Provided by:
libav-tools_9.11-2ubuntu2_i386 
NAME
avserver - avserver video server
SYNOPSIS
avserver [options]
DESCRIPTION
WARNING: avserver is unmaintained, largely broken and in need of a
complete rewrite. It probably won't work for you. Use at your own risk.
avserver is a streaming server for both audio and video. It supports
several live feeds, streaming from files and time shifting on live
feeds (you can seek to positions in the past on each live feed,
provided you specify a big enough feed storage in avserver.conf).
This documentation covers only the streaming aspects of avserver /
avconv. All questions about parameters for avconv, codec questions,
etc. are not covered here. Read avconv.html for more information.
How does it work?
avserver receives prerecorded files or FFM streams from some avconv
instance as input, then streams them over RTP/RTSP/HTTP.
An avserver instance will listen on some port as specified in the
configuration file. You can launch one or more instances of avconv and
send one or more FFM streams to the port where avserver is expecting to
receive them. Alternately, you can make avserver launch such avconv
instances at startup.
Input streams are called feeds, and each one is specified by a <Feed>
section in the configuration file.
For each feed you can have different output streams in various formats,
each one specified by a <Stream> section in the configuration file.
Status stream
avserver supports an HTTP interface which exposes the current status of
the server.
Simply point your browser to the address of the special status stream
specified in the configuration file.
For example if you have:
<Stream status.html>
Format status
# Only allow local people to get the status
ACL allow localhost
ACL allow 192.168.0.0 192.168.255.255
</Stream>
then the server will post a page with the status information when the
special stream status.html is requested.
What can this do?
When properly configured and running, you can capture video and audio
in real time from a suitable capture card, and stream it out over the
Internet to either Windows Media Player or RealAudio player (with some
restrictions).
It can also stream from files, though that is currently broken. Very
often, a web server can be used to serve up the files just as well.
It can stream prerecorded video from .ffm files, though it is somewhat
tricky to make it work correctly.
What do I need?
I use Linux on a 900 MHz Duron with a cheapo Bt848 based TV capture
card. I'm using stock Linux 2.4.17 with the stock drivers. [Actually
that isn't true, I needed some special drivers for my motherboard-based
sound card.]
I understand that FreeBSD systems work just fine as well.
How do I make it work?
First, build the kit. It *really* helps to have installed LAME first.
Then when you run the avserver ./configure, make sure that you have the
"--enable-libmp3lame" flag turned on.
LAME is important as it allows for streaming audio to Windows Media
Player. Don't ask why the other audio types do not work.
As a simple test, just run the following two command lines where
INPUTFILE is some file which you can decode with avconv:
./avserver -f doc/avserver.conf &
./avconv -i INPUTFILE http://localhost:8090/feed1.ffm
At this point you should be able to go to your Windows machine and fire
up Windows Media Player (WMP). Go to Open URL and enter
http://<linuxbox>:8090/test.asf
You should (after a short delay) see video and hear audio.
WARNING: trying to stream test1.mpg doesn't work with WMP as it tries
to transfer the entire file before starting to play. The same is true
of AVI files.
What happens next?
You should edit the avserver.conf file to suit your needs (in terms of
frame rates etc). Then install avserver and avconv, write a script to
start them up, and off you go.
Troubleshooting
I don't hear any audio, but video is fine.
Maybe you didn't install LAME, or got your ./configure statement wrong.
Check the avconv output to see if a line referring to MP3 is present.
If not, then your configuration was incorrect. If it is, then maybe
your wiring is not set up correctly. Maybe the sound card is not
getting data from the right input source. Maybe you have a really awful
audio interface (like I do) that only captures in stereo and also
requires that one channel be flipped. If you are one of these people,
then export 'AUDIO_FLIP_LEFT=1' before starting avconv.
The audio and video lose sync after a while.
Yes, they do.
After a long while, the video update rate goes way down in WMP.
Yes, it does. Who knows why?
WMP 6.4 behaves differently to WMP 7.
Yes, it does. Any thoughts on this would be gratefully received. These
differences extend to embedding WMP into a web page. [There are two
object IDs that you can use: The old one, which does not play well, and
the new one, which does (both tested on the same system). However, I
suspect that the new one is not available unless you have installed WMP
7].
What else can it do?
You can replay video from .ffm files that was recorded earlier.
However, there are a number of caveats, including the fact that the
avserver parameters must match the original parameters used to record
the file. If they do not, then avserver deletes the file before
recording into it. (Now that I write this, it seems broken).
You can fiddle with many of the codec choices and encoding parameters,
and there are a bunch more parameters that you cannot control. Post a
message to the mailing list if there are some 'must have' parameters.
Look in avserver.conf for a list of the currently available controls.
It will automatically generate the ASX or RAM files that are often used
in browsers. These files are actually redirections to the underlying
ASF or RM file. The reason for this is that the browser often fetches
the entire file before starting up the external viewer. The redirection
files are very small and can be transferred quickly. [The stream itself
is often 'infinite' and thus the browser tries to download it and never
finishes.]
Tips
* When you connect to a live stream, most players (WMP, RA, etc) want
to buffer a certain number of seconds of material so that they can
display the signal continuously. However, avserver (by default) starts
sending data in realtime. This means that there is a pause of a few
seconds while the buffering is being done by the player. The good news
is that this can be cured by adding a '?buffer=5' to the end of the
URL. This means that the stream should start 5 seconds in the past --
and so the first 5 seconds of the stream are sent as fast as the
network will allow. It will then slow down to real time. This
noticeably improves the startup experience.
You can also add a 'Preroll 15' statement into the avserver.conf that
will add the 15 second prebuffering on all requests that do not
otherwise specify a time. In addition, avserver will skip frames until
a key_frame is found. This further reduces the startup delay by not
transferring data that will be discarded.
* You may want to adjust the MaxBandwidth in the avserver.conf to limit
the amount of bandwidth consumed by live streams.
Why does the ?buffer / Preroll stop working after a time?
It turns out that (on my machine at least) the number of frames
successfully grabbed is marginally less than the number that ought to
be grabbed. This means that the timestamp in the encoded data stream
gets behind realtime. This means that if you say 'Preroll 10', then
when the stream gets 10 or more seconds behind, there is no Preroll
left.
Fixing this requires a change in the internals of how timestamps are
handled.
Does the "?date=" stuff work.
Yes (subject to the limitation outlined above). Also note that whenever
you start avserver, it deletes the ffm file (if any parameters have
changed), thus wiping out what you had recorded before.
The format of the "?date=xxxxxx" is fairly flexible. You should use one
of the following formats (the 'T' is literal):
* YYYY-MM-DDTHH:MM:SS (localtime)
* YYYY-MM-DDTHH:MM:SSZ (UTC)
You can omit the YYYY-MM-DD, and then it refers to the current day.
However note that ?date=16:00:00 refers to 16:00 on the current day --
this may be in the future and so is unlikely to be useful.
You use this by adding the ?date= to the end of the URL for the stream.
For example: http://localhost:8080/test.asf?date=2002-07-26T23:05:00.
OPTIONS
All the numerical options, if not specified otherwise, accept in input
a string representing a number, which may contain one of the SI unit
prefixes, for example 'K', 'M', 'G'. If 'i' is appended after the
prefix, binary prefixes are used, which are based on powers of 1024
instead of powers of 1000. The 'B' postfix multiplies the value by 8,
and can be appended after a unit prefix or used alone. This allows
using for example 'KB', 'MiB', 'G' and 'B' as number postfix.
Options which do not take arguments are boolean options, and set the
corresponding value to true. They can be set to false by prefixing with
"no" the option name, for example using "-nofoo" in the command line
will set to false the boolean option with name "foo".
Stream specifiers
Some options are applied per-stream, e.g. bitrate or codec. Stream
specifiers are used to precisely specify which stream(s) does a given
option belong to.
A stream specifier is a string generally appended to the option name
and separated from it by a colon. E.g. "-codec:a:1 ac3" option contains
"a:1" stream specifer, which matches the second audio stream. Therefore
it would select the ac3 codec for the second audio stream.
A stream specifier can match several stream, the option is then applied
to all of them. E.g. the stream specifier in "-b:a 128k" matches all
audio streams.
An empty stream specifier matches all streams, for example "-codec
copy" or "-codec: copy" would copy all the streams without reencoding.
Possible forms of stream specifiers are:
stream_index
Matches the stream with this index. E.g. "-threads:1 4" would set
the thread count for the second stream to 4.
stream_type[:stream_index]
stream_type is one of: 'v' for video, 'a' for audio, 's' for
subtitle, 'd' for data and 't' for attachments. If stream_index is
given, then matches stream number stream_index of this type.
Otherwise matches all streams of this type.
p:program_id[:stream_index]
If stream_index is given, then matches stream number stream_index
in program with id program_id. Otherwise matches all streams in
this program.
Generic options
These options are shared amongst the av* tools.
-L Show license.
-h, -?, -help, --help [arg]
Show help. An optional parameter may be specified to print help
about a specific item.
Possible values of arg are:
decoder=decoder_name
Print detailed information about the decoder named
decoder_name. Use the -decoders option to get a list of all
decoders.
encoder=encoder_name
Print detailed information about the encoder named
encoder_name. Use the -encoders option to get a list of all
encoders.
demuxer=demuxer_name
Print detailed information about the demuxer named
demuxer_name. Use the -formats option to get a list of all
demuxers and muxers.
muxer=muxer_name
Print detailed information about the muxer named muxer_name.
Use the -formats option to get a list of all muxers and
demuxers.
-version
Show version.
-formats
Show available formats.
The fields preceding the format names have the following meanings:
D Decoding available
E Encoding available
-codecs
Show all codecs known to libavcodec.
Note that the term 'codec' is used throughout this documentation as
a shortcut for what is more correctly called a media bitstream
format.
-decoders
Show available decoders.
-encoders
Show all available encoders.
-bsfs
Show available bitstream filters.
-protocols
Show available protocols.
-filters
Show available libavfilter filters.
-pix_fmts
Show available pixel formats.
-sample_fmts
Show available sample formats.
-loglevel loglevel | -v loglevel
Set the logging level used by the library. loglevel is a number or
a string containing one of the following values:
quiet
panic
fatal
error
warning
info
verbose
debug
By default the program logs to stderr, if coloring is supported by
the terminal, colors are used to mark errors and warnings. Log
coloring can be disabled setting the environment variable
AV_LOG_FORCE_NOCOLOR or NO_COLOR, or can be forced setting the
environment variable AV_LOG_FORCE_COLOR. The use of the
environment variable NO_COLOR is deprecated and will be dropped in
a following Libav version.
AVOptions
These options are provided directly by the libavformat, libavdevice and
libavcodec libraries. To see the list of available AVOptions, use the
-help option. They are separated into two categories:
generic
These options can be set for any container, codec or device.
Generic options are listed under AVFormatContext options for
containers/devices and under AVCodecContext options for codecs.
private
These options are specific to the given container, device or codec.
Private options are listed under their corresponding
containers/devices/codecs.
For example to write an ID3v2.3 header instead of a default ID3v2.4 to
an MP3 file, use the id3v2_version private option of the MP3 muxer:
avconv -i input.flac -id3v2_version 3 out.mp3
All codec AVOptions are obviously per-stream, so the chapter on stream
specifiers applies to them
Note -nooption syntax cannot be used for boolean AVOptions, use -option
0/-option 1.
Note2 old undocumented way of specifying per-stream AVOptions by
prepending v/a/s to the options name is now obsolete and will be
removed soon.
Codec AVOptions
-b[:stream_specifier] integer (output,audio,video)
set bitrate (in bits/s)
-bt[:stream_specifier] integer (output,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
minimum/maximum bitrate. Lowering tolerance too much has an adverse
effect on quality.
-flags[:stream_specifier] flags (input/output,audio,video)
Possible values:
mv4 use four motion vectors per macroblock (MPEG-4)
qpel
use 1/4-pel motion compensation
loop
use loop filter
qscale
use fixed qscale
gmc use gmc
mv0 always try a mb with mv=<0,0>
input_preserved
pass1
use internal 2-pass ratecontrol in first pass mode
pass2
use internal 2-pass ratecontrol in second pass mode
gray
only decode/encode grayscale
emu_edge
do not draw edges
psnr
error[?] variables will be set during encoding
truncated
naq normalize adaptive quantization
ildct
use interlaced DCT
low_delay
force low delay
global_header
place global headers in extradata instead of every keyframe
bitexact
use only bitexact functions (except (I)DCT)
aic H.263 advanced intra coding / MPEG-4 AC prediction
cbp Deprecated, use mpegvideo private options instead
qprd
Deprecated, use mpegvideo private options instead
ilme
interlaced motion estimation
cgop
closed GOP
-sub_id[:stream_specifier] integer ()
-me_method[:stream_specifier] integer (output,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 diamond 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[:stream_specifier] integer ()
-time_base[:stream_specifier] rational number ()
-g[:stream_specifier] integer (output,video)
set the group of picture (GOP) size
-ar[:stream_specifier] integer (input/output,audio)
set audio sampling rate (in Hz)
-ac[:stream_specifier] integer (input/output,audio)
set number of audio channels
-cutoff[:stream_specifier] integer (output,audio)
set cutoff bandwidth
-frame_size[:stream_specifier] integer (output,audio)
-frame_number[:stream_specifier] integer ()
-delay[:stream_specifier] integer ()
-qcomp[:stream_specifier] float (output,video)
video quantizer scale compression (VBR). Constant of ratecontrol
equation. Recommended range for default rc_eq: 0.0-1.0
-qblur[:stream_specifier] float (output,video)
video quantizer scale blur (VBR)
-qmin[:stream_specifier] integer (output,video)
minimum video quantizer scale (VBR)
-qmax[:stream_specifier] integer (output,video)
maximum video quantizer scale (VBR)
-qdiff[:stream_specifier] integer (output,video)
maximum difference between the quantizer scales (VBR)
-bf[:stream_specifier] integer (output,video)
use 'frames' B frames
-b_qfactor[:stream_specifier] float (output,video)
QP factor between P- and B-frames
-rc_strategy[:stream_specifier] integer (output,video)
ratecontrol method
-b_strategy[:stream_specifier] integer (output,video)
strategy to choose between I/P/B-frames
-ps[:stream_specifier] integer (output,video)
RTP payload size in bytes
-mv_bits[:stream_specifier] integer ()
-header_bits[:stream_specifier] integer ()
-i_tex_bits[:stream_specifier] integer ()
-p_tex_bits[:stream_specifier] integer ()
-i_count[:stream_specifier] integer ()
-p_count[:stream_specifier] integer ()
-skip_count[:stream_specifier] integer ()
-misc_bits[:stream_specifier] integer ()
-frame_bits[:stream_specifier] integer ()
-codec_tag[:stream_specifier] integer ()
-bug[:stream_specifier] flags (input,video)
work around not autodetected 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 work around various bugs in Microsoft's broken decoders
trunc
truncated frames
-lelim[:stream_specifier] integer (output,video)
single coefficient elimination threshold for luminance (negative
values also consider DC coefficient)
-celim[:stream_specifier] integer (output,video)
single coefficient elimination threshold for chrominance (negative
values also consider DC coefficient)
-strict[:stream_specifier] integer (input/output,audio,video)
how strictly to follow the standards
Possible values:
very
strictly conform to a older more strict version of the spec or
reference software
strict
strictly conform to all the things in the spec no matter what
the consequences
normal
unofficial
allow unofficial extensions
experimental
allow non-standardized experimental things
-b_qoffset[:stream_specifier] float (output,video)
QP offset between P- and B-frames
-err_detect[:stream_specifier] flags (input,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
-has_b_frames[:stream_specifier] integer ()
-block_align[:stream_specifier] integer ()
-mpeg_quant[:stream_specifier] integer (output,video)
use MPEG quantizers instead of H.263
-qsquish[:stream_specifier] float (output,video)
how to keep quantizer between qmin and qmax (0 = clip, 1 = use
differentiable function)
-rc_qmod_amp[:stream_specifier] float (output,video)
experimental quantizer modulation
-rc_qmod_freq[:stream_specifier] integer (output,video)
experimental quantizer modulation
-rc_override_count[:stream_specifier] integer ()
-rc_eq[:stream_specifier] string (output,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[:stream_specifier] integer (output,audio,video)
Set maximum bitrate tolerance (in bits/s). Requires bufsize to be
set.
-minrate[:stream_specifier] integer (output,audio,video)
Set minimum bitrate tolerance (in bits/s). Most useful in setting
up a CBR encode. It is of little use otherwise.
-bufsize[:stream_specifier] integer (output,audio,video)
set ratecontrol buffer size (in bits)
-rc_buf_aggressivity[:stream_specifier] float (output,video)
currently useless
-i_qfactor[:stream_specifier] float (output,video)
QP factor between P- and I-frames
-i_qoffset[:stream_specifier] float (output,video)
QP offset between P- and I-frames
-rc_init_cplx[:stream_specifier] float (output,video)
initial complexity for 1-pass encoding
-dct[:stream_specifier] integer (output,video)
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[:stream_specifier] float (output,video)
compresses bright areas stronger than medium ones
-tcplx_mask[:stream_specifier] float (output,video)
temporal complexity masking
-scplx_mask[:stream_specifier] float (output,video)
spatial complexity masking
-p_mask[:stream_specifier] float (output,video)
inter masking
-dark_mask[:stream_specifier] float (output,video)
compresses dark areas stronger than medium ones
-idct[:stream_specifier] integer (input/output,video)
select IDCT implementation
Possible values:
auto
int
simple
simplemmx
mmi
arm
altivec
sh4
simplearm
simplearmv5te
simplearmv6
simpleneon
simplealpha
h264
vp3
ipp
xvidmmx
faani
floating point AAN IDCT
-slice_count[:stream_specifier] integer ()
-ec[:stream_specifier] flags (input,video)
set error concealment strategy
Possible values:
guess_mvs
iterative motion vector (MV) search (slow)
deblock
use strong deblock filter for damaged MBs
-bits_per_coded_sample[:stream_specifier] integer ()
-pred[:stream_specifier] integer (output,video)
prediction method
Possible values:
left
plane
median
-aspect[:stream_specifier] rational number (output,video)
sample aspect ratio
-debug[:stream_specifier] flags (input/output,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)
mv motion vector
dct_coeff
skip
startcode
pts
er error recognition
mmco
memory management control operations (H.264)
bugs
vis_qp
visualize quantization parameter (QP), lower QP are tinted
greener
vis_mb_type
visualize block types
buffers
picture buffer allocations
thread_ops
threading operations
-vismv[:stream_specifier] integer (input,video)
visualize motion vectors (MVs)
Possible values:
pf forward predicted MVs of P-frames
bf forward predicted MVs of B-frames
bb backward predicted MVs of B-frames
-cmp[:stream_specifier] integer (output,video)
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
dctmax
chroma
-subcmp[:stream_specifier] integer (output,video)
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
dctmax
chroma
-mbcmp[:stream_specifier] integer (output,video)
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
dctmax
chroma
-ildctcmp[:stream_specifier] integer (output,video)
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
dctmax
chroma
-dia_size[:stream_specifier] integer (output,video)
diamond type & size for motion estimation
-last_pred[:stream_specifier] integer (output,video)
amount of motion predictors from the previous frame
-preme[:stream_specifier] integer (output,video)
pre motion estimation
-precmp[:stream_specifier] integer (output,video)
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
dctmax
chroma
-pre_dia_size[:stream_specifier] integer (output,video)
diamond type & size for motion estimation pre-pass
-subq[:stream_specifier] integer (output,video)
sub-pel motion estimation quality
-dtg_active_format[:stream_specifier] integer ()
-me_range[:stream_specifier] integer (output,video)
limit motion vectors range (1023 for DivX player)
-ibias[:stream_specifier] integer (output,video)
intra quant bias
-pbias[:stream_specifier] integer (output,video)
inter quant bias
-color_table_id[:stream_specifier] integer ()
-global_quality[:stream_specifier] integer (output,audio,video)
-coder[:stream_specifier] integer (output,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[:stream_specifier] integer (output,video)
context model
-slice_flags[:stream_specifier] integer ()
-xvmc_acceleration[:stream_specifier] integer ()
-mbd[:stream_specifier] integer (output,video)
macroblock decision algorithm (high quality mode)
Possible values:
simple
use mbcmp (default)
bits
use fewest bits
rd use best rate distortion
-stream_codec_tag[:stream_specifier] integer ()
-sc_threshold[:stream_specifier] integer (output,video)
scene change threshold
-lmin[:stream_specifier] integer (output,video)
minimum Lagrange factor (VBR)
-lmax[:stream_specifier] integer (output,video)
maximum Lagrange factor (VBR)
-nr[:stream_specifier] integer (output,video)
noise reduction
-rc_init_occupancy[:stream_specifier] integer (output,video)
number of bits which should be loaded into the rc buffer before
decoding starts
-inter_threshold[:stream_specifier] integer (output,video)
-flags2[:stream_specifier] flags (input/output,audio,video)
Possible values:
fast
allow non-spec-compliant speedup tricks
sgop
Deprecated, use mpegvideo private options instead
noout
skip bitstream encoding
local_header
place global headers at every keyframe instead of in extradata
skiprd
Deprecated, use mpegvideo private options instead
-error[:stream_specifier] integer (output,video)
-qns[:stream_specifier] integer (output,video)
deprecated, use mpegvideo private options instead
-threads[:stream_specifier] integer (input/output,video)
Possible values:
auto
autodetect a suitable number of threads to use
-me_threshold[:stream_specifier] integer (output,video)
motion estimation threshold
-mb_threshold[:stream_specifier] integer (output,video)
macroblock threshold
-dc[:stream_specifier] integer (output,video)
intra_dc_precision
-nssew[:stream_specifier] integer (output,video)
nsse weight
-skip_top[:stream_specifier] integer (input,video)
number of macroblock rows at the top which are skipped
-skip_bottom[:stream_specifier] integer (input,video)
number of macroblock rows at the bottom which are skipped
-profile[:stream_specifier] integer (output,audio,video)
Possible values:
unknown
aac_main
aac_low
aac_ssr
aac_ltp
aac_he
aac_he_v2
aac_ld
aac_eld
dts
dts_es
dts_96_24
dts_hd_hra
dts_hd_ma
-level[:stream_specifier] integer (output,audio,video)
Possible values:
unknown
-skip_threshold[:stream_specifier] integer (output,video)
frame skip threshold
-skip_factor[:stream_specifier] integer (output,video)
frame skip factor
-skip_exp[:stream_specifier] integer (output,video)
frame skip exponent
-skipcmp[:stream_specifier] integer (output,video)
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
dctmax
chroma
-border_mask[:stream_specifier] float (output,video)
increase the quantizer for macroblocks close to borders
-mblmin[:stream_specifier] integer (output,video)
minimum macroblock Lagrange factor (VBR)
-mblmax[:stream_specifier] integer (output,video)
maximum macroblock Lagrange factor (VBR)
-mepc[:stream_specifier] integer (output,video)
motion estimation bitrate penalty compensation (1.0 = 256)
-skip_loop_filter[:stream_specifier] integer (input,video)
Possible values:
none
default
noref
bidir
nokey
all
-skip_idct[:stream_specifier] integer (input,video)
Possible values:
none
default
noref
bidir
nokey
all
-skip_frame[:stream_specifier] integer (input,video)
Possible values:
none
default
noref
bidir
nokey
all
-bidir_refine[:stream_specifier] integer (output,video)
refine the two motion vectors used in bidirectional macroblocks
-brd_scale[:stream_specifier] integer (output,video)
downscale frames for dynamic B-frame decision
-keyint_min[:stream_specifier] integer (output,video)
minimum interval between IDR-frames (x264)
-refs[:stream_specifier] integer (output,video)
reference frames to consider for motion compensation
-chromaoffset[:stream_specifier] integer (output,video)
chroma QP offset from luma
-trellis[:stream_specifier] integer (output,audio,video)
rate-distortion optimal quantization
-sc_factor[:stream_specifier] integer (output,video)
multiplied by qscale for each frame and added to scene_change_score
-mv0_threshold[:stream_specifier] integer (output,video)
-b_sensitivity[:stream_specifier] integer (output,video)
adjust sensitivity of b_frame_strategy 1
-compression_level[:stream_specifier] integer (output,audio,video)
-min_prediction_order[:stream_specifier] integer (output,audio)
-max_prediction_order[:stream_specifier] integer (output,audio)
-timecode_frame_start[:stream_specifier] integer (output,video)
GOP timecode frame start number, in non-drop-frame format
-request_channels[:stream_specifier] integer (input,audio)
set desired number of audio channels
-bits_per_raw_sample[:stream_specifier] integer ()
-channel_layout[:stream_specifier] integer (input/output,audio)
Possible values:
-request_channel_layout[:stream_specifier] integer (input,audio)
Possible values:
-rc_max_vbv_use[:stream_specifier] float (output,video)
-rc_min_vbv_use[:stream_specifier] float (output,video)
-ticks_per_frame[:stream_specifier] integer (input/output,audio,video)
-color_primaries[:stream_specifier] integer (input/output,video)
-color_trc[:stream_specifier] integer (input/output,video)
-colorspace[:stream_specifier] integer (input/output,video)
-color_range[:stream_specifier] integer (input/output,video)
-chroma_sample_location[:stream_specifier] integer (input/output,video)
-log_level_offset[:stream_specifier] integer ()
set the log level offset
-slices[:stream_specifier] integer (output,video)
number of slices, used in parallelized encoding
-thread_type[:stream_specifier] flags (input/output,video)
select multithreading type
Possible values:
slice
frame
-audio_service_type[:stream_specifier] integer (output,audio)
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[:stream_specifier] integer (input,audio)
Possible values:
u8 8-bit unsigned integer
s16 16-bit signed integer
s32 32-bit signed integer
flt 32-bit float
dbl 64-bit double
u8p 8-bit unsigned integer planar
s16p
16-bit signed integer planar
s32p
32-bit signed integer planar
fltp
32-bit float planar
dblp
64-bit double planar
Format AVOptions
-probesize integer (input)
set probing size
-packetsize integer (output)
set packet size
-fflags flags (input/output)
Possible values:
ignidx
ignore index
genpts
generate pts
nofillin
do not fill in missing values that can be exactly calculated
noparse
disable AVParsers, this needs nofillin too
igndts
ignore dts
discardcorrupt
discard corrupted frames
nobuffer
reduce the latency introduced by optional buffering
-analyzeduration integer (input)
how many microseconds are analyzed to estimate duration
-cryptokey hexadecimal string (input)
decryption key
-indexmem integer (input)
max memory used for timestamp index (per stream)
-rtbufsize integer (input)
max memory used for buffering real-time frames
-fdebug flags (input/output)
print specific debug info
Possible values:
ts
-max_delay integer (input/output)
maximum muxing or demuxing delay in microseconds
-fpsprobesize integer (input)
number of frames used to probe fps
-f_err_detect flags (input)
set error detection flags (deprecated; use err_detect, save via
avconv)
Possible values:
crccheck
verify embedded CRCs
bitstream
detect bitstream specification deviations
buffer
detect improper bitstream length
explode
abort decoding on minor error detection
-err_detect flags (input)
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
Main options
-f configfile
Use configfile instead of /etc/avserver.conf.
-n Enable no-launch mode. This option disables all the Launch
directives within the various <Stream> sections. Since avserver
will not launch any avconv instances, you will have to launch them
manually.
-d Enable debug mode. This option increases log verbosity, directs log
messages to stdout.
SEE ALSO
avconv(1), avplay(1), avprobe(1), the avserver.conf example and the
Libav HTML documentation
AUTHORS
The Libav developers
2014-03-24 AVSERVER(1)