Ubuntu Manpage: ffmpeg-codecs

Provided by: ffmpeg_4.2.7-0ubuntu0.1_amd64

NAME

       ffmpeg-codecs - FFmpeg codecs

DESCRIPTION

       This document describes the codecs (decoders and encoders) provided by the libavcodec
       library.

CODEC OPTIONS

libavcodec provides some generic global options, which can be set on all the encoders and
decoders. In addition each codec may support so-called private options, which are specific
for a given codec.

Sometimes, a global option may only affect a specific kind of codec, and may be
nonsensical or ignored by another, so you need to be aware of the meaning of the specified
options. Also some options are meant only for decoding or encoding.

Options may be set by specifying -option value in the FFmpeg tools, or by setting the
value explicitly in the "AVCodecContext" options or using the libavutil/opt.h API for
programmatic use.

The list of supported options follow:

b integer (encoding,audio,video)
Set bitrate in bits/s. Default value is 200K.

ab integer (encoding,audio)
Set audio bitrate (in bits/s). Default value is 128K.

bt integer (encoding,video)
Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate tolerance specifies
how far ratecontrol is willing to deviate from the target average bitrate value. This
is not related to min/max bitrate. Lowering tolerance too much has an adverse effect
on quality.

flags flags (decoding/encoding,audio,video,subtitles)
Set generic flags.

Possible values:

mv4 Use four motion vector by macroblock (mpeg4).

qpel
Use 1/4 pel motion compensation.

loop
Use loop filter.

qscale
Use fixed qscale.

pass1
Use internal 2pass ratecontrol in first pass mode.

pass2
Use internal 2pass ratecontrol in second pass mode.

gray
Only decode/encode grayscale.

emu_edge
Do not draw edges.

psnr
Set error[?] variables during encoding.

truncated
drop_changed
Don't output frames whose parameters differ from first decoded frame in stream.
Error AVERROR_INPUT_CHANGED is returned when a frame is dropped.

ildct
Use interlaced DCT.

low_delay
Force low delay.

global_header
Place global headers in extradata instead of every keyframe.

bitexact
Only write platform-, build- and time-independent data. (except (I)DCT). This
ensures that file and data checksums are reproducible and match between platforms.
Its primary use is for regression testing.

aic Apply H263 advanced intra coding / mpeg4 ac prediction.

cbp Deprecated, use mpegvideo private options instead.

qprd
Deprecated, use mpegvideo private options instead.

ilme
Apply interlaced motion estimation.

cgop
Use closed gop.

me_method integer (encoding,video)
Set motion estimation method.

Possible values:

zero
zero motion estimation (fastest)

full
full motion estimation (slowest)

epzs
EPZS motion estimation (default)

esa esa motion estimation (alias for full)

tesa
tesa motion estimation

dia dia motion estimation (alias for epzs)

log log motion estimation

phods
phods motion estimation

x1 X1 motion estimation

hex hex motion estimation

umh umh motion estimation

iter
iter motion estimation

extradata_size integer
Set extradata size.

time_base rational number
Set codec time base.

It is the fundamental unit of time (in seconds) in terms of which frame timestamps are
represented. For fixed-fps content, timebase should be "1 / frame_rate" and timestamp
increments should be identically 1.

g integer (encoding,video)
Set the group of picture (GOP) size. Default value is 12.

ar integer (decoding/encoding,audio)
Set audio sampling rate (in Hz).

ac integer (decoding/encoding,audio)
Set number of audio channels.

cutoff integer (encoding,audio)
Set cutoff bandwidth. (Supported only by selected encoders, see their respective
documentation sections.)

frame_size integer (encoding,audio)
Set audio frame size.

Each submitted frame except the last must contain exactly frame_size samples per
channel. May be 0 when the codec has CODEC_CAP_VARIABLE_FRAME_SIZE set, in that case
the frame size is not restricted. It is set by some decoders to indicate constant
frame size.

frame_number integer
Set the frame number.

delay integer
qcomp float (encoding,video)
Set video quantizer scale compression (VBR). It is used as a constant in the
ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0.

qblur float (encoding,video)
Set video quantizer scale blur (VBR).

qmin integer (encoding,video)
Set min video quantizer scale (VBR). Must be included between -1 and 69, default value
is 2.

qmax integer (encoding,video)
Set max video quantizer scale (VBR). Must be included between -1 and 1024, default
value is 31.

qdiff integer (encoding,video)
Set max difference between the quantizer scale (VBR).

bf integer (encoding,video)
Set max number of B frames between non-B-frames.

Must be an integer between -1 and 16. 0 means that B-frames are disabled. If a value
of -1 is used, it will choose an automatic value depending on the encoder.

Default value is 0.

b_qfactor float (encoding,video)
Set qp factor between P and B frames.

rc_strategy integer (encoding,video)
Set ratecontrol method.

b_strategy integer (encoding,video)
Set strategy to choose between I/P/B-frames.

ps integer (encoding,video)
Set RTP payload size in bytes.

mv_bits integer
header_bits integer
i_tex_bits integer
p_tex_bits integer
i_count integer
p_count integer
skip_count integer
misc_bits integer
frame_bits integer
codec_tag integer
bug flags (decoding,video)
Workaround not auto detected encoder bugs.

Possible values:

autodetect
old_msmpeg4
some old lavc generated msmpeg4v3 files (no autodetection)

xvid_ilace
Xvid interlacing bug (autodetected if fourcc==XVIX)

ump4
(autodetected if fourcc==UMP4)

no_padding
padding bug (autodetected)

amv
ac_vlc
illegal vlc bug (autodetected per fourcc)

qpel_chroma
std_qpel
old standard qpel (autodetected per fourcc/version)

qpel_chroma2
direct_blocksize
direct-qpel-blocksize bug (autodetected per fourcc/version)

edge
edge padding bug (autodetected per fourcc/version)

hpel_chroma
dc_clip
ms Workaround various bugs in microsoft broken decoders.

trunc
trancated frames

lelim integer (encoding,video)
Set single coefficient elimination threshold for luminance (negative values also
consider DC coefficient).

celim integer (encoding,video)
Set single coefficient elimination threshold for chrominance (negative values also
consider dc coefficient)

strict integer (decoding/encoding,audio,video)
Specify how strictly to follow the standards.

Possible values:

very
strictly conform to an older more strict version of the spec or reference software

strict
strictly conform to all the things in the spec no matter what consequences

normal
unofficial
allow unofficial extensions

experimental
allow non standardized experimental things, experimental (unfinished/work in
progress/not well tested) decoders and encoders. Note: experimental decoders can
pose a security risk, do not use this for decoding untrusted input.

b_qoffset float (encoding,video)
Set QP offset between P and B frames.

err_detect flags (decoding,audio,video)
Set error detection flags.

Possible values:

crccheck
verify embedded CRCs

bitstream
detect bitstream specification deviations

buffer
detect improper bitstream length

explode
abort decoding on minor error detection

ignore_err
ignore decoding errors, and continue decoding. This is useful if you want to
analyze the content of a video and thus want everything to be decoded no matter
what. This option will not result in a video that is pleasing to watch in case of
errors.

careful
consider things that violate the spec and have not been seen in the wild as errors

compliant
consider all spec non compliancies as errors

aggressive
consider things that a sane encoder should not do as an error

has_b_frames integer
block_align integer
mpeg_quant integer (encoding,video)
Use MPEG quantizers instead of H.263.

qsquish float (encoding,video)
How to keep quantizer between qmin and qmax (0 = clip, 1 = use differentiable
function).

rc_qmod_amp float (encoding,video)
Set experimental quantizer modulation.

rc_qmod_freq integer (encoding,video)
Set experimental quantizer modulation.

rc_override_count integer
rc_eq string (encoding,video)
Set rate control equation. When computing the expression, besides the standard
functions defined in the section 'Expression Evaluation', the following functions are
available: bits2qp(bits), qp2bits(qp). Also the following constants are available:
iTex pTex tex mv fCode iCount mcVar var isI isP isB avgQP qComp avgIITex avgPITex
avgPPTex avgBPTex avgTex.

maxrate integer (encoding,audio,video)
Set max bitrate tolerance (in bits/s). Requires bufsize to be set.

minrate integer (encoding,audio,video)
Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR encode. It is
of little use elsewise.

bufsize integer (encoding,audio,video)
Set ratecontrol buffer size (in bits).

rc_buf_aggressivity float (encoding,video)
Currently useless.

i_qfactor float (encoding,video)
Set QP factor between P and I frames.

i_qoffset float (encoding,video)
Set QP offset between P and I frames.

rc_init_cplx float (encoding,video)
Set initial complexity for 1-pass encoding.

dct integer (encoding,video)
Set DCT algorithm.

Possible values:

auto
autoselect a good one (default)

fastint
fast integer

int accurate integer

mmx
altivec
faan
floating point AAN DCT

lumi_mask float (encoding,video)
Compress bright areas stronger than medium ones.

tcplx_mask float (encoding,video)
Set temporal complexity masking.

scplx_mask float (encoding,video)
Set spatial complexity masking.

p_mask float (encoding,video)
Set inter masking.

dark_mask float (encoding,video)
Compress dark areas stronger than medium ones.

idct integer (decoding/encoding,video)
Select IDCT implementation.

Possible values:

auto
int
simple
simplemmx
simpleauto
Automatically pick a IDCT compatible with the simple one

arm
altivec
sh4
simplearm
simplearmv5te
simplearmv6
simpleneon
simplealpha
ipp
xvidmmx
faani
floating point AAN IDCT

slice_count integer
ec flags (decoding,video)
Set error concealment strategy.

Possible values:

guess_mvs
iterative motion vector (MV) search (slow)

deblock
use strong deblock filter for damaged MBs

favor_inter
favor predicting from the previous frame instead of the current

bits_per_coded_sample integer
pred integer (encoding,video)
Set prediction method.

Possible values:

left
plane
median
aspect rational number (encoding,video)
Set sample aspect ratio.

sar rational number (encoding,video)
Set sample aspect ratio. Alias to aspect.

debug flags (decoding/encoding,audio,video,subtitles)
Print specific debug info.

Possible values:

pict
picture info

rc rate control

bitstream
mb_type
macroblock (MB) type

qp per-block quantization parameter (QP)

dct_coeff
green_metadata
display complexity metadata for the upcoming frame, GoP or for a given duration.

skip
startcode
er error recognition

mmco
memory management control operations (H.264)

bugs
buffers
picture buffer allocations

thread_ops
threading operations

nomc
skip motion compensation

cmp integer (encoding,video)
Set full pel me compare function.

Possible values:

sad sum of absolute differences, fast (default)

sse sum of squared errors

satd
sum of absolute Hadamard transformed differences

dct sum of absolute DCT transformed differences

psnr
sum of squared quantization errors (avoid, low quality)

bit number of bits needed for the block

rd rate distortion optimal, slow

zero
0

vsad
sum of absolute vertical differences

vsse
sum of squared vertical differences

nsse
noise preserving sum of squared differences

w53 5/3 wavelet, only used in snow

w97 9/7 wavelet, only used in snow

dctmax
chroma
subcmp integer (encoding,video)
Set sub pel me compare function.

Possible values:

sad sum of absolute differences, fast (default)

sse sum of squared errors

satd
sum of absolute Hadamard transformed differences

dct sum of absolute DCT transformed differences

psnr
sum of squared quantization errors (avoid, low quality)

bit number of bits needed for the block

rd rate distortion optimal, slow

zero
0

vsad
sum of absolute vertical differences

vsse
sum of squared vertical differences

nsse
noise preserving sum of squared differences

w53 5/3 wavelet, only used in snow

w97 9/7 wavelet, only used in snow

dctmax
chroma
mbcmp integer (encoding,video)
Set macroblock compare function.

Possible values:

sad sum of absolute differences, fast (default)

sse sum of squared errors

satd
sum of absolute Hadamard transformed differences

dct sum of absolute DCT transformed differences

psnr
sum of squared quantization errors (avoid, low quality)

bit number of bits needed for the block

rd rate distortion optimal, slow

zero
0

vsad
sum of absolute vertical differences

vsse
sum of squared vertical differences

nsse
noise preserving sum of squared differences

w53 5/3 wavelet, only used in snow

w97 9/7 wavelet, only used in snow

dctmax
chroma
ildctcmp integer (encoding,video)
Set interlaced dct compare function.

Possible values:

sad sum of absolute differences, fast (default)

sse sum of squared errors

satd
sum of absolute Hadamard transformed differences

dct sum of absolute DCT transformed differences

psnr
sum of squared quantization errors (avoid, low quality)

bit number of bits needed for the block

rd rate distortion optimal, slow

zero
0

vsad
sum of absolute vertical differences

vsse
sum of squared vertical differences

nsse
noise preserving sum of squared differences

w53 5/3 wavelet, only used in snow

w97 9/7 wavelet, only used in snow

dctmax
chroma
dia_size integer (encoding,video)
Set diamond type & size for motion estimation.

last_pred integer (encoding,video)
Set amount of motion predictors from the previous frame.

preme integer (encoding,video)
Set pre motion estimation.

precmp integer (encoding,video)
Set pre motion estimation compare function.

Possible values:

sad sum of absolute differences, fast (default)

sse sum of squared errors

satd
sum of absolute Hadamard transformed differences

dct sum of absolute DCT transformed differences

psnr
sum of squared quantization errors (avoid, low quality)

bit number of bits needed for the block

rd rate distortion optimal, slow

zero
0

vsad
sum of absolute vertical differences

vsse
sum of squared vertical differences

nsse
noise preserving sum of squared differences

w53 5/3 wavelet, only used in snow

w97 9/7 wavelet, only used in snow

dctmax
chroma
pre_dia_size integer (encoding,video)
Set diamond type & size for motion estimation pre-pass.

subq integer (encoding,video)
Set sub pel motion estimation quality.

dtg_active_format integer
me_range integer (encoding,video)
Set limit motion vectors range (1023 for DivX player).

ibias integer (encoding,video)
Set intra quant bias.

pbias integer (encoding,video)
Set inter quant bias.

color_table_id integer
global_quality integer (encoding,audio,video)
coder integer (encoding,video)
Possible values:

vlc variable length coder / huffman coder

ac arithmetic coder

raw raw (no encoding)

rle run-length coder

deflate
deflate-based coder

context integer (encoding,video)
Set context model.

slice_flags integer
mbd integer (encoding,video)
Set macroblock decision algorithm (high quality mode).

Possible values:

simple
use mbcmp (default)

bits
use fewest bits

rd use best rate distortion

stream_codec_tag integer
sc_threshold integer (encoding,video)
Set scene change threshold.

lmin integer (encoding,video)
Set min lagrange factor (VBR).

lmax integer (encoding,video)
Set max lagrange factor (VBR).

nr integer (encoding,video)
Set noise reduction.

rc_init_occupancy integer (encoding,video)
Set number of bits which should be loaded into the rc buffer before decoding starts.

flags2 flags (decoding/encoding,audio,video)
Possible values:

fast
Allow non spec compliant speedup tricks.

sgop
Deprecated, use mpegvideo private options instead.

noout
Skip bitstream encoding.

ignorecrop
Ignore cropping information from sps.

local_header
Place global headers at every keyframe instead of in extradata.

chunks
Frame data might be split into multiple chunks.

showall
Show all frames before the first keyframe.

export_mvs
Export motion vectors into frame side-data (see "AV_FRAME_DATA_MOTION_VECTORS")
for codecs that support it. See also doc/examples/export_mvs.c.

error integer (encoding,video)
qns integer (encoding,video)
Deprecated, use mpegvideo private options instead.

threads integer (decoding/encoding,video)
Set the number of threads to be used, in case the selected codec implementation
supports multi-threading.

Possible values:

auto, 0
automatically select the number of threads to set

Default value is auto.

me_threshold integer (encoding,video)
Set motion estimation threshold.

mb_threshold integer (encoding,video)
Set macroblock threshold.

dc integer (encoding,video)
Set intra_dc_precision.

nssew integer (encoding,video)
Set nsse weight.

skip_top integer (decoding,video)
Set number of macroblock rows at the top which are skipped.

skip_bottom integer (decoding,video)
Set number of macroblock rows at the bottom which are skipped.

profile integer (encoding,audio,video)
Possible values:

unknown
aac_main
aac_low
aac_ssr
aac_ltp
aac_he
aac_he_v2
aac_ld
aac_eld
mpeg2_aac_low
mpeg2_aac_he
mpeg4_sp
mpeg4_core
mpeg4_main
mpeg4_asp
dts
dts_es
dts_96_24
dts_hd_hra
dts_hd_ma
level integer (encoding,audio,video)
Possible values:

unknown
lowres integer (decoding,audio,video)
Decode at 1= 1/2, 2=1/4, 3=1/8 resolutions.

skip_threshold integer (encoding,video)
Set frame skip threshold.

skip_factor integer (encoding,video)
Set frame skip factor.

skip_exp integer (encoding,video)
Set frame skip exponent. Negative values behave identical to the corresponding
positive ones, except that the score is normalized. Positive values exist primarily
for compatibility reasons and are not so useful.

skipcmp integer (encoding,video)
Set frame skip compare function.

Possible values:

sad sum of absolute differences, fast (default)

sse sum of squared errors

satd
sum of absolute Hadamard transformed differences

dct sum of absolute DCT transformed differences

psnr
sum of squared quantization errors (avoid, low quality)

bit number of bits needed for the block

rd rate distortion optimal, slow

zero
0

vsad
sum of absolute vertical differences

vsse
sum of squared vertical differences

nsse
noise preserving sum of squared differences

w53 5/3 wavelet, only used in snow

w97 9/7 wavelet, only used in snow

dctmax
chroma
border_mask float (encoding,video)
Increase the quantizer for macroblocks close to borders.

mblmin integer (encoding,video)
Set min macroblock lagrange factor (VBR).

mblmax integer (encoding,video)
Set max macroblock lagrange factor (VBR).

mepc integer (encoding,video)
Set motion estimation bitrate penalty compensation (1.0 = 256).

skip_loop_filter integer (decoding,video)
skip_idct integer (decoding,video)
skip_frame integer (decoding,video)
Make decoder discard processing depending on the frame type selected by the option
value.

skip_loop_filter skips frame loop filtering, skip_idct skips frame
IDCT/dequantization, skip_frame skips decoding.

Possible values:

none
Discard no frame.

default
Discard useless frames like 0-sized frames.

noref
Discard all non-reference frames.

bidir
Discard all bidirectional frames.

nokey
Discard all frames excepts keyframes.

nointra
Discard all frames except I frames.

all Discard all frames.

Default value is default.

bidir_refine integer (encoding,video)
Refine the two motion vectors used in bidirectional macroblocks.

brd_scale integer (encoding,video)
Downscale frames for dynamic B-frame decision.

keyint_min integer (encoding,video)
Set minimum interval between IDR-frames.

refs integer (encoding,video)
Set reference frames to consider for motion compensation.

chromaoffset integer (encoding,video)
Set chroma qp offset from luma.

trellis integer (encoding,audio,video)
Set rate-distortion optimal quantization.

mv0_threshold integer (encoding,video)
b_sensitivity integer (encoding,video)
Adjust sensitivity of b_frame_strategy 1.

compression_level integer (encoding,audio,video)
min_prediction_order integer (encoding,audio)
max_prediction_order integer (encoding,audio)
timecode_frame_start integer (encoding,video)
Set GOP timecode frame start number, in non drop frame format.

request_channels integer (decoding,audio)
Set desired number of audio channels.

bits_per_raw_sample integer
channel_layout integer (decoding/encoding,audio)
Possible values:

request_channel_layout integer (decoding,audio)
Possible values:

rc_max_vbv_use float (encoding,video)
rc_min_vbv_use float (encoding,video)
ticks_per_frame integer (decoding/encoding,audio,video)
color_primaries integer (decoding/encoding,video)
Possible values:

bt709
BT.709

bt470m
BT.470 M

bt470bg
BT.470 BG

smpte170m
SMPTE 170 M

smpte240m
SMPTE 240 M

film
Film

bt2020
BT.2020

smpte428
smpte428_1
SMPTE ST 428-1

smpte431
SMPTE 431-2

smpte432
SMPTE 432-1

jedec-p22
JEDEC P22

color_trc integer (decoding/encoding,video)
Possible values:

bt709
BT.709

gamma22
BT.470 M

gamma28
BT.470 BG

smpte170m
SMPTE 170 M

smpte240m
SMPTE 240 M

linear
Linear

log
log100
Log

log_sqrt
log316
Log square root

iec61966_2_4
iec61966-2-4
IEC 61966-2-4

bt1361
bt1361e
BT.1361

iec61966_2_1
iec61966-2-1
IEC 61966-2-1

bt2020_10
bt2020_10bit
BT.2020 - 10 bit

bt2020_12
bt2020_12bit
BT.2020 - 12 bit

smpte2084
SMPTE ST 2084

smpte428
smpte428_1
SMPTE ST 428-1

arib-std-b67
ARIB STD-B67

colorspace integer (decoding/encoding,video)
Possible values:

rgb RGB

bt709
BT.709

fcc FCC

bt470bg
BT.470 BG

smpte170m
SMPTE 170 M

smpte240m
SMPTE 240 M

ycocg
YCOCG

bt2020nc
bt2020_ncl
BT.2020 NCL

bt2020c
bt2020_cl
BT.2020 CL

smpte2085
SMPTE 2085

color_range integer (decoding/encoding,video)
If used as input parameter, it serves as a hint to the decoder, which color_range the
input has. Possible values:

tv
mpeg
MPEG (219*2^(n-8))

pc
jpeg
JPEG (2^n-1)

chroma_sample_location integer (decoding/encoding,video)
Possible values:

left
center
topleft
top
bottomleft
bottom
log_level_offset integer
Set the log level offset.

slices integer (encoding,video)
Number of slices, used in parallelized encoding.

thread_type flags (decoding/encoding,video)
Select which multithreading methods to use.

Use of frame will increase decoding delay by one frame per thread, so clients which
cannot provide future frames should not use it.

Possible values:

slice
Decode more than one part of a single frame at once.

Multithreading using slices works only when the video was encoded with slices.

frame
Decode more than one frame at once.

Default value is slice+frame.

audio_service_type integer (encoding,audio)
Set audio service type.

Possible values:

ma Main Audio Service

ef Effects

vi Visually Impaired

hi Hearing Impaired

di Dialogue

co Commentary

em Emergency

vo Voice Over

ka Karaoke

request_sample_fmt sample_fmt (decoding,audio)
Set sample format audio decoders should prefer. Default value is "none".

pkt_timebase rational number
sub_charenc encoding (decoding,subtitles)
Set the input subtitles character encoding.

field_order field_order (video)
Set/override the field order of the video. Possible values:

progressive
Progressive video

tt Interlaced video, top field coded and displayed first

bb Interlaced video, bottom field coded and displayed first

tb Interlaced video, top coded first, bottom displayed first

bt Interlaced video, bottom coded first, top displayed first

skip_alpha bool (decoding,video)
Set to 1 to disable processing alpha (transparency). This works like the gray flag in
the flags option which skips chroma information instead of alpha. Default is 0.

codec_whitelist list (input)
"," separated list of allowed decoders. By default all are allowed.

dump_separator string (input)
Separator used to separate the fields printed on the command line about the Stream
parameters. For example, to separate the fields with newlines and indentation:

ffprobe -dump_separator "
" -i ~/videos/matrixbench_mpeg2.mpg

max_pixels integer (decoding/encoding,video)
Maximum number of pixels per image. This value can be used to avoid out of memory
failures due to large images.

apply_cropping bool (decoding,video)
Enable cropping if cropping parameters are multiples of the required alignment for the
left and top parameters. If the alignment is not met the cropping will be partially
applied to maintain alignment. Default is 1 (enabled). Note: The required alignment
depends on if "AV_CODEC_FLAG_UNALIGNED" is set and the CPU. "AV_CODEC_FLAG_UNALIGNED"
cannot be changed from the command line. Also hardware decoders will not apply
left/top Cropping.

DECODERS

       Decoders are configured elements in FFmpeg which allow the decoding of multimedia streams.

       When you configure your FFmpeg build, all the supported native decoders are enabled by
       default. Decoders requiring an external library must be enabled manually via the
       corresponding "--enable-lib" option. You can list all available decoders using the
       configure option "--list-decoders".

       You can disable all the decoders with the configure option "--disable-decoders" and
       selectively enable / disable single decoders with the options "--enable-decoder=DECODER" /
       "--disable-decoder=DECODER".

       The option "-decoders" of the ff* tools will display the list of enabled decoders.

VIDEO DECODERS

       A description of some of the currently available video decoders follows.

   rawvideo
       Raw video decoder.

       This decoder decodes rawvideo streams.

       Options

       top top_field_first
           Specify the assumed field type of the input video.

           -1  the video is assumed to be progressive (default)

           0   bottom-field-first is assumed

           1   top-field-first is assumed

   libdav1d
       dav1d AV1 decoder.

       libdav1d allows libavcodec to decode the AOMedia Video 1 (AV1) codec.  Requires the
       presence of the libdav1d headers and library during configuration.  You need to explicitly
       configure the build with "--enable-libdav1d".

       Options

       The following option is supported by the libdav1d wrapper.

       framethreads
           Set amount of frame threads to use during decoding. The default value is 0
           (autodetect).

       tilethreads
           Set amount of tile threads to use during decoding. The default value is 0
           (autodetect).

       filmgrain
           Apply film grain to the decoded video if present in the bitstream. The default value
           is true.

   libdavs2
       AVS2-P2/IEEE1857.4 video decoder wrapper.

       This decoder allows libavcodec to decode AVS2 streams with davs2 library.

AUDIO DECODERS

A description of some of the currently available audio decoders follows.

ac3
AC-3 audio decoder.

This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as the
undocumented RealAudio 3 (a.k.a. dnet).

AC-3 Decoder Options

-drc_scale value
Dynamic Range Scale Factor. The factor to apply to dynamic range values from the AC-3
stream. This factor is applied exponentially. There are 3 notable scale factor
ranges:

drc_scale == 0
DRC disabled. Produces full range audio.

0 < drc_scale <= 1
DRC enabled. Applies a fraction of the stream DRC value. Audio reproduction is
between full range and full compression.

drc_scale > 1
DRC enabled. Applies drc_scale asymmetrically. Loud sounds are fully compressed.
Soft sounds are enhanced.

flac
FLAC audio decoder.

This decoder aims to implement the complete FLAC specification from Xiph.

FLAC Decoder options

-use_buggy_lpc
The lavc FLAC encoder used to produce buggy streams with high lpc values (like the
default value). This option makes it possible to decode such streams correctly by
using lavc's old buggy lpc logic for decoding.

ffwavesynth
Internal wave synthesizer.

This decoder generates wave patterns according to predefined sequences. Its use is purely
internal and the format of the data it accepts is not publicly documented.

libcelt
libcelt decoder wrapper.

libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec. Requires
the presence of the libcelt headers and library during configuration. You need to
explicitly configure the build with "--enable-libcelt".

libgsm
libgsm decoder wrapper.

libgsm allows libavcodec to decode the GSM full rate audio codec. Requires the presence of
the libgsm headers and library during configuration. You need to explicitly configure the
build with "--enable-libgsm".

This decoder supports both the ordinary GSM and the Microsoft variant.

libilbc
libilbc decoder wrapper.

libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC) audio codec.
Requires the presence of the libilbc headers and library during configuration. You need to
explicitly configure the build with "--enable-libilbc".

Options

The following option is supported by the libilbc wrapper.

enhance
Enable the enhancement of the decoded audio when set to 1. The default value is 0
(disabled).

libopencore-amrnb
libopencore-amrnb decoder wrapper.

libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate Narrowband audio
codec. Using it requires the presence of the libopencore-amrnb headers and library during
configuration. You need to explicitly configure the build with
"--enable-libopencore-amrnb".

An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB without this
library.

libopencore-amrwb
libopencore-amrwb decoder wrapper.

libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate Wideband audio
codec. Using it requires the presence of the libopencore-amrwb headers and library during
configuration. You need to explicitly configure the build with
"--enable-libopencore-amrwb".

An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB without this
library.

libopus
libopus decoder wrapper.

libopus allows libavcodec to decode the Opus Interactive Audio Codec. Requires the
presence of the libopus headers and library during configuration. You need to explicitly
configure the build with "--enable-libopus".

An FFmpeg native decoder for Opus exists, so users can decode Opus without this library.

SUBTITLES DECODERS

libaribb24
ARIB STD-B24 caption decoder.

Implements profiles A and C of the ARIB STD-B24 standard.

libaribb24 Decoder Options

-aribb24-base-path path
Sets the base path for the libaribb24 library. This is utilized for reading of
configuration files (for custom unicode conversions), and for dumping of non-text
symbols as images under that location.

Unset by default.

-aribb24-skip-ruby-text boolean
Tells the decoder wrapper to skip text blocks that contain half-height ruby text.

Enabled by default.

dvbsub
Options

compute_clut
-1 Compute clut if no matching CLUT is in the stream.

0 Never compute CLUT

1 Always compute CLUT and override the one provided in the stream.

dvb_substream
Selects the dvb substream, or all substreams if -1 which is default.

dvdsub
This codec decodes the bitmap subtitles used in DVDs; the same subtitles can also be found
in VobSub file pairs and in some Matroska files.

Options

palette
Specify the global palette used by the bitmaps. When stored in VobSub, the palette is
normally specified in the index file; in Matroska, the palette is stored in the codec
extra-data in the same format as in VobSub. In DVDs, the palette is stored in the IFO
file, and therefore not available when reading from dumped VOB files.

The format for this option is a string containing 16 24-bits hexadecimal numbers
(without 0x prefix) separated by comas, for example "0d00ee, ee450d, 101010, eaeaea,
0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1, 7b2a0e, 0d950c, 0f007b, cf0dec,
cfa80c, 7c127b".

ifo_palette
Specify the IFO file from which the global palette is obtained. (experimental)

forced_subs_only
Only decode subtitle entries marked as forced. Some titles have forced and non-forced
subtitles in the same track. Setting this flag to 1 will only keep the forced
subtitles. Default value is 0.

libzvbi-teletext
Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext subtitles.
Requires the presence of the libzvbi headers and library during configuration. You need to
explicitly configure the build with "--enable-libzvbi".

Options

txt_page
List of teletext page numbers to decode. Pages that do not match the specified list
are dropped. You may use the special "*" string to match all pages, or "subtitle" to
match all subtitle pages. Default value is *.

txt_chop_top
Discards the top teletext line. Default value is 1.

txt_format
Specifies the format of the decoded subtitles.

bitmap
The default format, you should use this for teletext pages, because certain
graphics and colors cannot be expressed in simple text or even ASS.

text
Simple text based output without formatting.

ass Formatted ASS output, subtitle pages and teletext pages are returned in different
styles, subtitle pages are stripped down to text, but an effort is made to keep
the text alignment and the formatting.

txt_left
X offset of generated bitmaps, default is 0.

txt_top
Y offset of generated bitmaps, default is 0.

txt_chop_spaces
Chops leading and trailing spaces and removes empty lines from the generated text.
This option is useful for teletext based subtitles where empty spaces may be present
at the start or at the end of the lines or empty lines may be present between the
subtitle lines because of double-sized teletext characters. Default value is 1.

txt_duration
Sets the display duration of the decoded teletext pages or subtitles in milliseconds.
Default value is -1 which means infinity or until the next subtitle event comes.

txt_transparent
Force transparent background of the generated teletext bitmaps. Default value is 0
which means an opaque background.

txt_opacity
Sets the opacity (0-255) of the teletext background. If txt_transparent is not set, it
only affects characters between a start box and an end box, typically subtitles.
Default value is 0 if txt_transparent is set, 255 otherwise.

ENCODERS

       Encoders are configured elements in FFmpeg which allow the encoding of multimedia streams.

       When you configure your FFmpeg build, all the supported native encoders are enabled by
       default. Encoders requiring an external library must be enabled manually via the
       corresponding "--enable-lib" option. You can list all available encoders using the
       configure option "--list-encoders".

       You can disable all the encoders with the configure option "--disable-encoders" and
       selectively enable / disable single encoders with the options "--enable-encoder=ENCODER" /
       "--disable-encoder=ENCODER".

       The option "-encoders" of the ff* tools will display the list of enabled encoders.

AUDIO ENCODERS

A description of some of the currently available audio encoders follows.

aac
Advanced Audio Coding (AAC) encoder.

This encoder is the default AAC encoder, natively implemented into FFmpeg. Its quality is
on par or better than libfdk_aac at the default bitrate of 128kbps. This encoder also
implements more options, profiles and samplerates than other encoders (with only the AAC-
HE profile pending to be implemented) so this encoder has become the default and is the
recommended choice.

Options

b Set bit rate in bits/s. Setting this automatically activates constant bit rate (CBR)
mode. If this option is unspecified it is set to 128kbps.

q Set quality for variable bit rate (VBR) mode. This option is valid only using the
ffmpeg command-line tool. For library interface users, use global_quality.

cutoff
Set cutoff frequency. If unspecified will allow the encoder to dynamically adjust the
cutoff to improve clarity on low bitrates.

aac_coder
Set AAC encoder coding method. Possible values:

twoloop
Two loop searching (TLS) method.

This method first sets quantizers depending on band thresholds and then tries to
find an optimal combination by adding or subtracting a specific value from all
quantizers and adjusting some individual quantizer a little. Will tune itself
based on whether aac_is, aac_ms and aac_pns are enabled.

anmr
Average noise to mask ratio (ANMR) trellis-based solution.

This is an experimental coder which currently produces a lower quality, is more
unstable and is slower than the default twoloop coder but has potential.
Currently has no support for the aac_is or aac_pns options. Not currently
recommended.

fast
Constant quantizer method.

Uses a cheaper version of twoloop algorithm that doesn't try to do as many clever
adjustments. Worse with low bitrates (less than 64kbps), but is better and much
faster at higher bitrates. This is the default choice for a coder

aac_ms
Sets mid/side coding mode. The default value of "auto" will automatically use M/S with
bands which will benefit from such coding. Can be forced for all bands using the value
"enable", which is mainly useful for debugging or disabled using "disable".

aac_is
Sets intensity stereo coding tool usage. By default, it's enabled and will
automatically toggle IS for similar pairs of stereo bands if it's beneficial. Can be
disabled for debugging by setting the value to "disable".

aac_pns
Uses perceptual noise substitution to replace low entropy high frequency bands with
imperceptible white noise during the decoding process. By default, it's enabled, but
can be disabled for debugging purposes by using "disable".

aac_tns
Enables the use of a multitap FIR filter which spans through the high frequency bands
to hide quantization noise during the encoding process and is reverted by the decoder.
As well as decreasing unpleasant artifacts in the high range this also reduces the
entropy in the high bands and allows for more bits to be used by the mid-low bands. By
default it's enabled but can be disabled for debugging by setting the option to
"disable".

aac_ltp
Enables the use of the long term prediction extension which increases coding
efficiency in very low bandwidth situations such as encoding of voice or solo piano
music by extending constant harmonic peaks in bands throughout frames. This option is
implied by profile:a aac_low and is incompatible with aac_pred. Use in conjunction
with -ar to decrease the samplerate.

aac_pred
Enables the use of a more traditional style of prediction where the spectral
coefficients transmitted are replaced by the difference of the current coefficients
minus the previous "predicted" coefficients. In theory and sometimes in practice this
can improve quality for low to mid bitrate audio. This option implies the aac_main
profile and is incompatible with aac_ltp.

profile
Sets the encoding profile, possible values:

aac_low
The default, AAC "Low-complexity" profile. Is the most compatible and produces
decent quality.

mpeg2_aac_low
Equivalent to "-profile:a aac_low -aac_pns 0". PNS was introduced with the MPEG4
specifications.

aac_ltp
Long term prediction profile, is enabled by and will enable the aac_ltp option.
Introduced in MPEG4.

aac_main
Main-type prediction profile, is enabled by and will enable the aac_pred option.
Introduced in MPEG2.

If this option is unspecified it is set to aac_low.

ac3 and ac3_fixed
AC-3 audio encoders.

These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as the
undocumented RealAudio 3 (a.k.a. dnet).

The ac3 encoder uses floating-point math, while the ac3_fixed encoder only uses fixed-
point integer math. This does not mean that one is always faster, just that one or the
other may be better suited to a particular system. The floating-point encoder will
generally produce better quality audio for a given bitrate. The ac3_fixed encoder is not
the default codec for any of the output formats, so it must be specified explicitly using
the option "-acodec ac3_fixed" in order to use it.

AC-3 Metadata

The AC-3 metadata options are used to set parameters that describe the audio, but in most
cases do not affect the audio encoding itself. Some of the options do directly affect or
influence the decoding and playback of the resulting bitstream, while others are just for
informational purposes. A few of the options will add bits to the output stream that could
otherwise be used for audio data, and will thus affect the quality of the output. Those
will be indicated accordingly with a note in the option list below.

These parameters are described in detail in several publicly-available documents.

*<<http://www.atsc.org/cms/standards/a_52-2010.pdf>>
*<<http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf>>
*<<http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf>>
*<<http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf>>

Metadata Control Options

-per_frame_metadata boolean
Allow Per-Frame Metadata. Specifies if the encoder should check for changing metadata
for each frame.

0 The metadata values set at initialization will be used for every frame in the
stream. (default)

1 Metadata values can be changed before encoding each frame.

Downmix Levels

-center_mixlev level
Center Mix Level. The amount of gain the decoder should apply to the center channel
when downmixing to stereo. This field will only be written to the bitstream if a
center channel is present. The value is specified as a scale factor. There are 3 valid
values:

0.707
Apply -3dB gain

0.595
Apply -4.5dB gain (default)

0.500
Apply -6dB gain

-surround_mixlev level
Surround Mix Level. The amount of gain the decoder should apply to the surround
channel(s) when downmixing to stereo. This field will only be written to the bitstream
if one or more surround channels are present. The value is specified as a scale
factor. There are 3 valid values:

0.707
Apply -3dB gain

0.500
Apply -6dB gain (default)

0.000
Silence Surround Channel(s)

Audio Production Information

Audio Production Information is optional information describing the mixing environment.
Either none or both of the fields are written to the bitstream.

-mixing_level number
Mixing Level. Specifies peak sound pressure level (SPL) in the production environment
when the mix was mastered. Valid values are 80 to 111, or -1 for unknown or not
indicated. The default value is -1, but that value cannot be used if the Audio
Production Information is written to the bitstream. Therefore, if the "room_type"
option is not the default value, the "mixing_level" option must not be -1.

-room_type type
Room Type. Describes the equalization used during the final mixing session at the
studio or on the dubbing stage. A large room is a dubbing stage with the industry
standard X-curve equalization; a small room has flat equalization. This field will
not be written to the bitstream if both the "mixing_level" option and the "room_type"
option have the default values.

0
notindicated
Not Indicated (default)

1
large
Large Room

2
small
Small Room

Other Metadata Options

-copyright boolean
Copyright Indicator. Specifies whether a copyright exists for this audio.

0
off No Copyright Exists (default)

1
on Copyright Exists

-dialnorm value
Dialogue Normalization. Indicates how far the average dialogue level of the program is
below digital 100% full scale (0 dBFS). This parameter determines a level shift during
audio reproduction that sets the average volume of the dialogue to a preset level. The
goal is to match volume level between program sources. A value of -31dB will result in
no volume level change, relative to the source volume, during audio reproduction.
Valid values are whole numbers in the range -31 to -1, with -31 being the default.

-dsur_mode mode
Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround (Pro
Logic). This field will only be written to the bitstream if the audio stream is
stereo. Using this option does NOT mean the encoder will actually apply Dolby Surround
processing.

0
notindicated
Not Indicated (default)

1
off Not Dolby Surround Encoded

2
on Dolby Surround Encoded

-original boolean
Original Bit Stream Indicator. Specifies whether this audio is from the original
source and not a copy.

0
off Not Original Source

1
on Original Source (default)

Extended Bitstream Information

The extended bitstream options are part of the Alternate Bit Stream Syntax as specified in
Annex D of the A/52:2010 standard. It is grouped into 2 parts. If any one parameter in a
group is specified, all values in that group will be written to the bitstream. Default
values are used for those that are written but have not been specified. If the mixing
levels are written, the decoder will use these values instead of the ones specified in the
"center_mixlev" and "surround_mixlev" options if it supports the Alternate Bit Stream
Syntax.

Extended Bitstream Information - Part 1

-dmix_mode mode
Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt (Dolby Surround)
or Lo/Ro (normal stereo) as the preferred stereo downmix mode.

0
notindicated
Not Indicated (default)

1
ltrt
Lt/Rt Downmix Preferred

2
loro
Lo/Ro Downmix Preferred

-ltrt_cmixlev level
Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the center
channel when downmixing to stereo in Lt/Rt mode.

1.414
Apply +3dB gain

1.189
Apply +1.5dB gain

1.000
Apply 0dB gain

0.841
Apply -1.5dB gain

0.707
Apply -3.0dB gain

0.595
Apply -4.5dB gain (default)

0.500
Apply -6.0dB gain

0.000
Silence Center Channel

-ltrt_surmixlev level
Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the surround
channel(s) when downmixing to stereo in Lt/Rt mode.

0.841
Apply -1.5dB gain

0.707
Apply -3.0dB gain

0.595
Apply -4.5dB gain

0.500
Apply -6.0dB gain (default)

0.000
Silence Surround Channel(s)

-loro_cmixlev level
Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the center
channel when downmixing to stereo in Lo/Ro mode.

1.414
Apply +3dB gain

1.189
Apply +1.5dB gain

1.000
Apply 0dB gain

0.841
Apply -1.5dB gain

0.707
Apply -3.0dB gain

0.595
Apply -4.5dB gain (default)

0.500
Apply -6.0dB gain

0.000
Silence Center Channel

-loro_surmixlev level
Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the surround
channel(s) when downmixing to stereo in Lo/Ro mode.

0.841
Apply -1.5dB gain

0.707
Apply -3.0dB gain

0.595
Apply -4.5dB gain

0.500
Apply -6.0dB gain (default)

0.000
Silence Surround Channel(s)

Extended Bitstream Information - Part 2

-dsurex_mode mode
Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX (7.1
matrixed to 5.1). Using this option does NOT mean the encoder will actually apply
Dolby Surround EX processing.

0
notindicated
Not Indicated (default)

1
on Dolby Surround EX Off

2
off Dolby Surround EX On

-dheadphone_mode mode
Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone encoding
(multi-channel matrixed to 2.0 for use with headphones). Using this option does NOT
mean the encoder will actually apply Dolby Headphone processing.

0
notindicated
Not Indicated (default)

1
on Dolby Headphone Off

2
off Dolby Headphone On

-ad_conv_type type
A/D Converter Type. Indicates whether the audio has passed through HDCD A/D
conversion.

0
standard
Standard A/D Converter (default)

1
hdcd
HDCD A/D Converter

Other AC-3 Encoding Options

-stereo_rematrixing boolean
Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This is an
optional AC-3 feature that increases quality by selectively encoding the left/right
channels as mid/side. This option is enabled by default, and it is highly recommended
that it be left as enabled except for testing purposes.

cutoff frequency
Set lowpass cutoff frequency. If unspecified, the encoder selects a default determined
by various other encoding parameters.

Floating-Point-Only AC-3 Encoding Options

These options are only valid for the floating-point encoder and do not exist for the
fixed-point encoder due to the corresponding features not being implemented in fixed-
point.

-channel_coupling boolean
Enables/Disables use of channel coupling, which is an optional AC-3 feature that
increases quality by combining high frequency information from multiple channels into
a single channel. The per-channel high frequency information is sent with less
accuracy in both the frequency and time domains. This allows more bits to be used for
lower frequencies while preserving enough information to reconstruct the high
frequencies. This option is enabled by default for the floating-point encoder and
should generally be left as enabled except for testing purposes or to increase
encoding speed.

-1
auto
Selected by Encoder (default)

0
off Disable Channel Coupling

1
on Enable Channel Coupling

-cpl_start_band number
Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a value
higher than the bandwidth is used, it will be reduced to 1 less than the coupling end
band. If auto is used, the start band will be determined by the encoder based on the
bit rate, sample rate, and channel layout. This option has no effect if channel
coupling is disabled.

-1
auto
Selected by Encoder (default)

flac
FLAC (Free Lossless Audio Codec) Encoder

Options

The following options are supported by FFmpeg's flac encoder.

compression_level
Sets the compression level, which chooses defaults for many other options if they are
not set explicitly. Valid values are from 0 to 12, 5 is the default.

frame_size
Sets the size of the frames in samples per channel.

lpc_coeff_precision
Sets the LPC coefficient precision, valid values are from 1 to 15, 15 is the default.

lpc_type
Sets the first stage LPC algorithm

none
LPC is not used

fixed
fixed LPC coefficients

levinson
cholesky
lpc_passes
Number of passes to use for Cholesky factorization during LPC analysis

min_partition_order
The minimum partition order

max_partition_order
The maximum partition order

prediction_order_method
estimation
2level
4level
8level
search
Bruteforce search

log
ch_mode
Channel mode

auto
The mode is chosen automatically for each frame

indep
Channels are independently coded

left_side
right_side
mid_side
exact_rice_parameters
Chooses if rice parameters are calculated exactly or approximately. if set to 1 then
they are chosen exactly, which slows the code down slightly and improves compression
slightly.

multi_dim_quant
Multi Dimensional Quantization. If set to 1 then a 2nd stage LPC algorithm is applied
after the first stage to finetune the coefficients. This is quite slow and slightly
improves compression.

opus
Opus encoder.

This is a native FFmpeg encoder for the Opus format. Currently its in development and only
implements the CELT part of the codec. Its quality is usually worse and at best is equal
to the libopus encoder.

Options

b Set bit rate in bits/s. If unspecified it uses the number of channels and the layout
to make a good guess.

opus_delay
Sets the maximum delay in milliseconds. Lower delays than 20ms will very quickly
decrease quality.

libfdk_aac
libfdk-aac AAC (Advanced Audio Coding) encoder wrapper.

The libfdk-aac library is based on the Fraunhofer FDK AAC code from the Android project.

Requires the presence of the libfdk-aac headers and library during configuration. You need
to explicitly configure the build with "--enable-libfdk-aac". The library is also
incompatible with GPL, so if you allow the use of GPL, you should configure with
"--enable-gpl --enable-nonfree --enable-libfdk-aac".

This encoder is considered to produce output on par or worse at 128kbps to the the native
FFmpeg AAC encoder but can often produce better sounding audio at identical or lower
bitrates and has support for the AAC-HE profiles.

VBR encoding, enabled through the vbr or flags +qscale options, is experimental and only
works with some combinations of parameters.

Support for encoding 7.1 audio is only available with libfdk-aac 0.1.3 or higher.

For more information see the fdk-aac project at
<http://sourceforge.net/p/opencore-amr/fdk-aac/>.

Options

The following options are mapped on the shared FFmpeg codec options.

b Set bit rate in bits/s. If the bitrate is not explicitly specified, it is
automatically set to a suitable value depending on the selected profile.

In case VBR mode is enabled the option is ignored.

ar Set audio sampling rate (in Hz).

channels
Set the number of audio channels.

flags +qscale
Enable fixed quality, VBR (Variable Bit Rate) mode. Note that VBR is implicitly
enabled when the vbr value is positive.

cutoff
Set cutoff frequency. If not specified (or explicitly set to 0) it will use a value
automatically computed by the library. Default value is 0.

profile
Set audio profile.

The following profiles are recognized:

aac_low
Low Complexity AAC (LC)

aac_he
High Efficiency AAC (HE-AAC)

aac_he_v2
High Efficiency AAC version 2 (HE-AACv2)

aac_ld
Low Delay AAC (LD)

aac_eld
Enhanced Low Delay AAC (ELD)

If not specified it is set to aac_low.

The following are private options of the libfdk_aac encoder.

afterburner
Enable afterburner feature if set to 1, disabled if set to 0. This improves the
quality but also the required processing power.

Default value is 1.

eld_sbr
Enable SBR (Spectral Band Replication) for ELD if set to 1, disabled if set to 0.

Default value is 0.

eld_v2
Enable ELDv2 (LD-MPS extension for ELD stereo signals) for ELDv2 if set to 1, disabled
if set to 0.

Note that option is available when fdk-aac version
(AACENCODER_LIB_VL0.AACENCODER_LIB_VL1.AACENCODER_LIB_VL2) > (4.0.0).

Default value is 0.

signaling
Set SBR/PS signaling style.

It can assume one of the following values:

default
choose signaling implicitly (explicit hierarchical by default, implicit if global
header is disabled)

implicit
implicit backwards compatible signaling

explicit_sbr
explicit SBR, implicit PS signaling

explicit_hierarchical
explicit hierarchical signaling

Default value is default.

latm
Output LATM/LOAS encapsulated data if set to 1, disabled if set to 0.

Default value is 0.

header_period
Set StreamMuxConfig and PCE repetition period (in frames) for sending in-band
configuration buffers within LATM/LOAS transport layer.

Must be a 16-bits non-negative integer.

Default value is 0.

vbr Set VBR mode, from 1 to 5. 1 is lowest quality (though still pretty good) and 5 is
highest quality. A value of 0 will disable VBR, and CBR (Constant Bit Rate) is
enabled.

Currently only the aac_low profile supports VBR encoding.

VBR modes 1-5 correspond to roughly the following average bit rates:

1 32 kbps/channel

2 40 kbps/channel

3 48-56 kbps/channel

4 64 kbps/channel

5 about 80-96 kbps/channel

Default value is 0.

Examples

• Use ffmpeg to convert an audio file to VBR AAC in an M4A (MP4) container:

ffmpeg -i input.wav -codec:a libfdk_aac -vbr 3 output.m4a

• Use ffmpeg to convert an audio file to CBR 64k kbps AAC, using the High-Efficiency AAC
profile:

ffmpeg -i input.wav -c:a libfdk_aac -profile:a aac_he -b:a 64k output.m4a

libmp3lame
LAME (Lame Ain't an MP3 Encoder) MP3 encoder wrapper.

Requires the presence of the libmp3lame headers and library during configuration. You need
to explicitly configure the build with "--enable-libmp3lame".

See libshine for a fixed-point MP3 encoder, although with a lower quality.

Options

The following options are supported by the libmp3lame wrapper. The lame-equivalent of the
options are listed in parentheses.

b (-b)
Set bitrate expressed in bits/s for CBR or ABR. LAME "bitrate" is expressed in
kilobits/s.

q (-V)
Set constant quality setting for VBR. This option is valid only using the ffmpeg
command-line tool. For library interface users, use global_quality.

compression_level (-q)
Set algorithm quality. Valid arguments are integers in the 0-9 range, with 0 meaning
highest quality but slowest, and 9 meaning fastest while producing the worst quality.

cutoff (--lowpass)
Set lowpass cutoff frequency. If unspecified, the encoder dynamically adjusts the
cutoff.

reservoir
Enable use of bit reservoir when set to 1. Default value is 1. LAME has this enabled
by default, but can be overridden by use --nores option.

joint_stereo (-m j)
Enable the encoder to use (on a frame by frame basis) either L/R stereo or mid/side
stereo. Default value is 1.

abr (--abr)
Enable the encoder to use ABR when set to 1. The lame --abr sets the target bitrate,
while this options only tells FFmpeg to use ABR still relies on b to set bitrate.

libopencore-amrnb
OpenCORE Adaptive Multi-Rate Narrowband encoder.

Requires the presence of the libopencore-amrnb headers and library during configuration.
You need to explicitly configure the build with "--enable-libopencore-amrnb
--enable-version3".

This is a mono-only encoder. Officially it only supports 8000Hz sample rate, but you can
override it by setting strict to unofficial or lower.

Options

b Set bitrate in bits per second. Only the following bitrates are supported, otherwise
libavcodec will round to the nearest valid bitrate.

4750
5150
5900
6700
7400
7950
10200
12200
dtx Allow discontinuous transmission (generate comfort noise) when set to 1. The default
value is 0 (disabled).

libopus
libopus Opus Interactive Audio Codec encoder wrapper.

Requires the presence of the libopus headers and library during configuration. You need to
explicitly configure the build with "--enable-libopus".

Option Mapping

Most libopus options are modelled after the opusenc utility from opus-tools. The following
is an option mapping chart describing options supported by the libopus wrapper, and their
opusenc-equivalent in parentheses.

b (bitrate)
Set the bit rate in bits/s. FFmpeg's b option is expressed in bits/s, while opusenc's
bitrate in kilobits/s.

vbr (vbr, hard-cbr, and cvbr)
Set VBR mode. The FFmpeg vbr option has the following valid arguments, with the
opusenc equivalent options in parentheses:

off (hard-cbr)
Use constant bit rate encoding.

on (vbr)
Use variable bit rate encoding (the default).

constrained (cvbr)
Use constrained variable bit rate encoding.

compression_level (comp)
Set encoding algorithm complexity. Valid options are integers in the 0-10 range. 0
gives the fastest encodes but lower quality, while 10 gives the highest quality but
slowest encoding. The default is 10.

frame_duration (framesize)
Set maximum frame size, or duration of a frame in milliseconds. The argument must be
exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller frame sizes achieve lower
latency but less quality at a given bitrate. Sizes greater than 20ms are only
interesting at fairly low bitrates. The default is 20ms.

packet_loss (expect-loss)
Set expected packet loss percentage. The default is 0.

application (N.A.)
Set intended application type. Valid options are listed below:

voip
Favor improved speech intelligibility.

audio
Favor faithfulness to the input (the default).

lowdelay
Restrict to only the lowest delay modes.

cutoff (N.A.)
Set cutoff bandwidth in Hz. The argument must be exactly one of the following: 4000,
6000, 8000, 12000, or 20000, corresponding to narrowband, mediumband, wideband, super
wideband, and fullband respectively. The default is 0 (cutoff disabled).

mapping_family (mapping_family)
Set channel mapping family to be used by the encoder. The default value of -1 uses
mapping family 0 for mono and stereo inputs, and mapping family 1 otherwise. The
default also disables the surround masking and LFE bandwidth optimzations in libopus,
and requires that the input contains 8 channels or fewer.

Other values include 0 for mono and stereo, 1 for surround sound with masking and LFE
bandwidth optimizations, and 255 for independent streams with an unspecified channel
layout.

apply_phase_inv (N.A.) (requires libopus >= 1.2)
If set to 0, disables the use of phase inversion for intensity stereo, improving the
quality of mono downmixes, but slightly reducing normal stereo quality. The default is
1 (phase inversion enabled).

libshine
Shine Fixed-Point MP3 encoder wrapper.

Shine is a fixed-point MP3 encoder. It has a far better performance on platforms without
an FPU, e.g. armel CPUs, and some phones and tablets. However, as it is more targeted on
performance than quality, it is not on par with LAME and other production-grade encoders
quality-wise. Also, according to the project's homepage, this encoder may not be free of
bugs as the code was written a long time ago and the project was dead for at least 5
years.

This encoder only supports stereo and mono input. This is also CBR-only.

The original project (last updated in early 2007) is at
<http://sourceforge.net/projects/libshine-fxp/>. We only support the updated fork by the
Savonet/Liquidsoap project at <https://github.com/savonet/shine>.

Requires the presence of the libshine headers and library during configuration. You need
to explicitly configure the build with "--enable-libshine".

VIDEO ENCODERS

A description of some of the currently available video encoders follows.

Hap
Vidvox Hap video encoder.

Options

format integer
Specifies the Hap format to encode.

hap
hap_alpha
hap_q

Default value is hap.

chunks integer
Specifies the number of chunks to split frames into, between 1 and 64. This permits
multithreaded decoding of large frames, potentially at the cost of data-rate. The
encoder may modify this value to divide frames evenly.

Default value is 1.

compressor integer
Specifies the second-stage compressor to use. If set to none, chunks will be limited
to 1, as chunked uncompressed frames offer no benefit.

none
snappy

Default value is snappy.

jpeg2000
The native jpeg 2000 encoder is lossy by default, the "-q:v" option can be used to set the
encoding quality. Lossless encoding can be selected with "-pred 1".

Options

format
Can be set to either "j2k" or "jp2" (the default) that makes it possible to store non-
rgb pix_fmts.

libaom-av1
libaom AV1 encoder wrapper.

Requires the presence of the libaom headers and library during configuration. You need to
explicitly configure the build with "--enable-libaom".

Options

The wrapper supports the following standard libavcodec options:

b Set bitrate target in bits/second. By default this will use variable-bitrate mode.
If maxrate and minrate are also set to the same value then it will use constant-
bitrate mode, otherwise if crf is set as well then it will use constrained-quality
mode.

g keyint_min
Set key frame placement. The GOP size sets the maximum distance between key frames;
if zero the output stream will be intra-only. The minimum distance is ignored unless
it is the same as the GOP size, in which case key frames will always appear at a fixed
interval. Not set by default, so without this option the library has completely free
choice about where to place key frames.

qmin qmax
Set minimum/maximum quantisation values. Valid range is from 0 to 63 (warning: this
does not match the quantiser values actually used by AV1 - divide by four to map real
quantiser values to this range). Defaults to min/max (no constraint).

minrate maxrate bufsize rc_init_occupancy
Set rate control buffering parameters. Not used if not set - defaults to
unconstrained variable bitrate.

threads
Set the number of threads to use while encoding. This may require the tiles or row-mt
options to also be set to actually use the specified number of threads fully. Defaults
to the number of hardware threads supported by the host machine.

profile
Set the encoding profile. Defaults to using the profile which matches the bit depth
and chroma subsampling of the input.

The wrapper also has some specific options:

cpu-used
Set the quality/encoding speed tradeoff. Valid range is from 0 to 8, higher numbers
indicating greater speed and lower quality. The default value is 1, which will be
slow and high quality.

auto-alt-ref
Enable use of alternate reference frames. Defaults to the internal default of the
library.

arnr-max-frames (frames)
Set altref noise reduction max frame count. Default is -1.

arnr-strength (strength)
Set altref noise reduction filter strength. Range is -1 to 6. Default is -1.

aq-mode (aq-mode)
Set adaptive quantization mode. Possible values:

none (0)
Disabled.

variance (1)
Variance-based.

complexity (2)
Complexity-based.

cyclic (3)
Cyclic refresh.

lag-in-frames
Set the maximum number of frames which the encoder may keep in flight at any one time
for lookahead purposes. Defaults to the internal default of the library.

error-resilience
Enable error resilience features:

default
Improve resilience against losses of whole frames.

Not enabled by default.

crf Set the quality/size tradeoff for constant-quality (no bitrate target) and
constrained-quality (with maximum bitrate target) modes. Valid range is 0 to 63,
higher numbers indicating lower quality and smaller output size. Only used if set; by
default only the bitrate target is used.

static-thresh
Set a change threshold on blocks below which they will be skipped by the encoder.
Defined in arbitrary units as a nonnegative integer, defaulting to zero (no blocks are
skipped).

drop-threshold
Set a threshold for dropping frames when close to rate control bounds. Defined as a
percentage of the target buffer - when the rate control buffer falls below this
percentage, frames will be dropped until it has refilled above the threshold.
Defaults to zero (no frames are dropped).

denoise-noise-level (level)
Amount of noise to be removed for grain synthesis. Grain synthesis is disabled if this
option is not set or set to 0.

denoise-block-size (pixels)
Block size used for denoising for grain synthesis. If not set, AV1 codec uses the
default value of 32.

undershoot-pct (pct)
Set datarate undershoot (min) percentage of the target bitrate. Range is -1 to 100.
Default is -1.

overshoot-pct (pct)
Set datarate overshoot (max) percentage of the target bitrate. Range is -1 to 1000.
Default is -1.

minsection-pct (pct)
Minimum percentage variation of the GOP bitrate from the target bitrate. If
minsection-pct is not set, the libaomenc wrapper computes it as follows: "(minrate *
100 / bitrate)". Range is -1 to 100. Default is -1 (unset).

maxsection-pct (pct)
Maximum percentage variation of the GOP bitrate from the target bitrate. If
maxsection-pct is not set, the libaomenc wrapper computes it as follows: "(maxrate *
100 / bitrate)". Range is -1 to 5000. Default is -1 (unset).

frame-parallel (boolean)
Enable frame parallel decodability features. Default is true.

tiles
Set the number of tiles to encode the input video with, as columns x rows. Larger
numbers allow greater parallelism in both encoding and decoding, but may decrease
coding efficiency. Defaults to the minimum number of tiles required by the size of
the input video (this is 1x1 (that is, a single tile) for sizes up to and including
4K).

tile-columns tile-rows
Set the number of tiles as log2 of the number of tile rows and columns. Provided for
compatibility with libvpx/VP9.

row-mt (Requires libaom >= 1.0.0-759-g90a15f4f2)
Enable row based multi-threading. Disabled by default.

enable-cdef (boolean)
Enable Constrained Directional Enhancement Filter. The libaom-av1 encoder enables CDEF
by default.

enable-global-motion (boolean)
Enable the use of global motion for block prediction. Default is true.

enable-intrabc (boolean)
Enable block copy mode for intra block prediction. This mode is useful for screen
content. Default is true.

libkvazaar
Kvazaar H.265/HEVC encoder.

Requires the presence of the libkvazaar headers and library during configuration. You need
to explicitly configure the build with --enable-libkvazaar.

Options

b Set target video bitrate in bit/s and enable rate control.

kvazaar-params
Set kvazaar parameters as a list of name=value pairs separated by commas (,). See
kvazaar documentation for a list of options.

libopenh264
Cisco libopenh264 H.264/MPEG-4 AVC encoder wrapper.

This encoder requires the presence of the libopenh264 headers and library during
configuration. You need to explicitly configure the build with "--enable-libopenh264". The
library is detected using pkg-config.

For more information about the library see <http://www.openh264.org>.

Options

The following FFmpeg global options affect the configurations of the libopenh264 encoder.

b Set the bitrate (as a number of bits per second).

g Set the GOP size.

maxrate
Set the max bitrate (as a number of bits per second).

flags +global_header
Set global header in the bitstream.

slices
Set the number of slices, used in parallelized encoding. Default value is 0. This is
only used when slice_mode is set to fixed.

slice_mode
Set slice mode. Can assume one of the following possible values:

fixed
a fixed number of slices

rowmb
one slice per row of macroblocks

auto
automatic number of slices according to number of threads

dyn dynamic slicing

Default value is auto.

loopfilter
Enable loop filter, if set to 1 (automatically enabled). To disable set a value of 0.

profile
Set profile restrictions. If set to the value of main enable CABAC (set the
"SEncParamExt.iEntropyCodingModeFlag" flag to 1).

max_nal_size
Set maximum NAL size in bytes.

allow_skip_frames
Allow skipping frames to hit the target bitrate if set to 1.

libtheora
libtheora Theora encoder wrapper.

Requires the presence of the libtheora headers and library during configuration. You need
to explicitly configure the build with "--enable-libtheora".

For more information about the libtheora project see <http://www.theora.org/>.

Options

The following global options are mapped to internal libtheora options which affect the
quality and the bitrate of the encoded stream.

b Set the video bitrate in bit/s for CBR (Constant Bit Rate) mode. In case VBR
(Variable Bit Rate) mode is enabled this option is ignored.

flags
Used to enable constant quality mode (VBR) encoding through the qscale flag, and to
enable the "pass1" and "pass2" modes.

g Set the GOP size.

global_quality
Set the global quality as an integer in lambda units.

Only relevant when VBR mode is enabled with "flags +qscale". The value is converted to
QP units by dividing it by "FF_QP2LAMBDA", clipped in the [0 - 10] range, and then
multiplied by 6.3 to get a value in the native libtheora range [0-63]. A higher value
corresponds to a higher quality.

q Enable VBR mode when set to a non-negative value, and set constant quality value as a
double floating point value in QP units.

The value is clipped in the [0-10] range, and then multiplied by 6.3 to get a value in
the native libtheora range [0-63].

This option is valid only using the ffmpeg command-line tool. For library interface
users, use global_quality.

Examples

• Set maximum constant quality (VBR) encoding with ffmpeg:

ffmpeg -i INPUT -codec:v libtheora -q:v 10 OUTPUT.ogg

• Use ffmpeg to convert a CBR 1000 kbps Theora video stream:

ffmpeg -i INPUT -codec:v libtheora -b:v 1000k OUTPUT.ogg

libvpx
VP8/VP9 format supported through libvpx.

Requires the presence of the libvpx headers and library during configuration. You need to
explicitly configure the build with "--enable-libvpx".

Options

The following options are supported by the libvpx wrapper. The vpxenc-equivalent options
or values are listed in parentheses for easy migration.

To reduce the duplication of documentation, only the private options and some others
requiring special attention are documented here. For the documentation of the undocumented
generic options, see the Codec Options chapter.

To get more documentation of the libvpx options, invoke the command ffmpeg -h
encoder=libvpx, ffmpeg -h encoder=libvpx-vp9 or vpxenc --help. Further information is
available in the libvpx API documentation.

b (target-bitrate)
Set bitrate in bits/s. Note that FFmpeg's b option is expressed in bits/s, while
vpxenc's target-bitrate is in kilobits/s.

g (kf-max-dist)
keyint_min (kf-min-dist)
qmin (min-q)
qmax (max-q)
bufsize (buf-sz, buf-optimal-sz)
Set ratecontrol buffer size (in bits). Note vpxenc's options are specified in
milliseconds, the libvpx wrapper converts this value as follows: "buf-sz = bufsize *
1000 / bitrate", "buf-optimal-sz = bufsize * 1000 / bitrate * 5 / 6".

rc_init_occupancy (buf-initial-sz)
Set number of bits which should be loaded into the rc buffer before decoding starts.
Note vpxenc's option is specified in milliseconds, the libvpx wrapper converts this
value as follows: "rc_init_occupancy * 1000 / bitrate".

undershoot-pct
Set datarate undershoot (min) percentage of the target bitrate.

overshoot-pct
Set datarate overshoot (max) percentage of the target bitrate.

skip_threshold (drop-frame)
qcomp (bias-pct)
maxrate (maxsection-pct)
Set GOP max bitrate in bits/s. Note vpxenc's option is specified as a percentage of
the target bitrate, the libvpx wrapper converts this value as follows: "(maxrate * 100
/ bitrate)".

minrate (minsection-pct)
Set GOP min bitrate in bits/s. Note vpxenc's option is specified as a percentage of
the target bitrate, the libvpx wrapper converts this value as follows: "(minrate * 100
/ bitrate)".

minrate, maxrate, b end-usage=cbr
"(minrate == maxrate == bitrate)".

crf (end-usage=cq, cq-level)
tune (tune)
psnr (psnr)
ssim (ssim)
quality, deadline (deadline)
best
Use best quality deadline. Poorly named and quite slow, this option should be
avoided as it may give worse quality output than good.

good
Use good quality deadline. This is a good trade-off between speed and quality when
used with the cpu-used option.

realtime
Use realtime quality deadline.

speed, cpu-used (cpu-used)
Set quality/speed ratio modifier. Higher values speed up the encode at the cost of
quality.

nr (noise-sensitivity)
static-thresh
Set a change threshold on blocks below which they will be skipped by the encoder.

slices (token-parts)
Note that FFmpeg's slices option gives the total number of partitions, while vpxenc's
token-parts is given as "log2(partitions)".

max-intra-rate
Set maximum I-frame bitrate as a percentage of the target bitrate. A value of 0 means
unlimited.

force_key_frames
"VPX_EFLAG_FORCE_KF"

Alternate reference frame related
auto-alt-ref
Enable use of alternate reference frames (2-pass only). Values greater than 1
enable multi-layer alternate reference frames (VP9 only).

arnr-maxframes
Set altref noise reduction max frame count.

arnr-type
Set altref noise reduction filter type: backward, forward, centered.

arnr-strength
Set altref noise reduction filter strength.

rc-lookahead, lag-in-frames (lag-in-frames)
Set number of frames to look ahead for frametype and ratecontrol.

error-resilient
Enable error resiliency features.

sharpness integer
Increase sharpness at the expense of lower PSNR. The valid range is [0, 7].

VP8-specific options
ts-parameters
Sets the temporal scalability configuration using a :-separated list of key=value
pairs. For example, to specify temporal scalability parameters with "ffmpeg":

ffmpeg -i INPUT -c:v libvpx -ts-parameters ts_number_layers=3:\
ts_target_bitrate=250000,500000,1000000:ts_rate_decimator=4,2,1:\
ts_periodicity=4:ts_layer_id=0,2,1,2 OUTPUT

Below is a brief explanation of each of the parameters, please refer to "struct
vpx_codec_enc_cfg" in "vpx/vpx_encoder.h" for more details.

ts_number_layers
Number of temporal coding layers.

ts_target_bitrate
Target bitrate for each temporal layer.

ts_rate_decimator
Frame rate decimation factor for each temporal layer.

ts_periodicity
Length of the sequence defining frame temporal layer membership.

ts_layer_id
Template defining the membership of frames to temporal layers.

VP9-specific options
lossless
Enable lossless mode.

tile-columns
Set number of tile columns to use. Note this is given as "log2(tile_columns)". For
example, 8 tile columns would be requested by setting the tile-columns option to
3.

tile-rows
Set number of tile rows to use. Note this is given as "log2(tile_rows)". For
example, 4 tile rows would be requested by setting the tile-rows option to 2.

frame-parallel
Enable frame parallel decodability features.

aq-mode
Set adaptive quantization mode (0: off (default), 1: variance 2: complexity, 3:
cyclic refresh, 4: equator360).

colorspace color-space
Set input color space. The VP9 bitstream supports signaling the following
colorspaces:

rgb sRGB
bt709 bt709
unspecified unknown
bt470bg bt601
smpte170m smpte170
smpte240m smpte240
bt2020_ncl bt2020
row-mt boolean
Enable row based multi-threading.

tune-content
Set content type: default (0), screen (1), film (2).

corpus-complexity
Corpus VBR mode is a variant of standard VBR where the complexity distribution
midpoint is passed in rather than calculated for a specific clip or chunk.

The valid range is [0, 10000]. 0 (default) uses standard VBR.

enable-tpl boolean
Enable temporal dependency model.

For more information about libvpx see: <http://www.webmproject.org/>

libwebp
libwebp WebP Image encoder wrapper

libwebp is Google's official encoder for WebP images. It can encode in either lossy or
lossless mode. Lossy images are essentially a wrapper around a VP8 frame. Lossless images
are a separate codec developed by Google.

Pixel Format

Currently, libwebp only supports YUV420 for lossy and RGB for lossless due to limitations
of the format and libwebp. Alpha is supported for either mode. Because of API
limitations, if RGB is passed in when encoding lossy or YUV is passed in for encoding
lossless, the pixel format will automatically be converted using functions from libwebp.
This is not ideal and is done only for convenience.

Options

-lossless boolean
Enables/Disables use of lossless mode. Default is 0.

-compression_level integer
For lossy, this is a quality/speed tradeoff. Higher values give better quality for a
given size at the cost of increased encoding time. For lossless, this is a size/speed
tradeoff. Higher values give smaller size at the cost of increased encoding time. More
specifically, it controls the number of extra algorithms and compression tools used,
and varies the combination of these tools. This maps to the method option in libwebp.
The valid range is 0 to 6. Default is 4.

-qscale float
For lossy encoding, this controls image quality, 0 to 100. For lossless encoding, this
controls the effort and time spent at compressing more. The default value is 75. Note
that for usage via libavcodec, this option is called global_quality and must be
multiplied by FF_QP2LAMBDA.

-preset type
Configuration preset. This does some automatic settings based on the general type of
the image.

none
Do not use a preset.

default
Use the encoder default.

picture
Digital picture, like portrait, inner shot

photo
Outdoor photograph, with natural lighting

drawing
Hand or line drawing, with high-contrast details

icon
Small-sized colorful images

text
Text-like

libx264, libx264rgb
x264 H.264/MPEG-4 AVC encoder wrapper.

This encoder requires the presence of the libx264 headers and library during
configuration. You need to explicitly configure the build with "--enable-libx264".

libx264 supports an impressive number of features, including 8x8 and 4x4 adaptive spatial
transform, adaptive B-frame placement, CAVLC/CABAC entropy coding, interlacing (MBAFF),
lossless mode, psy optimizations for detail retention (adaptive quantization, psy-RD, psy-
trellis).

Many libx264 encoder options are mapped to FFmpeg global codec options, while unique
encoder options are provided through private options. Additionally the x264opts and
x264-params private options allows one to pass a list of key=value tuples as accepted by
the libx264 "x264_param_parse" function.

The x264 project website is at <http://www.videolan.org/developers/x264.html>.

The libx264rgb encoder is the same as libx264, except it accepts packed RGB pixel formats
as input instead of YUV.

Supported Pixel Formats

x264 supports 8- to 10-bit color spaces. The exact bit depth is controlled at x264's
configure time. FFmpeg only supports one bit depth in one particular build. In other
words, it is not possible to build one FFmpeg with multiple versions of x264 with
different bit depths.

Options

The following options are supported by the libx264 wrapper. The x264-equivalent options or
values are listed in parentheses for easy migration.

To get a more accurate and extensive documentation of the libx264 options, invoke the
command x264 --fullhelp or consult the libx264 documentation.

b (bitrate)
Set bitrate in bits/s. Note that FFmpeg's b option is expressed in bits/s, while
x264's bitrate is in kilobits/s.

bf (bframes)
g (keyint)
qmin (qpmin)
Minimum quantizer scale.

qmax (qpmax)
Maximum quantizer scale.

qdiff (qpstep)
Maximum difference between quantizer scales.

qblur (qblur)
Quantizer curve blur

qcomp (qcomp)
Quantizer curve compression factor

refs (ref)
Number of reference frames each P-frame can use. The range is from 0-16.

sc_threshold (scenecut)
Sets the threshold for the scene change detection.

trellis (trellis)
Performs Trellis quantization to increase efficiency. Enabled by default.

nr (nr)
me_range (merange)
Maximum range of the motion search in pixels.

me_method (me)
Set motion estimation method. Possible values in the decreasing order of speed:

dia (dia)
epzs (dia)
Diamond search with radius 1 (fastest). epzs is an alias for dia.

hex (hex)
Hexagonal search with radius 2.

umh (umh)
Uneven multi-hexagon search.

esa (esa)
Exhaustive search.

tesa (tesa)
Hadamard exhaustive search (slowest).

forced-idr
Normally, when forcing a I-frame type, the encoder can select any type of I-frame.
This option forces it to choose an IDR-frame.

subq (subme)
Sub-pixel motion estimation method.

b_strategy (b-adapt)
Adaptive B-frame placement decision algorithm. Use only on first-pass.

keyint_min (min-keyint)
Minimum GOP size.

coder
Set entropy encoder. Possible values:

ac Enable CABAC.

vlc Enable CAVLC and disable CABAC. It generates the same effect as x264's --no-cabac
option.

cmp Set full pixel motion estimation comparison algorithm. Possible values:

chroma
Enable chroma in motion estimation.

sad Ignore chroma in motion estimation. It generates the same effect as x264's
--no-chroma-me option.

threads (threads)
Number of encoding threads.

thread_type
Set multithreading technique. Possible values:

slice
Slice-based multithreading. It generates the same effect as x264's
--sliced-threads option.

frame
Frame-based multithreading.

flags
Set encoding flags. It can be used to disable closed GOP and enable open GOP by
setting it to "-cgop". The result is similar to the behavior of x264's --open-gop
option.

rc_init_occupancy (vbv-init)
preset (preset)
Set the encoding preset.

tune (tune)
Set tuning of the encoding params.

profile (profile)
Set profile restrictions.

fastfirstpass
Enable fast settings when encoding first pass, when set to 1. When set to 0, it has
the same effect of x264's --slow-firstpass option.

crf (crf)
Set the quality for constant quality mode.

crf_max (crf-max)
In CRF mode, prevents VBV from lowering quality beyond this point.

qp (qp)
Set constant quantization rate control method parameter.

aq-mode (aq-mode)
Set AQ method. Possible values:

none (0)
Disabled.

variance (1)
Variance AQ (complexity mask).

autovariance (2)
Auto-variance AQ (experimental).

aq-strength (aq-strength)
Set AQ strength, reduce blocking and blurring in flat and textured areas.

psy Use psychovisual optimizations when set to 1. When set to 0, it has the same effect as
x264's --no-psy option.

psy-rd (psy-rd)
Set strength of psychovisual optimization, in psy-rd:psy-trellis format.

rc-lookahead (rc-lookahead)
Set number of frames to look ahead for frametype and ratecontrol.

weightb
Enable weighted prediction for B-frames when set to 1. When set to 0, it has the same
effect as x264's --no-weightb option.

weightp (weightp)
Set weighted prediction method for P-frames. Possible values:

none (0)
Disabled

simple (1)
Enable only weighted refs

smart (2)
Enable both weighted refs and duplicates

ssim (ssim)
Enable calculation and printing SSIM stats after the encoding.

intra-refresh (intra-refresh)
Enable the use of Periodic Intra Refresh instead of IDR frames when set to 1.

avcintra-class (class)
Configure the encoder to generate AVC-Intra. Valid values are 50,100 and 200

bluray-compat (bluray-compat)
Configure the encoder to be compatible with the bluray standard. It is a shorthand
for setting "bluray-compat=1 force-cfr=1".

b-bias (b-bias)
Set the influence on how often B-frames are used.

b-pyramid (b-pyramid)
Set method for keeping of some B-frames as references. Possible values:

none (none)
Disabled.

strict (strict)
Strictly hierarchical pyramid.

normal (normal)
Non-strict (not Blu-ray compatible).

mixed-refs
Enable the use of one reference per partition, as opposed to one reference per
macroblock when set to 1. When set to 0, it has the same effect as x264's
--no-mixed-refs option.

8x8dct
Enable adaptive spatial transform (high profile 8x8 transform) when set to 1. When set
to 0, it has the same effect as x264's --no-8x8dct option.

fast-pskip
Enable early SKIP detection on P-frames when set to 1. When set to 0, it has the same
effect as x264's --no-fast-pskip option.

aud (aud)
Enable use of access unit delimiters when set to 1.

mbtree
Enable use macroblock tree ratecontrol when set to 1. When set to 0, it has the same
effect as x264's --no-mbtree option.

deblock (deblock)
Set loop filter parameters, in alpha:beta form.

cplxblur (cplxblur)
Set fluctuations reduction in QP (before curve compression).

partitions (partitions)
Set partitions to consider as a comma-separated list of. Possible values in the list:

p8x8
8x8 P-frame partition.

p4x4
4x4 P-frame partition.

b8x8
4x4 B-frame partition.

i8x8
8x8 I-frame partition.

i4x4
4x4 I-frame partition. (Enabling p4x4 requires p8x8 to be enabled. Enabling i8x8
requires adaptive spatial transform (8x8dct option) to be enabled.)

none (none)
Do not consider any partitions.

all (all)
Consider every partition.

direct-pred (direct)
Set direct MV prediction mode. Possible values:

none (none)
Disable MV prediction.

spatial (spatial)
Enable spatial predicting.

temporal (temporal)
Enable temporal predicting.

auto (auto)
Automatically decided.

slice-max-size (slice-max-size)
Set the limit of the size of each slice in bytes. If not specified but RTP payload
size (ps) is specified, that is used.

stats (stats)
Set the file name for multi-pass stats.

nal-hrd (nal-hrd)
Set signal HRD information (requires vbv-bufsize to be set). Possible values:

none (none)
Disable HRD information signaling.

vbr (vbr)
Variable bit rate.

cbr (cbr)
Constant bit rate (not allowed in MP4 container).

x264opts (N.A.)
Set any x264 option, see x264 --fullhelp for a list.

Argument is a list of key=value couples separated by ":". In filter and psy-rd options
that use ":" as a separator themselves, use "," instead. They accept it as well since
long ago but this is kept undocumented for some reason.

For example to specify libx264 encoding options with ffmpeg:

ffmpeg -i foo.mpg -c:v libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv

a53cc boolean
Import closed captions (which must be ATSC compatible format) into output. Only the
mpeg2 and h264 decoders provide these. Default is 1 (on).

x264-params (N.A.)
Override the x264 configuration using a :-separated list of key=value parameters.

This option is functionally the same as the x264opts, but is duplicated for
compatibility with the Libav fork.

For example to specify libx264 encoding options with ffmpeg:

ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\
cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\
no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT

Encoding ffpresets for common usages are provided so they can be used with the general
presets system (e.g. passing the pre option).

libx265
x265 H.265/HEVC encoder wrapper.

This encoder requires the presence of the libx265 headers and library during
configuration. You need to explicitly configure the build with --enable-libx265.

Options

preset
Set the x265 preset.

tune
Set the x265 tune parameter.

profile
Set profile restrictions.

crf Set the quality for constant quality mode.

forced-idr
Normally, when forcing a I-frame type, the encoder can select any type of I-frame.
This option forces it to choose an IDR-frame.

x265-params
Set x265 options using a list of key=value couples separated by ":". See x265 --help
for a list of options.

For example to specify libx265 encoding options with -x265-params:

ffmpeg -i input -c:v libx265 -x265-params crf=26:psy-rd=1 output.mp4

libxavs2
xavs2 AVS2-P2/IEEE1857.4 encoder wrapper.

This encoder requires the presence of the libxavs2 headers and library during
configuration. You need to explicitly configure the build with --enable-libxavs2.

The following standard libavcodec options are used:

• b / bit_rate

• g / gop_size

• bf / max_b_frames

The encoder also has its own specific options:

Options

lcu_row_threads
Set the number of parallel threads for rows from 1 to 8 (default 5).

initial_qp
Set the xavs2 quantization parameter from 1 to 63 (default 34). This is used to set
the initial qp for the first frame.

qp Set the xavs2 quantization parameter from 1 to 63 (default 34). This is used to set
the qp value under constant-QP mode.

max_qp
Set the max qp for rate control from 1 to 63 (default 55).

min_qp
Set the min qp for rate control from 1 to 63 (default 20).

speed_level
Set the Speed level from 0 to 9 (default 0). Higher is better but slower.

log_level
Set the log level from -1 to 3 (default 0). -1: none, 0: error, 1: warning, 2: info,
3: debug.

xavs2-params
Set xavs2 options using a list of key=value couples separated by ":".

For example to specify libxavs2 encoding options with -xavs2-params:

ffmpeg -i input -c:v libxavs2 -xavs2-params RdoqLevel=0 output.avs2

libxvid
Xvid MPEG-4 Part 2 encoder wrapper.

This encoder requires the presence of the libxvidcore headers and library during
configuration. You need to explicitly configure the build with "--enable-libxvid
--enable-gpl".

The native "mpeg4" encoder supports the MPEG-4 Part 2 format, so users can encode to this
format without this library.

Options

The following options are supported by the libxvid wrapper. Some of the following options
are listed but are not documented, and correspond to shared codec options. See the Codec
Options chapter for their documentation. The other shared options which are not listed
have no effect for the libxvid encoder.

b
g
qmin
qmax
mpeg_quant
threads
bf
b_qfactor
b_qoffset
flags
Set specific encoding flags. Possible values:

mv4 Use four motion vector by macroblock.

aic Enable high quality AC prediction.

gray
Only encode grayscale.

gmc Enable the use of global motion compensation (GMC).

qpel
Enable quarter-pixel motion compensation.

cgop
Enable closed GOP.

global_header
Place global headers in extradata instead of every keyframe.

trellis
me_method
Set motion estimation method. Possible values in decreasing order of speed and
increasing order of quality:

zero
Use no motion estimation (default).

phods
x1
log Enable advanced diamond zonal search for 16x16 blocks and half-pixel refinement
for 16x16 blocks. x1 and log are aliases for phods.

epzs
Enable all of the things described above, plus advanced diamond zonal search for
8x8 blocks, half-pixel refinement for 8x8 blocks, and motion estimation on chroma
planes.

full
Enable all of the things described above, plus extended 16x16 and 8x8 blocks
search.

mbd Set macroblock decision algorithm. Possible values in the increasing order of quality:

simple
Use macroblock comparing function algorithm (default).

bits
Enable rate distortion-based half pixel and quarter pixel refinement for 16x16
blocks.

rd Enable all of the things described above, plus rate distortion-based half pixel
and quarter pixel refinement for 8x8 blocks, and rate distortion-based search
using square pattern.

lumi_aq
Enable lumi masking adaptive quantization when set to 1. Default is 0 (disabled).

variance_aq
Enable variance adaptive quantization when set to 1. Default is 0 (disabled).

When combined with lumi_aq, the resulting quality will not be better than any of the
two specified individually. In other words, the resulting quality will be the worse
one of the two effects.

ssim
Set structural similarity (SSIM) displaying method. Possible values:

off Disable displaying of SSIM information.

avg Output average SSIM at the end of encoding to stdout. The format of showing the
average SSIM is:

Average SSIM: %f

For users who are not familiar with C, %f means a float number, or a decimal (e.g.
0.939232).

frame
Output both per-frame SSIM data during encoding and average SSIM at the end of
encoding to stdout. The format of per-frame information is:

SSIM: avg: %1.3f min: %1.3f max: %1.3f

For users who are not familiar with C, %1.3f means a float number rounded to 3
digits after the dot (e.g. 0.932).

ssim_acc
Set SSIM accuracy. Valid options are integers within the range of 0-4, while 0 gives
the most accurate result and 4 computes the fastest.

mpeg2
MPEG-2 video encoder.

Options

seq_disp_ext integer
Specifies if the encoder should write a sequence_display_extension to the output.

-1
auto
Decide automatically to write it or not (this is the default) by checking if the
data to be written is different from the default or unspecified values.

0
never
Never write it.

1
always
Always write it.

video_format integer
Specifies the video_format written into the sequence display extension indicating the
source of the video pictures. The default is unspecified, can be component, pal, ntsc,
secam or mac. For maximum compatibility, use component.

a53cc boolean
Import closed captions (which must be ATSC compatible format) into output. Default is
1 (on).

png
PNG image encoder.

Private options

dpi integer
Set physical density of pixels, in dots per inch, unset by default

dpm integer
Set physical density of pixels, in dots per meter, unset by default

ProRes
Apple ProRes encoder.

FFmpeg contains 2 ProRes encoders, the prores-aw and prores-ks encoder. The used encoder
can be chosen with the "-vcodec" option.

Private Options for prores-ks

profile integer
Select the ProRes profile to encode

proxy
lt
standard
hq
4444
4444xq
quant_mat integer
Select quantization matrix.

auto
default
proxy
lt
standard
hq

If set to auto, the matrix matching the profile will be picked. If not set, the
matrix providing the highest quality, default, will be picked.

bits_per_mb integer
How many bits to allot for coding one macroblock. Different profiles use between 200
and 2400 bits per macroblock, the maximum is 8000.

mbs_per_slice integer
Number of macroblocks in each slice (1-8); the default value (8) should be good in
almost all situations.

vendor string
Override the 4-byte vendor ID. A custom vendor ID like apl0 would claim the stream
was produced by the Apple encoder.

alpha_bits integer
Specify number of bits for alpha component. Possible values are 0, 8 and 16. Use 0
to disable alpha plane coding.

Speed considerations

In the default mode of operation the encoder has to honor frame constraints (i.e. not
produce frames with size bigger than requested) while still making output picture as good
as possible. A frame containing a lot of small details is harder to compress and the
encoder would spend more time searching for appropriate quantizers for each slice.

Setting a higher bits_per_mb limit will improve the speed.

For the fastest encoding speed set the qscale parameter (4 is the recommended value) and
do not set a size constraint.

QSV encoders
The family of Intel QuickSync Video encoders (MPEG-2, H.264 and HEVC)

The ratecontrol method is selected as follows:

• When global_quality is specified, a quality-based mode is used. Specifically this
means either

- CQP - constant quantizer scale, when the qscale codec flag is also set (the
-qscale ffmpeg option).

- LA_ICQ - intelligent constant quality with lookahead, when the look_ahead option
is also set.

- ICQ -- intelligent constant quality otherwise.

• Otherwise, a bitrate-based mode is used. For all of those, you should specify at least
the desired average bitrate with the b option.

- LA - VBR with lookahead, when the look_ahead option is specified.

- VCM - video conferencing mode, when the vcm option is set.

- CBR - constant bitrate, when maxrate is specified and equal to the average
bitrate.

- VBR - variable bitrate, when maxrate is specified, but is higher than the average
bitrate.

- AVBR - average VBR mode, when maxrate is not specified. This mode is further
configured by the avbr_accuracy and avbr_convergence options.

Note that depending on your system, a different mode than the one you specified may be
selected by the encoder. Set the verbosity level to verbose or higher to see the actual
settings used by the QSV runtime.

Additional libavcodec global options are mapped to MSDK options as follows:

• g/gop_size -> GopPicSize

• bf/max_b_frames+1 -> GopRefDist

• rc_init_occupancy/rc_initial_buffer_occupancy -> InitialDelayInKB

• slices -> NumSlice

• refs -> NumRefFrame

• b_strategy/b_frame_strategy -> BRefType

• cgop/CLOSED_GOP codec flag -> GopOptFlag

• For the CQP mode, the i_qfactor/i_qoffset and b_qfactor/b_qoffset set the difference
between QPP and QPI, and QPP and QPB respectively.

• Setting the coder option to the value vlc will make the H.264 encoder use CAVLC
instead of CABAC.

snow
Options

iterative_dia_size
dia size for the iterative motion estimation

VAAPI encoders
Wrappers for hardware encoders accessible via VAAPI.

These encoders only accept input in VAAPI hardware surfaces. If you have input in
software frames, use the hwupload filter to upload them to the GPU.

The following standard libavcodec options are used:

• g / gop_size

• bf / max_b_frames

• profile

If not set, this will be determined automatically from the format of the input frames
and the profiles supported by the driver.

• level

• b / bit_rate

• maxrate / rc_max_rate

• bufsize / rc_buffer_size

• rc_init_occupancy / rc_initial_buffer_occupancy

• compression_level

Speed / quality tradeoff: higher values are faster / worse quality.

• q / global_quality

Size / quality tradeoff: higher values are smaller / worse quality.

• qmin

• qmax

• i_qfactor / i_quant_factor

• i_qoffset / i_quant_offset

• b_qfactor / b_quant_factor

• b_qoffset / b_quant_offset

• slices

All encoders support the following options:

low_power
Some drivers/platforms offer a second encoder for some codecs intended to use less
power than the default encoder; setting this option will attempt to use that encoder.
Note that it may support a reduced feature set, so some other options may not be
available in this mode.

idr_interval
Set the number of normal intra frames between full-refresh (IDR) frames in open-GOP
mode. The intra frames are still IRAPs, but will not include global headers and may
have non-decodable leading pictures.

b_depth
Set the B-frame reference depth. When set to one (the default), all B-frames will
refer only to P- or I-frames. When set to greater values multiple layers of B-frames
will be present, frames in each layer only referring to frames in higher layers.

rc_mode
Set the rate control mode to use. A given driver may only support a subset of modes.

Possible modes:

auto
Choose the mode automatically based on driver support and the other options. This
is the default.

CQP Constant-quality.

CBR Constant-bitrate.

VBR Variable-bitrate.

ICQ Intelligent constant-quality.

QVBR
Quality-defined variable-bitrate.

AVBR
Average variable bitrate.

Each encoder also has its own specific options:

h264_vaapi
profile sets the value of profile_idc and the constraint_set*_flags. level sets the
value of level_idc.

coder
Set entropy encoder (default is cabac). Possible values:

ac
cabac
Use CABAC.

vlc
cavlc
Use CAVLC.

aud Include access unit delimiters in the stream (not included by default).

sei Set SEI message types to include. Some combination of the following values:

identifier
Include a user_data_unregistered message containing information about the
encoder.

timing
Include picture timing parameters (buffering_period and pic_timing messages).

recovery_point
Include recovery points where appropriate (recovery_point messages).

hevc_vaapi
profile and level set the values of general_profile_idc and general_level_idc
respectively.

aud Include access unit delimiters in the stream (not included by default).

tier
Set general_tier_flag. This may affect the level chosen for the stream if it is
not explicitly specified.

sei Set SEI message types to include. Some combination of the following values:

hdr Include HDR metadata if the input frames have it
(mastering_display_colour_volume and content_light_level messages).

mjpeg_vaapi
Only baseline DCT encoding is supported. The encoder always uses the standard
quantisation and huffman tables - global_quality scales the standard quantisation
table (range 1-100).

For YUV, 4:2:0, 4:2:2 and 4:4:4 subsampling modes are supported. RGB is also
supported, and will create an RGB JPEG.

jfif
Include JFIF header in each frame (not included by default).

huffman
Include standard huffman tables (on by default). Turning this off will save a few
hundred bytes in each output frame, but may lose compatibility with some JPEG
decoders which don't fully handle MJPEG.

mpeg2_vaapi
profile and level set the value of profile_and_level_indication.

vp8_vaapi
B-frames are not supported.

global_quality sets the q_idx used for non-key frames (range 0-127).

loop_filter_level
loop_filter_sharpness
Manually set the loop filter parameters.

vp9_vaapi
global_quality sets the q_idx used for P-frames (range 0-255).

loop_filter_level
loop_filter_sharpness
Manually set the loop filter parameters.

B-frames are supported, but the output stream is always in encode order rather than
display order. If B-frames are enabled, it may be necessary to use the
vp9_raw_reorder bitstream filter to modify the output stream to display frames in the
correct order.

Only normal frames are produced - the vp9_superframe bitstream filter may be required
to produce a stream usable with all decoders.

vc2
SMPTE VC-2 (previously BBC Dirac Pro). This codec was primarily aimed at professional
broadcasting but since it supports yuv420, yuv422 and yuv444 at 8 (limited range or full
range), 10 or 12 bits, this makes it suitable for other tasks which require low overhead
and low compression (like screen recording).

Options

b Sets target video bitrate. Usually that's around 1:6 of the uncompressed video bitrate
(e.g. for 1920x1080 50fps yuv422p10 that's around 400Mbps). Higher values (close to
the uncompressed bitrate) turn on lossless compression mode.

field_order
Enables field coding when set (e.g. to tt - top field first) for interlaced inputs.
Should increase compression with interlaced content as it splits the fields and
encodes each separately.

wavelet_depth
Sets the total amount of wavelet transforms to apply, between 1 and 5 (default).
Lower values reduce compression and quality. Less capable decoders may not be able to
handle values of wavelet_depth over 3.

wavelet_type
Sets the transform type. Currently only 5_3 (LeGall) and 9_7 (Deslauriers-Dubuc) are
implemented, with 9_7 being the one with better compression and thus is the default.

slice_width
slice_height
Sets the slice size for each slice. Larger values result in better compression. For
compatibility with other more limited decoders use slice_width of 32 and slice_height
of 8.

tolerance
Sets the undershoot tolerance of the rate control system in percent. This is to
prevent an expensive search from being run.

qm Sets the quantization matrix preset to use by default or when wavelet_depth is set to
5

- default Uses the default quantization matrix from the specifications, extended
with values for the fifth level. This provides a good balance between keeping
detail and omitting artifacts.

- flat Use a completely zeroed out quantization matrix. This increases PSNR but
might reduce perception. Use in bogus benchmarks.

- color Reduces detail but attempts to preserve color at extremely low bitrates.

SUBTITLES ENCODERS

   dvdsub
       This codec encodes the bitmap subtitle format that is used in DVDs.  Typically they are
       stored in VOBSUB file pairs (*.idx + *.sub), and they can also be used in Matroska files.

       Options

       even_rows_fix
           When set to 1, enable a work-around that makes the number of pixel rows even in all
           subtitles.  This fixes a problem with some players that cut off the bottom row if the
           number is odd.  The work-around just adds a fully transparent row if needed.  The
           overhead is low, typically one byte per subtitle on average.

           By default, this work-around is disabled.

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-CODECS(1)

NAME

DESCRIPTION

CODEC OPTIONS

DECODERS

VIDEO DECODERS

AUDIO DECODERS

SUBTITLES DECODERS

ENCODERS

AUDIO ENCODERS

VIDEO ENCODERS

SUBTITLES ENCODERS

SEE ALSO

AUTHORS