PeerStreamer

\input texinfo @c -*- texinfo -*-

@settitle FFmpeg Documentation

@titlepage

@sp 7

@center @titlefont{FFmpeg Documentation}

@sp 3

@end titlepage

@chapter Introduction

FFmpeg is a very fast video and audio converter. It can also grab from

a live audio/video source.

The command line interface is designed to be intuitive, in the sense

that ffmpeg tries to figure out all the parameters, when

possible. You have usually to give only the target bitrate you want.

FFmpeg can also convert from any sample rate to any other, and resize

video on the fly with a high quality polyphase filter.

@chapter Quick Start

@c man begin EXAMPLES

@section Video and Audio grabbing

FFmpeg can use a video4linux compatible video source and any Open Sound

System audio source:

@example

ffmpeg /tmp/out.mpg 

@end example

Note that you must activate the right video source and channel before

launching ffmpeg. You can use any TV viewer such as xawtv

(@url{http://bytesex.org/xawtv/}) by Gerd Knorr which I find very

good. You must also set correctly the audio recording levels with a

standard mixer.

@section Video and Audio file format conversion

* ffmpeg can use any supported file format and protocol as input: 

Examples:

* You can input from YUV files:

@example

ffmpeg -i /tmp/test%d.Y /tmp/out.mpg 

@end example

It will use the files: 

@example

/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,

/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...

@end example

The Y files use twice the resolution of the U and V files. They are

raw files, without header. They can be generated by all decent video

decoders. You must specify the size of the image with the @option{-s} option

if ffmpeg cannot guess it.

* You can input from a RAW YUV420P file:

@example

ffmpeg -i /tmp/test.yuv /tmp/out.avi

@end example

The RAW YUV420P is a file containing RAW YUV planar, for each frame first

come the Y plane followed by U and V planes, which are half vertical and

horizontal resolution.

* You can output to a RAW YUV420P file:

@example

ffmpeg -i mydivx.avi -o hugefile.yuv

@end example

* You can set several input files and output files:

@example

ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg

@end example

Convert the audio file a.wav and the raw yuv video file a.yuv

to mpeg file a.mpg

* You can also do audio and video conversions at the same time:

@example

ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2

@end example

Convert the sample rate of a.wav to 22050 Hz and encode it to MPEG audio.

* You can encode to several formats at the same time and define a

mapping from input stream to output streams:

@example

ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0

@end example

Convert a.wav to a.mp2 at 64 kbits and b.mp2 at 128 kbits. '-map

file:index' specify which input stream is used for each output

stream, in the order of the definition of output streams.

* You can transcode decrypted VOBs

@example

ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800 -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi

@end example

This is a typical DVD ripper example, input from a VOB file, output

to an AVI file with MPEG-4 video and MP3 audio, note that in this

command we use B frames so the MPEG-4 stream is DivX5 compatible, GOP

size is 300 that means an INTRA frame every 10 seconds for 29.97 fps

input video.  Also the audio stream is MP3 encoded so you need LAME

support which is enabled using @code{--enable-mp3lame} when

configuring.  The mapping is particularly useful for DVD transcoding

to get the desired audio language.

NOTE: to see the supported input formats, use @code{ffmpeg -formats}.

@c man end

@chapter Invocation

@section Syntax

The generic syntax is:

@example 

@c man begin SYNOPSIS

ffmpeg [[options][@option{-i} @var{input_file}]]... @{[options] @var{output_file}@}...

@c man end

@end example

@c man begin DESCRIPTION

If no input file is given, audio/video grabbing is done.

As a general rule, options are applied to the next specified

file. For example, if you give the @option{-b 64} option, it sets the video

bitrate of the next file. Format option may be needed for raw input

files.

By default, ffmpeg tries to convert as losslessly as possible: it

uses the same audio and video parameter for the outputs as the one

specified for the inputs.

@c man end

@c man begin OPTIONS

@section Main options

@table @option

@item -L

show license

@item -h

show help

@item -formats

show available formats, codecs, protocols, ...

@item -f fmt              

force format

@item -i filename         

input file name

@item -y                  

overwrite output files

@item -t duration         

set the recording time in seconds. @code{hh:mm:ss[.xxx]} syntax is also

supported.

@item -title string       

set the title

@item -author string      

set the author

@item -copyright string   

set the copyright

@item -comment string     

set the comment

@item -hq                 

activate high quality settings

@end table

@section Video Options

@table @option

@item -b bitrate

set the video bitrate in kbit/s (default = 200 kb/s)

@item -r fps           

set frame rate (default = 25)

@item -s size             

set frame size. The format is @samp{WxH} (default 160x128).  The

following abbreviations are recognized:

@table @samp

@item sqcif

128x96

@item qcif

176x144

@item cif

352x288

@item 4cif

704x576

@end table

@item -aspect aspect

set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)

@item -croptop size

set top crop band size (in pixels)

@item -cropbottom size

set bottom crop band size (in pixels)

@item -cropleft size

set left crop band size (in pixels)

@item -cropright size

set right crop band size (in pixels)

@item -vn

disable video recording

@item -bt tolerance       

set video bitrate tolerance (in kbit/s)

@item -maxrate bitrate

set max video bitrate tolerance (in kbit/s)

@item -minrate bitrate

set min video bitrate tolerance (in kbit/s)

@item -bufsize size

set ratecontrol buffere size (in kbit)

@item -vcodec codec       

force video codec to @var{codec}. Use the @code{copy} special value to

tell that the raw codec data must be copied as is.

@item -sameq

use same video quality as source (implies VBR)

@item -pass n  

select the pass number (1 or 2). It is useful to do two pass

encoding. The statistics of the video are recorded in the first pass and

the video at the exact requested bit rate is generated in the second

pass.

@item -passlogfile file   

select two pass log file name to @var{file}.

@end table

@section Advanced Video Options

@table @option

@item -g gop_size         

set the group of picture size

@item -intra              

use only intra frames

@item -qscale q           

use fixed video quantiser scale (VBR)

@item -qmin q             

min video quantiser scale (VBR)

@item -qmax q             

max video quantiser scale (VBR)

@item -qdiff q            

max difference between the quantiser scale (VBR)

@item -qblur blur         

video quantiser scale blur (VBR)

@item -qcomp compression  

video quantiser scale compression (VBR)

@item -rc_init_cplx complexity

initial complexity for 1-pass encoding

@item -b_qfactor factor

qp factor between p and b frames

@item -i_qfactor factor

qp factor between p and i frames

@item -b_qoffset offset

qp offset between p and b frames

@item -i_qoffset offset

qp offset between p and i frames

@item -rc_eq equation

set rate control equation (@pxref{FFmpeg formula

evaluator}). Default is @code{tex^qComp}.

@item -rc_override override

rate control override for specific intervals

@item -me method

set motion estimation method to @var{method}. Available methods are

(from lower to best quality):

@table @samp

@item zero

Try just the (0, 0) vector.

@item phods

@item log

@item x1

@item epzs

(default method)

@item full

exhaustive search (slow and marginally better than epzs)

@end table

@item -dct_algo algo

set dct algorithm to @var{algo}. Available values are:

@table @samp

@item 0

FF_DCT_AUTO (default)

@item 1

FF_DCT_FASTINT

@item 2

FF_DCT_INT

@item 3

FF_DCT_MMX

@item 4

FF_DCT_MLIB

@item 5

FF_DCT_ALTIVEC

@end table

@item -idct_algo algo

set idct algorithm to @var{algo}. Available values are:

@table @samp

@item 0

FF_IDCT_AUTO (default)

@item 1

FF_IDCT_INT          

@item 2

FF_IDCT_SIMPLE       

@item 3

FF_IDCT_SIMPLEMMX    

@item 4

FF_IDCT_LIBMPEG2MMX  

@item 5

FF_IDCT_PS2          

@item 6

FF_IDCT_MLIB         

@item 7

FF_IDCT_ARM          

@item 8

FF_IDCT_ALTIVEC      

@item 9

FF_IDCT_SH4          

@item 10

FF_IDCT_SIMPLEARM    

@end table

@item -er n

set error resilience to @var{n}.

@table @samp

@item 1 

FF_ER_CAREFULL (default)

@item 2

FF_ER_COMPLIANT

@item 3

FF_ER_AGGRESSIVE

@item 4

FF_ER_VERY_AGGRESSIVE

@end table

@item -ec bit_mask

set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of

the following values:

@table @samp

@item 1

FF_EC_GUESS_MVS (default=enabled)

@item 2

FF_EC_DEBLOCK (default=enabled)

@end table

@item -bf frames

use 'frames' B frames (supported for MPEG-1, MPEG-2 and MPEG-4)

@item -mbd mode

macroblock decision

@table @samp

@item 0

FF_MB_DECISION_SIMPLE: use mb_cmp (cannot change it yet in ffmpeg)

@item 1

FF_MB_DECISION_BITS: chooses the one which needs the fewest bits

@item 2

FF_MB_DECISION_RD: rate distoration

@end table

@item -4mv

use four motion vector by macroblock (only MPEG-4)

@item -part

use data partitioning (only MPEG-4)

@item -bug param

workaround not auto detected encoder bugs

@item -strict strictness

how strictly to follow the standarts

@item -aic

enable Advanced intra coding (h263+)

@item -umv

enable Unlimited Motion Vector (h263+)

@item -deinterlace

deinterlace pictures

@item -psnr

calculate PSNR of compressed frames

@item -vstats

dump video coding statistics to @file{vstats_HHMMSS.log}.

@item -vhook module

insert video processing @var{module}. @var{module} contains the module

name and its parameters separated by spaces.

@end table

@section Audio Options

@table @option

@item -ab bitrate         

set audio bitrate (in kbit/s)

@item -ar freq    

set the audio sampling freq (default = 44100 Hz)

@item -ab bitrate 

set the audio bitrate in kbit/s (default = 64)

@item -ac channels

set the number of audio channels (default = 1)

@item -an

disable audio recording

@item -acodec codec

force audio codec to @var{codec}. Use the @code{copy} special value to

tell that the raw codec data must be copied as is.

@end table

@section Audio/Video grab options

@table @option

@item -vd device

set video grab device (e.g. @file{/dev/video0})

@item -vc channel

set video grab channel (DV1394 only)

@item -tvstd standard

set television standard (NTSC, PAL (SECAM))

@item -dv1394

set DV1394 grab

@item -ad device

set audio device (e.g. @file{/dev/dsp})

@end table

@section Advanced options

@table @option

@item -map file:stream    

set input stream mapping

@item -debug

print specific debug info

@item -benchmark          

add timings for benchmarking

@item -hex                

dump each input packet

@item -bitexact

only use bit exact algorithms (for codec testing)

@item -ps size

set packet size in bits

@item -re

read input at native frame rate. Mainly used to simulate a grab device.

@item -loop

loop over the input stream. Currently it works only for image

streams. This option is used for ffserver automatic testing.

@end table

@node FFmpeg formula evaluator

@section FFmpeg formula evaluator

When evaluating a rate control string, FFmpeg uses an internal formula

evaluator. 

The following binary operators are available: @code{+}, @code{-},

@code{*}, @code{/}, @code{^}.

The following unary operators are available: @code{+}, @code{-},

@code{(...)}.

The following functions are available:

@table @var

@item sinh(x)

@item cosh(x)

@item tanh(x)

@item sin(x)

@item cos(x)

@item tan(x)

@item exp(x)

@item log(x)

@item squish(x)

@item gauss(x)

@item abs(x)

@item max(x, y)

@item min(x, y)

@item gt(x, y)

@item lt(x, y)

@item eq(x, y)

@item bits2qp(bits)

@item qp2bits(qp)

@end table

The following constants are available:

@table @var

@item PI

@item E

@item iTex

@item pTex

@item tex

@item mv

@item fCode

@item iCount

@item mcVar

@item var

@item isI

@item isP

@item isB

@item avgQP

@item qComp

@item avgIITex

@item avgPITex

@item avgPPTex

@item avgBPTex

@item avgTex

@end table

@c man end

@ignore

@setfilename ffmpeg

@settitle FFmpeg video converter

@c man begin SEEALSO

ffserver(1), ffplay(1) and the html documentation of @file{ffmpeg}.

@c man end

@c man begin AUTHOR

Fabrice Bellard

@c man end

@end ignore

@section Protocols

The filename can be @file{-} to read from the standard input or to write

to the standard output.

ffmpeg handles also many protocols specified with the URL syntax.

Use 'ffmpeg -formats' to have a list of the supported protocols.

The protocol @code{http:} is currently used only to communicate with

ffserver (see the ffserver documentation). When ffmpeg will be a

video player it will also be used for streaming :-)

@chapter Tips

@itemize

@item For streaming at very low bit rate application, use a low frame rate

and a small gop size. This is especially true for real video where

the Linux player does not seem to be very fast, so it can miss

frames. An example is:

@example

ffmpeg -g 3 -r 3 -t 10 -b 50 -s qcif -f rv10 /tmp/b.rm

@end example

@item  The parameter 'q' which is displayed while encoding is the current

quantizer. The value of 1 indicates that a very good quality could

be achieved. The value of 31 indicates the worst quality. If q=31

too often, it means that the encoder cannot compress enough to meet

your bit rate. You must either increase the bit rate, decrease the

frame rate or decrease the frame size.

@item If your computer is not fast enough, you can speed up the

compression at the expense of the compression ratio. You can use

'-me zero' to speed up motion estimation, and '-intra' to disable

completely motion estimation (you have only I frames, which means it

is about as good as JPEG compression).

@item To have very low bitrates in audio, reduce the sampling frequency

(down to 22050 kHz for mpeg audio, 22050 or 11025 for ac3).

@item To have a constant quality (but a variable bitrate), use the option

'-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst

quality).

@item When converting video files, you can use the '-sameq' option which

uses in the encoder the same quality factor than in the decoder. It

allows to be almost lossless in encoding.

@end itemize

@chapter Supported File Formats and Codecs

You can use the @code{-formats} option to have an exhaustive list.

@section File Formats

FFmpeg supports the following file formats through the @code{libavformat}

library:

@multitable @columnfractions .4 .1 .1

@item Supported File Format @tab Encoding @tab Decoding @tab Comments

@item MPEG audio @tab X @tab X

@item MPEG1 systems @tab X  @tab  X 

@tab muxed audio and video

@item MPEG2 PS @tab X  @tab  X 

@tab also known as @code{VOB} file

@item MPEG2 TS @tab    @tab  X 

@tab also known as DVB Transport Stream

@item ASF@tab X @tab X 

@item AVI@tab X @tab X 

@item WAV@tab X @tab X 

@item Macromedia Flash@tab X @tab X

@tab Only embedded audio is decoded

@item FLV              @tab  X @tab X

@tab Macromedia Flash video files

@item Real Audio and Video @tab X @tab X 

@item Raw AC3 @tab X  @tab  X 

@item Raw MJPEG @tab X  @tab  X 

@item Raw MPEG video @tab X  @tab  X 

@item Raw PCM8/16 bits, mulaw/Alaw@tab X  @tab  X 

@item SUN AU format @tab X  @tab  X 

@item Quicktime        @tab X @tab  X 

@item MPEG4            @tab X @tab  X 

@tab MPEG4 is a variant of Quicktime

@item Raw MPEG4 video  @tab  X @tab  X 

@item DV               @tab  X @tab  X

@item 4xm              @tab    @tab X

@tab 4X Technologies format, used in some games

@item Playstation STR  @tab    @tab X

@item Id RoQ           @tab    @tab X

@tab used in Quake III, Jedi Knight 2, other computer games

@item Interplay MVE    @tab    @tab X

@tab format used in various Interplay computer games

@item WC3 Movie        @tab    @tab X

@tab multimedia format used in Origin's Wing Commander III computer game

@item Sega FILM/CPK    @tab    @tab X

@tab used in many Sega Saturn console games

@item Westwood Studios VQA/AUD  @tab    @tab X

@tab Multimedia formats used in Westwood Studios games

@end multitable

@code{X} means that the encoding (resp. decoding) is supported.

@section Image Formats

FFmpeg can read and write images for each frame of a video sequence. The

following image formats are supported:

@multitable @columnfractions .4 .1 .1

@item Supported Image Format @tab Encoding @tab Decoding @tab Comments

@item PGM, PPM     @tab X @tab X 

@item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support

@item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0

@item JPEG         @tab X @tab X @tab Progressive JPEG is not supported

@item .Y.U.V       @tab X @tab X @tab One raw file per component

@item Animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated

@item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet

@end multitable

@code{X} means that the encoding (resp. decoding) is supported.

@section Video Codecs

@multitable @columnfractions .4 .1 .1 .7

@item Supported Codec @tab Encoding @tab Decoding @tab Comments

@item MPEG1 video            @tab  X  @tab  X

@item MPEG2 video            @tab  X  @tab  X 

@item MPEG4                  @tab  X  @tab  X @tab Also known as DIVX4/5

@item MSMPEG4 V1             @tab  X  @tab  X

@item MSMPEG4 V2             @tab  X  @tab  X

@item MSMPEG4 V3             @tab  X  @tab  X @tab Also known as DIVX3

@item WMV7                   @tab  X  @tab  X

@item WMV8                   @tab  X  @tab  X @tab Not completely working

@item H263(+)                @tab  X  @tab  X @tab Also known as Real Video 1.0

@item MJPEG                  @tab  X  @tab  X 

@item DV                     @tab  X  @tab  X 

@item Huff YUV               @tab  X  @tab  X

@item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1

@item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2

@item Creative YUV           @tab     @tab  X @tab fourcc: CYUV

@item H.264                  @tab     @tab  X

@item Sorenson Video 1       @tab     @tab  X @tab fourcc: SVQ1

@item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3

@item On2 VP3                @tab     @tab  X @tab still experimental

@item Intel Indeo 3          @tab     @tab  X @tab only works on i386 right now

@item FLV                    @tab  X  @tab  X @tab Flash H263 variant

@item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1

@item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR

@item 4X Video               @tab     @tab  X @tab used in certain computer games

@item Sony Playstation MDEC  @tab     @tab  X 

@item Id RoQ                 @tab     @tab  X @tab used in Quake III, Jedi Knight 2, other computer games

@item Xan/WC3                @tab     @tab  X @tab used in Wing Commander III .MVE files

@item Interplay Video        @tab     @tab  X @tab used in Interplay .MVE files

@item Apple Video            @tab     @tab  X @tab fourcc: rpza

@item Cinepak                @tab     @tab  X

@item Microsoft RLE          @tab     @tab  X

@item Microsoft Video-1      @tab     @tab  X

@end multitable

@code{X} means that the encoding (resp. decoding) is supported.

Check at @url{http://www.mplayerhq.hu/~michael/codec-features.html} to

get a precise comparison of FFmpeg MPEG4 codec compared to the other

solutions.

@section Audio Codecs

@multitable @columnfractions .4 .1 .1 .1 .7

@item Supported Codec @tab Encoding @tab Decoding @tab Comments

@item MPEG audio layer 2     @tab  IX  @tab  IX 

@item MPEG audio layer 1/3   @tab IX   @tab  IX

@tab MP3 encoding is supported through the external library LAME

@item AC3                    @tab  IX  @tab  X

@tab liba52 is used internally for decoding

@item Vorbis                 @tab  X   @tab  X

@tab supported through the external library libvorbis

@item WMA V1/V2              @tab      @tab X

@item Microsoft ADPCM        @tab X    @tab X

@item MS IMA ADPCM           @tab X    @tab X

@item QT IMA ADPCM           @tab      @tab X

@item 4X IMA ADPCM           @tab      @tab X

@item Duck DK3 IMA ADPCM     @tab      @tab X

@tab used in some Sega Saturn console games

@item Duck DK4 IMA ADPCM     @tab      @tab X

@tab used in some Sega Saturn console games

@item Westwood Studios IMA ADPCM @tab      @tab X

@tab used in Westwood Studios games likes Command and Conquer

@item RA144                  @tab      @tab X

@tab Real 14400 bit/s codec

@item RA288                  @tab      @tab X

@tab Real 28800 bit/s codec

@item AMR-NB                 @tab X    @tab X

@tab supported through an external library

@item AMR-WB                 @tab X    @tab X

@tab supported through an external library

@item DV audio               @tab      @tab X

@item Id RoQ DPCM            @tab      @tab X

@tab used in Quake III, Jedi Knight 2, other computer games

@item Interplay MVE DPCM     @tab      @tab X

@tab used in various Interplay computer games

@item Xan DPCM               @tab      @tab X

@tab used in Origin's Wing Commander IV AVI files

@end multitable

@code{X} means that the encoding (resp. decoding) is supported.

@code{I} means that an integer only version is available too (ensures highest

performances on systems without hardware floating point support).

@chapter Platform Specific information

@section Linux

ffmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the

preferred compiler now for ffmpeg. All future optimizations will depend on

features only found in GCC 3.2.

@section BSD

@section Windows

@subsection Native Windows compilation

@itemize

@item Install the current versions of MSYS and MinGW from

@url{http://www.mingw.org/}. You can find detailed installation

instructions in the download section and the FAQ.

@item If you want to test the FFmpeg Simple Media Player, also download 

the MinGW development library of SDL 1.2.x

(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from

@url{http://www.libsdl.org}. Unpack it in a temporary place, and

unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool

directory. Edit the @file{sdl-config} script so that it gives the

correct SDL directory when invoked.

@item Extract the current version of FFmpeg (the latest release version or the current CVS snapshot whichever is recommended).

@item Start the MSYS shell (file @file{msys.bat}).

@item Change to the FFMPEG directory and follow

 the instructions of how to compile ffmpeg (file

@file{INSTALL}). Usually, launching @file{./configure} and @file{make}

suffices. If you have problems using SDL, verify that

@file{sdl-config} can be launched from the MSYS command line.

@item You can install FFmpeg in @file{Program Files/FFmpeg} by typing @file{make install}. Don't forget to copy @file{SDL.dll} at the place you launch 

@file{ffplay}.

@end itemize

Notes: 

@itemize

@item The target @file{make wininstaller} can be used to create a

Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}

must be copied in the ffmpeg directory in order to build the

installer.

@item By using @code{./configure --enable-shared} when configuring ffmpeg, 

you can build @file{avcodec.dll} and @file{avformat.dll}. With

@code{make install} you install the FFmpeg DLLs and the associated

headers in @file{Program Files/FFmpeg}. 

@item Visual C++ compatibility: if you used @code{./configure --enable-shared} 

when configuring FFmpeg, then FFmpeg tries to use the Microsoft Visual

C++ @code{lib} tool to build @code{avcodec.lib} and

@code{avformat.lib}. With these libraries, you can link your Visual C++

code directly with the FFmpeg DLLs.

@end itemize

@subsection Cross compilation for Windows with Linux

You must use the MinGW cross compilation tools available at

@url{http://www.mingw.org/}.

Then configure ffmpeg with the following options:

@example

./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-

@end example

(you can change the cross-prefix according to the prefix choosen for the

MinGW tools).

Then you can easily test ffmpeg with wine

(@url{http://www.winehq.com/}).

@section MacOS X

@section BeOS

The configure script should guess the configuration itself.

Networking support is currently not finished.

errno issues fixed by Andrew Bachmann.

Old stuff:

Fran?ois Revol - revol at free dot fr - April 2002

The configure script should guess the configuration itself, 

however I still didn't tested building on net_server version of BeOS.

ffserver is broken (needs poll() implementation).

There is still issues with errno codes, which are negative in BeOs, and

that ffmpeg negates when returning. This ends up turning errors into 

valid results, then crashes.

(To be fixed)

@chapter Developers Guide

@section API

@itemize

@item libavcodec is the library containing the codecs (both encoding and

  decoding). See @file{libavcodec/apiexample.c} to see how to use it.

@item libavformat is the library containing the file formats handling (mux and

  demux code for several formats). See @file{ffplay.c} to use it in a

player. See @file{output_example.c} to use it to generate audio or video

streams.

@end itemize

@section Integrating libavcodec or libavformat in your program

You can integrate all the source code of the libraries to link them

statically to avoid any version problem. All you need is to provide a

'config.mak' and a 'config.h' in the parent directory. See the defines

generated by ./configure to understand what is needed.

You can use libavcodec or libavformat in your commercial program, but

@emph{any patch you make must be published}. The best way to proceed is

to send your patches to the ffmpeg mailing list.

@section Coding Rules

ffmpeg is programmed in ANSI C language. GCC extensions are

tolerated. Indent size is 4. The TAB character should not be used.

The presentation is the one specified by 'indent -i4 -kr'.

Main priority in ffmpeg is simplicity and small code size (=less

bugs).

Comments: for functions visible from other modules, use the JavaDoc

format (see examples in @file{libav/utils.c}) so that a documentation

can be generated automatically.

@section Submitting patches

When you submit your patch, try to send a unified diff (diff '-u'

option). I cannot read other diffs :-)

Run the regression tests before submitting a patch so that you can

verify that there are no big problems.

Patches should be posted as base64 encoded attachments (or any other

encoding which ensures that the patch wont be trashed during 

transmission) to the ffmpeg-devel mailinglist, see 

@url{http://lists.sourceforge.net/lists/listinfo/ffmpeg-devel}

@section Regression tests

Before submitting a patch (or committing with CVS), you should at least

test that you did not break anything.

The regression test build a synthetic video stream and a synthetic

audio stream. Then these are encoded then decoded with all codecs or

formats. The CRC (or MD5) of each generated file is recorded in a

result file. Then a 'diff' is launched with the reference results and

the result file.

The regression test then goes on to test the ffserver code with a 

limited set of streams. It is important that this step runs correctly

as well.

Run 'make test' to test all the codecs.

Run 'make fulltest' to test all the codecs, formats and ffserver.

[Of course, some patches may change the regression tests results. In

this case, the regression tests reference results shall be modified

accordingly].

@bye