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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, WB and NB. FFmpeg can make use of the
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AMR WB (floating-point mode) and the AMR NB (floating-point mode) reference
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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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@chapter Supported File Formats and Codecs
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You can use the @code{-formats} option to have an exhaustive list.
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@section File Formats
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FFmpeg supports the following file formats through the @code{libavformat}
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library:
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@multitable @columnfractions .4 .1 .1 .4
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@item Supported File Format @tab Encoding @tab Decoding @tab Comments
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@item MPEG audio @tab X @tab X
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@item MPEG-1 systems @tab X  @tab  X
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@tab muxed audio and video
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@item MPEG-2 PS @tab X  @tab  X
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@tab also known as @code{VOB} file
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@item MPEG-2 TS @tab    @tab  X
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@tab also known as DVB Transport Stream
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@item ASF@tab X @tab X
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@item AVI@tab X @tab X
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@item WAV@tab X @tab X
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@item Macromedia Flash@tab X @tab X
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@tab Only embedded audio is decoded.
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@item FLV              @tab  X @tab X
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@tab Macromedia Flash video files
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@item Real Audio and Video @tab X @tab X
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@item Raw AC3 @tab X  @tab  X
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@item Raw MJPEG @tab X  @tab  X
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@item Raw MPEG video @tab X  @tab  X
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@item Raw PCM8/16 bits, mulaw/Alaw@tab X  @tab  X
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@item Raw CRI ADX audio @tab X  @tab  X
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@item Raw Shorten audio @tab    @tab  X
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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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@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     @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 IX   @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      @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 Only SV7 is 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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@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 using 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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@itemize
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@item Install the current versions of MSYS and MinGW from
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@url{http://www.mingw.org/}. You can find detailed installation
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instructions in the download section and the FAQ.
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NOTE: Use at least bash 3.1. Older versions are known to be failing on the
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configure script.
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@item If you want to test the FFplay, also download
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the MinGW development library of SDL 1.2.x
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(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
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@url{http://www.libsdl.org}. Unpack it in a temporary directory, and
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unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
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directory. Edit the @file{sdl-config} script so that it gives the
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correct SDL directory when invoked.
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@item If you want to use vhooks, you must have a POSIX compliant libdl in your
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MinGW system. Get dlfcn-win32 from @url{http://code.google.com/p/dlfcn-win32}.
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@item Extract the current version of FFmpeg.
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@item Start the MSYS shell (file @file{msys.bat}).
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@item Change to the FFmpeg directory and follow
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 the instructions of how to compile FFmpeg (file
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@file{INSTALL}). Usually, launching @file{./configure} and @file{make}
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suffices. If you have problems using SDL, verify that
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@file{sdl-config} can be launched from the MSYS command line.
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@item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
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@file{make install}. Do not forget to copy @file{SDL.dll} to the place
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you launch @file{ffplay} from.
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@end itemize
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Notes:
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@itemize
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@item The target @file{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 @file{avcodec.dll} and @file{avformat.dll}. With
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@code{make install} you install the FFmpeg DLLs and the associated
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headers in @file{Program Files/FFmpeg}.
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@item Visual C++ compatibility: If you used @code{./configure --enable-shared}
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when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
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C++ @code{lib} tool to build @code{avcodec.lib} and
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@code{avformat.lib}. With these libraries you can link your Visual C++
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code directly with the FFmpeg DLLs (see below).
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@end itemize
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@subsection Visual C++ compatibility
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FFmpeg will not compile under Visual C++ -- and it has too many
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dependencies on the GCC compiler to make a port viable. However,
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if you want to use the FFmpeg libraries in your own applications,
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you can still compile those applications using Visual C++. An
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important restriction to this is that you have to use the
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dynamically linked versions of the FFmpeg libraries (i.e. the
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DLLs), and you have to make sure that Visual-C++-compatible
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import libraries are created during the FFmpeg build process.
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This description of how to use the FFmpeg libraries with Visual C++ is
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based on Visual C++ 2005 Express Edition Beta 2. If you have a different
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version, you might have to modify the procedures slightly.
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Here are the step-by-step instructions for building the FFmpeg libraries
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so they can be used with Visual C++:
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@enumerate
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@item Install Visual C++ (if you have not done so already).
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@item Install MinGW and MSYS as described above.
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@item Add a call to @file{vcvars32.bat} (which sets up the environment
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variables for the Visual C++ tools) as the first line of
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@file{msys.bat}. The standard location for @file{vcvars32.bat} is
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@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
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and the standard location for @file{msys.bat} is
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@file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
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following line as the first line of @file{msys.bat}:
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@code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
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@item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
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If you get a help message with the command line options of @code{link.exe},
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this means your environment variables are set up correctly, the
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Microsoft linker is on the path and will be used by FFmpeg to
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create Visual-C++-compatible import libraries.
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@item Extract the current version of FFmpeg and change to the FFmpeg directory.
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@item Type the command
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@code{./configure --enable-shared --disable-static --enable-memalign-hack}
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to configure and, if that did not produce any errors,
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type @code{make} to build FFmpeg.
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@item The subdirectories @file{libavformat}, @file{libavcodec}, and
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@file{libavutil} should now contain the files @file{avformat.dll},
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@file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
447
@file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
448
DLLs to your System32 directory (typically @file{C:\Windows\System32}).
449

    
450
@end enumerate
451

    
452
And here is how to use these libraries with Visual C++:
453

    
454
@enumerate
455

    
456
@item Create a new console application ("File / New / Project") and then
457
select "Win32 Console Application". On the appropriate page of the
458
Application Wizard, uncheck the "Precompiled headers" option.
459

    
460
@item Write the source code for your application, or, for testing, just
461
copy the code from an existing sample application into the source file
462
that Visual C++ has already created for you. (Note that your source
463
filehas to have a @code{.cpp} extension; otherwise, Visual C++ will not
464
compile the FFmpeg headers correctly because in C mode, it does not
465
recognize the @code{inline} keyword.)  For example, you can copy
466
@file{output_example.c} from the FFmpeg distribution (but you will
467
have to make minor modifications so the code will compile under
468
C++, see below).
469

    
470
@item Open the "Project / Properties" dialog box. In the "Configuration"
471
combo box, select "All Configurations" so that the changes you make will
472
affect both debug and release builds. In the tree view on the left hand
473
side, select "C/C++ / General", then edit the "Additional Include
474
Directories" setting to contain the complete paths to the
475
@file{libavformat}, @file{libavcodec}, and @file{libavutil}
476
subdirectories of your FFmpeg directory. Note that the directories have
477
to be separated using semicolons. Now select "Linker / General" from the
478
tree view and edit the "Additional Library Directories" setting to
479
contain the same three directories.
480

    
481
@item Still in the "Project / Properties" dialog box, select "Linker / Input"
482
from the tree view, then add the files @file{avformat.lib},
483
@file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
484
Dependencies". Note that the names of the libraries have to be separated
485
using spaces.
486

    
487
@item Now, select "C/C++ / Code Generation" from the tree view. Select
488
"Debug" in the "Configuration" combo box. Make sure that "Runtime
489
Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
490
the "Configuration" combo box and make sure that "Runtime Library" is
491
set to "Multi-threaded DLL".
492

    
493
@item Click "OK" to close the "Project / Properties" dialog box and build
494
the application. Hopefully, it should compile and run cleanly. If you
495
used @file{output_example.c} as your sample application, you will get a
496
few compiler errors, but they are easy to fix. The first type of error
497
occurs because Visual C++ does not allow an @code{int} to be converted to
498
an @code{enum} without a cast. To solve the problem, insert the required
499
casts (this error occurs once for a @code{CodecID} and once for a
500
@code{CodecType}).  The second type of error occurs because C++ requires
501
the return value of @code{malloc} to be cast to the exact type of the
502
pointer it is being assigned to. Visual C++ will complain that, for
503
example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
504
an explicit cast. So insert an explicit cast in these places to silence
505
the compiler. The third type of error occurs because the @code{snprintf}
506
library function is called @code{_snprintf} under Visual C++.  So just
507
add an underscore to fix the problem. With these changes,
508
@file{output_example.c} should compile under Visual C++, and the
509
resulting executable should produce valid video files.
510

    
511
@end enumerate
512

    
513
@subsection Cross compilation for Windows with Linux
514

    
515
You must use the MinGW cross compilation tools available at
516
@url{http://www.mingw.org/}.
517

    
518
Then configure FFmpeg with the following options:
519
@example
520
./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
521
@end example
522
(you can change the cross-prefix according to the prefix chosen for the
523
MinGW tools).
524

    
525
Then you can easily test FFmpeg with Wine
526
(@url{http://www.winehq.com/}).
527

    
528
@subsection Compilation under Cygwin
529

    
530
Cygwin works very much like Unix.
531

    
532
Just install your Cygwin with all the "Base" packages, plus the
533
following "Devel" ones:
534
@example
535
binutils, gcc-core, make, subversion
536
@end example
537

    
538
Do not install binutils-20060709-1 (they are buggy on shared builds);
539
use binutils-20050610-1 instead.
540

    
541
Then run
542

    
543
@example
544
./configure --enable-static --disable-shared
545
@end example
546

    
547
to make a static build or
548

    
549
@example
550
./configure --enable-shared --disable-static
551
@end example
552

    
553
to build shared libraries.
554

    
555
If you want to build FFmpeg with additional libraries, download Cygwin
556
"Devel" packages for Ogg and Vorbis from any Cygwin packages repository
557
and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
558
(@url{http://cygwinports.dotsrc.org/}).
559

    
560
@subsection Crosscompilation for Windows under Cygwin
561

    
562
With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
563

    
564
Just install your Cygwin as explained before, plus these additional
565
"Devel" packages:
566
@example
567
gcc-mingw-core, mingw-runtime, mingw-zlib
568
@end example
569

    
570
and add some special flags to your configure invocation.
571

    
572
For a static build run
573
@example
574
./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
575
@end example
576

    
577
and for a build with shared libraries
578
@example
579
./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
580
@end example
581

    
582
@section BeOS
583

    
584
BeOS support is broken in mysterious ways.
585

    
586
@chapter Developers Guide
587

    
588
@section API
589
@itemize @bullet
590
@item libavcodec is the library containing the codecs (both encoding and
591
decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
592

    
593
@item libavformat is the library containing the file format handling (mux and
594
demux code for several formats). Look at @file{ffplay.c} to use it in a
595
player. See @file{output_example.c} to use it to generate audio or video
596
streams.
597

    
598
@end itemize
599

    
600
@section Integrating libavcodec or libavformat in your program
601

    
602
You can integrate all the source code of the libraries to link them
603
statically to avoid any version problem. All you need is to provide a
604
'config.mak' and a 'config.h' in the parent directory. See the defines
605
generated by ./configure to understand what is needed.
606

    
607
You can use libavcodec or libavformat in your commercial program, but
608
@emph{any patch you make must be published}. The best way to proceed is
609
to send your patches to the FFmpeg mailing list.
610

    
611
@node Coding Rules
612
@section Coding Rules
613

    
614
FFmpeg is programmed in the ISO C90 language with a few additional
615
features from ISO C99, namely:
616
@itemize @bullet
617
@item
618
the @samp{inline} keyword;
619
@item
620
@samp{//} comments;
621
@item
622
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
623
@item
624
compound literals (@samp{x = (struct s) @{ 17, 23 @};})
625
@end itemize
626

    
627
These features are supported by all compilers we care about, so we will not
628
accept patches to remove their use unless they absolutely do not impair
629
clarity and performance.
630

    
631
All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
632
compiles with several other compilers, such as the Compaq ccc compiler
633
or Sun Studio 9, and we would like to keep it that way unless it would
634
be exceedingly involved. To ensure compatibility, please do not use any
635
additional C99 features or GCC extensions. Especially watch out for:
636
@itemize @bullet
637
@item
638
mixing statements and declarations;
639
@item
640
@samp{long long} (use @samp{int64_t} instead);
641
@item
642
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
643
@item
644
GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
645
@end itemize
646

    
647
Indent size is 4.
648
The presentation is the one specified by 'indent -i4 -kr -nut'.
649
The TAB character is forbidden outside of Makefiles as is any
650
form of trailing whitespace. Commits containing either will be
651
rejected by the Subversion repository.
652

    
653
The main priority in FFmpeg is simplicity and small code size in order to
654
minimize the bug count.
655

    
656
Comments: Use the JavaDoc/Doxygen
657
format (see examples below) so that code documentation
658
can be generated automatically. All nontrivial functions should have a comment
659
above them explaining what the function does, even if it is just one sentence.
660
All structures and their member variables should be documented, too.
661
@example
662
/**
663
 * @@file mpeg.c
664
 * MPEG codec.
665
 * @@author ...
666
 */
667

    
668
/**
669
 * Summary sentence.
670
 * more text ...
671
 * ...
672
 */
673
typedef struct Foobar@{
674
    int var1; /**< var1 description */
675
    int var2; ///< var2 description
676
    /** var3 description */
677
    int var3;
678
@} Foobar;
679

    
680
/**
681
 * Summary sentence.
682
 * more text ...
683
 * ...
684
 * @@param my_parameter description of my_parameter
685
 * @@return return value description
686
 */
687
int myfunc(int my_parameter)
688
...
689
@end example
690

    
691
fprintf and printf are forbidden in libavformat and libavcodec,
692
please use av_log() instead.
693

    
694
Casts should be used only when necessary. Unneeded parentheses
695
should also be avoided if they don't make the code easier to understand.
696

    
697
@section Development Policy
698

    
699
@enumerate
700
@item
701
   Contributions should be licensed under the LGPL 2.1, including an
702
   "or any later version" clause, or the MIT license.  GPL 2 including
703
   an "or any later version" clause is also acceptable, but LGPL is
704
   preferred.
705
@item
706
   You must not commit code which breaks FFmpeg! (Meaning unfinished but
707
   enabled code which breaks compilation or compiles but does not work or
708
   breaks the regression tests)
709
   You can commit unfinished stuff (for testing etc), but it must be disabled
710
   (#ifdef etc) by default so it does not interfere with other developers'
711
   work.
712
@item
713
   You do not have to over-test things. If it works for you, and you think it
714
   should work for others, then commit. If your code has problems
715
   (portability, triggers compiler bugs, unusual environment etc) they will be
716
   reported and eventually fixed.
717
@item
718
   Do not commit unrelated changes together, split them into self-contained
719
   pieces. Also do not forget that if part B depends on part A, but A does not
720
   depend on B, then A can and should be committed first and separate from B.
721
   Keeping changes well split into self-contained parts makes reviewing and
722
   understanding them on the commit log mailing list easier. This also helps
723
   in case of debugging later on.
724
   Also if you have doubts about splitting or not splitting, do not hesitate to
725
   ask/discuss it on the developer mailing list.
726
@item
727
   Do not change behavior of the program (renaming options etc) without
728
   first discussing it on the ffmpeg-devel mailing list. Do not remove
729
   functionality from the code. Just improve!
730

    
731
   Note: Redundant code can be removed.
732
@item
733
   Do not commit changes to the build system (Makefiles, configure script)
734
   which change behavior, defaults etc, without asking first. The same
735
   applies to compiler warning fixes, trivial looking fixes and to code
736
   maintained by other developers. We usually have a reason for doing things
737
   the way we do. Send your changes as patches to the ffmpeg-devel mailing
738
   list, and if the code maintainers say OK, you may commit. This does not
739
   apply to files you wrote and/or maintain.
740
@item
741
   We refuse source indentation and other cosmetic changes if they are mixed
742
   with functional changes, such commits will be rejected and removed. Every
743
   developer has his own indentation style, you should not change it. Of course
744
   if you (re)write something, you can use your own style, even though we would
745
   prefer if the indentation throughout FFmpeg was consistent (Many projects
746
   force a given indentation style - we do not.). If you really need to make
747
   indentation changes (try to avoid this), separate them strictly from real
748
   changes.
749

    
750
   NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
751
   then either do NOT change the indentation of the inner part within (do not
752
   move it to the right)! or do so in a separate commit
753
@item
754
   Always fill out the commit log message. Describe in a few lines what you
755
   changed and why. You can refer to mailing list postings if you fix a
756
   particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
757
@item
758
   If you apply a patch by someone else, include the name and email address in
759
   the log message. Since the ffmpeg-cvslog mailing list is publicly
760
   archived you should add some SPAM protection to the email address. Send an
761
   answer to ffmpeg-devel (or wherever you got the patch from) saying that
762
   you applied the patch.
763
@item
764
   When applying patches that have been discussed (at length) on the mailing
765
   list, reference the thread in the log message.
766
@item
767
    Do NOT commit to code actively maintained by others without permission.
768
    Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
769
    timeframe (12h for build failures and security fixes, 3 days small changes,
770
    1 week for big patches) then commit your patch if you think it is OK.
771
    Also note, the maintainer can simply ask for more time to review!
772
@item
773
    Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
774
    are sent there and reviewed by all the other developers. Bugs and possible
775
    improvements or general questions regarding commits are discussed there. We
776
    expect you to react if problems with your code are uncovered.
777
@item
778
    Update the documentation if you change behavior or add features. If you are
779
    unsure how best to do this, send a patch to ffmpeg-devel, the documentation
780
    maintainer(s) will review and commit your stuff.
781
@item
782
    Try to keep important discussions and requests (also) on the public
783
    developer mailing list, so that all developers can benefit from them.
784
@item
785
    Never write to unallocated memory, never write over the end of arrays,
786
    always check values read from some untrusted source before using them
787
    as array index or other risky things.
788
@item
789
    Remember to check if you need to bump versions for the specific libav
790
    parts (libavutil, libavcodec, libavformat) you are changing. You need
791
    to change the version integer and the version string.
792
    Incrementing the first component means no backward compatibility to
793
    previous versions (e.g. removal of a function from the public API).
794
    Incrementing the second component means backward compatible change
795
    (e.g. addition of a function to the public API).
796
    Incrementing the third component means a noteworthy binary compatible
797
    change (e.g. encoder bug fix that matters for the decoder).
798
@item
799
    If you add a new codec, remember to update the changelog, add it to
800
    the supported codecs table in the documentation and bump the second
801
    component of the @file{libavcodec} version number appropriately. If
802
    it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
803
    is only a decoder.
804
@item
805
    Do not change code to hide warnings without ensuring that the underlying
806
    logic is correct and thus the warning was inappropriate.
807
@item
808
    If you add a new file, give it a proper license header. Do not copy and
809
    paste it from a random place, use an existing file as template.
810
@end enumerate
811

    
812
We think our rules are not too hard. If you have comments, contact us.
813

    
814
Note, these rules are mostly borrowed from the MPlayer project.
815

    
816
@section Submitting patches
817

    
818
First, (@pxref{Coding Rules}) above if you did not yet.
819

    
820
When you submit your patch, try to send a unified diff (diff '-up'
821
option). We cannot read other diffs :-)
822

    
823
Also please do not submit a patch which contains several unrelated changes.
824
Split it into separate, self-contained pieces. This does not mean splitting
825
file by file. Instead, make the patch as small as possible while still
826
keeping it as a logical unit that contains an individual change, even
827
if it spans multiple files. This makes reviewing your patches much easier
828
for us and greatly increases your chances of getting your patch applied.
829

    
830
Run the regression tests before submitting a patch so that you can
831
verify that there are no big problems.
832

    
833
Patches should be posted as base64 encoded attachments (or any other
834
encoding which ensures that the patch will not be trashed during
835
transmission) to the ffmpeg-devel mailing list, see
836
@url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
837

    
838
It also helps quite a bit if you tell us what the patch does (for example
839
'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
840
and has no lrint()')
841

    
842
Also please if you send several patches, send each patch as a separate mail,
843
do not attach several unrelated patches to the same mail.
844

    
845
@section patch submission checklist
846

    
847
@enumerate
848
@item
849
    Do the regression tests pass with the patch applied?
850
@item
851
    Is the patch a unified diff?
852
@item
853
    Is the patch against latest FFmpeg SVN?
854
@item
855
    Are you subscribed to ffmpeg-dev?
856
    (the list is subscribers only due to spam)
857
@item
858
    Have you checked that the changes are minimal, so that the same cannot be
859
    achieved with a smaller patch and/or simpler final code?
860
@item
861
    If the change is to speed critical code, did you benchmark it?
862
@item
863
    If you did any benchmarks, did you provide them in the mail?
864
@item
865
    Have you checked that the patch does not introduce buffer overflows or
866
    other security issues?
867
@item
868
    Is the patch created from the root of the source tree, so it can be
869
    applied with @code{patch -p0}?
870
@item
871
    Does the patch not mix functional and cosmetic changes?
872
@item
873
    Did you add tabs or trailing whitespace to the code? Both are forbidden.
874
@item
875
    Is the patch attached to the email you send?
876
@item
877
    Is the mime type of the patch correct? It should be text/x-diff or
878
    text/x-patch or at least text/plain and not application/octet-stream.
879
@item
880
    If the patch fixes a bug, did you provide a verbose analysis of the bug?
881
@item
882
    If the patch fixes a bug, did you provide enough information, including
883
    a sample, so the bug can be reproduced and the fix can be verified?
884
    Note please do not attach samples >100k to mails but rather provide a
885
    URL, you can upload to ftp://upload.mplayerhq.hu
886
@item
887
    Did you provide a verbose summary about what the patch does change?
888
@item
889
    Did you provide a verbose explanation why it changes things like it does?
890
@item
891
    Did you provide a verbose summary of the user visible advantages and
892
    disadvantages if the patch is applied?
893
@item
894
    Did you provide an example so we can verify the new feature added by the
895
    patch easily?
896
@item
897
    If you added a new file, did you insert a license header? It should be
898
    taken from FFmpeg, not randomly copied and pasted from somewhere else.
899
@item
900
    You should maintain alphabetical order in alphabetically ordered lists as
901
    long as doing so does not break API/ABI compatibility.
902
@item
903
    Lines with similar content should be aligned vertically when doing so
904
    improves readability.
905
@item
906
    Did you provide a suggestion for a clear commit log message?
907
@end enumerate
908

    
909
@section Patch review process
910

    
911
All patches posted to ffmpeg-devel will be reviewed, unless they contain a
912
clear note that the patch is not for SVN.
913
Reviews and comments will be posted as replies to the patch on the
914
mailing list. The patch submitter then has to take care of every comment,
915
that can be by resubmitting a changed patch or by discussion. Resubmitted
916
patches will themselves be reviewed like any other patch. If at some point
917
a patch passes review with no comments then it is approved, that can for
918
simple and small patches happen immediately while large patches will generally
919
have to be changed and reviewed many times before they are approved.
920
After a patch is approved it will be committed to the repository.
921

    
922
We will review all submitted patches, but sometimes we are quite busy so
923
especially for large patches this can take several weeks.
924

    
925
When resubmitting patches, please do not make any significant changes
926
not related to the comments received during review. Such patches will
927
be rejected. Instead, submit  significant changes or new features as
928
separate patches.
929

    
930
@section Regression tests
931

    
932
Before submitting a patch (or committing to the repository), you should at least
933
test that you did not break anything.
934

    
935
The regression tests build a synthetic video stream and a synthetic
936
audio stream. These are then encoded and decoded with all codecs or
937
formats. The CRC (or MD5) of each generated file is recorded in a
938
result file. A 'diff' is launched to compare the reference results and
939
the result file.
940

    
941
The regression tests then go on to test the FFserver code with a
942
limited set of streams. It is important that this step runs correctly
943
as well.
944

    
945
Run 'make test' to test all the codecs and formats.
946

    
947
Run 'make fulltest' to test all the codecs, formats and FFserver.
948

    
949
[Of course, some patches may change the results of the regression tests. In
950
this case, the reference results of the regression tests shall be modified
951
accordingly].
952

    
953
@bye