
flattop
bharris
bnuttall
bhann
sine
nuttall
lanczos
gauss
tukey
dolph
cauchy
parzen
poisson
bohman
Default value is "hann".
orientation
Set orientation of time vs frequency axis. Can be "vertical" or "horizontal". Default
is "vertical".
gain
Set scale gain for calculating intensity color values. Default value is 1.
legend
Draw time and frequency axes and legends. Default is enabled.
rotation
Set color rotation, must be in [-1.0, 1.0] range. Default value is 0.
start
Set start frequency from which to display spectrogram. Default is 0.
stop
Set stop frequency to which to display spectrogram. Default is 0.
Examples
• Extract an audio spectrogram of a whole audio track in a 1024x1024 picture using
ffmpeg:
ffmpeg -i audio.flac -lavfi showspectrumpic=s=1024x1024 spectrogram.png
showvolume
Convert input audio volume to a video output.
The filter accepts the following options:
rate, r
Set video rate.
b Set border width, allowed range is [0, 5]. Default is 1.
w Set channel width, allowed range is [80, 8192]. Default is 400.
h Set channel height, allowed range is [1, 900]. Default is 20.
f Set fade, allowed range is [0, 1]. Default is 0.95.
c Set volume color expression.
The expression can use the following variables:
VOLUME
Current max volume of channel in dB.
PEAK
Current peak.
CHANNEL
Current channel number, starting from 0.
t If set, displays channel names. Default is enabled.
v If set, displays volume values. Default is enabled.
o Set orientation, can be horizontal: "h" or vertical: "v", default is "h".
s Set step size, allowed range is [0, 5]. Default is 0, which means step is disabled.
p Set background opacity, allowed range is [0, 1]. Default is 0.
m Set metering mode, can be peak: "p" or rms: "r", default is "p".
ds Set display scale, can be linear: "lin" or log: "log", default is "lin".
dm In second. If set to > 0., display a line for the max level in the previous seconds.
default is disabled: 0.
dmc The color of the max line. Use when "dm" option is set to > 0. default is: "orange"
showwaves
Convert input audio to a video output, representing the samples waves.
The filter accepts the following options:
size, s
Specify the video size for the output. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "600x240".
mode
Set display mode.
Available values are:
point
Draw a point for each sample.
line
Draw a vertical line for each sample.
p2p Draw a point for each sample and a line between them.
cline
Draw a centered vertical line for each sample.
Default value is "point".
n Set the number of samples which are printed on the same column. A larger value will
decrease the frame rate. Must be a positive integer. This option can be set only if
the value for rate is not explicitly specified.
rate, r
Set the (approximate) output frame rate. This is done by setting the option n. Default
value is "25".
split_channels
Set if channels should be drawn separately or overlap. Default value is 0.
colors
Set colors separated by '|' which are going to be used for drawing of each channel.
scale
Set amplitude scale.
Available values are:
lin Linear.
log Logarithmic.
sqrt
Square root.
cbrt
Cubic root.
Default is linear.
draw
Set the draw mode. This is mostly useful to set for high n.
Available values are:
scale
Scale pixel values for each drawn sample.
full
Draw every sample directly.
Default value is "scale".
Examples
• Output the input file audio and the corresponding video representation at the same
time:
amovie=a.mp3,asplit[out0],showwaves[out1]
• Create a synthetic signal and show it with showwaves, forcing a frame rate of 30
frames per second:
aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1]
showwavespic
Convert input audio to a single video frame, representing the samples waves.
The filter accepts the following options:
size, s
Specify the video size for the output. For the syntax of this option, check the "Video
size" section in the ffmpeg-utils manual. Default value is "600x240".
split_channels
Set if channels should be drawn separately or overlap. Default value is 0.
colors
Set colors separated by '|' which are going to be used for drawing of each channel.
scale
Set amplitude scale.
Available values are:
lin Linear.
log Logarithmic.
sqrt
Square root.
cbrt
Cubic root.
Default is linear.
draw
Set the draw mode.
Available values are:
scale
Scale pixel values for each drawn sample.
full
Draw every sample directly.
Default value is "scale".
Examples
• Extract a channel split representation of the wave form of a whole audio track in a
1024x800 picture using ffmpeg:
ffmpeg -i audio.flac -lavfi showwavespic=split_channels=1:s=1024x800 waveform.png
sidedata, asidedata
Delete frame side data, or select frames based on it.
This filter accepts the following options:
mode
Set mode of operation of the filter.
Can be one of the following:
select
Select every frame with side data of "type".
delete
Delete side data of "type". If "type" is not set, delete all side data in the
frame.
type
Set side data type used with all modes. Must be set for "select" mode. For the list of
frame side data types, refer to the "AVFrameSideDataType" enum in libavutil/frame.h.
For example, to choose "AV_FRAME_DATA_PANSCAN" side data, you must specify "PANSCAN".
spectrumsynth
Sythesize audio from 2 input video spectrums, first input stream represents magnitude
across time and second represents phase across time. The filter will transform from
frequency domain as displayed in videos back to time domain as presented in audio output.
This filter is primarily created for reversing processed showspectrum filter outputs, but
can synthesize sound from other spectrograms too. But in such case results are going to
be poor if the phase data is not available, because in such cases phase data need to be
recreated, usually it's just recreated from random noise. For best results use gray only
output ("channel" color mode in showspectrum filter) and "log" scale for magnitude video
and "lin" scale for phase video. To produce phase, for 2nd video, use "data" option.
Inputs videos should generally use "fullframe" slide mode as that saves resources needed
for decoding video.
The filter accepts the following options:
sample_rate
Specify sample rate of output audio, the sample rate of audio from which spectrum was
generated may differ.
channels
Set number of channels represented in input video spectrums.
scale
Set scale which was used when generating magnitude input spectrum. Can be "lin" or
"log". Default is "log".
slide
Set slide which was used when generating inputs spectrums. Can be "replace",
"scroll", "fullframe" or "rscroll". Default is "fullframe".
win_func
Set window function used for resynthesis.
overlap
Set window overlap. In range "[0, 1]". Default is 1, which means optimal overlap for
selected window function will be picked.
orientation
Set orientation of input videos. Can be "vertical" or "horizontal". Default is
"vertical".
Examples
• First create magnitude and phase videos from audio, assuming audio is stereo with
44100 sample rate, then resynthesize videos back to audio with spectrumsynth:
ffmpeg -i input.flac -lavfi showspectrum=mode=separate:scale=log:overlap=0.875:color=channel:slide=fullframe:data=magnitude -an -c:v rawvideo magnitude.nut
ffmpeg -i input.flac -lavfi showspectrum=mode=separate:scale=lin:overlap=0.875:color=channel:slide=fullframe:data=phase -an -c:v rawvideo phase.nut
ffmpeg -i magnitude.nut -i phase.nut -lavfi spectrumsynth=channels=2:sample_rate=44100:win_func=hann:overlap=0.875:slide=fullframe output.flac
split, asplit
Split input into several identical outputs.
"asplit" works with audio input, "split" with video.
The filter accepts a single parameter which specifies the number of outputs. If
unspecified, it defaults to 2.
Examples
• Create two separate outputs from the same input:
[in] split [out0][out1]
• To create 3 or more outputs, you need to specify the number of outputs, like in:
[in] asplit=3 [out0][out1][out2]
• Create two separate outputs from the same input, one cropped and one padded:
[in] split [splitout1][splitout2];
[splitout1] crop=100:100:0:0 [cropout];
[splitout2] pad=200:200:100:100 [padout];
• Create 5 copies of the input audio with ffmpeg:
ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT
zmq, azmq
Receive commands sent through a libzmq client, and forward them to filters in the
filtergraph.
"zmq" and "azmq" work as a pass-through filters. "zmq" must be inserted between two video
filters, "azmq" between two audio filters. Both are capable to send messages to any filter
type.
To enable these filters you need to install the libzmq library and headers and configure
FFmpeg with "--enable-libzmq".
For more information about libzmq see: <http://www.zeromq.org/>
The "zmq" and "azmq" filters work as a libzmq server, which receives messages sent through
a network interface defined by the bind_address (or the abbreviation "b") option. Default
value of this option is tcp://localhost:5555. You may want to alter this value to your
needs, but do not forget to escape any ':' signs (see filtergraph escaping).
The received message must be in the form:
<TARGET> <COMMAND> [<ARG>]
TARGET specifies the target of the command, usually the name of the filter class or a
specific filter instance name. The default filter instance name uses the pattern
Parsed_<filter_name>_<index>, but you can override this by using the filter_name@id syntax
(see Filtergraph syntax).
COMMAND specifies the name of the command for the target filter.
ARG is optional and specifies the optional argument list for the given COMMAND.
Upon reception, the message is processed and the corresponding command is injected into
the filtergraph. Depending on the result, the filter will send a reply to the client,
adopting the format:
<ERROR_CODE> <ERROR_REASON>
<MESSAGE>
MESSAGE is optional.
Examples
Look at tools/zmqsend for an example of a zmq client which can be used to send commands
processed by these filters.
Consider the following filtergraph generated by ffplay. In this example the last overlay
filter has an instance name. All other filters will have default instance names.
ffplay -dumpgraph 1 -f lavfi "
color=s=100x100:c=red [l];
color=s=100x100:c=blue [r];
nullsrc=s=200x100, zmq [bg];
[bg][l] overlay [bg+l];
[bg+l][r] overlay@my=x=100 "
To change the color of the left side of the video, the following command can be used:
echo Parsed_color_0 c yellow | tools/zmqsend
To change the right side:
echo Parsed_color_1 c pink | tools/zmqsend
To change the position of the right side:
echo overlay@my x 150 | tools/zmqsend
MULTIMEDIA SOURCES
Below is a description of the currently available multimedia sources.
amovie
This is the same as movie source, except it selects an audio stream by default.
movie
Read audio and/or video stream(s) from a movie container.
It accepts the following parameters:
filename
The name of the resource to read (not necessarily a file; it can also be a device or a
stream accessed through some protocol).
format_name, f
Specifies the format assumed for the movie to read, and can be either the name of a
container or an input device. If not specified, the format is guessed from movie_name
or by probing.
seek_point, sp
Specifies the seek point in seconds. The frames will be output starting from this seek
point. The parameter is evaluated with "av_strtod", so the numerical value may be
suffixed by an IS postfix. The default value is "0".
streams, s
Specifies the streams to read. Several streams can be specified, separated by "+". The
source will then have as many outputs, in the same order. The syntax is explained in
the "Stream specifiers" section in the ffmpeg manual. Two special names, "dv" and "da"
specify respectively the default (best suited) video and audio stream. Default is
"dv", or "da" if the filter is called as "amovie".
stream_index, si
Specifies the index of the video stream to read. If the value is -1, the most suitable
video stream will be automatically selected. The default value is "-1". Deprecated. If
the filter is called "amovie", it will select audio instead of video.
loop
Specifies how many times to read the stream in sequence. If the value is 0, the
stream will be looped infinitely. Default value is "1".
Note that when the movie is looped the source timestamps are not changed, so it will
generate non monotonically increasing timestamps.
discontinuity
Specifies the time difference between frames above which the point is considered a
timestamp discontinuity which is removed by adjusting the later timestamps.
It allows overlaying a second video on top of the main input of a filtergraph, as shown in
this graph:
input -----------> deltapts0 --> overlay --> output
^
|
movie --> scale--> deltapts1 -------+
Examples
• Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it on top of the
input labelled "in":
movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over];
[in] setpts=PTS-STARTPTS [main];
[main][over] overlay=16:16 [out]
• Read from a video4linux2 device, and overlay it on top of the input labelled "in":
movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over];
[in] setpts=PTS-STARTPTS [main];
[main][over] overlay=16:16 [out]
• Read the first video stream and the audio stream with id 0x81 from dvd.vob; the video
is connected to the pad named "video" and the audio is connected to the pad named
"audio":
movie=dvd.vob:s=v:0+#0x81 [video] [audio]
Commands
Both movie and amovie support the following commands:
seek
Perform seek using "av_seek_frame". The syntax is: seek stream_index|timestamp|flags
• stream_index: If stream_index is -1, a default stream is selected, and timestamp
is automatically converted from AV_TIME_BASE units to the stream specific
time_base.
• timestamp: Timestamp in AVStream.time_base units or, if no stream is specified, in
AV_TIME_BASE units.
• flags: Flags which select direction and seeking mode.
get_duration
Get movie duration in AV_TIME_BASE units.
SEE ALSO
ffmpeg(1), ffplay(1), ffprobe(1), libavfilter(3)
AUTHORS
The FFmpeg developers.
For details about the authorship, see the Git history of the project
(git://source.ffmpeg.org/ffmpeg), e.g. by typing the command git log in the FFmpeg source
directory, or browsing the online repository at <http://source.ffmpeg.org>.
Maintainers for the specific components are listed in the file MAINTAINERS in the source
code tree.
FFMPEG-FILTERS(1)