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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 parameters that can possibly be
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derived automatically. You usually only have to specify the target
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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 with any TV viewer such as xawtv
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(@url{http://bytesex.org/xawtv/}) by Gerd Knorr. You also
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have to set the audio recording levels correctly 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 use YUV files as input:
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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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test.yuv is a file containing raw YUV planar data. Each frame is composed
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of the Y plane followed by the U and V planes at 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 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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Converts 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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Converts a.wav to MPEG audio at 22050Hz sample rate.
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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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Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
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file:index' specifies 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 800k -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 ripping example; the input is a VOB file, the
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output 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, and
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GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
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input video. Furthermore, the audio stream is MP3-encoded so you need
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to enable LAME support by passing @code{--enable-mp3lame} to configure.
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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 [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
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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 64k} option, it sets the video
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bitrate of the next file. The 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 parameters 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 filename
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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.
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@code{hh:mm:ss[.xxx]} syntax is also supported.
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@item -ss position
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Seek to given time position in seconds.
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@code{hh:mm:ss[.xxx]} syntax is also 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 -track number
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Set the track.
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@item -year number
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Set the year.
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@item -target type
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Specify target file type ("vcd", "svcd", "dvd", "dv", "pal-vcd",
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"ntsc-svcd", ... ). All the format options (bitrate, codecs,
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buffer sizes) are then set automatically. You can just type:
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@example
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ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
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@end example
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Nevertheless you can specify additional options as long as you know
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they do not conflict with the standard, as in:
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@example
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ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
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@end example
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@item -itsoffset offset
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Set the input time offset in seconds.
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@code{[-]hh:mm:ss[.xxx]} syntax is also supported.
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This option affects all the input files that follow it.
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The offset is added to the timestamps of the input files.
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Specifying a positive offset means that the corresponding
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streams are delayed by 'offset' seconds.
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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 bit/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).
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The 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 -padtop size
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Set top pad band size (in pixels).
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@item -padbottom size
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Set bottom pad band size (in pixels).
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@item -padleft size
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Set left pad band size (in pixels).
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@item -padright size
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Set right pad band size (in pixels).
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@item -padcolor (hex color)
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Set color of padded bands. The value for padcolor is expressed
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as a six digit hexadecimal number where the first two digits
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represent red, the middle two digits green and last two digits
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blue (default = 000000 (black)).
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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 bit/s).
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@item -maxrate bitrate
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Set max video bitrate tolerance (in bit/s).
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@item -minrate bitrate
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Set min video bitrate tolerance (in bit/s).
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@item -bufsize size
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Set rate control buffer size (in bits).
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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
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pass and the video is generated at the exact requested bitrate
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in the second pass.
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@item -passlogfile file
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Set two pass logfile 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 pictures 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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minimum video quantiser scale (VBR)
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@item -qmax q
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maximum video quantiser scale (VBR)
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@item -qdiff q
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maximum difference between the quantiser scales (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 -lmin lambda
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minimum video lagrange factor (VBR)
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@item -lmax lambda
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max video lagrange factor (VBR)
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@item -mblmin lambda
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minimum macroblock quantizer scale (VBR)
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@item -mblmax lambda
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maximum macroblock quantizer scale (VBR)
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These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
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but you may use the QP2LAMBDA constant to easily convert from 'q' units:
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@example
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ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
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@end example
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@item -rc_init_cplx complexity
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initial complexity for single 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 = @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}.
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Available methods are (from lowest 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_CAREFUL (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: Choose the one which needs the fewest bits.
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@item 2
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FF_MB_DECISION_RD: rate distortion
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@end table
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@item -4mv
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Use four motion vector by macroblock (MPEG-4 only).
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@item -part
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Use data partitioning (MPEG-4 only).
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@item -bug param
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Work around encoder bugs that are not auto-detected.
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@item -strict strictness
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How strictly to follow the standards.
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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 -ilme
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Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
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Use this option if your input file is interlaced and you want
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to keep the interlaced format for minimum losses.
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The alternative is to deinterlace the input stream with
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@option{-deinterlace}, but deinterlacing introduces losses.
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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 -ar freq
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Set the audio sampling frequency (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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specify 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 input stream id[:input stream id]
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Set stream mapping from input streams to output streams.
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Just enumerate the input streams in the order you want them in the output.
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[input stream id] sets the (input) stream to sync against.
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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 automatic FFserver testing.
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@item -loop_output number_of_times
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Repeatedly loop output for formats that support looping such as animated GIF
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(0 will loop the output infinitely).
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@item -vsync parameter
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Video sync method. Video will be stretched/squeezed to match the timestamps,
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it is done by duplicating and dropping frames. With -map you can select from
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which stream the timestamps should be taken. You can leave either video or
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audio unchanged and sync the remaining stream(s) to the unchanged one.
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@item -async samples_per_second
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Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
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the parameter is the maximum samples per second by which the audio is changed.
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-async 1 is a special case where only the start of the audio stream is corrected
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without any later correction.
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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 standard input or to write
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to standard output.
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FFmpeg also handles many protocols specified with an URL syntax.
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Use 'ffmpeg -formats' to see 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 bitrate application, use a low frame rate
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and a small GOP size. This is especially true for RealVideo 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 50k -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 1 indicates that a very good quality could
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be achieved. The value 31 indicates the worst quality. If q=31 appears
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too often, it means that the encoder cannot compress enough to meet
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your bitrate. You must either increase the bitrate, 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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motion estimation completely (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 audio bitrates, 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 the same quality factor in the encoder as in the decoder.
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It allows almost lossless encoding.
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@end itemize
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@chapter Supported File Formats and Codecs
666

    
667
You can use the @code{-formats} option to have an exhaustive list.
668

    
669
@section File Formats
670

    
671
FFmpeg supports the following file formats through the @code{libavformat}
672
library:
673

    
674
@multitable @columnfractions .4 .1 .1 .4
675
@item Supported File Format @tab Encoding @tab Decoding @tab Comments
676
@item MPEG audio @tab X @tab X
677
@item MPEG-1 systems @tab X  @tab  X
678
@tab muxed audio and video
679
@item MPEG-2 PS @tab X  @tab  X
680
@tab also known as @code{VOB} file
681
@item MPEG-2 TS @tab    @tab  X
682
@tab also known as DVB Transport Stream
683
@item ASF@tab X @tab X
684
@item AVI@tab X @tab X
685
@item WAV@tab X @tab X
686
@item Macromedia Flash@tab X @tab X
687
@tab Only embedded audio is decoded.
688
@item FLV              @tab  X @tab X
689
@tab Macromedia Flash video files
690
@item Real Audio and Video @tab X @tab X
691
@item Raw AC3 @tab X  @tab  X
692
@item Raw MJPEG @tab X  @tab  X
693
@item Raw MPEG video @tab X  @tab  X
694
@item Raw PCM8/16 bits, mulaw/Alaw@tab X  @tab  X
695
@item Raw CRI ADX audio @tab X  @tab  X
696
@item Raw Shorten audio @tab    @tab  X
697
@item SUN AU format @tab X  @tab  X
698
@item NUT @tab X @tab X @tab NUT Open Container Format
699
@item QuickTime        @tab X @tab  X
700
@item MPEG-4           @tab X @tab  X
701
@tab MPEG-4 is a variant of QuickTime.
702
@item Raw MPEG4 video  @tab  X @tab  X
703
@item DV               @tab  X @tab  X
704
@item 4xm              @tab    @tab X
705
@tab 4X Technologies format, used in some games.
706
@item Playstation STR  @tab    @tab X
707
@item Id RoQ           @tab    @tab X
708
@tab Used in Quake III, Jedi Knight 2, other computer games.
709
@item Interplay MVE    @tab    @tab X
710
@tab Format used in various Interplay computer games.
711
@item WC3 Movie        @tab    @tab X
712
@tab Multimedia format used in Origin's Wing Commander III computer game.
713
@item Sega FILM/CPK    @tab    @tab X
714
@tab Used in many Sega Saturn console games.
715
@item Westwood Studios VQA/AUD  @tab    @tab X
716
@tab Multimedia formats used in Westwood Studios games.
717
@item Id Cinematic (.cin) @tab    @tab X
718
@tab Used in Quake II.
719
@item FLIC format      @tab    @tab X
720
@tab .fli/.flc files
721
@item Sierra VMD       @tab    @tab X
722
@tab Used in Sierra CD-ROM games.
723
@item Sierra Online    @tab    @tab X
724
@tab .sol files used in Sierra Online games.
725
@item Matroska         @tab    @tab X
726
@item Electronic Arts Multimedia    @tab    @tab X
727
@tab Used in various EA games; files have extensions like WVE and UV2.
728
@item Nullsoft Video (NSV) format @tab    @tab X
729
@item ADTS AAC audio @tab X @tab X
730
@item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
731
@item American Laser Games MM  @tab    @tab X
732
@tab Multimedia format used in games like Mad Dog McCree
733
@item AVS @tab    @tab X
734
@tab Multimedia format used by the Creature Shock game.
735
@item Smacker @tab    @tab X
736
@tab Multimedia format used by many games.
737
@item GXF @tab    @tab X
738
@end multitable
739

    
740
@code{X} means that encoding (resp. decoding) is supported.
741

    
742
@section Image Formats
743

    
744
FFmpeg can read and write images for each frame of a video sequence. The
745
following image formats are supported:
746

    
747
@multitable @columnfractions .4 .1 .1 .4
748
@item Supported Image Format @tab Encoding @tab Decoding @tab Comments
749
@item PGM, PPM     @tab X @tab X
750
@item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support.
751
@item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
752
@item JPEG         @tab X @tab X @tab Progressive JPEG is not supported.
753
@item .Y.U.V       @tab X @tab X @tab one raw file per component
754
@item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
755
@item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
756
@item SGI          @tab X @tab X @tab SGI RGB image format
757
@end multitable
758

    
759
@code{X} means that encoding (resp. decoding) is supported.
760

    
761
@section Video Codecs
762

    
763
@multitable @columnfractions .4 .1 .1 .4
764
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
765
@item MPEG-1 video           @tab  X  @tab  X
766
@item MPEG-2 video           @tab  X  @tab  X
767
@item MPEG-4                 @tab  X  @tab  X @tab also known as DivX4/5
768
@item MSMPEG4 V1             @tab  X  @tab  X
769
@item MSMPEG4 V2             @tab  X  @tab  X
770
@item MSMPEG4 V3             @tab  X  @tab  X @tab also known as DivX3
771
@item WMV7                   @tab  X  @tab  X
772
@item WMV8                   @tab  X  @tab  X @tab not completely working
773
@item H.261                  @tab  X  @tab  X
774
@item H.263(+)               @tab  X  @tab  X @tab also known as RealVideo 1.0
775
@item H.264                  @tab     @tab  X
776
@item RealVideo 1.0          @tab  X  @tab  X
777
@item RealVideo 2.0          @tab  X  @tab  X
778
@item MJPEG                  @tab  X  @tab  X
779
@item lossless MJPEG         @tab  X  @tab  X
780
@item JPEG-LS                @tab  X  @tab  X @tab fourcc: MJLS, lossless and near-lossless is supported
781
@item Apple MJPEG-B          @tab     @tab  X
782
@item Sunplus MJPEG          @tab     @tab  X @tab fourcc: SP5X
783
@item DV                     @tab  X  @tab  X
784
@item HuffYUV                @tab  X  @tab  X
785
@item FFmpeg Video 1         @tab  X  @tab  X @tab experimental lossless codec (fourcc: FFV1)
786
@item FFmpeg Snow            @tab  X  @tab  X @tab experimental wavelet codec (fourcc: SNOW)
787
@item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1
788
@item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2
789
@item Creative YUV           @tab     @tab  X @tab fourcc: CYUV
790
@item Sorenson Video 1       @tab  X  @tab  X @tab fourcc: SVQ1
791
@item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3
792
@item On2 VP3                @tab     @tab  X @tab still experimental
793
@item On2 VP5                @tab     @tab  X @tab fourcc: VP50
794
@item On2 VP6                @tab     @tab  X @tab fourcc: VP62
795
@item Theora                 @tab     @tab  X @tab still experimental
796
@item Intel Indeo 3          @tab     @tab  X
797
@item FLV                    @tab  X  @tab  X @tab Sorenson H.263 used in Flash
798
@item Flash Screen Video     @tab     @tab  X @tab fourcc: FSV1
799
@item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1
800
@item ATI VCR2               @tab     @tab  X @tab fourcc: VCR2
801
@item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR
802
@item 4X Video               @tab     @tab  X @tab Used in certain computer games.
803
@item Sony Playstation MDEC  @tab     @tab  X
804
@item Id RoQ                 @tab     @tab  X @tab Used in Quake III, Jedi Knight 2, other computer games.
805
@item Xan/WC3                @tab     @tab  X @tab Used in Wing Commander III .MVE files.
806
@item Interplay Video        @tab     @tab  X @tab Used in Interplay .MVE files.
807
@item Apple Animation        @tab     @tab  X @tab fourcc: 'rle '
808
@item Apple Graphics         @tab     @tab  X @tab fourcc: 'smc '
809
@item Apple Video            @tab     @tab  X @tab fourcc: rpza
810
@item Apple QuickDraw        @tab     @tab  X @tab fourcc: qdrw
811
@item Cinepak                @tab     @tab  X
812
@item Microsoft RLE          @tab     @tab  X
813
@item Microsoft Video-1      @tab     @tab  X
814
@item Westwood VQA           @tab     @tab  X
815
@item Id Cinematic Video     @tab     @tab  X @tab Used in Quake II.
816
@item Planar RGB             @tab     @tab  X @tab fourcc: 8BPS
817
@item FLIC video             @tab     @tab  X
818
@item Duck TrueMotion v1     @tab     @tab  X @tab fourcc: DUCK
819
@item Duck TrueMotion v2     @tab     @tab  X @tab fourcc: TM20
820
@item VMD Video              @tab     @tab  X @tab Used in Sierra VMD files.
821
@item MSZH                   @tab     @tab  X @tab Part of LCL
822
@item ZLIB                   @tab  X  @tab  X @tab Part of LCL, encoder experimental
823
@item TechSmith Camtasia     @tab     @tab  X @tab fourcc: TSCC
824
@item IBM Ultimotion         @tab     @tab  X @tab fourcc: ULTI
825
@item Miro VideoXL           @tab     @tab  X @tab fourcc: VIXL
826
@item QPEG                   @tab     @tab  X @tab fourccs: QPEG, Q1.0, Q1.1
827
@item LOCO                   @tab     @tab  X @tab
828
@item Winnov WNV1            @tab     @tab  X @tab
829
@item Autodesk Animator Studio Codec  @tab     @tab  X @tab fourcc: AASC
830
@item Fraps FPS1             @tab     @tab  X @tab
831
@item CamStudio              @tab     @tab  X @tab fourcc: CSCD
832
@item American Laser Games Video  @tab    @tab X @tab Used in games like Mad Dog McCree
833
@item ZMBV                   @tab     @tab  X @tab
834
@item AVS Video              @tab     @tab  X @tab Video encoding used by the Creature Shock game.
835
@item Smacker Video          @tab     @tab  X @tab Video encoding used in Smacker.
836
@item RTjpeg                 @tab     @tab  X @tab Video encoding used in NuppelVideo files.
837
@item KMVC                   @tab     @tab  X @tab Codec used in Worms games.
838
@item VMware Video           @tab     @tab  X @tab Codec used in videos captured by VMware.
839
@end multitable
840

    
841
@code{X} means that encoding (resp. decoding) is supported.
842

    
843
@section Audio Codecs
844

    
845
@multitable @columnfractions .4 .1 .1 .1 .7
846
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
847
@item MPEG audio layer 2     @tab  IX  @tab  IX
848
@item MPEG audio layer 1/3   @tab IX   @tab  IX
849
@tab MP3 encoding is supported through the external library LAME.
850
@item AC3                    @tab  IX  @tab  IX
851
@tab liba52 is used internally for decoding.
852
@item Vorbis                 @tab  X   @tab  X
853
@tab Supported through the external library libvorbis.
854
@item WMA V1/V2              @tab      @tab X
855
@item AAC                    @tab X    @tab X
856
@tab Supported through the external library libfaac/libfaad.
857
@item Microsoft ADPCM        @tab X    @tab X
858
@item MS IMA ADPCM           @tab X    @tab X
859
@item QT IMA ADPCM           @tab      @tab X
860
@item 4X IMA ADPCM           @tab      @tab X
861
@item G.726  ADPCM           @tab X    @tab X
862
@item Duck DK3 IMA ADPCM     @tab      @tab X
863
@tab Used in some Sega Saturn console games.
864
@item Duck DK4 IMA ADPCM     @tab      @tab X
865
@tab Used in some Sega Saturn console games.
866
@item Westwood Studios IMA ADPCM @tab      @tab X
867
@tab Used in Westwood Studios games like Command and Conquer.
868
@item SMJPEG IMA ADPCM       @tab      @tab X
869
@tab Used in certain Loki game ports.
870
@item CD-ROM XA ADPCM        @tab      @tab X
871
@item CRI ADX ADPCM          @tab X    @tab X
872
@tab Used in Sega Dreamcast games.
873
@item Electronic Arts ADPCM  @tab      @tab X
874
@tab Used in various EA titles.
875
@item Creative ADPCM         @tab      @tab X
876
@tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
877
@item RA144                  @tab      @tab X
878
@tab Real 14400 bit/s codec
879
@item RA288                  @tab      @tab X
880
@tab Real 28800 bit/s codec
881
@item RADnet                 @tab X    @tab IX
882
@tab Real low bitrate AC3 codec, liba52 is used for decoding.
883
@item AMR-NB                 @tab X    @tab X
884
@tab Supported through an external library.
885
@item AMR-WB                 @tab X    @tab X
886
@tab Supported through an external library.
887
@item DV audio               @tab      @tab X
888
@item Id RoQ DPCM            @tab      @tab X
889
@tab Used in Quake III, Jedi Knight 2, other computer games.
890
@item Interplay MVE DPCM     @tab      @tab X
891
@tab Used in various Interplay computer games.
892
@item Xan DPCM               @tab      @tab X
893
@tab Used in Origin's Wing Commander IV AVI files.
894
@item Sierra Online DPCM     @tab      @tab X
895
@tab Used in Sierra Online game audio files.
896
@item Apple MACE 3           @tab      @tab X
897
@item Apple MACE 6           @tab      @tab X
898
@item FLAC lossless audio    @tab      @tab X
899
@item Shorten lossless audio @tab      @tab X
900
@item Apple lossless audio   @tab      @tab X
901
@tab QuickTime fourcc 'alac'
902
@item FFmpeg Sonic           @tab X    @tab X
903
@tab experimental lossy/lossless codec
904
@item Qdesign QDM2           @tab      @tab X
905
@tab there are still some distortions
906
@item Real COOK              @tab      @tab X
907
@tab All versions except 5.1 are supported
908
@item DSP Group TrueSpeech   @tab      @tab X
909
@item True Audio (TTA)       @tab      @tab X
910
@item Smacker Audio          @tab      @tab X
911
@item WavPack Audio          @tab      @tab X
912
@end multitable
913

    
914
@code{X} means that encoding (resp. decoding) is supported.
915

    
916
@code{I} means that an integer-only version is available, too (ensures high
917
performance on systems without hardware floating point support).
918

    
919
@chapter Platform Specific information
920

    
921
@section Linux
922

    
923
FFmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
924
preferred compiler now for FFmpeg. All future optimizations will depend on
925
features only found in GCC 3.2.
926

    
927
@section BSD
928

    
929
BSD make will not build FFmpeg, you need to install and use GNU Make
930
(@file{gmake}).
931

    
932
@section Windows
933

    
934
@subsection Native Windows compilation
935

    
936
@itemize
937
@item Install the current versions of MSYS and MinGW from
938
@url{http://www.mingw.org/}. You can find detailed installation
939
instructions in the download section and the FAQ.
940

    
941
@item If you want to test the FFplay, also download
942
the MinGW development library of SDL 1.2.x
943
(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
944
@url{http://www.libsdl.org}. Unpack it in a temporary directory, and
945
unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
946
directory. Edit the @file{sdl-config} script so that it gives the
947
correct SDL directory when invoked.
948

    
949
@item Extract the current version of FFmpeg.
950

    
951
@item Start the MSYS shell (file @file{msys.bat}).
952

    
953
@item Change to the FFmpeg directory and follow
954
 the instructions of how to compile FFmpeg (file
955
@file{INSTALL}). Usually, launching @file{./configure} and @file{make}
956
suffices. If you have problems using SDL, verify that
957
@file{sdl-config} can be launched from the MSYS command line.
958

    
959
@item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
960
@file{make install}. Don't forget to copy @file{SDL.dll} to the place
961
you launch @file{ffplay} from.
962

    
963
@end itemize
964

    
965
Notes:
966
@itemize
967

    
968
@item The target @file{make wininstaller} can be used to create a
969
Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
970
must be copied to the FFmpeg directory in order to build the
971
installer.
972

    
973
@item By using @code{./configure --enable-shared} when configuring FFmpeg,
974
you can build @file{avcodec.dll} and @file{avformat.dll}. With
975
@code{make install} you install the FFmpeg DLLs and the associated
976
headers in @file{Program Files/FFmpeg}.
977

    
978
@item Visual C++ compatibility: If you used @code{./configure --enable-shared}
979
when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
980
C++ @code{lib} tool to build @code{avcodec.lib} and
981
@code{avformat.lib}. With these libraries you can link your Visual C++
982
code directly with the FFmpeg DLLs (see below).
983

    
984
@end itemize
985

    
986
@subsection Visual C++ compatibility
987

    
988
FFmpeg will not compile under Visual C++ -- and it has too many
989
dependencies on the GCC compiler to make a port viable. However,
990
if you want to use the FFmpeg libraries in your own applications,
991
you can still compile those applications using Visual C++. An
992
important restriction to this is that you have to use the
993
dynamically linked versions of the FFmpeg libraries (i.e. the
994
DLLs), and you have to make sure that Visual-C++-compatible
995
import libraries are created during the FFmpeg build process.
996

    
997
This description of how to use the FFmpeg libraries with Visual C++ is
998
based on Visual C++ 2005 Express Edition Beta 2. If you have a different
999
version, you might have to modify the procedures slightly.
1000

    
1001
Here are the step-by-step instructions for building the FFmpeg libraries
1002
so they can be used with Visual C++:
1003

    
1004
@enumerate
1005

    
1006
@item Install Visual C++ (if you haven't done so already).
1007

    
1008
@item Install MinGW and MSYS as described above.
1009

    
1010
@item Add a call to @file{vcvars32.bat} (which sets up the environment
1011
variables for the Visual C++ tools) as the first line of
1012
@file{msys.bat}. The standard location for @file{vcvars32.bat} is
1013
@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
1014
and the standard location for @file{msys.bat} is
1015
@file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
1016
following line as the first line of @file{msys.bat}:
1017

    
1018
@code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
1019

    
1020
@item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
1021
If you get a help message with the command line options of @code{link.exe},
1022
this means your environment variables are set up correctly, the
1023
Microsoft linker is on the path and will be used by FFmpeg to
1024
create Visual-C++-compatible import libraries.
1025

    
1026
@item Extract the current version of FFmpeg and change to the FFmpeg directory.
1027

    
1028
@item Type the command
1029
@code{./configure --enable-shared --disable-static --enable-memalign-hack}
1030
to configure and, if that didn't produce any errors,
1031
type @code{make} to build FFmpeg.
1032

    
1033
@item The subdirectories @file{libavformat}, @file{libavcodec}, and
1034
@file{libavutil} should now contain the files @file{avformat.dll},
1035
@file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1036
@file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1037
DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1038

    
1039
@end enumerate
1040

    
1041
And here is how to use these libraries with Visual C++:
1042

    
1043
@enumerate
1044

    
1045
@item Create a new console application ("File / New / Project") and then
1046
select "Win32 Console Application". On the appropriate page of the
1047
Application Wizard, uncheck the "Precompiled headers" option.
1048

    
1049
@item Write the source code for your application, or, for testing, just
1050
copy the code from an existing sample application into the source file
1051
that Visual C++ has already created for you. (Note that your source
1052
filehas to have a @code{.cpp} extension; otherwise, Visual C++ won't
1053
compile the FFmpeg headers correctly because in C mode, it doesn't
1054
recognize the @code{inline} keyword.)  For example, you can copy
1055
@file{output_example.c} from the FFmpeg distribution (but you will
1056
have to make minor modifications so the code will compile under
1057
C++, see below).
1058

    
1059
@item Open the "Project / Properties" dialog box. In the "Configuration"
1060
combo box, select "All Configurations" so that the changes you make will
1061
affect both debug and release builds. In the tree view on the left hand
1062
side, select "C/C++ / General", then edit the "Additional Include
1063
Directories" setting to contain the complete paths to the
1064
@file{libavformat}, @file{libavcodec}, and @file{libavutil}
1065
subdirectories of your FFmpeg directory. Note that the directories have
1066
to be separated using semicolons. Now select "Linker / General" from the
1067
tree view and edit the "Additional Library Directories" setting to
1068
contain the same three directories.
1069

    
1070
@item Still in the "Project / Properties" dialog box, select "Linker / Input"
1071
from the tree view, then add the files @file{avformat.lib},
1072
@file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1073
Dependencies". Note that the names of the libraries have to be separated
1074
using spaces.
1075

    
1076
@item Now, select "C/C++ / Code Generation" from the tree view. Select
1077
"Debug" in the "Configuration" combo box. Make sure that "Runtime
1078
Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1079
the "Configuration" combo box and make sure that "Runtime Library" is
1080
set to "Multi-threaded DLL".
1081

    
1082
@item Click "OK" to close the "Project / Properties" dialog box and build
1083
the application. Hopefully, it should compile and run cleanly. If you
1084
used @file{output_example.c} as your sample application, you will get a
1085
few compiler errors, but they are easy to fix. The first type of error
1086
occurs because Visual C++ doesn't allow an @code{int} to be converted to
1087
an @code{enum} without a cast. To solve the problem, insert the required
1088
casts (this error occurs once for a @code{CodecID} and once for a
1089
@code{CodecType}).  The second type of error occurs because C++ requires
1090
the return value of @code{malloc} to be cast to the exact type of the
1091
pointer it is being assigned to. Visual C++ will complain that, for
1092
example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1093
an explicit cast. So insert an explicit cast in these places to silence
1094
the compiler. The third type of error occurs because the @code{snprintf}
1095
library function is called @code{_snprintf} under Visual C++.  So just
1096
add an underscore to fix the problem. With these changes,
1097
@file{output_example.c} should compile under Visual C++, and the
1098
resulting executable should produce valid video files.
1099

    
1100
@end enumerate
1101

    
1102
@subsection Cross compilation for Windows with Linux
1103

    
1104
You must use the MinGW cross compilation tools available at
1105
@url{http://www.mingw.org/}.
1106

    
1107
Then configure FFmpeg with the following options:
1108
@example
1109
./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
1110
@end example
1111
(you can change the cross-prefix according to the prefix chosen for the
1112
MinGW tools).
1113

    
1114
Then you can easily test FFmpeg with Wine
1115
(@url{http://www.winehq.com/}).
1116

    
1117
@subsection Compilation under Cygwin
1118

    
1119
Cygwin works very much like Unix.
1120

    
1121
Just install your Cygwin with all the "Base" packages, plus the
1122
following "Devel" ones:
1123
@example
1124
binutils, gcc-core, make, subversion
1125
@end example
1126

    
1127
Do not install binutils-20060709-1 (they are buggy on shared builds);
1128
use binutils-20050610-1 instead.
1129

    
1130
Then run
1131

    
1132
@example
1133
./configure --enable-static --disable-shared
1134
@end example
1135

    
1136
to make a static build or
1137

    
1138
@example
1139
./configure --enable-shared --disable-static
1140
@end example
1141

    
1142
to build shared libraries.
1143

    
1144
If you want to build FFmpeg with additional libraries, download Cygwin
1145
"Devel" packages for Ogg and Vorbis from any Cygwin packages repository
1146
and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
1147
(@url{http://cygwinports.dotsrc.org/}).
1148

    
1149
@subsection Crosscompilation for Windows under Cygwin
1150

    
1151
With Cygwin you can create Windows binaries that don't need the cygwin1.dll.
1152

    
1153
Just install your Cygwin as explained before, plus these additional
1154
"Devel" packages:
1155
@example
1156
gcc-mingw-core, mingw-runtime, mingw-zlib
1157
@end example
1158

    
1159
and add some special flags to your configure invocation.
1160

    
1161
For a static build run
1162
@example
1163
./configure --enable-mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1164
@end example
1165

    
1166
and for a build with shared libraries
1167
@example
1168
./configure --enable-mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1169
@end example
1170

    
1171
@section Mac OS X
1172

    
1173
@section BeOS
1174

    
1175
The configure script should guess the configuration itself.
1176
Networking support is currently not finished.
1177
errno issues fixed by Andrew Bachmann.
1178

    
1179
Old stuff:
1180

    
1181
Fran├žois Revol - revol at free dot fr - April 2002
1182

    
1183
The configure script should guess the configuration itself,
1184
however I still didn't test building on the net_server version of BeOS.
1185

    
1186
FFserver is broken (needs poll() implementation).
1187

    
1188
There are still issues with errno codes, which are negative in BeOS, and
1189
that FFmpeg negates when returning. This ends up turning errors into
1190
valid results, then crashes.
1191
(To be fixed)
1192

    
1193
@chapter Developers Guide
1194

    
1195
@section API
1196
@itemize @bullet
1197
@item libavcodec is the library containing the codecs (both encoding and
1198
decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1199

    
1200
@item libavformat is the library containing the file format handling (mux and
1201
demux code for several formats). Look at @file{ffplay.c} to use it in a
1202
player. See @file{output_example.c} to use it to generate audio or video
1203
streams.
1204

    
1205
@end itemize
1206

    
1207
@section Integrating libavcodec or libavformat in your program
1208

    
1209
You can integrate all the source code of the libraries to link them
1210
statically to avoid any version problem. All you need is to provide a
1211
'config.mak' and a 'config.h' in the parent directory. See the defines
1212
generated by ./configure to understand what is needed.
1213

    
1214
You can use libavcodec or libavformat in your commercial program, but
1215
@emph{any patch you make must be published}. The best way to proceed is
1216
to send your patches to the FFmpeg mailing list.
1217

    
1218
@node Coding Rules
1219
@section Coding Rules
1220

    
1221
FFmpeg is programmed in the ISO C90 language with a few additional
1222
features from ISO C99, namely:
1223
@itemize @bullet
1224
@item
1225
the @samp{inline} keyword;
1226
@item
1227
@samp{//} comments;
1228
@item
1229
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1230
@item
1231
compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1232
@end itemize
1233

    
1234
These features are supported by all compilers we care about, so we won't
1235
accept patches to remove their use unless they absolutely don't impair
1236
clarity and performance.
1237

    
1238
All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1239
compiles with several other compilers, such as the Compaq ccc compiler
1240
or Sun Studio 9, and we would like to keep it that way unless it would
1241
be exceedingly involved. To ensure compatibility, please don't use any
1242
additional C99 features or GCC extensions. Especially watch out for:
1243
@itemize @bullet
1244
@item
1245
mixing statements and declarations;
1246
@item
1247
@samp{long long} (use @samp{int64_t} instead);
1248
@item
1249
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1250
@item
1251
GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1252
@end itemize
1253

    
1254
Indent size is 4.
1255
The presentation is the one specified by 'indent -i4 -kr -nut'.
1256
The TAB character is forbidden outside of Makefiles as is any
1257
form of trailing whitespace. Commits containing either will be
1258
rejected by the Subversion repository.
1259

    
1260
Main priority in FFmpeg is simplicity and small code size (=less
1261
bugs).
1262

    
1263
Comments: Use the JavaDoc/Doxygen
1264
format (see examples below) so that code documentation
1265
can be generated automatically. All nontrivial functions should have a comment
1266
above them explaining what the function does, even if it's just one sentence.
1267
All structures and their member variables should be documented, too.
1268
@example
1269
/**
1270
 * @@file mpeg.c
1271
 * MPEG codec.
1272
 * @@author ...
1273
 */
1274

    
1275
/**
1276
 * Summary sentence.
1277
 * more text ...
1278
 * ...
1279
 */
1280
typedef struct Foobar@{
1281
    int var1; /**< var1 description */
1282
    int var2; ///< var2 description
1283
    /** var3 description */
1284
    int var3;
1285
@} Foobar;
1286

    
1287
/**
1288
 * Summary sentence.
1289
 * more text ...
1290
 * ...
1291
 * @@param my_parameter description of my_parameter
1292
 * @@return return value description
1293
 */
1294
int myfunc(int my_parameter)
1295
...
1296
@end example
1297

    
1298
fprintf and printf are forbidden in libavformat and libavcodec,
1299
please use av_log() instead.
1300

    
1301
@section Development Policy
1302

    
1303
@enumerate
1304
@item
1305
   You must not commit code which breaks FFmpeg! (Meaning unfinished but
1306
   enabled code which breaks compilation or compiles but does not work or
1307
   breaks the regression tests)
1308
   You can commit unfinished stuff (for testing etc), but it must be disabled
1309
   (#ifdef etc) by default so it does not interfere with other developers'
1310
   work.
1311
@item
1312
   You don't have to over-test things. If it works for you, and you think it
1313
   should work for others, then commit. If your code has problems
1314
   (portability, triggers compiler bugs, unusual environment etc) they will be
1315
   reported and eventually fixed.
1316
@item
1317
   Do not commit unrelated changes together, split them into self-contained
1318
   pieces.
1319
@item
1320
   Do not change behavior of the program (renaming options etc) without
1321
   first discussing it on the ffmpeg-devel mailing list. Do not remove
1322
   functionality from the code. Just improve!
1323

    
1324
   Note: Redundant code can be removed.
1325
@item
1326
   Do not commit changes to the build system (Makefiles, configure script)
1327
   which change behavior, defaults etc, without asking first. The same
1328
   applies to compiler warning fixes, trivial looking fixes and to code
1329
   maintained by other developers. We usually have a reason for doing things
1330
   the way we do. Send your changes as patches to the ffmpeg-devel mailing
1331
   list, and if the code maintainers say OK, you may commit. This does not
1332
   apply to files you wrote and/or maintain.
1333
@item
1334
   We refuse source indentation and other cosmetic changes if they are mixed
1335
   with functional changes, such commits will be rejected and removed. Every
1336
   developer has his own indentation style, you should not change it. Of course
1337
   if you (re)write something, you can use your own style, even though we would
1338
   prefer if the indentation throughout FFmpeg was consistent (Many projects
1339
   force a given indentation style - we don't.). If you really need to make
1340
   indentation changes (try to avoid this), separate them strictly from real
1341
   changes.
1342

    
1343
   NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1344
   then either do NOT change the indentation of the inner part within (don't
1345
   move it to the right)! or do so in a separate commit
1346
@item
1347
   Always fill out the commit log message. Describe in a few lines what you
1348
   changed and why. You can refer to mailing list postings if you fix a
1349
   particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1350
@item
1351
   If you apply a patch by someone else, include the name and email address in
1352
   the log message. Since the ffmpeg-cvslog mailing list is publicly
1353
   archived you should add some SPAM protection to the email address. Send an
1354
   answer to ffmpeg-devel (or wherever you got the patch from) saying that
1355
   you applied the patch.
1356
@item
1357
    Do NOT commit to code actively maintained by others without permission.
1358
    Send a patch to ffmpeg-devel instead. If noone answers within a reasonable
1359
    timeframe (12h for build failures and security fixes, 3 days small changes,
1360
    1 week for big patches) then commit your patch if you think it's OK.
1361
    Also note, the maintainer can simply ask for more time to review!
1362
@item
1363
    Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1364
    are sent there and reviewed by all the other developers. Bugs and possible
1365
    improvements or general questions regarding commits are discussed there. We
1366
    expect you to react if problems with your code are uncovered.
1367
@item
1368
    Update the documentation if you change behavior or add features. If you are
1369
    unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1370
    maintainer(s) will review and commit your stuff.
1371
@item
1372
    Never write to unallocated memory, never write over the end of arrays,
1373
    always check values read from some untrusted source before using them
1374
    as array index or other risky things.
1375
@item
1376
    Remember to check if you need to bump versions for the specific libav
1377
    parts (libavutil, libavcodec, libavformat) you are changing. You need
1378
    to change the version integer and the version string.
1379
    Incrementing the first component means no backward compatibility to
1380
    previous versions (e.g. removal of a function from the public API).
1381
    Incrementing the second component means backward compatible change
1382
    (e.g. addition of a function to the public API).
1383
    Incrementing the third component means a noteworthy binary compatible
1384
    change (e.g. encoder bug fix that matters for the decoder).
1385
@item
1386
    If you add a new codec, remember to update the changelog, add it to
1387
    the supported codecs table in the documentation and bump the second
1388
    component of the @file{libavcodec} version number appropriately. If
1389
    it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1390
    is only a decoder.
1391
@end enumerate
1392

    
1393
We think our rules are not too hard. If you have comments, contact us.
1394

    
1395
Note, these rules are mostly borrowed from the MPlayer project.
1396

    
1397
@section Submitting patches
1398

    
1399
First, (@pxref{Coding Rules}) above if you didn't yet.
1400

    
1401
When you submit your patch, try to send a unified diff (diff '-up'
1402
option). I cannot read other diffs :-)
1403

    
1404
Also please do not submit patches which contain several unrelated changes.
1405
Split them into individual self-contained patches; this makes reviewing
1406
them much easier.
1407

    
1408
Run the regression tests before submitting a patch so that you can
1409
verify that there are no big problems.
1410

    
1411
Patches should be posted as base64 encoded attachments (or any other
1412
encoding which ensures that the patch won't be trashed during
1413
transmission) to the ffmpeg-devel mailing list, see
1414
@url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1415

    
1416
It also helps quite a bit if you tell us what the patch does (for example
1417
'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1418
and has no lrint()')
1419

    
1420
We reply to all submitted patches and either apply or reject with some
1421
explanation why, but sometimes we are quite busy so it can take a week or two.
1422

    
1423
@section Regression tests
1424

    
1425
Before submitting a patch (or committing to the repository), you should at least
1426
test that you did not break anything.
1427

    
1428
The regression tests build a synthetic video stream and a synthetic
1429
audio stream. These are then encoded and decoded with all codecs or
1430
formats. The CRC (or MD5) of each generated file is recorded in a
1431
result file. A 'diff' is launched to compare the reference results and
1432
the result file.
1433

    
1434
The regression tests then go on to test the FFserver code with a
1435
limited set of streams. It is important that this step runs correctly
1436
as well.
1437

    
1438
Run 'make test' to test all the codecs and formats.
1439

    
1440
Run 'make fulltest' to test all the codecs, formats and FFserver.
1441

    
1442
[Of course, some patches may change the results of the regression tests. In
1443
this case, the reference results of the regression tests shall be modified
1444
accordingly].
1445

    
1446
@bye