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.
- filter=filter_name
- Print detailed information about the filter name
filter_name. Use the -filters option to get a list of all
filters.
- -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.
- -cpuflags mask (global)
- Set a mask that's applied to autodetected CPU flags. This
option is intended for testing. Do not use it unless you know what you're
doing.
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:
- unaligned
- allow decoders to produce unaligned output
- 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
- ilme
- interlaced motion estimation
- cgop
- closed GOP
- output_corrupt
- Output even potentially corrupted frames
- -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
- -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)
- -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
- -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
- -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
- -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_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
- arm
- altivec
- sh4
- simplearm
- simplearmv5te
- simplearmv6
- simpleneon
- simplealpha
- ipp
- xvidmmx
- faani
- floating point AAN IDCT
- -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
- -pred[:stream_specifier] integer
(output,video )
- prediction method
Possible values:
- -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
- -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
- -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
- -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
- -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
- -flags2[:stream_specifier] flags
(input/output,audio,video )
- Possible values:
- fast
- allow non-spec-compliant speedup tricks
- noout
- skip bitstream encoding
- ignorecrop
- ignore cropping information from sps
- local_header
- place global headers at every keyframe instead of in
extradata
- -error[:stream_specifier] integer
(output,video )
- -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
- mpeg2_aac_low
- mpeg2_aac_he
- dts
- dts_es
- dts_96_24
- dts_hd_hra
- dts_hd_ma
- -level[:stream_specifier] integer
(output,audio,video )
- Possible values:
- -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
- -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)
- -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:
- -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
- -refcounted_frames[:stream_specifier] integer
(input,audio,video)
- -probesize integer
(input)
- set probing size
- -packetsize integer
(output)
- set packet size
- -fflags flags
(input/output)
- Possible values:
- flush_packets
- reduce the latency by flushing out packets immediately
- 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:
- -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
- -max_interleave_delta integer
(output )
- maximum buffering duration for interleaving
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