avserver Documentation

Table of Contents

1. Synopsys

The generic syntax is:

 
avserver [options]

2. 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.

2.1 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.

2.2 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.

2.3 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.

2.4 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.

2.5 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.

2.6 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.

2.7 Troubleshooting

2.7.1 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.

2.7.2 The audio and video lose sync after a while.

Yes, they do.

2.7.3 After a long while, the video update rate goes way down in WMP.

Yes, it does. Who knows why?

2.7.4 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].

2.8 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.]

2.9 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.

2.10 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.

2.11 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’.

3. 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".

3.1 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.

3.2 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.

3.3 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.

3.4 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

3.5 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

3.6 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.