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\input texinfo @c -*- texinfo -*-
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@settitle General Documentation
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@titlepage
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@sp 7
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@center @titlefont{General Documentation}
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@sp 3
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@end titlepage
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@chapter external libraries
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FFmpeg can be hooked up with a number of external libraries to add support
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for more formats. None of them are used by default, their use has to be
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explicitly requested by passing the appropriate flags to @file{./configure}.
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@section AMR
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AMR comes in two different flavors, wideband and narrowband. FFmpeg can make
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use of the AMR wideband (floating-point mode) and the AMR narrowband
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(floating-point mode) reference decoders and encoders.
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Go to @url{http://www.penguin.cz/~utx/amr} and follow the instructions for
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installing the libraries. Then pass @code{--enable-libamr-nb} and/or
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@code{--enable-libamr-wb} to configure to enable the libraries.
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Note that libamr is copyrighted without any sort of license grant. This means
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that you can use it if you legally obtained it but you are not allowed to
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redistribute it in any way. @strong{Any FFmpeg binaries with libamr support
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you create are non-free and unredistributable!}
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@chapter Supported File Formats and Codecs
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You can use the @code{-formats} option to have an exhaustive list.
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@section File Formats
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FFmpeg supports the following file formats through the @code{libavformat}
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library:
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@multitable @columnfractions .4 .1 .1 .4
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@item Supported File Format @tab Encoding @tab Decoding @tab Comments
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@item MPEG audio @tab X @tab X
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@item MPEG-1 systems @tab X  @tab  X
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@tab muxed audio and video
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@item MPEG-2 PS @tab X  @tab  X
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@tab also known as @code{VOB} file
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@item MPEG-2 TS @tab    @tab  X
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@tab also known as DVB Transport Stream
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@item ASF@tab X @tab X
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@item AVI@tab X @tab X
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@item WAV@tab X @tab X
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@item Macromedia Flash@tab X @tab X
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@item AVM2 (Flash 9) @tab X @tab X
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@tab Only embedded audio is decoded.
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@item FLV              @tab  X @tab X
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@tab Macromedia Flash video files
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@item Real Audio and Video @tab X @tab X
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@item Raw AC3 @tab X  @tab  X
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@item Raw MJPEG @tab X  @tab  X
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@item Raw MPEG video @tab X  @tab  X
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@item Raw PCM8/16 bits, mulaw/Alaw@tab X  @tab  X
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@item Raw CRI ADX audio @tab X  @tab  X
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@item Raw Shorten audio @tab    @tab  X
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@item SUN AU format @tab X  @tab  X
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@item NUT @tab X @tab X @tab NUT Open Container Format
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@item QuickTime        @tab X @tab  X
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@item MPEG-4           @tab X @tab  X
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@tab MPEG-4 is a variant of QuickTime.
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@item Raw MPEG4 video  @tab  X @tab  X
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@item DV               @tab  X @tab  X
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@item 4xm              @tab    @tab X
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@tab 4X Technologies format, used in some games.
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@item Playstation STR  @tab    @tab X
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@item Id RoQ           @tab X  @tab X
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@tab Used in Quake III, Jedi Knight 2, other computer games.
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@item Interplay MVE    @tab    @tab X
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@tab Format used in various Interplay computer games.
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@item WC3 Movie        @tab    @tab X
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@tab Multimedia format used in Origin's Wing Commander III computer game.
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@item Sega FILM/CPK    @tab    @tab X
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@tab Used in many Sega Saturn console games.
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@item Westwood Studios VQA/AUD  @tab    @tab X
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@tab Multimedia formats used in Westwood Studios games.
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@item Id Cinematic (.cin) @tab    @tab X
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@tab Used in Quake II.
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@item FLIC format      @tab    @tab X
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@tab .fli/.flc files
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@item Sierra VMD       @tab    @tab X
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@tab Used in Sierra CD-ROM games.
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@item Sierra Online    @tab    @tab X
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@tab .sol files used in Sierra Online games.
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@item Matroska         @tab X  @tab X
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@item Electronic Arts Multimedia    @tab    @tab X
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@tab Used in various EA games; files have extensions like WVE and UV2.
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@item Nullsoft Video (NSV) format @tab    @tab X
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@item ADTS AAC audio @tab X @tab X
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@item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
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@item American Laser Games MM  @tab    @tab X
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@tab Multimedia format used in games like Mad Dog McCree
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@item AVS @tab    @tab X
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@tab Multimedia format used by the Creature Shock game.
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@item Smacker @tab    @tab X
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@tab Multimedia format used by many games.
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@item GXF @tab  X @tab X
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@tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
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@item CIN @tab    @tab X
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@tab Multimedia format used by Delphine Software games.
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@item MXF @tab    @tab X
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@tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
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@item SEQ @tab    @tab X
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@tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
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@item DXA @tab    @tab X
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@tab This format is used in non-Windows version of Feeble Files game and
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different game cutscenes repacked for use with ScummVM.
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@item THP @tab    @tab X
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@tab Used on the Nintendo GameCube.
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@item C93 @tab    @tab X
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@tab Used in the game Cyberia from Interplay.
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@item Bethsoft VID @tab    @tab X
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@tab Used in some games from Bethesda Softworks.
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@item CRYO APC @tab    @tab X
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@tab Audio format used in some games by CRYO Interactive Entertainment.
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@item Monkey's Audio @tab    @tab X
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@item SIFF @tab    @tab X
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@tab Audio and video format used in some games by Beam Software
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@end multitable
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@code{X} means that encoding (resp. decoding) is supported.
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@section Image Formats
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FFmpeg can read and write images for each frame of a video sequence. The
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following image formats are supported:
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@multitable @columnfractions .4 .1 .1 .4
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@item Supported Image Format @tab Encoding @tab Decoding @tab Comments
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@item PGM, PPM     @tab X @tab X
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@item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support.
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@item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
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@item JPEG         @tab X @tab X @tab Progressive JPEG is not supported.
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@item .Y.U.V       @tab X @tab X @tab one raw file per component
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@item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
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@item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
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@item Targa        @tab   @tab X @tab Targa (.TGA) image format.
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@item TIFF         @tab X @tab X @tab YUV, JPEG and some extension is not supported yet.
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@item SGI          @tab X @tab X @tab SGI RGB image format
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@item PTX          @tab   @tab X @tab V.Flash PTX format
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@end multitable
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@code{X} means that encoding (resp. decoding) is supported.
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@section Video Codecs
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@multitable @columnfractions .4 .1 .1 .4
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@item Supported Codec @tab Encoding @tab Decoding @tab Comments
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@item MPEG-1 video           @tab  X  @tab  X
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@item MPEG-2 video           @tab  X  @tab  X
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@item MPEG-4                 @tab  X  @tab  X
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@item MSMPEG4 V1             @tab  X  @tab  X
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@item MSMPEG4 V2             @tab  X  @tab  X
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@item MSMPEG4 V3             @tab  X  @tab  X
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@item WMV7                   @tab  X  @tab  X
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@item WMV8                   @tab  X  @tab  X @tab not completely working
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@item WMV9                   @tab     @tab  X @tab not completely working
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@item VC1                    @tab     @tab  X
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@item H.261                  @tab  X  @tab  X
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@item H.263(+)               @tab  X  @tab  X @tab also known as RealVideo 1.0
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@item H.264                  @tab     @tab  X
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@item RealVideo 1.0          @tab  X  @tab  X
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@item RealVideo 2.0          @tab  X  @tab  X
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@item MJPEG                  @tab  X  @tab  X
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@item lossless MJPEG         @tab  X  @tab  X
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@item JPEG-LS                @tab  X  @tab  X @tab fourcc: MJLS, lossless and near-lossless is supported
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@item Apple MJPEG-B          @tab     @tab  X
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@item Sunplus MJPEG          @tab     @tab  X @tab fourcc: SP5X
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@item DV                     @tab  X  @tab  X
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@item HuffYUV                @tab  X  @tab  X
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@item FFmpeg Video 1         @tab  X  @tab  X @tab experimental lossless codec (fourcc: FFV1)
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@item FFmpeg Snow            @tab  X  @tab  X @tab experimental wavelet codec (fourcc: SNOW)
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@item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1
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@item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2
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@item Creative YUV           @tab     @tab  X @tab fourcc: CYUV
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@item Sorenson Video 1       @tab  X  @tab  X @tab fourcc: SVQ1
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@item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3
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@item On2 VP3                @tab     @tab  X @tab still experimental
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@item On2 VP5                @tab     @tab  X @tab fourcc: VP50
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@item On2 VP6                @tab     @tab  X @tab fourcc: VP60,VP61,VP62
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@item Theora                 @tab  X  @tab  X @tab still experimental
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@item Intel Indeo 3          @tab     @tab  X
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@item FLV                    @tab  X  @tab  X @tab Sorenson H.263 used in Flash
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@item Flash Screen Video     @tab  X  @tab  X @tab fourcc: FSV1
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@item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1
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@item ATI VCR2               @tab     @tab  X @tab fourcc: VCR2
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@item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR
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@item 4X Video               @tab     @tab  X @tab Used in certain computer games.
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@item Sony Playstation MDEC  @tab     @tab  X
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@item Id RoQ                 @tab  X  @tab  X @tab Used in Quake III, Jedi Knight 2, other computer games.
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@item Xan/WC3                @tab     @tab  X @tab Used in Wing Commander III .MVE files.
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@item Interplay Video        @tab     @tab  X @tab Used in Interplay .MVE files.
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@item Apple Animation        @tab  X  @tab  X @tab fourcc: 'rle '
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@item Apple Graphics         @tab     @tab  X @tab fourcc: 'smc '
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@item Apple Video            @tab     @tab  X @tab fourcc: rpza
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@item Apple QuickDraw        @tab     @tab  X @tab fourcc: qdrw
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@item Cinepak                @tab     @tab  X
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@item Microsoft RLE          @tab     @tab  X
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@item Microsoft Video-1      @tab     @tab  X
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@item Westwood VQA           @tab     @tab  X
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@item Id Cinematic Video     @tab     @tab  X @tab Used in Quake II.
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@item Planar RGB             @tab     @tab  X @tab fourcc: 8BPS
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@item FLIC video             @tab     @tab  X
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@item Duck TrueMotion v1     @tab     @tab  X @tab fourcc: DUCK
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@item Duck TrueMotion v2     @tab     @tab  X @tab fourcc: TM20
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@item VMD Video              @tab     @tab  X @tab Used in Sierra VMD files.
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@item MSZH                   @tab     @tab  X @tab Part of LCL
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@item ZLIB                   @tab  X  @tab  X @tab Part of LCL, encoder experimental
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@item TechSmith Camtasia     @tab     @tab  X @tab fourcc: TSCC
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@item IBM Ultimotion         @tab     @tab  X @tab fourcc: ULTI
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@item Miro VideoXL           @tab     @tab  X @tab fourcc: VIXL
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@item QPEG                   @tab     @tab  X @tab fourccs: QPEG, Q1.0, Q1.1
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@item LOCO                   @tab     @tab  X @tab
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@item Winnov WNV1            @tab     @tab  X @tab
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@item Autodesk Animator Studio Codec  @tab     @tab  X @tab fourcc: AASC
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@item Fraps FPS1             @tab     @tab  X @tab
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@item CamStudio              @tab     @tab  X @tab fourcc: CSCD
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@item American Laser Games Video  @tab    @tab X @tab Used in games like Mad Dog McCree
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@item ZMBV                   @tab   X @tab  X @tab Encoder works only on PAL8
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@item AVS Video              @tab     @tab  X @tab Video encoding used by the Creature Shock game.
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@item Smacker Video          @tab     @tab  X @tab Video encoding used in Smacker.
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@item RTjpeg                 @tab     @tab  X @tab Video encoding used in NuppelVideo files.
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@item KMVC                   @tab     @tab  X @tab Codec used in Worms games.
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@item VMware Video           @tab     @tab  X @tab Codec used in videos captured by VMware.
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@item Cin Video              @tab     @tab  X @tab Codec used in Delphine Software games.
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@item Tiertex Seq Video      @tab     @tab  X @tab Codec used in DOS CDROM FlashBack game.
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@item DXA Video              @tab     @tab  X @tab Codec originally used in Feeble Files game.
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@item AVID DNxHD             @tab   X @tab  X @tab aka SMPTE VC3
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@item C93 Video              @tab     @tab  X @tab Codec used in Cyberia game.
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@item THP                    @tab     @tab  X @tab Used on the Nintendo GameCube.
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@item Bethsoft VID           @tab     @tab  X @tab Used in some games from Bethesda Softworks.
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@item Renderware TXD         @tab     @tab  X @tab Texture dictionaries used by the Renderware Engine.
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@item AMV                    @tab     @tab  X @tab Used in Chinese MP3 players.
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@end multitable
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@code{X} means that encoding (resp. decoding) is supported.
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@section Audio Codecs
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@multitable @columnfractions .4 .1 .1 .1 .7
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@item Supported Codec @tab Encoding @tab Decoding @tab Comments
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@item MPEG audio layer 2     @tab  IX  @tab  IX
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@item MPEG audio layer 1/3   @tab X   @tab  IX
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@tab MP3 encoding is supported through the external library LAME.
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@item AC3                    @tab  IX  @tab  IX
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@tab liba52 is used internally for decoding.
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@item Vorbis                 @tab  X   @tab  X
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@item WMA V1/V2              @tab X    @tab X
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@item AAC                    @tab X    @tab X
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@tab Supported through the external library libfaac/libfaad.
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@item Microsoft ADPCM        @tab X    @tab X
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@item AMV IMA ADPCM          @tab      @tab X
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@tab Used in AMV files
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@item MS IMA ADPCM           @tab X    @tab X
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@item QT IMA ADPCM           @tab X    @tab X
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@item 4X IMA ADPCM           @tab      @tab X
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@item G.726  ADPCM           @tab X    @tab X
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@item Duck DK3 IMA ADPCM     @tab      @tab X
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@tab Used in some Sega Saturn console games.
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@item Duck DK4 IMA ADPCM     @tab      @tab X
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@tab Used in some Sega Saturn console games.
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@item Westwood Studios IMA ADPCM @tab      @tab X
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@tab Used in Westwood Studios games like Command and Conquer.
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@item SMJPEG IMA ADPCM       @tab      @tab X
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@tab Used in certain Loki game ports.
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@item CD-ROM XA ADPCM        @tab      @tab X
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@item CRI ADX ADPCM          @tab X    @tab X
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@tab Used in Sega Dreamcast games.
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@item Electronic Arts ADPCM  @tab      @tab X
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@tab Used in various EA titles.
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@item Creative ADPCM         @tab      @tab X
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@tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
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@item THP ADPCM              @tab      @tab X
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@tab Used on the Nintendo GameCube.
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@item RA144                  @tab      @tab X
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@tab Real 14400 bit/s codec
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@item RA288                  @tab      @tab X
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@tab Real 28800 bit/s codec
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@item RADnet                 @tab X    @tab IX
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@tab Real low bitrate AC3 codec, liba52 is used for decoding.
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@item AMR-NB                 @tab X    @tab X
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@tab Supported through an external library.
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@item AMR-WB                 @tab X    @tab X
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@tab Supported through an external library.
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@item DV audio               @tab      @tab X
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@item Id RoQ DPCM            @tab X    @tab X
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@tab Used in Quake III, Jedi Knight 2, other computer games.
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@item Interplay MVE DPCM     @tab      @tab X
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@tab Used in various Interplay computer games.
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@item Xan DPCM               @tab      @tab X
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@tab Used in Origin's Wing Commander IV AVI files.
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@item Sierra Online DPCM     @tab      @tab X
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@tab Used in Sierra Online game audio files.
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@item Apple MACE 3           @tab      @tab X
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@item Apple MACE 6           @tab      @tab X
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@item FLAC lossless audio    @tab X    @tab X
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@item Shorten lossless audio @tab      @tab X
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@item Apple lossless audio   @tab      @tab X
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@tab QuickTime fourcc 'alac'
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@item FFmpeg Sonic           @tab X    @tab X
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@tab experimental lossy/lossless codec
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@item Qdesign QDM2           @tab      @tab X
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@tab there are still some distortions
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@item Real COOK              @tab      @tab X
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@tab All versions except 5.1 are supported
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@item DSP Group TrueSpeech   @tab      @tab X
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@item True Audio (TTA)       @tab      @tab X
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@item Smacker Audio          @tab      @tab X
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@item WavPack Audio          @tab      @tab X
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@item Cin Audio              @tab      @tab X
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@tab Codec used in Delphine Software games.
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@item Intel Music Coder      @tab      @tab X
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@item Musepack               @tab      @tab X
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@tab SV7 and SV8 are supported
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@item DT$ Coherent Audio     @tab      @tab X
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@item ATRAC 3                @tab      @tab X
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@item Monkey's Audio         @tab      @tab X @tab Only versions 3.97-3.99 are supported
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@item Nellymoser ASAO        @tab      @tab X
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@end multitable
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@code{X} means that encoding (resp. decoding) is supported.
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@code{I} means that an integer-only version is available, too (ensures high
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performance on systems without hardware floating point support).
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@chapter Platform Specific information
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@section BSD
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BSD make will not build FFmpeg, you need to install and use GNU Make
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(@file{gmake}).
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@section Windows
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To get help and instructions for building FFmpeg under Windows, check out
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the FFmpeg Windows Help Forum at
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@url{http://arrozcru.no-ip.org/ffmpeg/}.
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@subsection Native Windows compilation
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FFmpeg can be built to run natively on Windows using the MinGW tools. Install
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the current versions of MSYS and MinGW from @url{http://www.mingw.org/}. Also
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install the coreutils package. You can find detailed installation
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instructions in the download section and the FAQ.
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Within the MSYS shell, configure and make with:
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@example
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./configure --enable-memalign-hack
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make
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make install
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@end example
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This will install @file{ffmpeg.exe} along with many other development files
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to @file{/usr/local}. You may specify another install path using the
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@code{--prefix} option in @file{configure}.
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Notes:
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@itemize
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@item Use at least bash 3.1. Older versions are known to fail on the
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configure script.
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@item In order to compile vhooks, you must have a POSIX-compliant libdl in
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your MinGW system. Get dlfcn-win32 from
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@url{http://code.google.com/p/dlfcn-win32}.
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@item In order to compile FFplay, you must have the MinGW development library
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of SDL. Get it from @url{http://www.libsdl.org}.
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Edit the @file{bin/sdl-config} script so that it points to the correct prefix
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where SDL was installed. Verify that @file{sdl-config} can be launched from
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the MSYS command line.
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@item The target @code{make wininstaller} can be used to create a
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Nullsoft-based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
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must be copied to the FFmpeg directory in order to build the
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installer.
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@item By using @code{./configure --enable-shared} when configuring FFmpeg,
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you can build libavutil, libavcodec and libavformat as DLLs.
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@end itemize
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@subsection Microsoft Visual C++ compatibility
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As stated in the FAQ, FFmpeg will not compile under MSVC++. However, if you
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want to use the libav* libraries in your own applications, you can still
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compile those applications using MSVC++. But the libav* libraries you link
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to @emph{must} be built with MinGW. However, you will not be able to debug
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inside the libav* libraries, since MSVC++ does not recognize the debug
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symbols generated by GCC.
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We strongly recommend you to move over from MSVC++ to MinGW tools.
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This description of how to use the FFmpeg libraries with MSVC++ is based on
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Microsoft Visual C++ 2005 Express Edition. If you have a different version,
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you might have to modify the procedures slightly.
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@subsubsection Using static libraries
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Assuming you have just built and installed FFmpeg in @file{/usr/local}.
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@enumerate
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@item Create a new console application ("File / New / Project") and then
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select "Win32 Console Application". On the appropriate page of the
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Application Wizard, uncheck the "Precompiled headers" option.
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@item Write the source code for your application, or, for testing, just
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copy the code from an existing sample application into the source file
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that MSVC++ has already created for you. For example, you can copy
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@file{output_example.c} from the FFmpeg distribution.
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@item Open the "Project / Properties" dialog box. In the "Configuration"
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combo box, select "All Configurations" so that the changes you make will
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affect both debug and release builds. In the tree view on the left hand
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side, select "C/C++ / General", then edit the "Additional Include
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Directories" setting to contain the path where the FFmpeg includes were
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installed (i.e. @file{c:\msys\1.0\local\include}).
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@item Still in the "Project / Properties" dialog box, select
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"Linker / General" from the tree view and edit the
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"Additional Library Directories" setting to contain the @file{lib}
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directory where FFmpeg was installed (i.e. @file{c:\msys\1.0\local\lib}),
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the directory where MinGW libs are installed (i.e. @file{c:\mingw\lib}),
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and the directory where MinGW's GCC libs are installed
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(i.e. @file{C:\mingw\lib\gcc\mingw32\4.2.1-sjlj}). Then select
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"Linker / Input" from the tree view, and add the files @file{libavformat.a},
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@file{libavcodec.a}, @file{libavutil.a}, @file{libmingwex.a},
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@file{libgcc.a}, and any other libraries you used (i.e. @file{libz.a})
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to the end of "Additional Dependencies".
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@item Now, select "C/C++ / Code Generation" from the tree view. Select
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"Debug" in the "Configuration" combo box. Make sure that "Runtime
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Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
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the "Configuration" combo box and make sure that "Runtime Library" is
446
set to "Multi-threaded DLL".
447

    
448
@item Click "OK" to close the "Project / Properties" dialog box.
449

    
450
@item MSVC++ lacks some C99 header files that are fundamental for FFmpeg.
451
Get msinttypes from @url{http://code.google.com/p/msinttypes/downloads/list}
452
and install it in MSVC++'s include directory
453
(i.e. @file{C:\Program Files\Microsoft Visual Studio 8\VC\include}).
454

    
455
@item MSVC++ also does not understand the @code{inline} keyword used by
456
FFmpeg, so you must add this line before @code{#include}ing libav*:
457
@example
458
#define inline _inline
459
@end example
460

    
461
@item If you used @file{output_example.c} as your sample application,
462
you will have to edit the @code{#include}s to point to the files which
463
are under the @file{ffmpeg} directory (i.e. @code{<ffmpeg/avformat.h>}).
464

    
465
@item Build your application, everything should work.
466

    
467
@end enumerate
468

    
469
@subsubsection Using shared libraries
470

    
471
This is how to create DLL and LIB files that are compatible with MSVC++:
472

    
473
@enumerate
474

    
475
@item Add a call to @file{vcvars32.bat} (which sets up the environment
476
variables for the Visual C++ tools) as the first line of @file{msys.bat}.
477
The standard location for @file{vcvars32.bat} is
478
@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
479
and the standard location for @file{msys.bat} is @file{C:\msys\1.0\msys.bat}.
480
If this corresponds to your setup, add the following line as the first line
481
of @file{msys.bat}:
482

    
483
@example
484
call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"
485
@end example
486

    
487
Alternatively, you may start the @file{Visual Studio 2005 Command Prompt},
488
and run @file{c:\msys\1.0\msys.bat} from there.
489

    
490
@item Within the MSYS shell, run @code{lib.exe}. If you get a help message
491
from @file{Microsoft (R) Library Manager}, this means your environment
492
variables are set up correctly, the @file{Microsoft (R) Library Manager}
493
is on the path and will be used by FFmpeg to create
494
MSVC++-compatible import libraries.
495

    
496
@item Build FFmpeg with
497

    
498
@example
499
./configure --enable-shared --enable-memalign-hack
500
make
501
make install
502
@end example
503

    
504
Your install path (@file{/usr/local/} by default) should now have the
505
necessary DLL and LIB files under the @file{bin} directory.
506

    
507
@end enumerate
508

    
509
To use those files with MSVC++, do the same as you would do with
510
the static libraries, as described above. But in Step 4,
511
you should only need to add the directory where the LIB files are installed
512
(i.e. @file{c:\msys\usr\local\bin}). This is not a typo, the LIB files are
513
installed in the @file{bin} directory. And instead of adding @file{libxx.a}
514
files, you should add @file{avcodec.lib}, @file{avformat.lib}, and
515
@file{avutil.lib}. There should be no need for @file{libmingwex.a},
516
@file{libgcc.a}, and @file{wsock32.lib}, nor any other external library
517
statically linked into the DLLs. The @file{bin} directory contains a bunch
518
of DLL files, but the ones that are actually used to run your application
519
are the ones with a major version number in their filenames
520
(i.e. @file{avcodec-51.dll}).
521

    
522
@subsection Cross compilation for Windows with Linux
523

    
524
You must use the MinGW cross compilation tools available at
525
@url{http://www.mingw.org/}.
526

    
527
Then configure FFmpeg with the following options:
528
@example
529
./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
530
@end example
531
(you can change the cross-prefix according to the prefix chosen for the
532
MinGW tools).
533

    
534
Then you can easily test FFmpeg with Wine
535
(@url{http://www.winehq.com/}).
536

    
537
@subsection Compilation under Cygwin
538

    
539
The main issue with Cygwin is that newlib, its C library, does not
540
contain llrint().  However, it is possible to leverage the
541
implementation in MinGW.
542

    
543
Just install your Cygwin with all the "Base" packages, plus the
544
following "Devel" ones:
545
@example
546
binutils, gcc-core, make, subversion, mingw-runtime
547
@end example
548

    
549
Do not install binutils-20060709-1 (they are buggy on shared builds);
550
use binutils-20050610-1 instead.
551

    
552
Then create a small library that just contains llrint():
553

    
554
@example
555
ar x /usr/lib/mingw/libmingwex.a llrint.o
556
ar cq /usr/local/lib/libllrint.a llrint.o
557
@end example
558

    
559
Then run
560

    
561
@example
562
./configure --enable-static --disable-shared  --extra-ldflags='-L /usr/local/lib' --extra-libs='-l llrint'
563
@end example
564

    
565
to make a static build or
566

    
567
@example
568
./configure --enable-shared --disable-static  --extra-ldflags='-L /usr/local/lib' --extra-libs='-l llrint'
569
@end example
570

    
571
to build shared libraries.
572

    
573
If you want to build FFmpeg with additional libraries, download Cygwin
574
"Devel" packages for Ogg and Vorbis from any Cygwin packages repository
575
and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
576
(@url{http://cygwinports.dotsrc.org/}).
577

    
578
@subsection Crosscompilation for Windows under Cygwin
579

    
580
With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
581

    
582
Just install your Cygwin as explained before, plus these additional
583
"Devel" packages:
584
@example
585
gcc-mingw-core, mingw-runtime, mingw-zlib
586
@end example
587

    
588
and add some special flags to your configure invocation.
589

    
590
For a static build run
591
@example
592
./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
593
@end example
594

    
595
and for a build with shared libraries
596
@example
597
./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
598
@end example
599

    
600
@section BeOS
601

    
602
BeOS support is broken in mysterious ways.
603

    
604
@section OS/2
605

    
606
For information about compiling FFmpeg on OS/2 see
607
@url{http://www.edm2.com/index.php/FFmpeg}.
608

    
609
@chapter Developers Guide
610

    
611
@section API
612
@itemize @bullet
613
@item libavcodec is the library containing the codecs (both encoding and
614
decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
615

    
616
@item libavformat is the library containing the file format handling (mux and
617
demux code for several formats). Look at @file{ffplay.c} to use it in a
618
player. See @file{output_example.c} to use it to generate audio or video
619
streams.
620

    
621
@end itemize
622

    
623
@section Integrating libavcodec or libavformat in your program
624

    
625
You can integrate all the source code of the libraries to link them
626
statically to avoid any version problem. All you need is to provide a
627
'config.mak' and a 'config.h' in the parent directory. See the defines
628
generated by ./configure to understand what is needed.
629

    
630
You can use libavcodec or libavformat in your commercial program, but
631
@emph{any patch you make must be published}. The best way to proceed is
632
to send your patches to the FFmpeg mailing list.
633

    
634
@node Coding Rules
635
@section Coding Rules
636

    
637
FFmpeg is programmed in the ISO C90 language with a few additional
638
features from ISO C99, namely:
639
@itemize @bullet
640
@item
641
the @samp{inline} keyword;
642
@item
643
@samp{//} comments;
644
@item
645
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
646
@item
647
compound literals (@samp{x = (struct s) @{ 17, 23 @};})
648
@end itemize
649

    
650
These features are supported by all compilers we care about, so we will not
651
accept patches to remove their use unless they absolutely do not impair
652
clarity and performance.
653

    
654
All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
655
compiles with several other compilers, such as the Compaq ccc compiler
656
or Sun Studio 9, and we would like to keep it that way unless it would
657
be exceedingly involved. To ensure compatibility, please do not use any
658
additional C99 features or GCC extensions. Especially watch out for:
659
@itemize @bullet
660
@item
661
mixing statements and declarations;
662
@item
663
@samp{long long} (use @samp{int64_t} instead);
664
@item
665
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
666
@item
667
GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
668
@end itemize
669

    
670
Indent size is 4.
671
The presentation is the one specified by 'indent -i4 -kr -nut'.
672
The TAB character is forbidden outside of Makefiles as is any
673
form of trailing whitespace. Commits containing either will be
674
rejected by the Subversion repository.
675

    
676
The main priority in FFmpeg is simplicity and small code size in order to
677
minimize the bug count.
678

    
679
Comments: Use the JavaDoc/Doxygen
680
format (see examples below) so that code documentation
681
can be generated automatically. All nontrivial functions should have a comment
682
above them explaining what the function does, even if it is just one sentence.
683
All structures and their member variables should be documented, too.
684
@example
685
/**
686
 * @@file mpeg.c
687
 * MPEG codec.
688
 * @@author ...
689
 */
690

    
691
/**
692
 * Summary sentence.
693
 * more text ...
694
 * ...
695
 */
696
typedef struct Foobar@{
697
    int var1; /**< var1 description */
698
    int var2; ///< var2 description
699
    /** var3 description */
700
    int var3;
701
@} Foobar;
702

    
703
/**
704
 * Summary sentence.
705
 * more text ...
706
 * ...
707
 * @@param my_parameter description of my_parameter
708
 * @@return return value description
709
 */
710
int myfunc(int my_parameter)
711
...
712
@end example
713

    
714
fprintf and printf are forbidden in libavformat and libavcodec,
715
please use av_log() instead.
716

    
717
Casts should be used only when necessary. Unneeded parentheses
718
should also be avoided if they don't make the code easier to understand.
719

    
720
@section Development Policy
721

    
722
@enumerate
723
@item
724
   Contributions should be licensed under the LGPL 2.1, including an
725
   "or any later version" clause, or the MIT license.  GPL 2 including
726
   an "or any later version" clause is also acceptable, but LGPL is
727
   preferred.
728
@item
729
   You must not commit code which breaks FFmpeg! (Meaning unfinished but
730
   enabled code which breaks compilation or compiles but does not work or
731
   breaks the regression tests)
732
   You can commit unfinished stuff (for testing etc), but it must be disabled
733
   (#ifdef etc) by default so it does not interfere with other developers'
734
   work.
735
@item
736
   You do not have to over-test things. If it works for you, and you think it
737
   should work for others, then commit. If your code has problems
738
   (portability, triggers compiler bugs, unusual environment etc) they will be
739
   reported and eventually fixed.
740
@item
741
   Do not commit unrelated changes together, split them into self-contained
742
   pieces. Also do not forget that if part B depends on part A, but A does not
743
   depend on B, then A can and should be committed first and separate from B.
744
   Keeping changes well split into self-contained parts makes reviewing and
745
   understanding them on the commit log mailing list easier. This also helps
746
   in case of debugging later on.
747
   Also if you have doubts about splitting or not splitting, do not hesitate to
748
   ask/discuss it on the developer mailing list.
749
@item
750
   Do not change behavior of the program (renaming options etc) without
751
   first discussing it on the ffmpeg-devel mailing list. Do not remove
752
   functionality from the code. Just improve!
753

    
754
   Note: Redundant code can be removed.
755
@item
756
   Do not commit changes to the build system (Makefiles, configure script)
757
   which change behavior, defaults etc, without asking first. The same
758
   applies to compiler warning fixes, trivial looking fixes and to code
759
   maintained by other developers. We usually have a reason for doing things
760
   the way we do. Send your changes as patches to the ffmpeg-devel mailing
761
   list, and if the code maintainers say OK, you may commit. This does not
762
   apply to files you wrote and/or maintain.
763
@item
764
   We refuse source indentation and other cosmetic changes if they are mixed
765
   with functional changes, such commits will be rejected and removed. Every
766
   developer has his own indentation style, you should not change it. Of course
767
   if you (re)write something, you can use your own style, even though we would
768
   prefer if the indentation throughout FFmpeg was consistent (Many projects
769
   force a given indentation style - we do not.). If you really need to make
770
   indentation changes (try to avoid this), separate them strictly from real
771
   changes.
772

    
773
   NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
774
   then either do NOT change the indentation of the inner part within (do not
775
   move it to the right)! or do so in a separate commit
776
@item
777
   Always fill out the commit log message. Describe in a few lines what you
778
   changed and why. You can refer to mailing list postings if you fix a
779
   particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
780
@item
781
   If you apply a patch by someone else, include the name and email address in
782
   the log message. Since the ffmpeg-cvslog mailing list is publicly
783
   archived you should add some SPAM protection to the email address. Send an
784
   answer to ffmpeg-devel (or wherever you got the patch from) saying that
785
   you applied the patch.
786
@item
787
   When applying patches that have been discussed (at length) on the mailing
788
   list, reference the thread in the log message.
789
@item
790
    Do NOT commit to code actively maintained by others without permission.
791
    Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
792
    timeframe (12h for build failures and security fixes, 3 days small changes,
793
    1 week for big patches) then commit your patch if you think it is OK.
794
    Also note, the maintainer can simply ask for more time to review!
795
@item
796
    Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
797
    are sent there and reviewed by all the other developers. Bugs and possible
798
    improvements or general questions regarding commits are discussed there. We
799
    expect you to react if problems with your code are uncovered.
800
@item
801
    Update the documentation if you change behavior or add features. If you are
802
    unsure how best to do this, send a patch to ffmpeg-devel, the documentation
803
    maintainer(s) will review and commit your stuff.
804
@item
805
    Try to keep important discussions and requests (also) on the public
806
    developer mailing list, so that all developers can benefit from them.
807
@item
808
    Never write to unallocated memory, never write over the end of arrays,
809
    always check values read from some untrusted source before using them
810
    as array index or other risky things.
811
@item
812
    Remember to check if you need to bump versions for the specific libav
813
    parts (libavutil, libavcodec, libavformat) you are changing. You need
814
    to change the version integer and the version string.
815
    Incrementing the first component means no backward compatibility to
816
    previous versions (e.g. removal of a function from the public API).
817
    Incrementing the second component means backward compatible change
818
    (e.g. addition of a function to the public API).
819
    Incrementing the third component means a noteworthy binary compatible
820
    change (e.g. encoder bug fix that matters for the decoder).
821
@item
822
    If you add a new codec, remember to update the changelog, add it to
823
    the supported codecs table in the documentation and bump the second
824
    component of the @file{libavcodec} version number appropriately. If
825
    it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
826
    is only a decoder.
827
@item
828
    Compiler warnings indicate potential bugs or code with bad style. If a type of
829
    warning always points to correct and clean code, that warning should
830
    be disabled, not the code changed.
831
    Thus the remaining warnings can either be bugs or correct code.
832
    If it is a bug, the bug has to be fixed. If it is not, the code should
833
    be changed to not generate a warning unless that causes a slowdown
834
    or obfuscates the code.
835
@item
836
    If you add a new file, give it a proper license header. Do not copy and
837
    paste it from a random place, use an existing file as template.
838
@end enumerate
839

    
840
We think our rules are not too hard. If you have comments, contact us.
841

    
842
Note, these rules are mostly borrowed from the MPlayer project.
843

    
844
@section Submitting patches
845

    
846
First, (@pxref{Coding Rules}) above if you did not yet.
847

    
848
When you submit your patch, try to send a unified diff (diff '-up'
849
option). We cannot read other diffs :-)
850

    
851
Also please do not submit a patch which contains several unrelated changes.
852
Split it into separate, self-contained pieces. This does not mean splitting
853
file by file. Instead, make the patch as small as possible while still
854
keeping it as a logical unit that contains an individual change, even
855
if it spans multiple files. This makes reviewing your patches much easier
856
for us and greatly increases your chances of getting your patch applied.
857

    
858
Run the regression tests before submitting a patch so that you can
859
verify that there are no big problems.
860

    
861
Patches should be posted as base64 encoded attachments (or any other
862
encoding which ensures that the patch will not be trashed during
863
transmission) to the ffmpeg-devel mailing list, see
864
@url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
865

    
866
It also helps quite a bit if you tell us what the patch does (for example
867
'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
868
and has no lrint()')
869

    
870
Also please if you send several patches, send each patch as a separate mail,
871
do not attach several unrelated patches to the same mail.
872

    
873
@section patch submission checklist
874

    
875
@enumerate
876
@item
877
    Do the regression tests pass with the patch applied?
878
@item
879
    Is the patch a unified diff?
880
@item
881
    Is the patch against latest FFmpeg SVN?
882
@item
883
    Are you subscribed to ffmpeg-dev?
884
    (the list is subscribers only due to spam)
885
@item
886
    Have you checked that the changes are minimal, so that the same cannot be
887
    achieved with a smaller patch and/or simpler final code?
888
@item
889
    If the change is to speed critical code, did you benchmark it?
890
@item
891
    If you did any benchmarks, did you provide them in the mail?
892
@item
893
    Have you checked that the patch does not introduce buffer overflows or
894
    other security issues?
895
@item
896
    Is the patch created from the root of the source tree, so it can be
897
    applied with @code{patch -p0}?
898
@item
899
    Does the patch not mix functional and cosmetic changes?
900
@item
901
    Did you add tabs or trailing whitespace to the code? Both are forbidden.
902
@item
903
    Is the patch attached to the email you send?
904
@item
905
    Is the mime type of the patch correct? It should be text/x-diff or
906
    text/x-patch or at least text/plain and not application/octet-stream.
907
@item
908
    If the patch fixes a bug, did you provide a verbose analysis of the bug?
909
@item
910
    If the patch fixes a bug, did you provide enough information, including
911
    a sample, so the bug can be reproduced and the fix can be verified?
912
    Note please do not attach samples >100k to mails but rather provide a
913
    URL, you can upload to ftp://upload.mplayerhq.hu
914
@item
915
    Did you provide a verbose summary about what the patch does change?
916
@item
917
    Did you provide a verbose explanation why it changes things like it does?
918
@item
919
    Did you provide a verbose summary of the user visible advantages and
920
    disadvantages if the patch is applied?
921
@item
922
    Did you provide an example so we can verify the new feature added by the
923
    patch easily?
924
@item
925
    If you added a new file, did you insert a license header? It should be
926
    taken from FFmpeg, not randomly copied and pasted from somewhere else.
927
@item
928
    You should maintain alphabetical order in alphabetically ordered lists as
929
    long as doing so does not break API/ABI compatibility.
930
@item
931
    Lines with similar content should be aligned vertically when doing so
932
    improves readability.
933
@item
934
    Did you provide a suggestion for a clear commit log message?
935
@item
936
    Did you test your decoder or demuxer against damaged data? If no, see
937
    tools/trasher and the noise bitstream filter. Your decoder or demuxer
938
    should not crash or end in a (near) infinite loop when fed damaged data.
939
@end enumerate
940

    
941
@section Patch review process
942

    
943
All patches posted to ffmpeg-devel will be reviewed, unless they contain a
944
clear note that the patch is not for SVN.
945
Reviews and comments will be posted as replies to the patch on the
946
mailing list. The patch submitter then has to take care of every comment,
947
that can be by resubmitting a changed patch or by discussion. Resubmitted
948
patches will themselves be reviewed like any other patch. If at some point
949
a patch passes review with no comments then it is approved, that can for
950
simple and small patches happen immediately while large patches will generally
951
have to be changed and reviewed many times before they are approved.
952
After a patch is approved it will be committed to the repository.
953

    
954
We will review all submitted patches, but sometimes we are quite busy so
955
especially for large patches this can take several weeks.
956

    
957
When resubmitting patches, please do not make any significant changes
958
not related to the comments received during review. Such patches will
959
be rejected. Instead, submit  significant changes or new features as
960
separate patches.
961

    
962
@section Regression tests
963

    
964
Before submitting a patch (or committing to the repository), you should at least
965
test that you did not break anything.
966

    
967
The regression tests build a synthetic video stream and a synthetic
968
audio stream. These are then encoded and decoded with all codecs or
969
formats. The CRC (or MD5) of each generated file is recorded in a
970
result file. A 'diff' is launched to compare the reference results and
971
the result file.
972

    
973
The regression tests then go on to test the FFserver code with a
974
limited set of streams. It is important that this step runs correctly
975
as well.
976

    
977
Run 'make test' to test all the codecs and formats.
978

    
979
Run 'make fulltest' to test all the codecs, formats and FFserver.
980

    
981
[Of course, some patches may change the results of the regression tests. In
982
this case, the reference results of the regression tests shall be modified
983
accordingly].
984

    
985
@bye