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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 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 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 64} 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 -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 -hq
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Activate high quality settings.
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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 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).
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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 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 rate control buffer 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
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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 -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 -interlace
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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 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 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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@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 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 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
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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 .4
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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 MPEG-1 systems @tab X  @tab  X
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@tab muxed audio and video
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@item MPEG-2 PS @tab X  @tab  X
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@tab also known as @code{VOB} file
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@item MPEG-2 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 Raw CRI ADX audio @tab X  @tab  X
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@item Raw Shorten audio @tab    @tab  X
667
@item SUN AU format @tab X  @tab  X
668
@item NUT @tab X @tab X @tab NUT Open Container Format
669
@item QuickTime        @tab X @tab  X
670
@item MPEG-4           @tab X @tab  X
671
@tab MPEG-4 is a variant of QuickTime.
672
@item Raw MPEG4 video  @tab  X @tab  X
673
@item DV               @tab  X @tab  X
674
@item 4xm              @tab    @tab X
675
@tab 4X Technologies format, used in some games.
676
@item Playstation STR  @tab    @tab X
677
@item Id RoQ           @tab    @tab X
678
@tab Used in Quake III, Jedi Knight 2, other computer games.
679
@item Interplay MVE    @tab    @tab X
680
@tab Format used in various Interplay computer games.
681
@item WC3 Movie        @tab    @tab X
682
@tab Multimedia format used in Origin's Wing Commander III computer game.
683
@item Sega FILM/CPK    @tab    @tab X
684
@tab Used in many Sega Saturn console games.
685
@item Westwood Studios VQA/AUD  @tab    @tab X
686
@tab Multimedia formats used in Westwood Studios games.
687
@item Id Cinematic (.cin) @tab    @tab X
688
@tab Used in Quake II.
689
@item FLIC format      @tab    @tab X
690
@tab .fli/.flc files
691
@item Sierra VMD       @tab    @tab X
692
@tab Used in Sierra CD-ROM games.
693
@item Sierra Online    @tab    @tab X
694
@tab .sol files used in Sierra Online games.
695
@item Matroska         @tab    @tab X
696
@item Electronic Arts Multimedia    @tab    @tab X
697
@tab Used in various EA games; files have extensions like WVE and UV2.
698
@item Nullsoft Video (NSV) format @tab    @tab X
699
@item ADTS AAC audio @tab X @tab X
700
@item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
701
@item American Laser Games MM  @tab    @tab X
702
@tab Multimedia format used in games like Mad Dog McCree
703
@item AVS @tab    @tab X
704
@tab Multimedia format used by the Creature Shock game.
705
@item Smacker @tab    @tab X
706
@tab Multimedia format used by many games.
707
@item GXF @tab    @tab X
708
@end multitable
709

    
710
@code{X} means that encoding (resp. decoding) is supported.
711

    
712
@section Image Formats
713

    
714
FFmpeg can read and write images for each frame of a video sequence. The
715
following image formats are supported:
716

    
717
@multitable @columnfractions .4 .1 .1 .4
718
@item Supported Image Format @tab Encoding @tab Decoding @tab Comments
719
@item PGM, PPM     @tab X @tab X
720
@item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support.
721
@item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
722
@item JPEG         @tab X @tab X @tab Progressive JPEG is not supported.
723
@item .Y.U.V       @tab X @tab X @tab one raw file per component
724
@item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
725
@item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
726
@item SGI          @tab X @tab X @tab SGI RGB image format
727
@end multitable
728

    
729
@code{X} means that encoding (resp. decoding) is supported.
730

    
731
@section Video Codecs
732

    
733
@multitable @columnfractions .4 .1 .1 .4
734
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
735
@item MPEG-1 video           @tab  X  @tab  X
736
@item MPEG-2 video           @tab  X  @tab  X
737
@item MPEG-4                 @tab  X  @tab  X @tab also known as DivX4/5
738
@item MSMPEG4 V1             @tab  X  @tab  X
739
@item MSMPEG4 V2             @tab  X  @tab  X
740
@item MSMPEG4 V3             @tab  X  @tab  X @tab also known as DivX3
741
@item WMV7                   @tab  X  @tab  X
742
@item WMV8                   @tab  X  @tab  X @tab not completely working
743
@item H.261                  @tab  X  @tab  X
744
@item H.263(+)               @tab  X  @tab  X @tab also known as RealVideo 1.0
745
@item H.264                  @tab     @tab  X
746
@item RealVideo 1.0          @tab  X  @tab  X
747
@item RealVideo 2.0          @tab  X  @tab  X
748
@item MJPEG                  @tab  X  @tab  X
749
@item lossless MJPEG         @tab  X  @tab  X
750
@item JPEG-LS                @tab  X  @tab  X @tab fourcc: MJLS, lossless and near-lossless is supported
751
@item Apple MJPEG-B          @tab     @tab  X
752
@item Sunplus MJPEG          @tab     @tab  X @tab fourcc: SP5X
753
@item DV                     @tab  X  @tab  X
754
@item HuffYUV                @tab  X  @tab  X
755
@item FFmpeg Video 1         @tab  X  @tab  X @tab experimental lossless codec (fourcc: FFV1)
756
@item FFmpeg Snow            @tab  X  @tab  X @tab experimental wavelet codec (fourcc: SNOW)
757
@item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1
758
@item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2
759
@item Creative YUV           @tab     @tab  X @tab fourcc: CYUV
760
@item Sorenson Video 1       @tab  X  @tab  X @tab fourcc: SVQ1
761
@item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3
762
@item On2 VP3                @tab     @tab  X @tab still experimental
763
@item Theora                 @tab     @tab  X @tab still experimental
764
@item Intel Indeo 3          @tab     @tab  X
765
@item FLV                    @tab  X  @tab  X @tab Sorenson H.263 used in Flash
766
@item Flash Screen Video     @tab     @tab  X @tab fourcc: FSV1
767
@item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1
768
@item ATI VCR2               @tab     @tab  X @tab fourcc: VCR2
769
@item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR
770
@item 4X Video               @tab     @tab  X @tab Used in certain computer games.
771
@item Sony Playstation MDEC  @tab     @tab  X
772
@item Id RoQ                 @tab     @tab  X @tab Used in Quake III, Jedi Knight 2, other computer games.
773
@item Xan/WC3                @tab     @tab  X @tab Used in Wing Commander III .MVE files.
774
@item Interplay Video        @tab     @tab  X @tab Used in Interplay .MVE files.
775
@item Apple Animation        @tab     @tab  X @tab fourcc: 'rle '
776
@item Apple Graphics         @tab     @tab  X @tab fourcc: 'smc '
777
@item Apple Video            @tab     @tab  X @tab fourcc: rpza
778
@item Apple QuickDraw        @tab     @tab  X @tab fourcc: qdrw
779
@item Cinepak                @tab     @tab  X
780
@item Microsoft RLE          @tab     @tab  X
781
@item Microsoft Video-1      @tab     @tab  X
782
@item Westwood VQA           @tab     @tab  X
783
@item Id Cinematic Video     @tab     @tab  X @tab Used in Quake II.
784
@item Planar RGB             @tab     @tab  X @tab fourcc: 8BPS
785
@item FLIC video             @tab     @tab  X
786
@item Duck TrueMotion v1     @tab     @tab  X @tab fourcc: DUCK
787
@item Duck TrueMotion v2     @tab     @tab  X @tab fourcc: TM20
788
@item VMD Video              @tab     @tab  X @tab Used in Sierra VMD files.
789
@item MSZH                   @tab     @tab  X @tab Part of LCL
790
@item ZLIB                   @tab  X  @tab  X @tab Part of LCL, encoder experimental
791
@item TechSmith Camtasia     @tab     @tab  X @tab fourcc: TSCC
792
@item IBM Ultimotion         @tab     @tab  X @tab fourcc: ULTI
793
@item Miro VideoXL           @tab     @tab  X @tab fourcc: VIXL
794
@item QPEG                   @tab     @tab  X @tab fourccs: QPEG, Q1.0, Q1.1
795
@item LOCO                   @tab     @tab  X @tab
796
@item Winnov WNV1            @tab     @tab  X @tab
797
@item Autodesk Animator Studio Codec  @tab     @tab  X @tab fourcc: AASC
798
@item Fraps FPS1             @tab     @tab  X @tab
799
@item CamStudio              @tab     @tab  X @tab fourcc: CSCD
800
@item American Laser Games Video  @tab    @tab X @tab Used in games like Mad Dog McCree
801
@item ZMBV                   @tab     @tab  X @tab
802
@item AVS Video              @tab     @tab  X @tab Video encoding used by the Creature Shock game.
803
@item Smacker Video          @tab     @tab  X @tab Video encoding used in Smacker.
804
@item RTjpeg                 @tab     @tab  X @tab Video encoding used in NuppelVideo files.
805
@item KMVC                   @tab     @tab  X @tab Codec used in Worms games.
806
@end multitable
807

    
808
@code{X} means that encoding (resp. decoding) is supported.
809

    
810
See @url{http://mplayerhq.hu/~michael/codec-features.html} to
811
get a precise comparison of the FFmpeg MPEG-4 codec compared to
812
other implementations.
813

    
814
@section Audio Codecs
815

    
816
@multitable @columnfractions .4 .1 .1 .1 .7
817
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
818
@item MPEG audio layer 2     @tab  IX  @tab  IX
819
@item MPEG audio layer 1/3   @tab IX   @tab  IX
820
@tab MP3 encoding is supported through the external library LAME.
821
@item AC3                    @tab  IX  @tab  IX
822
@tab liba52 is used internally for decoding.
823
@item Vorbis                 @tab  X   @tab  X
824
@tab Supported through the external library libvorbis.
825
@item WMA V1/V2              @tab      @tab X
826
@item AAC                    @tab X    @tab X
827
@tab Supported through the external library libfaac/libfaad.
828
@item Microsoft ADPCM        @tab X    @tab X
829
@item MS IMA ADPCM           @tab X    @tab X
830
@item QT IMA ADPCM           @tab      @tab X
831
@item 4X IMA ADPCM           @tab      @tab X
832
@item G.726  ADPCM           @tab X    @tab X
833
@item Duck DK3 IMA ADPCM     @tab      @tab X
834
@tab Used in some Sega Saturn console games.
835
@item Duck DK4 IMA ADPCM     @tab      @tab X
836
@tab Used in some Sega Saturn console games.
837
@item Westwood Studios IMA ADPCM @tab      @tab X
838
@tab Used in Westwood Studios games like Command and Conquer.
839
@item SMJPEG IMA ADPCM       @tab      @tab X
840
@tab Used in certain Loki game ports.
841
@item CD-ROM XA ADPCM        @tab      @tab X
842
@item CRI ADX ADPCM          @tab X    @tab X
843
@tab Used in Sega Dreamcast games.
844
@item Electronic Arts ADPCM  @tab      @tab X
845
@tab Used in various EA titles.
846
@item Creative ADPCM         @tab      @tab X
847
@tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
848
@item RA144                  @tab      @tab X
849
@tab Real 14400 bit/s codec
850
@item RA288                  @tab      @tab X
851
@tab Real 28800 bit/s codec
852
@item RADnet                 @tab X    @tab IX
853
@tab Real low bitrate AC3 codec, liba52 is used for decoding.
854
@item AMR-NB                 @tab X    @tab X
855
@tab Supported through an external library.
856
@item AMR-WB                 @tab X    @tab X
857
@tab Supported through an external library.
858
@item DV audio               @tab      @tab X
859
@item Id RoQ DPCM            @tab      @tab X
860
@tab Used in Quake III, Jedi Knight 2, other computer games.
861
@item Interplay MVE DPCM     @tab      @tab X
862
@tab Used in various Interplay computer games.
863
@item Xan DPCM               @tab      @tab X
864
@tab Used in Origin's Wing Commander IV AVI files.
865
@item Sierra Online DPCM     @tab      @tab X
866
@tab Used in Sierra Online game audio files.
867
@item Apple MACE 3           @tab      @tab X
868
@item Apple MACE 6           @tab      @tab X
869
@item FLAC lossless audio    @tab      @tab X
870
@item Shorten lossless audio @tab      @tab X
871
@item Apple lossless audio   @tab      @tab X
872
@tab QuickTime fourcc 'alac'
873
@item FFmpeg Sonic           @tab X    @tab X
874
@tab experimental lossy/lossless codec
875
@item Qdesign QDM2           @tab      @tab X
876
@tab there are still some distortions
877
@item Real COOK              @tab      @tab X
878
@tab All versions except 5.1 are supported
879
@item DSP Group TrueSpeech   @tab      @tab X
880
@item True Audio (TTA)       @tab      @tab X
881
@item Smacker Audio          @tab      @tab X
882
@end multitable
883

    
884
@code{X} means that encoding (resp. decoding) is supported.
885

    
886
@code{I} means that an integer-only version is available, too (ensures high
887
performance on systems without hardware floating point support).
888

    
889
@chapter Platform Specific information
890

    
891
@section Linux
892

    
893
FFmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
894
preferred compiler now for FFmpeg. All future optimizations will depend on
895
features only found in GCC 3.2.
896

    
897
@section BSD
898

    
899
BSD make will not build FFmpeg, you need to install and use GNU Make
900
(@file{gmake}).
901

    
902
@section Windows
903

    
904
@subsection Native Windows compilation
905

    
906
@itemize
907
@item Install the current versions of MSYS and MinGW from
908
@url{http://www.mingw.org/}. You can find detailed installation
909
instructions in the download section and the FAQ.
910

    
911
@item If you want to test the FFplay, also download
912
the MinGW development library of SDL 1.2.x
913
(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
914
@url{http://www.libsdl.org}. Unpack it in a temporary directory, and
915
unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
916
directory. Edit the @file{sdl-config} script so that it gives the
917
correct SDL directory when invoked.
918

    
919
@item Extract the current version of FFmpeg.
920

    
921
@item Start the MSYS shell (file @file{msys.bat}).
922

    
923
@item Change to the FFmpeg directory and follow
924
 the instructions of how to compile FFmpeg (file
925
@file{INSTALL}). Usually, launching @file{./configure} and @file{make}
926
suffices. If you have problems using SDL, verify that
927
@file{sdl-config} can be launched from the MSYS command line.
928

    
929
@item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
930
@file{make install}. Don't forget to copy @file{SDL.dll} to the place
931
you launch @file{ffplay} from.
932

    
933
@end itemize
934

    
935
Notes:
936
@itemize
937

    
938
@item The target @file{make wininstaller} can be used to create a
939
Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
940
must be copied to the FFmpeg directory in order to build the
941
installer.
942

    
943
@item By using @code{./configure --enable-shared} when configuring FFmpeg,
944
you can build @file{avcodec.dll} and @file{avformat.dll}. With
945
@code{make install} you install the FFmpeg DLLs and the associated
946
headers in @file{Program Files/FFmpeg}.
947

    
948
@item Visual C++ compatibility: If you used @code{./configure --enable-shared}
949
when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
950
C++ @code{lib} tool to build @code{avcodec.lib} and
951
@code{avformat.lib}. With these libraries you can link your Visual C++
952
code directly with the FFmpeg DLLs (see below).
953

    
954
@end itemize
955

    
956
@subsection Visual C++ compatibility
957

    
958
FFmpeg will not compile under Visual C++ -- and it has too many
959
dependencies on the GCC compiler to make a port viable. However,
960
if you want to use the FFmpeg libraries in your own applications,
961
you can still compile those applications using Visual C++. An
962
important restriction to this is that you have to use the
963
dynamically linked versions of the FFmpeg libraries (i.e. the
964
DLLs), and you have to make sure that Visual-C++-compatible
965
import libraries are created during the FFmpeg build process.
966

    
967
This description of how to use the FFmpeg libraries with Visual C++ is
968
based on Visual C++ 2005 Express Edition Beta 2. If you have a different
969
version, you might have to modify the procedures slightly.
970

    
971
Here are the step-by-step instructions for building the FFmpeg libraries
972
so they can be used with Visual C++:
973

    
974
@enumerate
975

    
976
@item Install Visual C++ (if you haven't done so already).
977

    
978
@item Install MinGW and MSYS as described above.
979

    
980
@item Add a call to @file{vcvars32.bat} (which sets up the environment
981
variables for the Visual C++ tools) as the first line of
982
@file{msys.bat}. The standard location for @file{vcvars32.bat} is
983
@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
984
and the standard location for @file{msys.bat} is
985
@file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
986
following line as the first line of @file{msys.bat}:
987

    
988
@code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
989

    
990
@item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
991
If you get a help message with the command line options of @code{link.exe},
992
this means your environment variables are set up correctly, the
993
Microsoft linker is on the path and will be used by FFmpeg to
994
create Visual-C++-compatible import libraries.
995

    
996
@item Extract the current version of FFmpeg and change to the FFmpeg directory.
997

    
998
@item Type the command
999
@code{./configure --enable-shared --disable-static --enable-memalign-hack}
1000
to configure and, if that didn't produce any errors,
1001
type @code{make} to build FFmpeg.
1002

    
1003
@item The subdirectories @file{libavformat}, @file{libavcodec}, and
1004
@file{libavutil} should now contain the files @file{avformat.dll},
1005
@file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1006
@file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1007
DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1008

    
1009
@end enumerate
1010

    
1011
And here is how to use these libraries with Visual C++:
1012

    
1013
@enumerate
1014

    
1015
@item Create a new console application ("File / New / Project") and then
1016
select "Win32 Console Application". On the appropriate page of the
1017
Application Wizard, uncheck the "Precompiled headers" option.
1018

    
1019
@item Write the source code for your application, or, for testing, just
1020
copy the code from an existing sample application into the source file
1021
that Visual C++ has already created for you. (Note that your source
1022
filehas to have a @code{.cpp} extension; otherwise, Visual C++ won't
1023
compile the FFmpeg headers correctly because in C mode, it doesn't
1024
recognize the @code{inline} keyword.)  For example, you can copy
1025
@file{output_example.c} from the FFmpeg distribution (but you will
1026
have to make minor modifications so the code will compile under
1027
C++, see below).
1028

    
1029
@item Open the "Project / Properties" dialog box. In the "Configuration"
1030
combo box, select "All Configurations" so that the changes you make will
1031
affect both debug and release builds. In the tree view on the left hand
1032
side, select "C/C++ / General", then edit the "Additional Include
1033
Directories" setting to contain the complete paths to the
1034
@file{libavformat}, @file{libavcodec}, and @file{libavutil}
1035
subdirectories of your FFmpeg directory. Note that the directories have
1036
to be separated using semicolons. Now select "Linker / General" from the
1037
tree view and edit the "Additional Library Directories" setting to
1038
contain the same three directories.
1039

    
1040
@item Still in the "Project / Properties" dialog box, select "Linker / Input"
1041
from the tree view, then add the files @file{avformat.lib},
1042
@file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1043
Dependencies". Note that the names of the libraries have to be separated
1044
using spaces.
1045

    
1046
@item Now, select "C/C++ / Code Generation" from the tree view. Select
1047
"Debug" in the "Configuration" combo box. Make sure that "Runtime
1048
Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1049
the "Configuration" combo box and make sure that "Runtime Library" is
1050
set to "Multi-threaded DLL".
1051

    
1052
@item Click "OK" to close the "Project / Properties" dialog box and build
1053
the application. Hopefully, it should compile and run cleanly. If you
1054
used @file{output_example.c} as your sample application, you will get a
1055
few compiler errors, but they are easy to fix. The first type of error
1056
occurs because Visual C++ doesn't allow an @code{int} to be converted to
1057
an @code{enum} without a cast. To solve the problem, insert the required
1058
casts (this error occurs once for a @code{CodecID} and once for a
1059
@code{CodecType}).  The second type of error occurs because C++ requires
1060
the return value of @code{malloc} to be cast to the exact type of the
1061
pointer it is being assigned to. Visual C++ will complain that, for
1062
example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1063
an explicit cast. So insert an explicit cast in these places to silence
1064
the compiler. The third type of error occurs because the @code{snprintf}
1065
library function is called @code{_snprintf} under Visual C++.  So just
1066
add an underscore to fix the problem. With these changes,
1067
@file{output_example.c} should compile under Visual C++, and the
1068
resulting executable should produce valid video files.
1069

    
1070
@end enumerate
1071

    
1072
@subsection Cross compilation for Windows with Linux
1073

    
1074
You must use the MinGW cross compilation tools available at
1075
@url{http://www.mingw.org/}.
1076

    
1077
Then configure FFmpeg with the following options:
1078
@example
1079
./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
1080
@end example
1081
(you can change the cross-prefix according to the prefix chosen for the
1082
MinGW tools).
1083

    
1084
Then you can easily test FFmpeg with Wine
1085
(@url{http://www.winehq.com/}).
1086

    
1087
@section Mac OS X
1088

    
1089
@section BeOS
1090

    
1091
The configure script should guess the configuration itself.
1092
Networking support is currently not finished.
1093
errno issues fixed by Andrew Bachmann.
1094

    
1095
Old stuff:
1096

    
1097
Fran├žois Revol - revol at free dot fr - April 2002
1098

    
1099
The configure script should guess the configuration itself,
1100
however I still didn't test building on the net_server version of BeOS.
1101

    
1102
FFserver is broken (needs poll() implementation).
1103

    
1104
There are still issues with errno codes, which are negative in BeOS, and
1105
that FFmpeg negates when returning. This ends up turning errors into
1106
valid results, then crashes.
1107
(To be fixed)
1108

    
1109
@chapter Developers Guide
1110

    
1111
@section API
1112
@itemize
1113
@item libavcodec is the library containing the codecs (both encoding and
1114
decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1115

    
1116
@item libavformat is the library containing the file format handling (mux and
1117
demux code for several formats). Look at @file{ffplay.c} to use it in a
1118
player. See @file{output_example.c} to use it to generate audio or video
1119
streams.
1120

    
1121
@end itemize
1122

    
1123
@section Integrating libavcodec or libavformat in your program
1124

    
1125
You can integrate all the source code of the libraries to link them
1126
statically to avoid any version problem. All you need is to provide a
1127
'config.mak' and a 'config.h' in the parent directory. See the defines
1128
generated by ./configure to understand what is needed.
1129

    
1130
You can use libavcodec or libavformat in your commercial program, but
1131
@emph{any patch you make must be published}. The best way to proceed is
1132
to send your patches to the FFmpeg mailing list.
1133

    
1134
@node Coding Rules
1135
@section Coding Rules
1136

    
1137
FFmpeg is programmed in the ISO C90 language with a few additional
1138
features from ISO C99, namely:
1139
@itemize @bullet
1140
@item
1141
the @samp{inline} keyword;
1142
@item
1143
@samp{//} comments;
1144
@item
1145
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1146
@item
1147
compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1148
@end itemize
1149

    
1150
These features are supported by all compilers we care about, so we won't
1151
accept patches to remove their use unless they absolutely don't impair
1152
clarity and performance.
1153

    
1154
All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1155
compiles with several other compilers, such as the Compaq ccc compiler
1156
or Sun Studio 9, and we would like to keep it that way unless it would
1157
be exceedingly involved. To ensure compatibility, please don't use any
1158
additional C99 features or GCC extensions. Especially watch out for:
1159
@itemize @bullet
1160
@item
1161
mixing statements and declarations;
1162
@item
1163
@samp{long long} (use @samp{int64_t} instead);
1164
@item
1165
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1166
@item
1167
GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1168
@end itemize
1169

    
1170
Indent size is 4.
1171
The presentation is the one specified by 'indent -i4 -kr -nut'.
1172
The TAB character is forbidden outside of Makefiles as is any
1173
form of trailing whitespace. Commits containing either will be
1174
rejected by the Subversion repository.
1175

    
1176
Main priority in FFmpeg is simplicity and small code size (=less
1177
bugs).
1178

    
1179
Comments: Use the JavaDoc/Doxygen
1180
format (see examples below) so that code documentation
1181
can be generated automatically. All nontrivial functions should have a comment
1182
above them explaining what the function does, even if it's just one sentence.
1183
All structures and their member variables should be documented, too.
1184
@example
1185
/**
1186
 * @@file mpeg.c
1187
 * MPEG codec.
1188
 * @@author ...
1189
 */
1190

    
1191
/**
1192
 * Summary sentence.
1193
 * more text ...
1194
 * ...
1195
 */
1196
typedef struct Foobar@{
1197
    int var1; /**< var1 description */
1198
    int var2; ///< var2 description
1199
    /** var3 description */
1200
    int var3;
1201
@} Foobar;
1202

    
1203
/**
1204
 * Summary sentence.
1205
 * more text ...
1206
 * ...
1207
 * @@param my_parameter description of my_parameter
1208
 * @@return return value description
1209
 */
1210
int myfunc(int my_parameter)
1211
...
1212
@end example
1213

    
1214
fprintf and printf are forbidden in libavformat and libavcodec,
1215
please use av_log() instead.
1216

    
1217
@node Development Policy
1218
@section Development Policy
1219

    
1220
@enumerate
1221
@item
1222
   You must not commit code which breaks FFmpeg! (Meaning unfinished but
1223
   enabled code which breaks compilation or compiles but does not work or
1224
   breaks the regression tests)
1225
   You can commit unfinished stuff (for testing etc), but it must be disabled
1226
   (#ifdef etc) by default so it does not interfere with other developers'
1227
   work.
1228
@item
1229
   You don't have to over-test things. If it works for you, and you think it
1230
   should work for others, then commit. If your code has problems
1231
   (portability, triggers compiler bugs, unusual environment etc) they will be
1232
   reported and eventually fixed.
1233
@item
1234
   Do not commit unrelated changes together, split them into self-contained
1235
   pieces.
1236
@item
1237
   Do not change behavior of the program (renaming options etc) without
1238
   first discussing it on the ffmpeg-devel mailing list. Do not remove
1239
   functionality from the code. Just improve!
1240

    
1241
   Note: Redundant code can be removed.
1242
@item
1243
   Do not commit changes to the build system (Makefiles, configure script)
1244
   which change behavior, defaults etc, without asking first. The same
1245
   applies to compiler warning fixes, trivial looking fixes and to code
1246
   maintained by other developers. We usually have a reason for doing things
1247
   the way we do. Send your changes as patches to the ffmpeg-devel mailing
1248
   list, and if the code maintainers say OK, you may commit. This does not
1249
   apply to files you wrote and/or maintain.
1250
@item
1251
   We refuse source indentation and other cosmetic changes if they are mixed
1252
   with functional changes, such commits will be rejected and removed. Every
1253
   developer has his own indentation style, you should not change it. Of course
1254
   if you (re)write something, you can use your own style, even though we would
1255
   prefer if the indentation throughout FFmpeg was consistent (Many projects
1256
   force a given indentation style - we don't.). If you really need to make
1257
   indentation changes (try to avoid this), separate them strictly from real
1258
   changes.
1259

    
1260
   NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1261
   then either do NOT change the indentation of the inner part within (don't
1262
   move it to the right)! or do so in a separate commit
1263
@item
1264
   Always fill out the commit log message. Describe in a few lines what you
1265
   changed and why. You can refer to mailing list postings if you fix a
1266
   particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1267
@item
1268
   If you apply a patch by someone else, include the name and email address in
1269
   the log message. Since the ffmpeg-cvslog mailing list is publicly
1270
   archived you should add some SPAM protection to the email address. Send an
1271
   answer to ffmpeg-devel (or wherever you got the patch from) saying that
1272
   you applied the patch.
1273
@item
1274
   Do NOT commit to code actively maintained by others without permission. Send
1275
   a patch to ffmpeg-devel instead.
1276
@item
1277
    Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1278
    are sent there and reviewed by all the other developers. Bugs and possible
1279
    improvements or general questions regarding commits are discussed there. We
1280
    expect you to react if problems with your code are uncovered.
1281
@item
1282
    Update the documentation if you change behavior or add features. If you are
1283
    unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1284
    maintainer(s) will review and commit your stuff.
1285
@item
1286
    Never write to unallocated memory, never write over the end of arrays,
1287
    always check values read from some untrusted source before using them
1288
    as array index or other risky things.
1289
@item
1290
    Remember to check if you need to bump versions for the specific libav
1291
    parts (libavutil, libavcodec, libavformat) you are changing. You need
1292
    to change the version integer and the version string.
1293
    Incrementing the first component means no backward compatibility to
1294
    previous versions (e.g. removal of a function).
1295
    Incrementing the second component means backward compatible change
1296
    (e.g. addition of a function).
1297
    Incrementing the third component means a noteworthy binary compatible
1298
    change (e.g. encoder bug fix that matters for the decoder).
1299
@item
1300
    If you add a new codec, remember to update the changelog, add it to
1301
    the supported codecs table in the documentation and bump the second
1302
    component of the @file{libavcodec} version number appropriately. If
1303
    it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1304
    is only a decoder.
1305
@end enumerate
1306

    
1307
We think our rules are not too hard. If you have comments, contact us.
1308

    
1309
Note, these rules are mostly borrowed from the MPlayer project.
1310

    
1311
@subsection Renaming/moving files or content of files
1312
  You CANNOT do that. Post a request for such a change to the mailing list
1313
  Do NOT remove & readd a file - it will kill the changelog!!!!
1314

    
1315
@section Submitting patches
1316

    
1317
First, (@pxref{Coding Rules}) above if you didn't yet.
1318

    
1319
When you submit your patch, try to send a unified diff (diff '-up'
1320
option). I cannot read other diffs :-)
1321

    
1322
Also please do not submit patches which contain several unrelated changes.
1323
Split them into individual self-contained patches; this makes reviewing
1324
them much easier.
1325

    
1326
Run the regression tests before submitting a patch so that you can
1327
verify that there are no big problems.
1328

    
1329
Patches should be posted as base64 encoded attachments (or any other
1330
encoding which ensures that the patch won't be trashed during
1331
transmission) to the ffmpeg-devel mailing list, see
1332
@url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1333

    
1334
It also helps quite a bit if you tell us what the patch does (for example
1335
'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1336
and has no lrint()')
1337

    
1338
We reply to all submitted patches and either apply or reject with some
1339
explanation why, but sometimes we are quite busy so it can take a week or two.
1340

    
1341
@section Regression tests
1342

    
1343
Before submitting a patch (or committing to the repository), you should at least
1344
test that you did not break anything.
1345

    
1346
The regression tests build a synthetic video stream and a synthetic
1347
audio stream. These are then encoded and decoded with all codecs or
1348
formats. The CRC (or MD5) of each generated file is recorded in a
1349
result file. A 'diff' is launched to compare the reference results and
1350
the result file.
1351

    
1352
The regression tests then go on to test the FFserver code with a
1353
limited set of streams. It is important that this step runs correctly
1354
as well.
1355

    
1356
Run 'make test' to test all the codecs and formats.
1357

    
1358
Run 'make fulltest' to test all the codecs, formats and FFserver.
1359

    
1360
[Of course, some patches may change the results of the regression tests. In
1361
this case, the reference results of the regression tests shall be modified
1362
accordingly].
1363

    
1364
@bye