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\input texinfo @c -*- texinfo -*-
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@settitle FFmpeg Documentation
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@titlepage
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@sp 7
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@center @titlefont{FFmpeg Documentation}
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@sp 3
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@end titlepage
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@chapter Introduction
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FFmpeg is a very fast video and audio converter. It can also grab from
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a live audio/video source.
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The command line interface is designed to be intuitive, in the sense
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that ffmpeg tries to figure out all the parameters, when
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possible. You have usually to give only the target bitrate you want.
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FFmpeg can also convert from any sample rate to any other, and resize
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video on the fly with a high quality polyphase filter.
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@chapter Quick Start
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@c man begin EXAMPLES
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@section Video and Audio grabbing
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FFmpeg can use a video4linux compatible video source and any Open Sound
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System audio source:
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@example
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ffmpeg /tmp/out.mpg 
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@end example
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Note that you must activate the right video source and channel before
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launching ffmpeg. You can use any TV viewer such as xawtv
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(@url{http://bytesex.org/xawtv/}) by Gerd Knorr which I find very
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good. You must also set correctly the audio recording levels with a
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standard mixer.
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@section Video and Audio file format conversion
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* ffmpeg can use any supported file format and protocol as input: 
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Examples:
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* You can input from YUV files:
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@example
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ffmpeg -i /tmp/test%d.Y /tmp/out.mpg 
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@end example
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It will use the files: 
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@example
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/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
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/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
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@end example
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The Y files use twice the resolution of the U and V files. They are
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raw files, without header. They can be generated by all decent video
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decoders. You must specify the size of the image with the @option{-s} option
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if ffmpeg cannot guess it.
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* You can input from a RAW YUV420P file:
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@example
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ffmpeg -i /tmp/test.yuv /tmp/out.avi
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@end example
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The RAW YUV420P is a file containing RAW YUV planar, for each frame first
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come the Y plane followed by U and V planes, which are half vertical and
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horizontal resolution.
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* You can output to a RAW YUV420P file:
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@example
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ffmpeg -i mydivx.avi -o hugefile.yuv
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@end example
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* You can set several input files and output files:
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@example
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ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
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@end example
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Convert the audio file a.wav and the raw yuv video file a.yuv
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to mpeg file a.mpg
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* You can also do audio and video conversions at the same time:
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@example
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ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
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@end example
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Convert the sample rate of a.wav to 22050 Hz and encode it to MPEG audio.
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* You can encode to several formats at the same time and define a
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mapping from input stream to output streams:
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@example
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ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0
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@end example
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Convert a.wav to a.mp2 at 64 kbits and b.mp2 at 128 kbits. '-map
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file:index' specify which input stream is used for each output
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stream, in the order of the definition of output streams.
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* You can transcode decrypted VOBs
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@example
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ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800 -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi
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@end example
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This is a typical DVD ripper example, input from a VOB file, output
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to an AVI file with MPEG-4 video and MP3 audio, note that in this
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command we use B frames so the MPEG-4 stream is DivX5 compatible, GOP
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size is 300 that means an INTRA frame every 10 seconds for 29.97 fps
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input video.  Also the audio stream is MP3 encoded so you need LAME
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support which is enabled using @code{--enable-mp3lame} when
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configuring.  The mapping is particularly useful for DVD transcoding
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to get the desired audio language.
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NOTE: to see the supported input formats, use @code{ffmpeg -formats}.
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@c man end
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@chapter Invocation
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@section Syntax
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The generic syntax is:
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@example 
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@c man begin SYNOPSIS
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ffmpeg [[options][@option{-i} @var{input_file}]]... @{[options] @var{output_file}@}...
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@c man end
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@end example
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@c man begin DESCRIPTION
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If no input file is given, audio/video grabbing is done.
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As a general rule, options are applied to the next specified
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file. For example, if you give the @option{-b 64} option, it sets the video
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bitrate of the next file. Format option may be needed for raw input
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files.
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By default, ffmpeg tries to convert as losslessly as possible: it
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uses the same audio and video parameter for the outputs as the one
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specified for the inputs.
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@c man end
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@c man begin OPTIONS
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@section Main options
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@table @option
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@item -L
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show license
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@item -h
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show help
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@item -formats
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show available formats, codecs, protocols, ...
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@item -f fmt              
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force format
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@item -i filename         
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input file name
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@item -y                  
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overwrite output files
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@item -t duration         
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set the recording time in seconds. @code{hh:mm:ss[.xxx]} syntax is also
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supported.
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@item -title string       
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set the title
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@item -author string      
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set the author
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@item -copyright string   
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set the copyright
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@item -comment string     
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set the comment
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@item -hq                 
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activate high quality settings
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@end table
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@section Video Options
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@table @option
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@item -b bitrate
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set the video bitrate in kbit/s (default = 200 kb/s)
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@item -r fps           
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set frame rate (default = 25)
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@item -s size             
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set frame size. The format is @samp{WxH} (default 160x128).  The
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following abbreviations are recognized:
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@table @samp
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@item sqcif
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128x96
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@item qcif
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176x144
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@item cif
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352x288
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@item 4cif
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704x576
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@end table
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@item -aspect aspect
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set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)
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@item -croptop size
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set top crop band size (in pixels)
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@item -cropbottom size
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set bottom crop band size (in pixels)
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@item -cropleft size
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set left crop band size (in pixels)
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@item -cropright size
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set right crop band size (in pixels)
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@item -vn
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disable video recording
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@item -bt tolerance       
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set video bitrate tolerance (in kbit/s)
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@item -maxrate bitrate
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set max video bitrate tolerance (in kbit/s)
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@item -minrate bitrate
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set min video bitrate tolerance (in kbit/s)
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@item -bufsize size
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set ratecontrol buffere size (in kbit)
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@item -vcodec codec       
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force video codec to @var{codec}. Use the @code{copy} special value to
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tell that the raw codec data must be copied as is.
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@item -sameq
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use same video quality as source (implies VBR)
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@item -pass n  
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select the pass number (1 or 2). It is useful to do two pass
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encoding. The statistics of the video are recorded in the first pass and
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the video at the exact requested bit rate is generated in the second
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pass.
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@item -passlogfile file   
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select two pass log file name to @var{file}.
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@end table
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@section Advanced Video Options
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@table @option
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@item -g gop_size         
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set the group of picture size
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@item -intra              
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use only intra frames
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@item -qscale q           
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use fixed video quantiser scale (VBR)
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@item -qmin q             
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min video quantiser scale (VBR)
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@item -qmax q             
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max video quantiser scale (VBR)
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@item -qdiff q            
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max difference between the quantiser scale (VBR)
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@item -qblur blur         
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video quantiser scale blur (VBR)
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@item -qcomp compression  
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video quantiser scale compression (VBR)
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@item -rc_init_cplx complexity
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initial complexity for 1-pass encoding
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@item -b_qfactor factor
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qp factor between p and b frames
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@item -i_qfactor factor
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qp factor between p and i frames
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@item -b_qoffset offset
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qp offset between p and b frames
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@item -i_qoffset offset
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qp offset between p and i frames
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@item -rc_eq equation
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set rate control equation (@pxref{FFmpeg formula
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evaluator}). Default is @code{tex^qComp}.
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@item -rc_override override
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rate control override for specific intervals
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@item -me method
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set motion estimation method to @var{method}. Available methods are
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(from lower to best quality):
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@table @samp
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@item zero
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Try just the (0, 0) vector.
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@item phods
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@item log
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@item x1
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@item epzs
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(default method)
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@item full
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exhaustive search (slow and marginally better than epzs)
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@end table
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@item -dct_algo algo
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set dct algorithm to @var{algo}. Available values are:
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@table @samp
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@item 0
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FF_DCT_AUTO (default)
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@item 1
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FF_DCT_FASTINT
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@item 2
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FF_DCT_INT
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@item 3
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FF_DCT_MMX
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@item 4
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FF_DCT_MLIB
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@item 5
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FF_DCT_ALTIVEC
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@end table
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@item -idct_algo algo
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set idct algorithm to @var{algo}. Available values are:
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@table @samp
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@item 0
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FF_IDCT_AUTO (default)
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@item 1
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FF_IDCT_INT          
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@item 2
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FF_IDCT_SIMPLE       
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@item 3
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FF_IDCT_SIMPLEMMX    
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@item 4
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FF_IDCT_LIBMPEG2MMX  
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@item 5
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FF_IDCT_PS2          
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@item 6
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FF_IDCT_MLIB         
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@item 7
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FF_IDCT_ARM          
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@item 8
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FF_IDCT_ALTIVEC      
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@item 9
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FF_IDCT_SH4          
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@item 10
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FF_IDCT_SIMPLEARM    
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@end table
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@item -er n
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set error resilience to @var{n}.
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@table @samp
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@item 1 
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FF_ER_CAREFULL (default)
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@item 2
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FF_ER_COMPLIANT
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@item 3
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FF_ER_AGGRESSIVE
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@item 4
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FF_ER_VERY_AGGRESSIVE
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@end table
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@item -ec bit_mask
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set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
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the following values:
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@table @samp
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@item 1
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FF_EC_GUESS_MVS (default=enabled)
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@item 2
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FF_EC_DEBLOCK (default=enabled)
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@end table
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@item -bf frames
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use 'frames' B frames (supported for MPEG-1, MPEG-2 and MPEG-4)
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@item -mbd mode
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macroblock decision
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@table @samp
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@item 0
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FF_MB_DECISION_SIMPLE: use mb_cmp (cannot change it yet in ffmpeg)
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@item 1
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FF_MB_DECISION_BITS: chooses the one which needs the fewest bits
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@item 2
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FF_MB_DECISION_RD: rate distoration
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@end table
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@item -4mv
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use four motion vector by macroblock (only MPEG-4)
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@item -part
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use data partitioning (only MPEG-4)
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@item -bug param
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workaround not auto detected encoder bugs
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@item -strict strictness
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how strictly to follow the standarts
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@item -aic
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enable Advanced intra coding (h263+)
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@item -umv
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enable Unlimited Motion Vector (h263+)
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@item -deinterlace
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deinterlace pictures
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@item -psnr
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calculate PSNR of compressed frames
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@item -vstats
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dump video coding statistics to @file{vstats_HHMMSS.log}.
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@item -vhook module
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insert video processing @var{module}. @var{module} contains the module
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name and its parameters separated by spaces.
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@end table
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@section Audio Options
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@table @option
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@item -ab bitrate         
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set audio bitrate (in kbit/s)
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@item -ar freq    
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set the audio sampling freq (default = 44100 Hz)
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@item -ab bitrate 
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set the audio bitrate in kbit/s (default = 64)
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@item -ac channels
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set the number of audio channels (default = 1)
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@item -an
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disable audio recording
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@item -acodec codec
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force audio codec to @var{codec}. Use the @code{copy} special value to
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tell that the raw codec data must be copied as is.
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@end table
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@section Audio/Video grab options
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@table @option
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@item -vd device
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set video grab device (e.g. @file{/dev/video0})
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@item -vc channel
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set video grab channel (DV1394 only)
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@item -tvstd standard
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set television standard (NTSC, PAL (SECAM))
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@item -dv1394
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set DV1394 grab
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@item -ad device
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set audio device (e.g. @file{/dev/dsp})
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@end table
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@section Advanced options
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@table @option
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@item -map file:stream    
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set input stream mapping
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@item -debug
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print specific debug info
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@item -benchmark          
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add timings for benchmarking
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@item -hex                
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dump each input packet
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@item -bitexact
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only use bit exact algorithms (for codec testing)
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@item -ps size
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set packet size in bits
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@item -re
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read input at native frame rate. Mainly used to simulate a grab device.
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@item -loop
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loop over the input stream. Currently it works only for image
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streams. This option is used for ffserver automatic testing.
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@end table
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@node FFmpeg formula evaluator
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@section FFmpeg formula evaluator
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When evaluating a rate control string, FFmpeg uses an internal formula
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evaluator. 
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The following binary operators are available: @code{+}, @code{-},
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@code{*}, @code{/}, @code{^}.
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The following unary operators are available: @code{+}, @code{-},
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@code{(...)}.
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The following functions are available:
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@table @var
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@item sinh(x)
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@item cosh(x)
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@item tanh(x)
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@item sin(x)
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@item cos(x)
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@item tan(x)
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@item exp(x)
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@item log(x)
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@item squish(x)
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@item gauss(x)
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@item abs(x)
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@item max(x, y)
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@item min(x, y)
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@item gt(x, y)
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@item lt(x, y)
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@item eq(x, y)
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@item bits2qp(bits)
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@item qp2bits(qp)
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@end table
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The following constants are available:
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@table @var
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@item PI
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@item E
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@item iTex
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@item pTex
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@item tex
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@item mv
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@item fCode
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@item iCount
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@item mcVar
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@item var
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@item isI
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@item isP
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@item isB
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@item avgQP
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@item qComp
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@item avgIITex
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@item avgPITex
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@item avgPPTex
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@item avgBPTex
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@item avgTex
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@end table
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@c man end
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@ignore
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@setfilename ffmpeg
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@settitle FFmpeg video converter
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@c man begin SEEALSO
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ffserver(1), ffplay(1) and the html documentation of @file{ffmpeg}.
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@c man end
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@c man begin AUTHOR
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Fabrice Bellard
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@c man end
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@end ignore
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@section Protocols
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The filename can be @file{-} to read from the standard input or to write
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to the standard output.
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ffmpeg handles also many protocols specified with the URL syntax.
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Use 'ffmpeg -formats' to have a list of the supported protocols.
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The protocol @code{http:} is currently used only to communicate with
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ffserver (see the ffserver documentation). When ffmpeg will be a
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video player it will also be used for streaming :-)
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@chapter Tips
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@itemize
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@item For streaming at very low bit rate application, use a low frame rate
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and a small gop size. This is especially true for real video where
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the Linux player does not seem to be very fast, so it can miss
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frames. An example is:
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@example
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ffmpeg -g 3 -r 3 -t 10 -b 50 -s qcif -f rv10 /tmp/b.rm
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@end example
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@item  The parameter 'q' which is displayed while encoding is the current
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quantizer. The value of 1 indicates that a very good quality could
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be achieved. The value of 31 indicates the worst quality. If q=31
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too often, it means that the encoder cannot compress enough to meet
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your bit rate. You must either increase the bit rate, decrease the
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frame rate or decrease the frame size.
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@item If your computer is not fast enough, you can speed up the
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compression at the expense of the compression ratio. You can use
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'-me zero' to speed up motion estimation, and '-intra' to disable
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completely motion estimation (you have only I frames, which means it
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is about as good as JPEG compression).
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@item To have very low bitrates in audio, reduce the sampling frequency
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(down to 22050 kHz for mpeg audio, 22050 or 11025 for ac3).
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@item To have a constant quality (but a variable bitrate), use the option
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'-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
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quality).
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@item When converting video files, you can use the '-sameq' option which
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uses in the encoder the same quality factor than in the decoder. It
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allows to be almost lossless in encoding.
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@end itemize
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@chapter Supported File Formats and Codecs
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You can use the @code{-formats} option to have an exhaustive list.
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@section File Formats
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FFmpeg supports the following file formats through the @code{libavformat}
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library:
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@multitable @columnfractions .4 .1 .1
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@item Supported File Format @tab Encoding @tab Decoding @tab Comments
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@item MPEG audio @tab X @tab X
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@item MPEG1 systems @tab X  @tab  X 
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@tab muxed audio and video
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@item MPEG2 PS @tab X  @tab  X 
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@tab also known as @code{VOB} file
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@item MPEG2 TS @tab    @tab  X 
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@tab also known as DVB Transport Stream
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@item ASF@tab X @tab X 
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@item AVI@tab X @tab X 
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@item WAV@tab X @tab X 
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@item Macromedia Flash@tab X @tab X
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@tab Only embedded audio is decoded
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@item FLV              @tab  X @tab X
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@tab Macromedia Flash video files
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@item Real Audio and Video @tab X @tab X 
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@item Raw AC3 @tab X  @tab  X 
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@item Raw MJPEG @tab X  @tab  X 
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@item Raw MPEG video @tab X  @tab  X 
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@item Raw PCM8/16 bits, mulaw/Alaw@tab X  @tab  X 
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@item SUN AU format @tab X  @tab  X 
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@item Quicktime        @tab X @tab  X 
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@item MPEG4            @tab X @tab  X 
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@tab MPEG4 is a variant of Quicktime
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@item Raw MPEG4 video  @tab  X @tab  X 
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@item DV               @tab  @tab X
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@item 4xm              @tab    @tab X
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@tab 4X Technologies format, used in some games
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@item Playstation STR  @tab    @tab X
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@item Id RoQ           @tab    @tab X
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@tab used in Quake III, Jedi Knight 2, other computer games
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@item Interplay MVE    @tab    @tab X
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@tab format used in various Interplay computer games
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@item WC3 Movie        @tab    @tab X
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@tab multimedia format used in Origin's Wing Commander III computer game
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@end multitable
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@code{X} means that the encoding (resp. decoding) is supported.
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@section Image Formats
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FFmpeg can read and write images for each frame of a video sequence. The
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following image formats are supported:
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@multitable @columnfractions .4 .1 .1
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@item Supported Image Format @tab Encoding @tab Decoding @tab Comments
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@item PGM, PPM     @tab X @tab X 
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@item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support
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@item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
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@item JPEG         @tab X @tab X @tab Progressive JPEG is not supported
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@item .Y.U.V       @tab X @tab X @tab One raw file per component
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@item Animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated
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@item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet
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@end multitable
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@code{X} means that the encoding (resp. decoding) is supported.
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@section Video Codecs
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@multitable @columnfractions .4 .1 .1 .7
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@item Supported Codec @tab Encoding @tab Decoding @tab Comments
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@item MPEG1 video            @tab  X  @tab  X
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@item MPEG2 video            @tab  X  @tab  X 
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@item MPEG4                  @tab  X  @tab  X @tab Also known as DIVX4/5
660
@item MSMPEG4 V1             @tab  X  @tab  X
661
@item MSMPEG4 V2             @tab  X  @tab  X
662
@item MSMPEG4 V3             @tab  X  @tab  X @tab Also known as DIVX3
663
@item WMV7                   @tab  X  @tab  X
664
@item WMV8                   @tab  X  @tab  X @tab Not completely working
665
@item H263(+)                @tab  X  @tab  X @tab Also known as Real Video 1.0
666
@item MJPEG                  @tab  X  @tab  X 
667
@item DV                     @tab     @tab  X 
668
@item Huff YUV               @tab  X  @tab  X
669
@item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1
670
@item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2
671
@item Creative YUV           @tab     @tab  X @tab fourcc: CYUV
672
@item H.264                  @tab     @tab  X
673
@item Sorenson Video 1       @tab     @tab  X @tab fourcc: SVQ1
674
@item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3
675
@item On2 VP3                @tab     @tab  X @tab still experimental
676
@item Intel Indeo 3          @tab     @tab  X @tab only works on i386 right now
677
@item FLV                    @tab  X  @tab  X @tab Flash H263 variant
678
@item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1
679
@item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR
680
@item 4X Video               @tab     @tab  X @tab used in certain computer games
681
@item Sony Playstation MDEC  @tab     @tab  X 
682
@item Id RoQ                 @tab     @tab  X @tab used in Quake III, Jedi Knight 2, other computer games
683
@item Xan/WC3                @tab     @tab  X @tab used in Wing Commander III .MVE files
684
@item Interplay Video        @tab     @tab  X @tab used in Interplay .MVE files
685
@end multitable
686

    
687
@code{X} means that the encoding (resp. decoding) is supported.
688

    
689
Check at @url{http://www.mplayerhq.hu/~michael/codec-features.html} to
690
get a precise comparison of FFmpeg MPEG4 codec compared to the other
691
solutions.
692

    
693
@section Audio Codecs
694

    
695
@multitable @columnfractions .4 .1 .1 .1 .7
696
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
697
@item MPEG audio layer 2     @tab  IX  @tab  IX 
698
@item MPEG audio layer 1/3   @tab IX   @tab  IX
699
@tab MP3 encoding is supported through the external library LAME
700
@item AC3                    @tab  IX  @tab  X
701
@tab liba52 is used internally for decoding
702
@item Vorbis                 @tab  X   @tab  X
703
@tab supported through the external library libvorbis
704
@item WMA V1/V2              @tab      @tab X
705
@item Microsoft ADPCM        @tab X    @tab X
706
@item MS IMA ADPCM           @tab X    @tab X
707
@item QT IMA ADPCM           @tab      @tab X
708
@item 4X IMA ADPCM           @tab      @tab X
709
@item Duck DK3 IMA ADPCM     @tab      @tab X
710
@tab used in some Sega Saturn console games
711
@item Duck DK4 IMA ADPCM     @tab      @tab X
712
@tab used in some Sega Saturn console games
713
@item RA144                  @tab      @tab X
714
@tab Real 14400 bit/s codec
715
@item RA288                  @tab      @tab X
716
@tab Real 28800 bit/s codec
717
@item AMR-NB                 @tab X    @tab X
718
@tab supported through an external library
719
@item DV audio               @tab      @tab X
720
@item Id RoQ DPCM            @tab      @tab X
721
@tab used in Quake III, Jedi Knight 2, other computer games
722
@item Interplay MVE DPCM     @tab      @tab X
723
@tab used in various Interplay computer games
724
@item Xan DPCM               @tab      @tab X
725
@tab used in Origin's Wing Commander IV AVI files
726
@end multitable
727

    
728
@code{X} means that the encoding (resp. decoding) is supported.
729

    
730
@code{I} means that an integer only version is available too (ensures highest
731
performances on systems without hardware floating point support).
732

    
733
@chapter Platform Specific information
734

    
735
@section Linux
736

    
737
ffmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
738
preferred compiler now for ffmpeg. All future optimizations will depend on
739
features only found in GCC 3.2.
740

    
741
@section BSD
742

    
743
@section Windows
744

    
745
@subsection Native Windows compilation
746

    
747
@itemize
748
@item Install the current versions of MSYS and MinGW from
749
@url{http://www.mingw.org/}. You can find detailed installation
750
instructions in the download section and the FAQ.
751

    
752
@item If you want to test the FFmpeg Simple Media Player, also download 
753
the MinGW development library of SDL 1.2.x
754
(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
755
@url{http://www.libsdl.org}. Unpack it in a temporary place, and
756
unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
757
directory.
758

    
759
@item Extract the current version of FFmpeg (the latest release version or the current CVS snapshot whichever is recommended).
760
 
761
@item Start the MSYS shell (file @file{msys.bat}).
762

    
763
@item Change to the FFMPEG directory and follow
764
 the instructions of how to compile ffmpeg (file
765
@file{INSTALL}). Usually, launching @file{./configure} and @file{make}
766
suffices. If you have problems using SDL, verify that
767
@file{sdl-config} can be launched from the MSYS command line.
768

    
769
@item You can install FFmpeg in @file{Program Files/FFmpeg} by typing @file{make install}.
770

    
771
@end itemize
772

    
773
Note: The target @file{make wininstaller} can be used to create a Nullsoft based Windows installer for FFmpeg and FFplay.
774

    
775
@subsection How to create a single Windows DLL from libavcodec and libavformat
776
 
777
Read @url{http://ffmpeg.org/win32.html}.
778

    
779
@subsection Cross compilation for Windows with Linux
780

    
781
You must use the MinGW cross compilation tools available at
782
@url{http://www.mingw.org/}.
783

    
784
Then configure ffmpeg with the following options:
785
@example
786
./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
787
@end example
788
(you can change the cross-prefix according to the prefix choosen for the
789
MinGW tools).
790

    
791
Then you can easily test ffmpeg with wine
792
(@url{http://www.winehq.com/}).
793

    
794
@section MacOS X
795

    
796
@section BeOS
797

    
798
The configure script should guess the configuration itself.
799
Networking support is currently not finished.
800
errno issues fixed by Andrew Bachmann.
801

    
802
Old stuff:
803

    
804
Fran?ois Revol - revol at free dot fr - April 2002
805

    
806
The configure script should guess the configuration itself, 
807
however I still didn't tested building on net_server version of BeOS.
808

    
809
ffserver is broken (needs poll() implementation).
810

    
811
There is still issues with errno codes, which are negative in BeOs, and
812
that ffmpeg negates when returning. This ends up turning errors into 
813
valid results, then crashes.
814
(To be fixed)
815

    
816
@chapter Developers Guide
817

    
818
@section API
819
@itemize
820
@item libavcodec is the library containing the codecs (both encoding and
821
  decoding). See @file{libavcodec/apiexample.c} to see how to use it.
822

    
823
@item libavformat is the library containing the file formats handling (mux and
824
  demux code for several formats). See @file{ffplay.c} to use it in a
825
player. See @file{output_example.c} to use it to generate audio or video
826
streams.
827

    
828
@end itemize
829

    
830
@section Integrating libavcodec or libavformat in your program
831

    
832
You can integrate all the source code of the libraries to link them
833
statically to avoid any version problem. All you need is to provide a
834
'config.mak' and a 'config.h' in the parent directory. See the defines
835
generated by ./configure to understand what is needed.
836

    
837
You can use libavcodec or libavformat in your commercial program, but
838
@emph{any patch you make must be published}. The best way to proceed is
839
to send your patches to the ffmpeg mailing list.
840

    
841
@section Coding Rules
842

    
843
ffmpeg is programmed in ANSI C language. GCC extensions are
844
tolerated. Indent size is 4. The TAB character should not be used.
845

    
846
The presentation is the one specified by 'indent -i4 -kr'.
847

    
848
Main priority in ffmpeg is simplicity and small code size (=less
849
bugs).
850

    
851
Comments: for functions visible from other modules, use the JavaDoc
852
format (see examples in @file{libav/utils.c}) so that a documentation
853
can be generated automatically.
854

    
855
@section Submitting patches
856

    
857
When you submit your patch, try to send a unified diff (diff '-u'
858
option). I cannot read other diffs :-)
859

    
860
Run the regression tests before submitting a patch so that you can
861
verify that there are no big problems.
862

    
863
Patches should be posted as base64 encoded attachments (or any other
864
encoding which ensures that the patch wont be trashed during 
865
transmission) to the ffmpeg-devel mailinglist, see 
866
@url{http://lists.sourceforge.net/lists/listinfo/ffmpeg-devel}
867

    
868
@section Regression tests
869

    
870
Before submitting a patch (or committing with CVS), you should at least
871
test that you did not break anything.
872

    
873
The regression test build a synthetic video stream and a synthetic
874
audio stream. Then these are encoded then decoded with all codecs or
875
formats. The CRC (or MD5) of each generated file is recorded in a
876
result file. Then a 'diff' is launched with the reference results and
877
the result file.
878

    
879
The regression test then goes on to test the ffserver code with a 
880
limited set of streams. It is important that this step runs correctly
881
as well.
882

    
883
Run 'make test' to test all the codecs.
884

    
885
Run 'make fulltest' to test all the codecs, formats and ffserver.
886

    
887
[Of course, some patches may change the regression tests results. In
888
this case, the regression tests reference results shall be modified
889
accordingly].
890

    
891
@bye