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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 -version
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Show version.
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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 -fs limit_size
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Set the file size limit.
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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 -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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@item -title string
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Set the title.
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@item -timestamp time
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Set the timestamp.
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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 -album string
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Set the album.
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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 -v verbose
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Control amount of logging.
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@item -target type
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Specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "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 -dframes number
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Set the number of data frames to record.
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@item -scodec codec
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Force subtitle codec ('copy' to copy stream).
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@item -newsubtitle
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Add a new subtitle stream to the current output stream.
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@item -slang code
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Set the ISO 639 language code (3 letters) of the current subtitle stream.
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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 -vframes number
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Set the number of video frames to record.
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@item -r fps
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Set frame rate (Hz value, fraction or abbreviation), (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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@item -newvideo
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Add a new video stream to the current output stream.
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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 -pix_fmt format
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Set pixel format.
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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 -vdt n
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Discard threshold.
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@item -qscale q
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Use fixed video quantizer scale (VBR).
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@item -qmin q
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minimum video quantizer scale (VBR)
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@item -qmax q
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maximum video quantizer scale (VBR)
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@item -qdiff q
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maximum difference between the quantizer scales (VBR)
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@item -qblur blur
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video quantizer scale blur (VBR)
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@item -qcomp compression
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video quantizer 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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@item -top n
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top=1/bottom=0/auto=-1 field first
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@item -dc precision
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Intra_dc_precision.
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@item -vtag fourcc/tag
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Force video tag/fourcc.
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@item -qphist
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Show QP histogram.
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@item -vbsf bitstream filter
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Bitstream filters available are "dump_extra", "remove_extra", "noise".
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@end table
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@section Audio Options
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@table @option
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@item -aframes number
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Set the number of audio frames to record.
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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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@item -newaudio
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Add a new audio track to the output file. If you want to specify parameters,
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do so before @code{-newaudio} (@code{-acodec}, @code{-ab}, etc..).
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Mapping will be done automatically, if the number of output streams is equal to
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the number of input streams, else it will pick the first one that matches. You
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can override the mapping using @code{-map} as usual.
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Example:
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@example
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ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384 test.mpg -acodec mp2 -ab 192 -newaudio
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@end example
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@item -alang code
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Set the ISO 639 language code (3 letters) of the current audio stream.
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@end table
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@section Advanced Audio options:
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@table @option
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@item -atag fourcc/tag
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Force audio tag/fourcc.
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@item -absf bitstream filter
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Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
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@end table
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@section Subtitle options:
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@table @option
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@item -scodec codec
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Force subtitle codec ('copy' to copy stream).
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@item -newsubtitle
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Add a new subtitle stream to the current output stream.
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@item -slang code
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Set the ISO 639 language code (3 letters) of the current subtitle stream.
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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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@item -grab format
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Request grabbing using.
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@item -gd device
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Set grab device.
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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 -map_meta_data outfile:infile
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Set meta data information of outfile from infile.
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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 -dump
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Dump each input packet.
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@item -hex
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When dumping packets, also dump the payload.
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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_input
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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 -threads count
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Thread count.
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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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665
The following constants are available:
666
@table @var
667
@item PI
668
@item E
669
@item iTex
670
@item pTex
671
@item tex
672
@item mv
673
@item fCode
674
@item iCount
675
@item mcVar
676
@item var
677
@item isI
678
@item isP
679
@item isB
680
@item avgQP
681
@item qComp
682
@item avgIITex
683
@item avgPITex
684
@item avgPPTex
685
@item avgBPTex
686
@item avgTex
687
@end table
688

    
689
@c man end
690

    
691
@ignore
692

    
693
@setfilename ffmpeg
694
@settitle FFmpeg video converter
695

    
696
@c man begin SEEALSO
697
ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
698
@c man end
699

    
700
@c man begin AUTHOR
701
Fabrice Bellard
702
@c man end
703

    
704
@end ignore
705

    
706
@section Protocols
707

    
708
The filename can be @file{-} to read from standard input or to write
709
to standard output.
710

    
711
FFmpeg also handles many protocols specified with an URL syntax.
712

    
713
Use 'ffmpeg -formats' to see a list of the supported protocols.
714

    
715
The protocol @code{http:} is currently used only to communicate with
716
FFserver (see the FFserver documentation). When FFmpeg will be a
717
video player it will also be used for streaming :-)
718

    
719
@chapter Tips
720

    
721
@itemize
722
@item For streaming at very low bitrate application, use a low frame rate
723
and a small GOP size. This is especially true for RealVideo where
724
the Linux player does not seem to be very fast, so it can miss
725
frames. An example is:
726

    
727
@example
728
ffmpeg -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
729
@end example
730

    
731
@item  The parameter 'q' which is displayed while encoding is the current
732
quantizer. The value 1 indicates that a very good quality could
733
be achieved. The value 31 indicates the worst quality. If q=31 appears
734
too often, it means that the encoder cannot compress enough to meet
735
your bitrate. You must either increase the bitrate, decrease the
736
frame rate or decrease the frame size.
737

    
738
@item If your computer is not fast enough, you can speed up the
739
compression at the expense of the compression ratio. You can use
740
'-me zero' to speed up motion estimation, and '-intra' to disable
741
motion estimation completely (you have only I-frames, which means it
742
is about as good as JPEG compression).
743

    
744
@item To have very low audio bitrates, reduce the sampling frequency
745
(down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
746

    
747
@item To have a constant quality (but a variable bitrate), use the option
748
'-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
749
quality).
750

    
751
@item When converting video files, you can use the '-sameq' option which
752
uses the same quality factor in the encoder as in the decoder.
753
It allows almost lossless encoding.
754

    
755
@end itemize
756

    
757
@chapter Supported File Formats and Codecs
758

    
759
You can use the @code{-formats} option to have an exhaustive list.
760

    
761
@section File Formats
762

    
763
FFmpeg supports the following file formats through the @code{libavformat}
764
library:
765

    
766
@multitable @columnfractions .4 .1 .1 .4
767
@item Supported File Format @tab Encoding @tab Decoding @tab Comments
768
@item MPEG audio @tab X @tab X
769
@item MPEG-1 systems @tab X  @tab  X
770
@tab muxed audio and video
771
@item MPEG-2 PS @tab X  @tab  X
772
@tab also known as @code{VOB} file
773
@item MPEG-2 TS @tab    @tab  X
774
@tab also known as DVB Transport Stream
775
@item ASF@tab X @tab X
776
@item AVI@tab X @tab X
777
@item WAV@tab X @tab X
778
@item Macromedia Flash@tab X @tab X
779
@tab Only embedded audio is decoded.
780
@item FLV              @tab  X @tab X
781
@tab Macromedia Flash video files
782
@item Real Audio and Video @tab X @tab X
783
@item Raw AC3 @tab X  @tab  X
784
@item Raw MJPEG @tab X  @tab  X
785
@item Raw MPEG video @tab X  @tab  X
786
@item Raw PCM8/16 bits, mulaw/Alaw@tab X  @tab  X
787
@item Raw CRI ADX audio @tab X  @tab  X
788
@item Raw Shorten audio @tab    @tab  X
789
@item SUN AU format @tab X  @tab  X
790
@item NUT @tab X @tab X @tab NUT Open Container Format
791
@item QuickTime        @tab X @tab  X
792
@item MPEG-4           @tab X @tab  X
793
@tab MPEG-4 is a variant of QuickTime.
794
@item Raw MPEG4 video  @tab  X @tab  X
795
@item DV               @tab  X @tab  X
796
@item 4xm              @tab    @tab X
797
@tab 4X Technologies format, used in some games.
798
@item Playstation STR  @tab    @tab X
799
@item Id RoQ           @tab    @tab X
800
@tab Used in Quake III, Jedi Knight 2, other computer games.
801
@item Interplay MVE    @tab    @tab X
802
@tab Format used in various Interplay computer games.
803
@item WC3 Movie        @tab    @tab X
804
@tab Multimedia format used in Origin's Wing Commander III computer game.
805
@item Sega FILM/CPK    @tab    @tab X
806
@tab Used in many Sega Saturn console games.
807
@item Westwood Studios VQA/AUD  @tab    @tab X
808
@tab Multimedia formats used in Westwood Studios games.
809
@item Id Cinematic (.cin) @tab    @tab X
810
@tab Used in Quake II.
811
@item FLIC format      @tab    @tab X
812
@tab .fli/.flc files
813
@item Sierra VMD       @tab    @tab X
814
@tab Used in Sierra CD-ROM games.
815
@item Sierra Online    @tab    @tab X
816
@tab .sol files used in Sierra Online games.
817
@item Matroska         @tab    @tab X
818
@item Electronic Arts Multimedia    @tab    @tab X
819
@tab Used in various EA games; files have extensions like WVE and UV2.
820
@item Nullsoft Video (NSV) format @tab    @tab X
821
@item ADTS AAC audio @tab X @tab X
822
@item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
823
@item American Laser Games MM  @tab    @tab X
824
@tab Multimedia format used in games like Mad Dog McCree
825
@item AVS @tab    @tab X
826
@tab Multimedia format used by the Creature Shock game.
827
@item Smacker @tab    @tab X
828
@tab Multimedia format used by many games.
829
@item GXF @tab  X @tab X
830
@tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
831
@item CIN @tab    @tab X
832
@tab Multimedia format used by Delphine Software games.
833
@item MXF @tab    @tab X
834
@tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
835
@item SEQ @tab    @tab X
836
@tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
837
@end multitable
838

    
839
@code{X} means that encoding (resp. decoding) is supported.
840

    
841
@section Image Formats
842

    
843
FFmpeg can read and write images for each frame of a video sequence. The
844
following image formats are supported:
845

    
846
@multitable @columnfractions .4 .1 .1 .4
847
@item Supported Image Format @tab Encoding @tab Decoding @tab Comments
848
@item PGM, PPM     @tab X @tab X
849
@item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support.
850
@item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
851
@item JPEG         @tab X @tab X @tab Progressive JPEG is not supported.
852
@item .Y.U.V       @tab X @tab X @tab one raw file per component
853
@item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
854
@item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
855
@item Targa        @tab   @tab X @tab Targa (.TGA) image format.
856
@item TIFF         @tab   @tab X @tab Only 24 bit/pixel images are supported.
857
@item SGI          @tab X @tab X @tab SGI RGB image format
858
@end multitable
859

    
860
@code{X} means that encoding (resp. decoding) is supported.
861

    
862
@section Video Codecs
863

    
864
@multitable @columnfractions .4 .1 .1 .4
865
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
866
@item MPEG-1 video           @tab  X  @tab  X
867
@item MPEG-2 video           @tab  X  @tab  X
868
@item MPEG-4                 @tab  X  @tab  X
869
@item MSMPEG4 V1             @tab  X  @tab  X
870
@item MSMPEG4 V2             @tab  X  @tab  X
871
@item MSMPEG4 V3             @tab  X  @tab  X
872
@item WMV7                   @tab  X  @tab  X
873
@item WMV8                   @tab  X  @tab  X @tab not completely working
874
@item WMV9                   @tab     @tab  X @tab not completely working
875
@item VC1                    @tab     @tab  X
876
@item H.261                  @tab  X  @tab  X
877
@item H.263(+)               @tab  X  @tab  X @tab also known as RealVideo 1.0
878
@item H.264                  @tab     @tab  X
879
@item RealVideo 1.0          @tab  X  @tab  X
880
@item RealVideo 2.0          @tab  X  @tab  X
881
@item MJPEG                  @tab  X  @tab  X
882
@item lossless MJPEG         @tab  X  @tab  X
883
@item JPEG-LS                @tab  X  @tab  X @tab fourcc: MJLS, lossless and near-lossless is supported
884
@item Apple MJPEG-B          @tab     @tab  X
885
@item Sunplus MJPEG          @tab     @tab  X @tab fourcc: SP5X
886
@item DV                     @tab  X  @tab  X
887
@item HuffYUV                @tab  X  @tab  X
888
@item FFmpeg Video 1         @tab  X  @tab  X @tab experimental lossless codec (fourcc: FFV1)
889
@item FFmpeg Snow            @tab  X  @tab  X @tab experimental wavelet codec (fourcc: SNOW)
890
@item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1
891
@item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2
892
@item Creative YUV           @tab     @tab  X @tab fourcc: CYUV
893
@item Sorenson Video 1       @tab  X  @tab  X @tab fourcc: SVQ1
894
@item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3
895
@item On2 VP3                @tab     @tab  X @tab still experimental
896
@item On2 VP5                @tab     @tab  X @tab fourcc: VP50
897
@item On2 VP6                @tab     @tab  X @tab fourcc: VP62
898
@item Theora                 @tab     @tab  X @tab still experimental
899
@item Intel Indeo 3          @tab     @tab  X
900
@item FLV                    @tab  X  @tab  X @tab Sorenson H.263 used in Flash
901
@item Flash Screen Video     @tab     @tab  X @tab fourcc: FSV1
902
@item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1
903
@item ATI VCR2               @tab     @tab  X @tab fourcc: VCR2
904
@item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR
905
@item 4X Video               @tab     @tab  X @tab Used in certain computer games.
906
@item Sony Playstation MDEC  @tab     @tab  X
907
@item Id RoQ                 @tab     @tab  X @tab Used in Quake III, Jedi Knight 2, other computer games.
908
@item Xan/WC3                @tab     @tab  X @tab Used in Wing Commander III .MVE files.
909
@item Interplay Video        @tab     @tab  X @tab Used in Interplay .MVE files.
910
@item Apple Animation        @tab     @tab  X @tab fourcc: 'rle '
911
@item Apple Graphics         @tab     @tab  X @tab fourcc: 'smc '
912
@item Apple Video            @tab     @tab  X @tab fourcc: rpza
913
@item Apple QuickDraw        @tab     @tab  X @tab fourcc: qdrw
914
@item Cinepak                @tab     @tab  X
915
@item Microsoft RLE          @tab     @tab  X
916
@item Microsoft Video-1      @tab     @tab  X
917
@item Westwood VQA           @tab     @tab  X
918
@item Id Cinematic Video     @tab     @tab  X @tab Used in Quake II.
919
@item Planar RGB             @tab     @tab  X @tab fourcc: 8BPS
920
@item FLIC video             @tab     @tab  X
921
@item Duck TrueMotion v1     @tab     @tab  X @tab fourcc: DUCK
922
@item Duck TrueMotion v2     @tab     @tab  X @tab fourcc: TM20
923
@item VMD Video              @tab     @tab  X @tab Used in Sierra VMD files.
924
@item MSZH                   @tab     @tab  X @tab Part of LCL
925
@item ZLIB                   @tab  X  @tab  X @tab Part of LCL, encoder experimental
926
@item TechSmith Camtasia     @tab     @tab  X @tab fourcc: TSCC
927
@item IBM Ultimotion         @tab     @tab  X @tab fourcc: ULTI
928
@item Miro VideoXL           @tab     @tab  X @tab fourcc: VIXL
929
@item QPEG                   @tab     @tab  X @tab fourccs: QPEG, Q1.0, Q1.1
930
@item LOCO                   @tab     @tab  X @tab
931
@item Winnov WNV1            @tab     @tab  X @tab
932
@item Autodesk Animator Studio Codec  @tab     @tab  X @tab fourcc: AASC
933
@item Fraps FPS1             @tab     @tab  X @tab
934
@item CamStudio              @tab     @tab  X @tab fourcc: CSCD
935
@item American Laser Games Video  @tab    @tab X @tab Used in games like Mad Dog McCree
936
@item ZMBV                   @tab     @tab  X @tab
937
@item AVS Video              @tab     @tab  X @tab Video encoding used by the Creature Shock game.
938
@item Smacker Video          @tab     @tab  X @tab Video encoding used in Smacker.
939
@item RTjpeg                 @tab     @tab  X @tab Video encoding used in NuppelVideo files.
940
@item KMVC                   @tab     @tab  X @tab Codec used in Worms games.
941
@item VMware Video           @tab     @tab  X @tab Codec used in videos captured by VMware.
942
@item Cin Video              @tab     @tab  X @tab Codec used in Delphine Software games.
943
@item Tiertex Seq Video      @tab     @tab  X @tab Codec used in DOS CDROM FlashBack game.
944
@end multitable
945

    
946
@code{X} means that encoding (resp. decoding) is supported.
947

    
948
@section Audio Codecs
949

    
950
@multitable @columnfractions .4 .1 .1 .1 .7
951
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
952
@item MPEG audio layer 2     @tab  IX  @tab  IX
953
@item MPEG audio layer 1/3   @tab IX   @tab  IX
954
@tab MP3 encoding is supported through the external library LAME.
955
@item AC3                    @tab  IX  @tab  IX
956
@tab liba52 is used internally for decoding.
957
@item Vorbis                 @tab  X   @tab  X
958
@item WMA V1/V2              @tab      @tab X
959
@item AAC                    @tab X    @tab X
960
@tab Supported through the external library libfaac/libfaad.
961
@item Microsoft ADPCM        @tab X    @tab X
962
@item MS IMA ADPCM           @tab X    @tab X
963
@item QT IMA ADPCM           @tab      @tab X
964
@item 4X IMA ADPCM           @tab      @tab X
965
@item G.726  ADPCM           @tab X    @tab X
966
@item Duck DK3 IMA ADPCM     @tab      @tab X
967
@tab Used in some Sega Saturn console games.
968
@item Duck DK4 IMA ADPCM     @tab      @tab X
969
@tab Used in some Sega Saturn console games.
970
@item Westwood Studios IMA ADPCM @tab      @tab X
971
@tab Used in Westwood Studios games like Command and Conquer.
972
@item SMJPEG IMA ADPCM       @tab      @tab X
973
@tab Used in certain Loki game ports.
974
@item CD-ROM XA ADPCM        @tab      @tab X
975
@item CRI ADX ADPCM          @tab X    @tab X
976
@tab Used in Sega Dreamcast games.
977
@item Electronic Arts ADPCM  @tab      @tab X
978
@tab Used in various EA titles.
979
@item Creative ADPCM         @tab      @tab X
980
@tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
981
@item RA144                  @tab      @tab X
982
@tab Real 14400 bit/s codec
983
@item RA288                  @tab      @tab X
984
@tab Real 28800 bit/s codec
985
@item RADnet                 @tab X    @tab IX
986
@tab Real low bitrate AC3 codec, liba52 is used for decoding.
987
@item AMR-NB                 @tab X    @tab X
988
@tab Supported through an external library.
989
@item AMR-WB                 @tab X    @tab X
990
@tab Supported through an external library.
991
@item DV audio               @tab      @tab X
992
@item Id RoQ DPCM            @tab      @tab X
993
@tab Used in Quake III, Jedi Knight 2, other computer games.
994
@item Interplay MVE DPCM     @tab      @tab X
995
@tab Used in various Interplay computer games.
996
@item Xan DPCM               @tab      @tab X
997
@tab Used in Origin's Wing Commander IV AVI files.
998
@item Sierra Online DPCM     @tab      @tab X
999
@tab Used in Sierra Online game audio files.
1000
@item Apple MACE 3           @tab      @tab X
1001
@item Apple MACE 6           @tab      @tab X
1002
@item FLAC lossless audio    @tab      @tab X
1003
@item Shorten lossless audio @tab      @tab X
1004
@item Apple lossless audio   @tab      @tab X
1005
@tab QuickTime fourcc 'alac'
1006
@item FFmpeg Sonic           @tab X    @tab X
1007
@tab experimental lossy/lossless codec
1008
@item Qdesign QDM2           @tab      @tab X
1009
@tab there are still some distortions
1010
@item Real COOK              @tab      @tab X
1011
@tab All versions except 5.1 are supported
1012
@item DSP Group TrueSpeech   @tab      @tab X
1013
@item True Audio (TTA)       @tab      @tab X
1014
@item Smacker Audio          @tab      @tab X
1015
@item WavPack Audio          @tab      @tab X
1016
@item Cin Audio              @tab      @tab X
1017
@tab Codec used in Delphine Software games.
1018
@item Intel Music Coder      @tab      @tab X
1019
@end multitable
1020

    
1021
@code{X} means that encoding (resp. decoding) is supported.
1022

    
1023
@code{I} means that an integer-only version is available, too (ensures high
1024
performance on systems without hardware floating point support).
1025

    
1026
@chapter Platform Specific information
1027

    
1028
@section Linux
1029

    
1030
FFmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
1031
preferred compiler now for FFmpeg. All future optimizations will depend on
1032
features only found in GCC 3.2.
1033

    
1034
@section BSD
1035

    
1036
BSD make will not build FFmpeg, you need to install and use GNU Make
1037
(@file{gmake}).
1038

    
1039
@section Windows
1040

    
1041
@subsection Native Windows compilation
1042

    
1043
@itemize
1044
@item Install the current versions of MSYS and MinGW from
1045
@url{http://www.mingw.org/}. You can find detailed installation
1046
instructions in the download section and the FAQ.
1047

    
1048
@item If you want to test the FFplay, also download
1049
the MinGW development library of SDL 1.2.x
1050
(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
1051
@url{http://www.libsdl.org}. Unpack it in a temporary directory, and
1052
unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
1053
directory. Edit the @file{sdl-config} script so that it gives the
1054
correct SDL directory when invoked.
1055

    
1056
@item Extract the current version of FFmpeg.
1057

    
1058
@item Start the MSYS shell (file @file{msys.bat}).
1059

    
1060
@item Change to the FFmpeg directory and follow
1061
 the instructions of how to compile FFmpeg (file
1062
@file{INSTALL}). Usually, launching @file{./configure} and @file{make}
1063
suffices. If you have problems using SDL, verify that
1064
@file{sdl-config} can be launched from the MSYS command line.
1065

    
1066
@item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
1067
@file{make install}. Don't forget to copy @file{SDL.dll} to the place
1068
you launch @file{ffplay} from.
1069

    
1070
@end itemize
1071

    
1072
Notes:
1073
@itemize
1074

    
1075
@item The target @file{make wininstaller} can be used to create a
1076
Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
1077
must be copied to the FFmpeg directory in order to build the
1078
installer.
1079

    
1080
@item By using @code{./configure --enable-shared} when configuring FFmpeg,
1081
you can build @file{avcodec.dll} and @file{avformat.dll}. With
1082
@code{make install} you install the FFmpeg DLLs and the associated
1083
headers in @file{Program Files/FFmpeg}.
1084

    
1085
@item Visual C++ compatibility: If you used @code{./configure --enable-shared}
1086
when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
1087
C++ @code{lib} tool to build @code{avcodec.lib} and
1088
@code{avformat.lib}. With these libraries you can link your Visual C++
1089
code directly with the FFmpeg DLLs (see below).
1090

    
1091
@end itemize
1092

    
1093
@subsection Visual C++ compatibility
1094

    
1095
FFmpeg will not compile under Visual C++ -- and it has too many
1096
dependencies on the GCC compiler to make a port viable. However,
1097
if you want to use the FFmpeg libraries in your own applications,
1098
you can still compile those applications using Visual C++. An
1099
important restriction to this is that you have to use the
1100
dynamically linked versions of the FFmpeg libraries (i.e. the
1101
DLLs), and you have to make sure that Visual-C++-compatible
1102
import libraries are created during the FFmpeg build process.
1103

    
1104
This description of how to use the FFmpeg libraries with Visual C++ is
1105
based on Visual C++ 2005 Express Edition Beta 2. If you have a different
1106
version, you might have to modify the procedures slightly.
1107

    
1108
Here are the step-by-step instructions for building the FFmpeg libraries
1109
so they can be used with Visual C++:
1110

    
1111
@enumerate
1112

    
1113
@item Install Visual C++ (if you haven't done so already).
1114

    
1115
@item Install MinGW and MSYS as described above.
1116

    
1117
@item Add a call to @file{vcvars32.bat} (which sets up the environment
1118
variables for the Visual C++ tools) as the first line of
1119
@file{msys.bat}. The standard location for @file{vcvars32.bat} is
1120
@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
1121
and the standard location for @file{msys.bat} is
1122
@file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
1123
following line as the first line of @file{msys.bat}:
1124

    
1125
@code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
1126

    
1127
@item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
1128
If you get a help message with the command line options of @code{link.exe},
1129
this means your environment variables are set up correctly, the
1130
Microsoft linker is on the path and will be used by FFmpeg to
1131
create Visual-C++-compatible import libraries.
1132

    
1133
@item Extract the current version of FFmpeg and change to the FFmpeg directory.
1134

    
1135
@item Type the command
1136
@code{./configure --enable-shared --disable-static --enable-memalign-hack}
1137
to configure and, if that didn't produce any errors,
1138
type @code{make} to build FFmpeg.
1139

    
1140
@item The subdirectories @file{libavformat}, @file{libavcodec}, and
1141
@file{libavutil} should now contain the files @file{avformat.dll},
1142
@file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1143
@file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1144
DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1145

    
1146
@end enumerate
1147

    
1148
And here is how to use these libraries with Visual C++:
1149

    
1150
@enumerate
1151

    
1152
@item Create a new console application ("File / New / Project") and then
1153
select "Win32 Console Application". On the appropriate page of the
1154
Application Wizard, uncheck the "Precompiled headers" option.
1155

    
1156
@item Write the source code for your application, or, for testing, just
1157
copy the code from an existing sample application into the source file
1158
that Visual C++ has already created for you. (Note that your source
1159
filehas to have a @code{.cpp} extension; otherwise, Visual C++ won't
1160
compile the FFmpeg headers correctly because in C mode, it doesn't
1161
recognize the @code{inline} keyword.)  For example, you can copy
1162
@file{output_example.c} from the FFmpeg distribution (but you will
1163
have to make minor modifications so the code will compile under
1164
C++, see below).
1165

    
1166
@item Open the "Project / Properties" dialog box. In the "Configuration"
1167
combo box, select "All Configurations" so that the changes you make will
1168
affect both debug and release builds. In the tree view on the left hand
1169
side, select "C/C++ / General", then edit the "Additional Include
1170
Directories" setting to contain the complete paths to the
1171
@file{libavformat}, @file{libavcodec}, and @file{libavutil}
1172
subdirectories of your FFmpeg directory. Note that the directories have
1173
to be separated using semicolons. Now select "Linker / General" from the
1174
tree view and edit the "Additional Library Directories" setting to
1175
contain the same three directories.
1176

    
1177
@item Still in the "Project / Properties" dialog box, select "Linker / Input"
1178
from the tree view, then add the files @file{avformat.lib},
1179
@file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1180
Dependencies". Note that the names of the libraries have to be separated
1181
using spaces.
1182

    
1183
@item Now, select "C/C++ / Code Generation" from the tree view. Select
1184
"Debug" in the "Configuration" combo box. Make sure that "Runtime
1185
Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1186
the "Configuration" combo box and make sure that "Runtime Library" is
1187
set to "Multi-threaded DLL".
1188

    
1189
@item Click "OK" to close the "Project / Properties" dialog box and build
1190
the application. Hopefully, it should compile and run cleanly. If you
1191
used @file{output_example.c} as your sample application, you will get a
1192
few compiler errors, but they are easy to fix. The first type of error
1193
occurs because Visual C++ doesn't allow an @code{int} to be converted to
1194
an @code{enum} without a cast. To solve the problem, insert the required
1195
casts (this error occurs once for a @code{CodecID} and once for a
1196
@code{CodecType}).  The second type of error occurs because C++ requires
1197
the return value of @code{malloc} to be cast to the exact type of the
1198
pointer it is being assigned to. Visual C++ will complain that, for
1199
example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1200
an explicit cast. So insert an explicit cast in these places to silence
1201
the compiler. The third type of error occurs because the @code{snprintf}
1202
library function is called @code{_snprintf} under Visual C++.  So just
1203
add an underscore to fix the problem. With these changes,
1204
@file{output_example.c} should compile under Visual C++, and the
1205
resulting executable should produce valid video files.
1206

    
1207
@end enumerate
1208

    
1209
@subsection Cross compilation for Windows with Linux
1210

    
1211
You must use the MinGW cross compilation tools available at
1212
@url{http://www.mingw.org/}.
1213

    
1214
Then configure FFmpeg with the following options:
1215
@example
1216
./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
1217
@end example
1218
(you can change the cross-prefix according to the prefix chosen for the
1219
MinGW tools).
1220

    
1221
Then you can easily test FFmpeg with Wine
1222
(@url{http://www.winehq.com/}).
1223

    
1224
@subsection Compilation under Cygwin
1225

    
1226
Cygwin works very much like Unix.
1227

    
1228
Just install your Cygwin with all the "Base" packages, plus the
1229
following "Devel" ones:
1230
@example
1231
binutils, gcc-core, make, subversion
1232
@end example
1233

    
1234
Do not install binutils-20060709-1 (they are buggy on shared builds);
1235
use binutils-20050610-1 instead.
1236

    
1237
Then run
1238

    
1239
@example
1240
./configure --enable-static --disable-shared
1241
@end example
1242

    
1243
to make a static build or
1244

    
1245
@example
1246
./configure --enable-shared --disable-static
1247
@end example
1248

    
1249
to build shared libraries.
1250

    
1251
If you want to build FFmpeg with additional libraries, download Cygwin
1252
"Devel" packages for Ogg and Vorbis from any Cygwin packages repository
1253
and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
1254
(@url{http://cygwinports.dotsrc.org/}).
1255

    
1256
@subsection Crosscompilation for Windows under Cygwin
1257

    
1258
With Cygwin you can create Windows binaries that don't need the cygwin1.dll.
1259

    
1260
Just install your Cygwin as explained before, plus these additional
1261
"Devel" packages:
1262
@example
1263
gcc-mingw-core, mingw-runtime, mingw-zlib
1264
@end example
1265

    
1266
and add some special flags to your configure invocation.
1267

    
1268
For a static build run
1269
@example
1270
./configure --enable-mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1271
@end example
1272

    
1273
and for a build with shared libraries
1274
@example
1275
./configure --enable-mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1276
@end example
1277

    
1278
@section Mac OS X
1279

    
1280
@section BeOS
1281

    
1282
The configure script should guess the configuration itself.
1283
Networking support is currently not finished.
1284
errno issues fixed by Andrew Bachmann.
1285

    
1286
Old stuff:
1287

    
1288
Fran├žois Revol - revol at free dot fr - April 2002
1289

    
1290
The configure script should guess the configuration itself,
1291
however I still didn't test building on the net_server version of BeOS.
1292

    
1293
FFserver is broken (needs poll() implementation).
1294

    
1295
There are still issues with errno codes, which are negative in BeOS, and
1296
that FFmpeg negates when returning. This ends up turning errors into
1297
valid results, then crashes.
1298
(To be fixed)
1299

    
1300
@chapter Developers Guide
1301

    
1302
@section API
1303
@itemize @bullet
1304
@item libavcodec is the library containing the codecs (both encoding and
1305
decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1306

    
1307
@item libavformat is the library containing the file format handling (mux and
1308
demux code for several formats). Look at @file{ffplay.c} to use it in a
1309
player. See @file{output_example.c} to use it to generate audio or video
1310
streams.
1311

    
1312
@end itemize
1313

    
1314
@section Integrating libavcodec or libavformat in your program
1315

    
1316
You can integrate all the source code of the libraries to link them
1317
statically to avoid any version problem. All you need is to provide a
1318
'config.mak' and a 'config.h' in the parent directory. See the defines
1319
generated by ./configure to understand what is needed.
1320

    
1321
You can use libavcodec or libavformat in your commercial program, but
1322
@emph{any patch you make must be published}. The best way to proceed is
1323
to send your patches to the FFmpeg mailing list.
1324

    
1325
@node Coding Rules
1326
@section Coding Rules
1327

    
1328
FFmpeg is programmed in the ISO C90 language with a few additional
1329
features from ISO C99, namely:
1330
@itemize @bullet
1331
@item
1332
the @samp{inline} keyword;
1333
@item
1334
@samp{//} comments;
1335
@item
1336
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1337
@item
1338
compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1339
@end itemize
1340

    
1341
These features are supported by all compilers we care about, so we won't
1342
accept patches to remove their use unless they absolutely don't impair
1343
clarity and performance.
1344

    
1345
All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1346
compiles with several other compilers, such as the Compaq ccc compiler
1347
or Sun Studio 9, and we would like to keep it that way unless it would
1348
be exceedingly involved. To ensure compatibility, please don't use any
1349
additional C99 features or GCC extensions. Especially watch out for:
1350
@itemize @bullet
1351
@item
1352
mixing statements and declarations;
1353
@item
1354
@samp{long long} (use @samp{int64_t} instead);
1355
@item
1356
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1357
@item
1358
GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1359
@end itemize
1360

    
1361
Indent size is 4.
1362
The presentation is the one specified by 'indent -i4 -kr -nut'.
1363
The TAB character is forbidden outside of Makefiles as is any
1364
form of trailing whitespace. Commits containing either will be
1365
rejected by the Subversion repository.
1366

    
1367
Main priority in FFmpeg is simplicity and small code size (=less
1368
bugs).
1369

    
1370
Comments: Use the JavaDoc/Doxygen
1371
format (see examples below) so that code documentation
1372
can be generated automatically. All nontrivial functions should have a comment
1373
above them explaining what the function does, even if it's just one sentence.
1374
All structures and their member variables should be documented, too.
1375
@example
1376
/**
1377
 * @@file mpeg.c
1378
 * MPEG codec.
1379
 * @@author ...
1380
 */
1381

    
1382
/**
1383
 * Summary sentence.
1384
 * more text ...
1385
 * ...
1386
 */
1387
typedef struct Foobar@{
1388
    int var1; /**< var1 description */
1389
    int var2; ///< var2 description
1390
    /** var3 description */
1391
    int var3;
1392
@} Foobar;
1393

    
1394
/**
1395
 * Summary sentence.
1396
 * more text ...
1397
 * ...
1398
 * @@param my_parameter description of my_parameter
1399
 * @@return return value description
1400
 */
1401
int myfunc(int my_parameter)
1402
...
1403
@end example
1404

    
1405
fprintf and printf are forbidden in libavformat and libavcodec,
1406
please use av_log() instead.
1407

    
1408
@section Development Policy
1409

    
1410
@enumerate
1411
@item
1412
   You must not commit code which breaks FFmpeg! (Meaning unfinished but
1413
   enabled code which breaks compilation or compiles but does not work or
1414
   breaks the regression tests)
1415
   You can commit unfinished stuff (for testing etc), but it must be disabled
1416
   (#ifdef etc) by default so it does not interfere with other developers'
1417
   work.
1418
@item
1419
   You don't have to over-test things. If it works for you, and you think it
1420
   should work for others, then commit. If your code has problems
1421
   (portability, triggers compiler bugs, unusual environment etc) they will be
1422
   reported and eventually fixed.
1423
@item
1424
   Do not commit unrelated changes together, split them into self-contained
1425
   pieces.
1426
@item
1427
   Do not change behavior of the program (renaming options etc) without
1428
   first discussing it on the ffmpeg-devel mailing list. Do not remove
1429
   functionality from the code. Just improve!
1430

    
1431
   Note: Redundant code can be removed.
1432
@item
1433
   Do not commit changes to the build system (Makefiles, configure script)
1434
   which change behavior, defaults etc, without asking first. The same
1435
   applies to compiler warning fixes, trivial looking fixes and to code
1436
   maintained by other developers. We usually have a reason for doing things
1437
   the way we do. Send your changes as patches to the ffmpeg-devel mailing
1438
   list, and if the code maintainers say OK, you may commit. This does not
1439
   apply to files you wrote and/or maintain.
1440
@item
1441
   We refuse source indentation and other cosmetic changes if they are mixed
1442
   with functional changes, such commits will be rejected and removed. Every
1443
   developer has his own indentation style, you should not change it. Of course
1444
   if you (re)write something, you can use your own style, even though we would
1445
   prefer if the indentation throughout FFmpeg was consistent (Many projects
1446
   force a given indentation style - we don't.). If you really need to make
1447
   indentation changes (try to avoid this), separate them strictly from real
1448
   changes.
1449

    
1450
   NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1451
   then either do NOT change the indentation of the inner part within (don't
1452
   move it to the right)! or do so in a separate commit
1453
@item
1454
   Always fill out the commit log message. Describe in a few lines what you
1455
   changed and why. You can refer to mailing list postings if you fix a
1456
   particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1457
@item
1458
   If you apply a patch by someone else, include the name and email address in
1459
   the log message. Since the ffmpeg-cvslog mailing list is publicly
1460
   archived you should add some SPAM protection to the email address. Send an
1461
   answer to ffmpeg-devel (or wherever you got the patch from) saying that
1462
   you applied the patch.
1463
@item
1464
    Do NOT commit to code actively maintained by others without permission.
1465
    Send a patch to ffmpeg-devel instead. If noone answers within a reasonable
1466
    timeframe (12h for build failures and security fixes, 3 days small changes,
1467
    1 week for big patches) then commit your patch if you think it's OK.
1468
    Also note, the maintainer can simply ask for more time to review!
1469
@item
1470
    Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1471
    are sent there and reviewed by all the other developers. Bugs and possible
1472
    improvements or general questions regarding commits are discussed there. We
1473
    expect you to react if problems with your code are uncovered.
1474
@item
1475
    Update the documentation if you change behavior or add features. If you are
1476
    unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1477
    maintainer(s) will review and commit your stuff.
1478
@item
1479
    Never write to unallocated memory, never write over the end of arrays,
1480
    always check values read from some untrusted source before using them
1481
    as array index or other risky things.
1482
@item
1483
    Remember to check if you need to bump versions for the specific libav
1484
    parts (libavutil, libavcodec, libavformat) you are changing. You need
1485
    to change the version integer and the version string.
1486
    Incrementing the first component means no backward compatibility to
1487
    previous versions (e.g. removal of a function from the public API).
1488
    Incrementing the second component means backward compatible change
1489
    (e.g. addition of a function to the public API).
1490
    Incrementing the third component means a noteworthy binary compatible
1491
    change (e.g. encoder bug fix that matters for the decoder).
1492
@item
1493
    If you add a new codec, remember to update the changelog, add it to
1494
    the supported codecs table in the documentation and bump the second
1495
    component of the @file{libavcodec} version number appropriately. If
1496
    it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1497
    is only a decoder.
1498
@end enumerate
1499

    
1500
We think our rules are not too hard. If you have comments, contact us.
1501

    
1502
Note, these rules are mostly borrowed from the MPlayer project.
1503

    
1504
@section Submitting patches
1505

    
1506
First, (@pxref{Coding Rules}) above if you didn't yet.
1507

    
1508
When you submit your patch, try to send a unified diff (diff '-up'
1509
option). I cannot read other diffs :-)
1510

    
1511
Also please do not submit patches which contain several unrelated changes.
1512
Split them into individual self-contained patches; this makes reviewing
1513
them much easier.
1514

    
1515
Run the regression tests before submitting a patch so that you can
1516
verify that there are no big problems.
1517

    
1518
Patches should be posted as base64 encoded attachments (or any other
1519
encoding which ensures that the patch won't be trashed during
1520
transmission) to the ffmpeg-devel mailing list, see
1521
@url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1522

    
1523
It also helps quite a bit if you tell us what the patch does (for example
1524
'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1525
and has no lrint()')
1526

    
1527
We reply to all submitted patches and either apply or reject with some
1528
explanation why, but sometimes we are quite busy so it can take a week or two.
1529

    
1530
@section Regression tests
1531

    
1532
Before submitting a patch (or committing to the repository), you should at least
1533
test that you did not break anything.
1534

    
1535
The regression tests build a synthetic video stream and a synthetic
1536
audio stream. These are then encoded and decoded with all codecs or
1537
formats. The CRC (or MD5) of each generated file is recorded in a
1538
result file. A 'diff' is launched to compare the reference results and
1539
the result file.
1540

    
1541
The regression tests then go on to test the FFserver code with a
1542
limited set of streams. It is important that this step runs correctly
1543
as well.
1544

    
1545
Run 'make test' to test all the codecs and formats.
1546

    
1547
Run 'make fulltest' to test all the codecs, formats and FFserver.
1548

    
1549
[Of course, some patches may change the results of the regression tests. In
1550
this case, the reference results of the regression tests shall be modified
1551
accordingly].
1552

    
1553
@bye