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							- \input texinfo @c -*- texinfo -*-
 - 
 - @settitle FFmpeg Documentation
 - @titlepage
 - @sp 7
 - @center @titlefont{FFmpeg Documentation}
 - @sp 3
 - @end titlepage
 - 
 - 
 - @chapter Introduction
 - 
 - FFmpeg is a very fast video and audio converter. It can also grab from
 - a live audio/video source.
 - 
 - The command line interface is designed to be intuitive, in the sense
 - that FFmpeg tries to figure out all parameters that can possibly be
 - derived automatically. You usually only have to specify the target
 - bitrate you want.
 - 
 - FFmpeg can also convert from any sample rate to any other, and resize
 - video on the fly with a high quality polyphase filter.
 - 
 - @chapter Quick Start
 - 
 - @c man begin EXAMPLES
 - @section Video and Audio grabbing
 - 
 - FFmpeg can use a video4linux compatible video source and any Open Sound
 - System audio source:
 - 
 - @example
 - ffmpeg /tmp/out.mpg
 - @end example
 - 
 - Note that you must activate the right video source and channel before
 - launching FFmpeg with any TV viewer such as xawtv
 - (@url{http://bytesex.org/xawtv/}) by Gerd Knorr. You also
 - have to set the audio recording levels correctly with a
 - standard mixer.
 - 
 - @section Video and Audio file format conversion
 - 
 - * FFmpeg can use any supported file format and protocol as input:
 - 
 - Examples:
 - 
 - * You can use YUV files as input:
 - 
 - @example
 - ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
 - @end example
 - 
 - It will use the files:
 - @example
 - /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
 - /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
 - @end example
 - 
 - The Y files use twice the resolution of the U and V files. They are
 - raw files, without header. They can be generated by all decent video
 - decoders. You must specify the size of the image with the @option{-s} option
 - if FFmpeg cannot guess it.
 - 
 - * You can input from a raw YUV420P file:
 - 
 - @example
 - ffmpeg -i /tmp/test.yuv /tmp/out.avi
 - @end example
 - 
 - test.yuv is a file containing raw YUV planar data. Each frame is composed
 - of the Y plane followed by the U and V planes at half vertical and
 - horizontal resolution.
 - 
 - * You can output to a raw YUV420P file:
 - 
 - @example
 - ffmpeg -i mydivx.avi hugefile.yuv
 - @end example
 - 
 - * You can set several input files and output files:
 - 
 - @example
 - ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
 - @end example
 - 
 - Converts the audio file a.wav and the raw YUV video file a.yuv
 - to MPEG file a.mpg.
 - 
 - * You can also do audio and video conversions at the same time:
 - 
 - @example
 - ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
 - @end example
 - 
 - Converts a.wav to MPEG audio at 22050Hz sample rate.
 - 
 - * You can encode to several formats at the same time and define a
 - mapping from input stream to output streams:
 - 
 - @example
 - ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0
 - @end example
 - 
 - Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
 - file:index' specifies which input stream is used for each output
 - stream, in the order of the definition of output streams.
 - 
 - * You can transcode decrypted VOBs
 - 
 - @example
 - ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800k -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi
 - @end example
 - 
 - This is a typical DVD ripping example; the input is a VOB file, the
 - output an AVI file with MPEG-4 video and MP3 audio. Note that in this
 - command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
 - GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
 - input video. Furthermore, the audio stream is MP3-encoded so you need
 - to enable LAME support by passing @code{--enable-mp3lame} to configure.
 - The mapping is particularly useful for DVD transcoding
 - to get the desired audio language.
 - 
 - NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
 - @c man end
 - 
 - @chapter Invocation
 - 
 - @section Syntax
 - 
 - The generic syntax is:
 - 
 - @example
 - @c man begin SYNOPSIS
 - ffmpeg [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
 - @c man end
 - @end example
 - @c man begin DESCRIPTION
 - If no input file is given, audio/video grabbing is done.
 - 
 - As a general rule, options are applied to the next specified
 - file. For example, if you give the @option{-b 64k} option, it sets the video
 - bitrate of the next file. The format option may be needed for raw input
 - files.
 - 
 - By default, FFmpeg tries to convert as losslessly as possible: It
 - uses the same audio and video parameters for the outputs as the one
 - specified for the inputs.
 - @c man end
 - 
 - @c man begin OPTIONS
 - @section Main options
 - 
 - @table @option
 - @item -L
 - Show license.
 - 
 - @item -h
 - Show help.
 - 
 - @item -formats
 - Show available formats, codecs, protocols, ...
 - 
 - @item -f fmt
 - Force format.
 - 
 - @item -i filename
 - input filename
 - 
 - @item -y
 - Overwrite output files.
 - 
 - @item -t duration
 - Set the recording time in seconds.
 - @code{hh:mm:ss[.xxx]} syntax is also supported.
 - 
 - @item -ss position
 - Seek to given time position in seconds.
 - @code{hh:mm:ss[.xxx]} syntax is also supported.
 - 
 - @item -title string
 - Set the title.
 - 
 - @item -author string
 - Set the author.
 - 
 - @item -copyright string
 - Set the copyright.
 - 
 - @item -comment string
 - Set the comment.
 - 
 - @item -track number
 - Set the track.
 - 
 - @item -year number
 - Set the year.
 - 
 - @item -target type
 - Specify target file type ("vcd", "svcd", "dvd", "dv", "pal-vcd",
 - "ntsc-svcd", ... ). All the format options (bitrate, codecs,
 - buffer sizes) are then set automatically. You can just type:
 - 
 - @example
 - ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
 - @end example
 - 
 - Nevertheless you can specify additional options as long as you know
 - they do not conflict with the standard, as in:
 - 
 - @example
 - ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
 - @end example
 - 
 - @item -itsoffset offset
 - Set the input time offset in seconds.
 - @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
 - This option affects all the input files that follow it.
 - The offset is added to the timestamps of the input files.
 - Specifying a positive offset means that the corresponding
 - streams are delayed by 'offset' seconds.
 - 
 - @end table
 - 
 - @section Video Options
 - 
 - @table @option
 - @item -b bitrate
 - Set the video bitrate in bit/s (default = 200 kb/s).
 - @item -r fps
 - Set frame rate (default = 25).
 - @item -s size
 - Set frame size. The format is @samp{wxh} (default = 160x128).
 - The following abbreviations are recognized:
 - @table @samp
 - @item sqcif
 - 128x96
 - @item qcif
 - 176x144
 - @item cif
 - 352x288
 - @item 4cif
 - 704x576
 - @end table
 - 
 - @item -aspect aspect
 - Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
 - @item -croptop size
 - Set top crop band size (in pixels).
 - @item -cropbottom size
 - Set bottom crop band size (in pixels).
 - @item -cropleft size
 - Set left crop band size (in pixels).
 - @item -cropright size
 - Set right crop band size (in pixels).
 - @item -padtop size
 - Set top pad band size (in pixels).
 - @item -padbottom size
 - Set bottom pad band size (in pixels).
 - @item -padleft size
 - Set left pad band size (in pixels).
 - @item -padright size
 - Set right pad band size (in pixels).
 - @item -padcolor (hex color)
 - Set color of padded bands. The value for padcolor is expressed
 - as a six digit hexadecimal number where the first two digits
 - represent red, the middle two digits green and last two digits
 - blue (default = 000000 (black)).
 - @item -vn
 - Disable video recording.
 - @item -bt tolerance
 - Set video bitrate tolerance (in bit/s).
 - @item -maxrate bitrate
 - Set max video bitrate tolerance (in bit/s).
 - @item -minrate bitrate
 - Set min video bitrate tolerance (in bit/s).
 - @item -bufsize size
 - Set rate control buffer size (in bits).
 - @item -vcodec codec
 - Force video codec to @var{codec}. Use the @code{copy} special value to
 - tell that the raw codec data must be copied as is.
 - @item -sameq
 - Use same video quality as source (implies VBR).
 - 
 - @item -pass n
 - Select the pass number (1 or 2). It is useful to do two pass
 - encoding. The statistics of the video are recorded in the first
 - pass and the video is generated at the exact requested bitrate
 - in the second pass.
 - 
 - @item -passlogfile file
 - Set two pass logfile name to @var{file}.
 - 
 - @end table
 - 
 - @section Advanced Video Options
 - 
 - @table @option
 - @item -g gop_size
 - Set the group of pictures size.
 - @item -intra
 - Use only intra frames.
 - @item -qscale q
 - Use fixed video quantizer scale (VBR).
 - @item -qmin q
 - minimum video quantizer scale (VBR)
 - @item -qmax q
 - maximum video quantizer scale (VBR)
 - @item -qdiff q
 - maximum difference between the quantizer scales (VBR)
 - @item -qblur blur
 - video quantizer scale blur (VBR)
 - @item -qcomp compression
 - video quantizer scale compression (VBR)
 - 
 - @item -lmin lambda
 - minimum video lagrange factor (VBR)
 - @item -lmax lambda
 - max video lagrange factor (VBR)
 - @item -mblmin lambda
 - minimum macroblock quantizer scale (VBR)
 - @item -mblmax lambda
 - maximum macroblock quantizer scale (VBR)
 - 
 - These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
 - but you may use the QP2LAMBDA constant to easily convert from 'q' units:
 - @example
 - ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
 - @end example
 - 
 - @item -rc_init_cplx complexity
 - initial complexity for single pass encoding
 - @item -b_qfactor factor
 - qp factor between P- and B-frames
 - @item -i_qfactor factor
 - qp factor between P- and I-frames
 - @item -b_qoffset offset
 - qp offset between P- and B-frames
 - @item -i_qoffset offset
 - qp offset between P- and I-frames
 - @item -rc_eq equation
 - Set rate control equation (@pxref{FFmpeg formula
 - evaluator}) (default = @code{tex^qComp}).
 - @item -rc_override override
 - rate control override for specific intervals
 - @item -me method
 - Set motion estimation method to @var{method}.
 - Available methods are (from lowest to best quality):
 - @table @samp
 - @item zero
 - Try just the (0, 0) vector.
 - @item phods
 - @item log
 - @item x1
 - @item epzs
 - (default method)
 - @item full
 - exhaustive search (slow and marginally better than epzs)
 - @end table
 - 
 - @item -dct_algo algo
 - Set DCT algorithm to @var{algo}. Available values are:
 - @table @samp
 - @item 0
 - FF_DCT_AUTO (default)
 - @item 1
 - FF_DCT_FASTINT
 - @item 2
 - FF_DCT_INT
 - @item 3
 - FF_DCT_MMX
 - @item 4
 - FF_DCT_MLIB
 - @item 5
 - FF_DCT_ALTIVEC
 - @end table
 - 
 - @item -idct_algo algo
 - Set IDCT algorithm to @var{algo}. Available values are:
 - @table @samp
 - @item 0
 - FF_IDCT_AUTO (default)
 - @item 1
 - FF_IDCT_INT
 - @item 2
 - FF_IDCT_SIMPLE
 - @item 3
 - FF_IDCT_SIMPLEMMX
 - @item 4
 - FF_IDCT_LIBMPEG2MMX
 - @item 5
 - FF_IDCT_PS2
 - @item 6
 - FF_IDCT_MLIB
 - @item 7
 - FF_IDCT_ARM
 - @item 8
 - FF_IDCT_ALTIVEC
 - @item 9
 - FF_IDCT_SH4
 - @item 10
 - FF_IDCT_SIMPLEARM
 - @end table
 - 
 - @item -er n
 - Set error resilience to @var{n}.
 - @table @samp
 - @item 1
 - FF_ER_CAREFUL (default)
 - @item 2
 - FF_ER_COMPLIANT
 - @item 3
 - FF_ER_AGGRESSIVE
 - @item 4
 - FF_ER_VERY_AGGRESSIVE
 - @end table
 - 
 - @item -ec bit_mask
 - Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
 - the following values:
 - @table @samp
 - @item 1
 - FF_EC_GUESS_MVS (default = enabled)
 - @item 2
 - FF_EC_DEBLOCK (default = enabled)
 - @end table
 - 
 - @item -bf frames
 - Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
 - @item -mbd mode
 - macroblock decision
 - @table @samp
 - @item 0
 - FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
 - @item 1
 - FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
 - @item 2
 - FF_MB_DECISION_RD: rate distortion
 - @end table
 - 
 - @item -4mv
 - Use four motion vector by macroblock (MPEG-4 only).
 - @item -part
 - Use data partitioning (MPEG-4 only).
 - @item -bug param
 - Work around encoder bugs that are not auto-detected.
 - @item -strict strictness
 - How strictly to follow the standards.
 - @item -aic
 - Enable Advanced intra coding (h263+).
 - @item -umv
 - Enable Unlimited Motion Vector (h263+)
 - 
 - @item -deinterlace
 - Deinterlace pictures.
 - @item -ilme
 - Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
 - Use this option if your input file is interlaced and you want
 - to keep the interlaced format for minimum losses.
 - The alternative is to deinterlace the input stream with
 - @option{-deinterlace}, but deinterlacing introduces losses.
 - @item -psnr
 - Calculate PSNR of compressed frames.
 - @item -vstats
 - Dump video coding statistics to @file{vstats_HHMMSS.log}.
 - @item -vhook module
 - Insert video processing @var{module}. @var{module} contains the module
 - name and its parameters separated by spaces.
 - @end table
 - 
 - @section Audio Options
 - 
 - @table @option
 - @item -ar freq
 - Set the audio sampling frequency (default = 44100 Hz).
 - @item -ab bitrate
 - Set the audio bitrate in kbit/s (default = 64).
 - @item -ac channels
 - Set the number of audio channels (default = 1).
 - @item -an
 - Disable audio recording.
 - @item -acodec codec
 - Force audio codec to @var{codec}. Use the @code{copy} special value to
 - specify that the raw codec data must be copied as is.
 - @end table
 - 
 - @section Audio/Video grab options
 - 
 - @table @option
 - @item -vd device
 - sEt video grab device (e.g. @file{/dev/video0}).
 - @item -vc channel
 - Set video grab channel (DV1394 only).
 - @item -tvstd standard
 - Set television standard (NTSC, PAL (SECAM)).
 - @item -dv1394
 - Set DV1394 grab.
 - @item -ad device
 - Set audio device (e.g. @file{/dev/dsp}).
 - @end table
 - 
 - @section Advanced options
 - 
 - @table @option
 - @item -map input stream id[:input stream id]
 - Set stream mapping from input streams to output streams.
 - Just enumerate the input streams in the order you want them in the output.
 - [input stream id] sets the (input) stream to sync against.
 - @item -debug
 - Print specific debug info.
 - @item -benchmark
 - Add timings for benchmarking.
 - @item -hex
 - Dump each input packet.
 - @item -bitexact
 - Only use bit exact algorithms (for codec testing).
 - @item -ps size
 - Set packet size in bits.
 - @item -re
 - Read input at native frame rate. Mainly used to simulate a grab device.
 - @item -loop
 - Loop over the input stream. Currently it works only for image
 - streams. This option is used for automatic FFserver testing.
 - @item -loop_output number_of_times
 - Repeatedly loop output for formats that support looping such as animated GIF
 - (0 will loop the output infinitely).
 - @item -vsync parameter
 - Video sync method. Video will be stretched/squeezed to match the timestamps,
 - it is done by duplicating and dropping frames. With -map you can select from
 - which stream the timestamps should be taken. You can leave either video or
 - audio unchanged and sync the remaining stream(s) to the unchanged one.
 - @item -async samples_per_second
 - Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
 - the parameter is the maximum samples per second by which the audio is changed.
 - -async 1 is a special case where only the start of the audio stream is corrected
 - without any later correction.
 - @end table
 - 
 - @node FFmpeg formula evaluator
 - @section FFmpeg formula evaluator
 - 
 - When evaluating a rate control string, FFmpeg uses an internal formula
 - evaluator.
 - 
 - The following binary operators are available: @code{+}, @code{-},
 - @code{*}, @code{/}, @code{^}.
 - 
 - The following unary operators are available: @code{+}, @code{-},
 - @code{(...)}.
 - 
 - The following functions are available:
 - @table @var
 - @item sinh(x)
 - @item cosh(x)
 - @item tanh(x)
 - @item sin(x)
 - @item cos(x)
 - @item tan(x)
 - @item exp(x)
 - @item log(x)
 - @item squish(x)
 - @item gauss(x)
 - @item abs(x)
 - @item max(x, y)
 - @item min(x, y)
 - @item gt(x, y)
 - @item lt(x, y)
 - @item eq(x, y)
 - @item bits2qp(bits)
 - @item qp2bits(qp)
 - @end table
 - 
 - The following constants are available:
 - @table @var
 - @item PI
 - @item E
 - @item iTex
 - @item pTex
 - @item tex
 - @item mv
 - @item fCode
 - @item iCount
 - @item mcVar
 - @item var
 - @item isI
 - @item isP
 - @item isB
 - @item avgQP
 - @item qComp
 - @item avgIITex
 - @item avgPITex
 - @item avgPPTex
 - @item avgBPTex
 - @item avgTex
 - @end table
 - 
 - @c man end
 - 
 - @ignore
 - 
 - @setfilename ffmpeg
 - @settitle FFmpeg video converter
 - 
 - @c man begin SEEALSO
 - ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
 - @c man end
 - 
 - @c man begin AUTHOR
 - Fabrice Bellard
 - @c man end
 - 
 - @end ignore
 - 
 - @section Protocols
 - 
 - The filename can be @file{-} to read from standard input or to write
 - to standard output.
 - 
 - FFmpeg also handles many protocols specified with an URL syntax.
 - 
 - Use 'ffmpeg -formats' to see a list of the supported protocols.
 - 
 - The protocol @code{http:} is currently used only to communicate with
 - FFserver (see the FFserver documentation). When FFmpeg will be a
 - video player it will also be used for streaming :-)
 - 
 - @chapter Tips
 - 
 - @itemize
 - @item For streaming at very low bitrate application, use a low frame rate
 - and a small GOP size. This is especially true for RealVideo where
 - the Linux player does not seem to be very fast, so it can miss
 - frames. An example is:
 - 
 - @example
 - ffmpeg -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
 - @end example
 - 
 - @item  The parameter 'q' which is displayed while encoding is the current
 - quantizer. The value 1 indicates that a very good quality could
 - be achieved. The value 31 indicates the worst quality. If q=31 appears
 - too often, it means that the encoder cannot compress enough to meet
 - your bitrate. You must either increase the bitrate, decrease the
 - frame rate or decrease the frame size.
 - 
 - @item If your computer is not fast enough, you can speed up the
 - compression at the expense of the compression ratio. You can use
 - '-me zero' to speed up motion estimation, and '-intra' to disable
 - motion estimation completely (you have only I-frames, which means it
 - is about as good as JPEG compression).
 - 
 - @item To have very low audio bitrates, reduce the sampling frequency
 - (down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
 - 
 - @item To have a constant quality (but a variable bitrate), use the option
 - '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
 - quality).
 - 
 - @item When converting video files, you can use the '-sameq' option which
 - uses the same quality factor in the encoder as in the decoder.
 - It allows almost lossless encoding.
 - 
 - @end itemize
 - 
 - @chapter Supported File Formats and Codecs
 - 
 - You can use the @code{-formats} option to have an exhaustive list.
 - 
 - @section File Formats
 - 
 - FFmpeg supports the following file formats through the @code{libavformat}
 - library:
 - 
 - @multitable @columnfractions .4 .1 .1 .4
 - @item Supported File Format @tab Encoding @tab Decoding @tab Comments
 - @item MPEG audio @tab X @tab X
 - @item MPEG-1 systems @tab X  @tab  X
 - @tab muxed audio and video
 - @item MPEG-2 PS @tab X  @tab  X
 - @tab also known as @code{VOB} file
 - @item MPEG-2 TS @tab    @tab  X
 - @tab also known as DVB Transport Stream
 - @item ASF@tab X @tab X
 - @item AVI@tab X @tab X
 - @item WAV@tab X @tab X
 - @item Macromedia Flash@tab X @tab X
 - @tab Only embedded audio is decoded.
 - @item FLV              @tab  X @tab X
 - @tab Macromedia Flash video files
 - @item Real Audio and Video @tab X @tab X
 - @item Raw AC3 @tab X  @tab  X
 - @item Raw MJPEG @tab X  @tab  X
 - @item Raw MPEG video @tab X  @tab  X
 - @item Raw PCM8/16 bits, mulaw/Alaw@tab X  @tab  X
 - @item Raw CRI ADX audio @tab X  @tab  X
 - @item Raw Shorten audio @tab    @tab  X
 - @item SUN AU format @tab X  @tab  X
 - @item NUT @tab X @tab X @tab NUT Open Container Format
 - @item QuickTime        @tab X @tab  X
 - @item MPEG-4           @tab X @tab  X
 - @tab MPEG-4 is a variant of QuickTime.
 - @item Raw MPEG4 video  @tab  X @tab  X
 - @item DV               @tab  X @tab  X
 - @item 4xm              @tab    @tab X
 - @tab 4X Technologies format, used in some games.
 - @item Playstation STR  @tab    @tab X
 - @item Id RoQ           @tab    @tab X
 - @tab Used in Quake III, Jedi Knight 2, other computer games.
 - @item Interplay MVE    @tab    @tab X
 - @tab Format used in various Interplay computer games.
 - @item WC3 Movie        @tab    @tab X
 - @tab Multimedia format used in Origin's Wing Commander III computer game.
 - @item Sega FILM/CPK    @tab    @tab X
 - @tab Used in many Sega Saturn console games.
 - @item Westwood Studios VQA/AUD  @tab    @tab X
 - @tab Multimedia formats used in Westwood Studios games.
 - @item Id Cinematic (.cin) @tab    @tab X
 - @tab Used in Quake II.
 - @item FLIC format      @tab    @tab X
 - @tab .fli/.flc files
 - @item Sierra VMD       @tab    @tab X
 - @tab Used in Sierra CD-ROM games.
 - @item Sierra Online    @tab    @tab X
 - @tab .sol files used in Sierra Online games.
 - @item Matroska         @tab    @tab X
 - @item Electronic Arts Multimedia    @tab    @tab X
 - @tab Used in various EA games; files have extensions like WVE and UV2.
 - @item Nullsoft Video (NSV) format @tab    @tab X
 - @item ADTS AAC audio @tab X @tab X
 - @item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
 - @item American Laser Games MM  @tab    @tab X
 - @tab Multimedia format used in games like Mad Dog McCree
 - @item AVS @tab    @tab X
 - @tab Multimedia format used by the Creature Shock game.
 - @item Smacker @tab    @tab X
 - @tab Multimedia format used by many games.
 - @item GXF @tab  X @tab X
 - @tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
 - @item CIN @tab    @tab X
 - @tab Multimedia format used by Delphine Software games.
 - @item MXF @tab    @tab X
 - @tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
 - @item SEQ @tab    @tab X
 - @tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
 - @end multitable
 - 
 - @code{X} means that encoding (resp. decoding) is supported.
 - 
 - @section Image Formats
 - 
 - FFmpeg can read and write images for each frame of a video sequence. The
 - following image formats are supported:
 - 
 - @multitable @columnfractions .4 .1 .1 .4
 - @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
 - @item PGM, PPM     @tab X @tab X
 - @item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support.
 - @item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
 - @item JPEG         @tab X @tab X @tab Progressive JPEG is not supported.
 - @item .Y.U.V       @tab X @tab X @tab one raw file per component
 - @item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
 - @item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
 - @item Targa        @tab   @tab X @tab Targa (.TGA) image format.
 - @item TIFF         @tab   @tab X @tab Only 24 bit/pixel images are supported.
 - @item SGI          @tab X @tab X @tab SGI RGB image format
 - @end multitable
 - 
 - @code{X} means that encoding (resp. decoding) is supported.
 - 
 - @section Video Codecs
 - 
 - @multitable @columnfractions .4 .1 .1 .4
 - @item Supported Codec @tab Encoding @tab Decoding @tab Comments
 - @item MPEG-1 video           @tab  X  @tab  X
 - @item MPEG-2 video           @tab  X  @tab  X
 - @item MPEG-4                 @tab  X  @tab  X
 - @item MSMPEG4 V1             @tab  X  @tab  X
 - @item MSMPEG4 V2             @tab  X  @tab  X
 - @item MSMPEG4 V3             @tab  X  @tab  X
 - @item WMV7                   @tab  X  @tab  X
 - @item WMV8                   @tab  X  @tab  X @tab not completely working
 - @item H.261                  @tab  X  @tab  X
 - @item H.263(+)               @tab  X  @tab  X @tab also known as RealVideo 1.0
 - @item H.264                  @tab     @tab  X
 - @item RealVideo 1.0          @tab  X  @tab  X
 - @item RealVideo 2.0          @tab  X  @tab  X
 - @item MJPEG                  @tab  X  @tab  X
 - @item lossless MJPEG         @tab  X  @tab  X
 - @item JPEG-LS                @tab  X  @tab  X @tab fourcc: MJLS, lossless and near-lossless is supported
 - @item Apple MJPEG-B          @tab     @tab  X
 - @item Sunplus MJPEG          @tab     @tab  X @tab fourcc: SP5X
 - @item DV                     @tab  X  @tab  X
 - @item HuffYUV                @tab  X  @tab  X
 - @item FFmpeg Video 1         @tab  X  @tab  X @tab experimental lossless codec (fourcc: FFV1)
 - @item FFmpeg Snow            @tab  X  @tab  X @tab experimental wavelet codec (fourcc: SNOW)
 - @item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1
 - @item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2
 - @item Creative YUV           @tab     @tab  X @tab fourcc: CYUV
 - @item Sorenson Video 1       @tab  X  @tab  X @tab fourcc: SVQ1
 - @item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3
 - @item On2 VP3                @tab     @tab  X @tab still experimental
 - @item On2 VP5                @tab     @tab  X @tab fourcc: VP50
 - @item On2 VP6                @tab     @tab  X @tab fourcc: VP62
 - @item Theora                 @tab     @tab  X @tab still experimental
 - @item Intel Indeo 3          @tab     @tab  X
 - @item FLV                    @tab  X  @tab  X @tab Sorenson H.263 used in Flash
 - @item Flash Screen Video     @tab     @tab  X @tab fourcc: FSV1
 - @item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1
 - @item ATI VCR2               @tab     @tab  X @tab fourcc: VCR2
 - @item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR
 - @item 4X Video               @tab     @tab  X @tab Used in certain computer games.
 - @item Sony Playstation MDEC  @tab     @tab  X
 - @item Id RoQ                 @tab     @tab  X @tab Used in Quake III, Jedi Knight 2, other computer games.
 - @item Xan/WC3                @tab     @tab  X @tab Used in Wing Commander III .MVE files.
 - @item Interplay Video        @tab     @tab  X @tab Used in Interplay .MVE files.
 - @item Apple Animation        @tab     @tab  X @tab fourcc: 'rle '
 - @item Apple Graphics         @tab     @tab  X @tab fourcc: 'smc '
 - @item Apple Video            @tab     @tab  X @tab fourcc: rpza
 - @item Apple QuickDraw        @tab     @tab  X @tab fourcc: qdrw
 - @item Cinepak                @tab     @tab  X
 - @item Microsoft RLE          @tab     @tab  X
 - @item Microsoft Video-1      @tab     @tab  X
 - @item Westwood VQA           @tab     @tab  X
 - @item Id Cinematic Video     @tab     @tab  X @tab Used in Quake II.
 - @item Planar RGB             @tab     @tab  X @tab fourcc: 8BPS
 - @item FLIC video             @tab     @tab  X
 - @item Duck TrueMotion v1     @tab     @tab  X @tab fourcc: DUCK
 - @item Duck TrueMotion v2     @tab     @tab  X @tab fourcc: TM20
 - @item VMD Video              @tab     @tab  X @tab Used in Sierra VMD files.
 - @item MSZH                   @tab     @tab  X @tab Part of LCL
 - @item ZLIB                   @tab  X  @tab  X @tab Part of LCL, encoder experimental
 - @item TechSmith Camtasia     @tab     @tab  X @tab fourcc: TSCC
 - @item IBM Ultimotion         @tab     @tab  X @tab fourcc: ULTI
 - @item Miro VideoXL           @tab     @tab  X @tab fourcc: VIXL
 - @item QPEG                   @tab     @tab  X @tab fourccs: QPEG, Q1.0, Q1.1
 - @item LOCO                   @tab     @tab  X @tab
 - @item Winnov WNV1            @tab     @tab  X @tab
 - @item Autodesk Animator Studio Codec  @tab     @tab  X @tab fourcc: AASC
 - @item Fraps FPS1             @tab     @tab  X @tab
 - @item CamStudio              @tab     @tab  X @tab fourcc: CSCD
 - @item American Laser Games Video  @tab    @tab X @tab Used in games like Mad Dog McCree
 - @item ZMBV                   @tab     @tab  X @tab
 - @item AVS Video              @tab     @tab  X @tab Video encoding used by the Creature Shock game.
 - @item Smacker Video          @tab     @tab  X @tab Video encoding used in Smacker.
 - @item RTjpeg                 @tab     @tab  X @tab Video encoding used in NuppelVideo files.
 - @item KMVC                   @tab     @tab  X @tab Codec used in Worms games.
 - @item VMware Video           @tab     @tab  X @tab Codec used in videos captured by VMware.
 - @item Cin Video              @tab     @tab  X @tab Codec used in Delphine Software games.
 - @item Tiertex Seq Video      @tab     @tab  X @tab Codec used in DOS CDROM FlashBack game.
 - @end multitable
 - 
 - @code{X} means that encoding (resp. decoding) is supported.
 - 
 - @section Audio Codecs
 - 
 - @multitable @columnfractions .4 .1 .1 .1 .7
 - @item Supported Codec @tab Encoding @tab Decoding @tab Comments
 - @item MPEG audio layer 2     @tab  IX  @tab  IX
 - @item MPEG audio layer 1/3   @tab IX   @tab  IX
 - @tab MP3 encoding is supported through the external library LAME.
 - @item AC3                    @tab  IX  @tab  IX
 - @tab liba52 is used internally for decoding.
 - @item Vorbis                 @tab  X   @tab  X
 - @tab Supported through the external library libvorbis.
 - @item WMA V1/V2              @tab      @tab X
 - @item AAC                    @tab X    @tab X
 - @tab Supported through the external library libfaac/libfaad.
 - @item Microsoft ADPCM        @tab X    @tab X
 - @item MS IMA ADPCM           @tab X    @tab X
 - @item QT IMA ADPCM           @tab      @tab X
 - @item 4X IMA ADPCM           @tab      @tab X
 - @item G.726  ADPCM           @tab X    @tab X
 - @item Duck DK3 IMA ADPCM     @tab      @tab X
 - @tab Used in some Sega Saturn console games.
 - @item Duck DK4 IMA ADPCM     @tab      @tab X
 - @tab Used in some Sega Saturn console games.
 - @item Westwood Studios IMA ADPCM @tab      @tab X
 - @tab Used in Westwood Studios games like Command and Conquer.
 - @item SMJPEG IMA ADPCM       @tab      @tab X
 - @tab Used in certain Loki game ports.
 - @item CD-ROM XA ADPCM        @tab      @tab X
 - @item CRI ADX ADPCM          @tab X    @tab X
 - @tab Used in Sega Dreamcast games.
 - @item Electronic Arts ADPCM  @tab      @tab X
 - @tab Used in various EA titles.
 - @item Creative ADPCM         @tab      @tab X
 - @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
 - @item RA144                  @tab      @tab X
 - @tab Real 14400 bit/s codec
 - @item RA288                  @tab      @tab X
 - @tab Real 28800 bit/s codec
 - @item RADnet                 @tab X    @tab IX
 - @tab Real low bitrate AC3 codec, liba52 is used for decoding.
 - @item AMR-NB                 @tab X    @tab X
 - @tab Supported through an external library.
 - @item AMR-WB                 @tab X    @tab X
 - @tab Supported through an external library.
 - @item DV audio               @tab      @tab X
 - @item Id RoQ DPCM            @tab      @tab X
 - @tab Used in Quake III, Jedi Knight 2, other computer games.
 - @item Interplay MVE DPCM     @tab      @tab X
 - @tab Used in various Interplay computer games.
 - @item Xan DPCM               @tab      @tab X
 - @tab Used in Origin's Wing Commander IV AVI files.
 - @item Sierra Online DPCM     @tab      @tab X
 - @tab Used in Sierra Online game audio files.
 - @item Apple MACE 3           @tab      @tab X
 - @item Apple MACE 6           @tab      @tab X
 - @item FLAC lossless audio    @tab      @tab X
 - @item Shorten lossless audio @tab      @tab X
 - @item Apple lossless audio   @tab      @tab X
 - @tab QuickTime fourcc 'alac'
 - @item FFmpeg Sonic           @tab X    @tab X
 - @tab experimental lossy/lossless codec
 - @item Qdesign QDM2           @tab      @tab X
 - @tab there are still some distortions
 - @item Real COOK              @tab      @tab X
 - @tab All versions except 5.1 are supported
 - @item DSP Group TrueSpeech   @tab      @tab X
 - @item True Audio (TTA)       @tab      @tab X
 - @item Smacker Audio          @tab      @tab X
 - @item WavPack Audio          @tab      @tab X
 - @item Cin Audio              @tab      @tab X
 - @tab Codec used in Delphine Software games.
 - @end multitable
 - 
 - @code{X} means that encoding (resp. decoding) is supported.
 - 
 - @code{I} means that an integer-only version is available, too (ensures high
 - performance on systems without hardware floating point support).
 - 
 - @chapter Platform Specific information
 - 
 - @section Linux
 - 
 - FFmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
 - preferred compiler now for FFmpeg. All future optimizations will depend on
 - features only found in GCC 3.2.
 - 
 - @section BSD
 - 
 - BSD make will not build FFmpeg, you need to install and use GNU Make
 - (@file{gmake}).
 - 
 - @section Windows
 - 
 - @subsection Native Windows compilation
 - 
 - @itemize
 - @item Install the current versions of MSYS and MinGW from
 - @url{http://www.mingw.org/}. You can find detailed installation
 - instructions in the download section and the FAQ.
 - 
 - @item If you want to test the FFplay, also download
 - the MinGW development library of SDL 1.2.x
 - (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
 - @url{http://www.libsdl.org}. Unpack it in a temporary directory, and
 - unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
 - directory. Edit the @file{sdl-config} script so that it gives the
 - correct SDL directory when invoked.
 - 
 - @item Extract the current version of FFmpeg.
 - 
 - @item Start the MSYS shell (file @file{msys.bat}).
 - 
 - @item Change to the FFmpeg directory and follow
 -  the instructions of how to compile FFmpeg (file
 - @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
 - suffices. If you have problems using SDL, verify that
 - @file{sdl-config} can be launched from the MSYS command line.
 - 
 - @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
 - @file{make install}. Don't forget to copy @file{SDL.dll} to the place
 - you launch @file{ffplay} from.
 - 
 - @end itemize
 - 
 - Notes:
 - @itemize
 - 
 - @item The target @file{make wininstaller} can be used to create a
 - Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
 - must be copied to the FFmpeg directory in order to build the
 - installer.
 - 
 - @item By using @code{./configure --enable-shared} when configuring FFmpeg,
 - you can build @file{avcodec.dll} and @file{avformat.dll}. With
 - @code{make install} you install the FFmpeg DLLs and the associated
 - headers in @file{Program Files/FFmpeg}.
 - 
 - @item Visual C++ compatibility: If you used @code{./configure --enable-shared}
 - when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
 - C++ @code{lib} tool to build @code{avcodec.lib} and
 - @code{avformat.lib}. With these libraries you can link your Visual C++
 - code directly with the FFmpeg DLLs (see below).
 - 
 - @end itemize
 - 
 - @subsection Visual C++ compatibility
 - 
 - FFmpeg will not compile under Visual C++ -- and it has too many
 - dependencies on the GCC compiler to make a port viable. However,
 - if you want to use the FFmpeg libraries in your own applications,
 - you can still compile those applications using Visual C++. An
 - important restriction to this is that you have to use the
 - dynamically linked versions of the FFmpeg libraries (i.e. the
 - DLLs), and you have to make sure that Visual-C++-compatible
 - import libraries are created during the FFmpeg build process.
 - 
 - This description of how to use the FFmpeg libraries with Visual C++ is
 - based on Visual C++ 2005 Express Edition Beta 2. If you have a different
 - version, you might have to modify the procedures slightly.
 - 
 - Here are the step-by-step instructions for building the FFmpeg libraries
 - so they can be used with Visual C++:
 - 
 - @enumerate
 - 
 - @item Install Visual C++ (if you haven't done so already).
 - 
 - @item Install MinGW and MSYS as described above.
 - 
 - @item Add a call to @file{vcvars32.bat} (which sets up the environment
 - variables for the Visual C++ tools) as the first line of
 - @file{msys.bat}. The standard location for @file{vcvars32.bat} is
 - @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
 - and the standard location for @file{msys.bat} is
 - @file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
 - following line as the first line of @file{msys.bat}:
 - 
 - @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
 - 
 - @item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
 - If you get a help message with the command line options of @code{link.exe},
 - this means your environment variables are set up correctly, the
 - Microsoft linker is on the path and will be used by FFmpeg to
 - create Visual-C++-compatible import libraries.
 - 
 - @item Extract the current version of FFmpeg and change to the FFmpeg directory.
 - 
 - @item Type the command
 - @code{./configure --enable-shared --disable-static --enable-memalign-hack}
 - to configure and, if that didn't produce any errors,
 - type @code{make} to build FFmpeg.
 - 
 - @item The subdirectories @file{libavformat}, @file{libavcodec}, and
 - @file{libavutil} should now contain the files @file{avformat.dll},
 - @file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
 - @file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
 - DLLs to your System32 directory (typically @file{C:\Windows\System32}).
 - 
 - @end enumerate
 - 
 - And here is how to use these libraries with Visual C++:
 - 
 - @enumerate
 - 
 - @item Create a new console application ("File / New / Project") and then
 - select "Win32 Console Application". On the appropriate page of the
 - Application Wizard, uncheck the "Precompiled headers" option.
 - 
 - @item Write the source code for your application, or, for testing, just
 - copy the code from an existing sample application into the source file
 - that Visual C++ has already created for you. (Note that your source
 - filehas to have a @code{.cpp} extension; otherwise, Visual C++ won't
 - compile the FFmpeg headers correctly because in C mode, it doesn't
 - recognize the @code{inline} keyword.)  For example, you can copy
 - @file{output_example.c} from the FFmpeg distribution (but you will
 - have to make minor modifications so the code will compile under
 - C++, see below).
 - 
 - @item Open the "Project / Properties" dialog box. In the "Configuration"
 - combo box, select "All Configurations" so that the changes you make will
 - affect both debug and release builds. In the tree view on the left hand
 - side, select "C/C++ / General", then edit the "Additional Include
 - Directories" setting to contain the complete paths to the
 - @file{libavformat}, @file{libavcodec}, and @file{libavutil}
 - subdirectories of your FFmpeg directory. Note that the directories have
 - to be separated using semicolons. Now select "Linker / General" from the
 - tree view and edit the "Additional Library Directories" setting to
 - contain the same three directories.
 - 
 - @item Still in the "Project / Properties" dialog box, select "Linker / Input"
 - from the tree view, then add the files @file{avformat.lib},
 - @file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
 - Dependencies". Note that the names of the libraries have to be separated
 - using spaces.
 - 
 - @item Now, select "C/C++ / Code Generation" from the tree view. Select
 - "Debug" in the "Configuration" combo box. Make sure that "Runtime
 - Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
 - the "Configuration" combo box and make sure that "Runtime Library" is
 - set to "Multi-threaded DLL".
 - 
 - @item Click "OK" to close the "Project / Properties" dialog box and build
 - the application. Hopefully, it should compile and run cleanly. If you
 - used @file{output_example.c} as your sample application, you will get a
 - few compiler errors, but they are easy to fix. The first type of error
 - occurs because Visual C++ doesn't allow an @code{int} to be converted to
 - an @code{enum} without a cast. To solve the problem, insert the required
 - casts (this error occurs once for a @code{CodecID} and once for a
 - @code{CodecType}).  The second type of error occurs because C++ requires
 - the return value of @code{malloc} to be cast to the exact type of the
 - pointer it is being assigned to. Visual C++ will complain that, for
 - example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
 - an explicit cast. So insert an explicit cast in these places to silence
 - the compiler. The third type of error occurs because the @code{snprintf}
 - library function is called @code{_snprintf} under Visual C++.  So just
 - add an underscore to fix the problem. With these changes,
 - @file{output_example.c} should compile under Visual C++, and the
 - resulting executable should produce valid video files.
 - 
 - @end enumerate
 - 
 - @subsection Cross compilation for Windows with Linux
 - 
 - You must use the MinGW cross compilation tools available at
 - @url{http://www.mingw.org/}.
 - 
 - Then configure FFmpeg with the following options:
 - @example
 - ./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
 - @end example
 - (you can change the cross-prefix according to the prefix chosen for the
 - MinGW tools).
 - 
 - Then you can easily test FFmpeg with Wine
 - (@url{http://www.winehq.com/}).
 - 
 - @subsection Compilation under Cygwin
 - 
 - Cygwin works very much like Unix.
 - 
 - Just install your Cygwin with all the "Base" packages, plus the
 - following "Devel" ones:
 - @example
 - binutils, gcc-core, make, subversion
 - @end example
 - 
 - Do not install binutils-20060709-1 (they are buggy on shared builds);
 - use binutils-20050610-1 instead.
 - 
 - Then run
 - 
 - @example
 - ./configure --enable-static --disable-shared
 - @end example
 - 
 - to make a static build or
 - 
 - @example
 - ./configure --enable-shared --disable-static
 - @end example
 - 
 - to build shared libraries.
 - 
 - If you want to build FFmpeg with additional libraries, download Cygwin
 - "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
 - and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
 - (@url{http://cygwinports.dotsrc.org/}).
 - 
 - @subsection Crosscompilation for Windows under Cygwin
 - 
 - With Cygwin you can create Windows binaries that don't need the cygwin1.dll.
 - 
 - Just install your Cygwin as explained before, plus these additional
 - "Devel" packages:
 - @example
 - gcc-mingw-core, mingw-runtime, mingw-zlib
 - @end example
 - 
 - and add some special flags to your configure invocation.
 - 
 - For a static build run
 - @example
 - ./configure --enable-mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
 - @end example
 - 
 - and for a build with shared libraries
 - @example
 - ./configure --enable-mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
 - @end example
 - 
 - @section Mac OS X
 - 
 - @section BeOS
 - 
 - The configure script should guess the configuration itself.
 - Networking support is currently not finished.
 - errno issues fixed by Andrew Bachmann.
 - 
 - Old stuff:
 - 
 - François Revol - revol at free dot fr - April 2002
 - 
 - The configure script should guess the configuration itself,
 - however I still didn't test building on the net_server version of BeOS.
 - 
 - FFserver is broken (needs poll() implementation).
 - 
 - There are still issues with errno codes, which are negative in BeOS, and
 - that FFmpeg negates when returning. This ends up turning errors into
 - valid results, then crashes.
 - (To be fixed)
 - 
 - @chapter Developers Guide
 - 
 - @section API
 - @itemize @bullet
 - @item libavcodec is the library containing the codecs (both encoding and
 - decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
 - 
 - @item libavformat is the library containing the file format handling (mux and
 - demux code for several formats). Look at @file{ffplay.c} to use it in a
 - player. See @file{output_example.c} to use it to generate audio or video
 - streams.
 - 
 - @end itemize
 - 
 - @section Integrating libavcodec or libavformat in your program
 - 
 - You can integrate all the source code of the libraries to link them
 - statically to avoid any version problem. All you need is to provide a
 - 'config.mak' and a 'config.h' in the parent directory. See the defines
 - generated by ./configure to understand what is needed.
 - 
 - You can use libavcodec or libavformat in your commercial program, but
 - @emph{any patch you make must be published}. The best way to proceed is
 - to send your patches to the FFmpeg mailing list.
 - 
 - @node Coding Rules
 - @section Coding Rules
 - 
 - FFmpeg is programmed in the ISO C90 language with a few additional
 - features from ISO C99, namely:
 - @itemize @bullet
 - @item
 - the @samp{inline} keyword;
 - @item
 - @samp{//} comments;
 - @item
 - designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
 - @item
 - compound literals (@samp{x = (struct s) @{ 17, 23 @};})
 - @end itemize
 - 
 - These features are supported by all compilers we care about, so we won't
 - accept patches to remove their use unless they absolutely don't impair
 - clarity and performance.
 - 
 - All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
 - compiles with several other compilers, such as the Compaq ccc compiler
 - or Sun Studio 9, and we would like to keep it that way unless it would
 - be exceedingly involved. To ensure compatibility, please don't use any
 - additional C99 features or GCC extensions. Especially watch out for:
 - @itemize @bullet
 - @item
 - mixing statements and declarations;
 - @item
 - @samp{long long} (use @samp{int64_t} instead);
 - @item
 - @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
 - @item
 - GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
 - @end itemize
 - 
 - Indent size is 4.
 - The presentation is the one specified by 'indent -i4 -kr -nut'.
 - The TAB character is forbidden outside of Makefiles as is any
 - form of trailing whitespace. Commits containing either will be
 - rejected by the Subversion repository.
 - 
 - Main priority in FFmpeg is simplicity and small code size (=less
 - bugs).
 - 
 - Comments: Use the JavaDoc/Doxygen
 - format (see examples below) so that code documentation
 - can be generated automatically. All nontrivial functions should have a comment
 - above them explaining what the function does, even if it's just one sentence.
 - All structures and their member variables should be documented, too.
 - @example
 - /**
 -  * @@file mpeg.c
 -  * MPEG codec.
 -  * @@author ...
 -  */
 - 
 - /**
 -  * Summary sentence.
 -  * more text ...
 -  * ...
 -  */
 - typedef struct Foobar@{
 -     int var1; /**< var1 description */
 -     int var2; ///< var2 description
 -     /** var3 description */
 -     int var3;
 - @} Foobar;
 - 
 - /**
 -  * Summary sentence.
 -  * more text ...
 -  * ...
 -  * @@param my_parameter description of my_parameter
 -  * @@return return value description
 -  */
 - int myfunc(int my_parameter)
 - ...
 - @end example
 - 
 - fprintf and printf are forbidden in libavformat and libavcodec,
 - please use av_log() instead.
 - 
 - @section Development Policy
 - 
 - @enumerate
 - @item
 -    You must not commit code which breaks FFmpeg! (Meaning unfinished but
 -    enabled code which breaks compilation or compiles but does not work or
 -    breaks the regression tests)
 -    You can commit unfinished stuff (for testing etc), but it must be disabled
 -    (#ifdef etc) by default so it does not interfere with other developers'
 -    work.
 - @item
 -    You don't have to over-test things. If it works for you, and you think it
 -    should work for others, then commit. If your code has problems
 -    (portability, triggers compiler bugs, unusual environment etc) they will be
 -    reported and eventually fixed.
 - @item
 -    Do not commit unrelated changes together, split them into self-contained
 -    pieces.
 - @item
 -    Do not change behavior of the program (renaming options etc) without
 -    first discussing it on the ffmpeg-devel mailing list. Do not remove
 -    functionality from the code. Just improve!
 - 
 -    Note: Redundant code can be removed.
 - @item
 -    Do not commit changes to the build system (Makefiles, configure script)
 -    which change behavior, defaults etc, without asking first. The same
 -    applies to compiler warning fixes, trivial looking fixes and to code
 -    maintained by other developers. We usually have a reason for doing things
 -    the way we do. Send your changes as patches to the ffmpeg-devel mailing
 -    list, and if the code maintainers say OK, you may commit. This does not
 -    apply to files you wrote and/or maintain.
 - @item
 -    We refuse source indentation and other cosmetic changes if they are mixed
 -    with functional changes, such commits will be rejected and removed. Every
 -    developer has his own indentation style, you should not change it. Of course
 -    if you (re)write something, you can use your own style, even though we would
 -    prefer if the indentation throughout FFmpeg was consistent (Many projects
 -    force a given indentation style - we don't.). If you really need to make
 -    indentation changes (try to avoid this), separate them strictly from real
 -    changes.
 - 
 -    NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
 -    then either do NOT change the indentation of the inner part within (don't
 -    move it to the right)! or do so in a separate commit
 - @item
 -    Always fill out the commit log message. Describe in a few lines what you
 -    changed and why. You can refer to mailing list postings if you fix a
 -    particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
 - @item
 -    If you apply a patch by someone else, include the name and email address in
 -    the log message. Since the ffmpeg-cvslog mailing list is publicly
 -    archived you should add some SPAM protection to the email address. Send an
 -    answer to ffmpeg-devel (or wherever you got the patch from) saying that
 -    you applied the patch.
 - @item
 -     Do NOT commit to code actively maintained by others without permission.
 -     Send a patch to ffmpeg-devel instead. If noone answers within a reasonable
 -     timeframe (12h for build failures and security fixes, 3 days small changes,
 -     1 week for big patches) then commit your patch if you think it's OK.
 -     Also note, the maintainer can simply ask for more time to review!
 - @item
 -     Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
 -     are sent there and reviewed by all the other developers. Bugs and possible
 -     improvements or general questions regarding commits are discussed there. We
 -     expect you to react if problems with your code are uncovered.
 - @item
 -     Update the documentation if you change behavior or add features. If you are
 -     unsure how best to do this, send a patch to ffmpeg-devel, the documentation
 -     maintainer(s) will review and commit your stuff.
 - @item
 -     Never write to unallocated memory, never write over the end of arrays,
 -     always check values read from some untrusted source before using them
 -     as array index or other risky things.
 - @item
 -     Remember to check if you need to bump versions for the specific libav
 -     parts (libavutil, libavcodec, libavformat) you are changing. You need
 -     to change the version integer and the version string.
 -     Incrementing the first component means no backward compatibility to
 -     previous versions (e.g. removal of a function from the public API).
 -     Incrementing the second component means backward compatible change
 -     (e.g. addition of a function to the public API).
 -     Incrementing the third component means a noteworthy binary compatible
 -     change (e.g. encoder bug fix that matters for the decoder).
 - @item
 -     If you add a new codec, remember to update the changelog, add it to
 -     the supported codecs table in the documentation and bump the second
 -     component of the @file{libavcodec} version number appropriately. If
 -     it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
 -     is only a decoder.
 - @end enumerate
 - 
 - We think our rules are not too hard. If you have comments, contact us.
 - 
 - Note, these rules are mostly borrowed from the MPlayer project.
 - 
 - @section Submitting patches
 - 
 - First, (@pxref{Coding Rules}) above if you didn't yet.
 - 
 - When you submit your patch, try to send a unified diff (diff '-up'
 - option). I cannot read other diffs :-)
 - 
 - Also please do not submit patches which contain several unrelated changes.
 - Split them into individual self-contained patches; this makes reviewing
 - them much easier.
 - 
 - Run the regression tests before submitting a patch so that you can
 - verify that there are no big problems.
 - 
 - Patches should be posted as base64 encoded attachments (or any other
 - encoding which ensures that the patch won't be trashed during
 - transmission) to the ffmpeg-devel mailing list, see
 - @url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
 - 
 - It also helps quite a bit if you tell us what the patch does (for example
 - 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
 - and has no lrint()')
 - 
 - We reply to all submitted patches and either apply or reject with some
 - explanation why, but sometimes we are quite busy so it can take a week or two.
 - 
 - @section Regression tests
 - 
 - Before submitting a patch (or committing to the repository), you should at least
 - test that you did not break anything.
 - 
 - The regression tests build a synthetic video stream and a synthetic
 - audio stream. These are then encoded and decoded with all codecs or
 - formats. The CRC (or MD5) of each generated file is recorded in a
 - result file. A 'diff' is launched to compare the reference results and
 - the result file.
 - 
 - The regression tests then go on to test the FFserver code with a
 - limited set of streams. It is important that this step runs correctly
 - as well.
 - 
 - Run 'make test' to test all the codecs and formats.
 - 
 - Run 'make fulltest' to test all the codecs, formats and FFserver.
 - 
 - [Of course, some patches may change the results of the regression tests. In
 - this case, the reference results of the regression tests shall be modified
 - accordingly].
 - 
 - @bye
 
 
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