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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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@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 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},
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@file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
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DLLs to your System32 directory (typically @file{C:\Windows\System32}).
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@end enumerate
448

    
449
And here is how to use these libraries with Visual C++:
450

    
451
@enumerate
452

    
453
@item Create a new console application ("File / New / Project") and then
454
select "Win32 Console Application". On the appropriate page of the
455
Application Wizard, uncheck the "Precompiled headers" option.
456

    
457
@item Write the source code for your application, or, for testing, just
458
copy the code from an existing sample application into the source file
459
that Visual C++ has already created for you. (Note that your source
460
filehas to have a @code{.cpp} extension; otherwise, Visual C++ will not
461
compile the FFmpeg headers correctly because in C mode, it does not
462
recognize the @code{inline} keyword.)  For example, you can copy
463
@file{output_example.c} from the FFmpeg distribution (but you will
464
have to make minor modifications so the code will compile under
465
C++, see below).
466

    
467
@item Open the "Project / Properties" dialog box. In the "Configuration"
468
combo box, select "All Configurations" so that the changes you make will
469
affect both debug and release builds. In the tree view on the left hand
470
side, select "C/C++ / General", then edit the "Additional Include
471
Directories" setting to contain the complete paths to the
472
@file{libavformat}, @file{libavcodec}, and @file{libavutil}
473
subdirectories of your FFmpeg directory. Note that the directories have
474
to be separated using semicolons. Now select "Linker / General" from the
475
tree view and edit the "Additional Library Directories" setting to
476
contain the same three directories.
477

    
478
@item Still in the "Project / Properties" dialog box, select "Linker / Input"
479
from the tree view, then add the files @file{avformat.lib},
480
@file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
481
Dependencies". Note that the names of the libraries have to be separated
482
using spaces.
483

    
484
@item Now, select "C/C++ / Code Generation" from the tree view. Select
485
"Debug" in the "Configuration" combo box. Make sure that "Runtime
486
Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
487
the "Configuration" combo box and make sure that "Runtime Library" is
488
set to "Multi-threaded DLL".
489

    
490
@item Click "OK" to close the "Project / Properties" dialog box and build
491
the application. Hopefully, it should compile and run cleanly. If you
492
used @file{output_example.c} as your sample application, you will get a
493
few compiler errors, but they are easy to fix. The first type of error
494
occurs because Visual C++ does not allow an @code{int} to be converted to
495
an @code{enum} without a cast. To solve the problem, insert the required
496
casts (this error occurs once for a @code{CodecID} and once for a
497
@code{CodecType}).  The second type of error occurs because C++ requires
498
the return value of @code{malloc} to be cast to the exact type of the
499
pointer it is being assigned to. Visual C++ will complain that, for
500
example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
501
an explicit cast. So insert an explicit cast in these places to silence
502
the compiler. The third type of error occurs because the @code{snprintf}
503
library function is called @code{_snprintf} under Visual C++.  So just
504
add an underscore to fix the problem. With these changes,
505
@file{output_example.c} should compile under Visual C++, and the
506
resulting executable should produce valid video files.
507

    
508
@end enumerate
509

    
510
@subsection Cross compilation for Windows with Linux
511

    
512
You must use the MinGW cross compilation tools available at
513
@url{http://www.mingw.org/}.
514

    
515
Then configure FFmpeg with the following options:
516
@example
517
./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
518
@end example
519
(you can change the cross-prefix according to the prefix chosen for the
520
MinGW tools).
521

    
522
Then you can easily test FFmpeg with Wine
523
(@url{http://www.winehq.com/}).
524

    
525
@subsection Compilation under Cygwin
526

    
527
Cygwin works very much like Unix.
528

    
529
Just install your Cygwin with all the "Base" packages, plus the
530
following "Devel" ones:
531
@example
532
binutils, gcc-core, make, subversion
533
@end example
534

    
535
Do not install binutils-20060709-1 (they are buggy on shared builds);
536
use binutils-20050610-1 instead.
537

    
538
Then run
539

    
540
@example
541
./configure --enable-static --disable-shared
542
@end example
543

    
544
to make a static build or
545

    
546
@example
547
./configure --enable-shared --disable-static
548
@end example
549

    
550
to build shared libraries.
551

    
552
If you want to build FFmpeg with additional libraries, download Cygwin
553
"Devel" packages for Ogg and Vorbis from any Cygwin packages repository
554
and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
555
(@url{http://cygwinports.dotsrc.org/}).
556

    
557
@subsection Crosscompilation for Windows under Cygwin
558

    
559
With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
560

    
561
Just install your Cygwin as explained before, plus these additional
562
"Devel" packages:
563
@example
564
gcc-mingw-core, mingw-runtime, mingw-zlib
565
@end example
566

    
567
and add some special flags to your configure invocation.
568

    
569
For a static build run
570
@example
571
./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
572
@end example
573

    
574
and for a build with shared libraries
575
@example
576
./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
577
@end example
578

    
579
@section BeOS
580

    
581
BeOS support is broken in mysterious ways.
582

    
583
@chapter Developers Guide
584

    
585
@section API
586
@itemize @bullet
587
@item libavcodec is the library containing the codecs (both encoding and
588
decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
589

    
590
@item libavformat is the library containing the file format handling (mux and
591
demux code for several formats). Look at @file{ffplay.c} to use it in a
592
player. See @file{output_example.c} to use it to generate audio or video
593
streams.
594

    
595
@end itemize
596

    
597
@section Integrating libavcodec or libavformat in your program
598

    
599
You can integrate all the source code of the libraries to link them
600
statically to avoid any version problem. All you need is to provide a
601
'config.mak' and a 'config.h' in the parent directory. See the defines
602
generated by ./configure to understand what is needed.
603

    
604
You can use libavcodec or libavformat in your commercial program, but
605
@emph{any patch you make must be published}. The best way to proceed is
606
to send your patches to the FFmpeg mailing list.
607

    
608
@node Coding Rules
609
@section Coding Rules
610

    
611
FFmpeg is programmed in the ISO C90 language with a few additional
612
features from ISO C99, namely:
613
@itemize @bullet
614
@item
615
the @samp{inline} keyword;
616
@item
617
@samp{//} comments;
618
@item
619
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
620
@item
621
compound literals (@samp{x = (struct s) @{ 17, 23 @};})
622
@end itemize
623

    
624
These features are supported by all compilers we care about, so we will not
625
accept patches to remove their use unless they absolutely do not impair
626
clarity and performance.
627

    
628
All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
629
compiles with several other compilers, such as the Compaq ccc compiler
630
or Sun Studio 9, and we would like to keep it that way unless it would
631
be exceedingly involved. To ensure compatibility, please do not use any
632
additional C99 features or GCC extensions. Especially watch out for:
633
@itemize @bullet
634
@item
635
mixing statements and declarations;
636
@item
637
@samp{long long} (use @samp{int64_t} instead);
638
@item
639
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
640
@item
641
GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
642
@end itemize
643

    
644
Indent size is 4.
645
The presentation is the one specified by 'indent -i4 -kr -nut'.
646
The TAB character is forbidden outside of Makefiles as is any
647
form of trailing whitespace. Commits containing either will be
648
rejected by the Subversion repository.
649

    
650
The main priority in FFmpeg is simplicity and small code size in order to
651
minimize the bug count.
652

    
653
Comments: Use the JavaDoc/Doxygen
654
format (see examples below) so that code documentation
655
can be generated automatically. All nontrivial functions should have a comment
656
above them explaining what the function does, even if it is just one sentence.
657
All structures and their member variables should be documented, too.
658
@example
659
/**
660
 * @@file mpeg.c
661
 * MPEG codec.
662
 * @@author ...
663
 */
664

    
665
/**
666
 * Summary sentence.
667
 * more text ...
668
 * ...
669
 */
670
typedef struct Foobar@{
671
    int var1; /**< var1 description */
672
    int var2; ///< var2 description
673
    /** var3 description */
674
    int var3;
675
@} Foobar;
676

    
677
/**
678
 * Summary sentence.
679
 * more text ...
680
 * ...
681
 * @@param my_parameter description of my_parameter
682
 * @@return return value description
683
 */
684
int myfunc(int my_parameter)
685
...
686
@end example
687

    
688
fprintf and printf are forbidden in libavformat and libavcodec,
689
please use av_log() instead.
690

    
691
Casts should be used only when necessary. Unneeded parentheses
692
should also be avoided if they don't make the code easier to understand.
693

    
694
@section Development Policy
695

    
696
@enumerate
697
@item
698
   Contributions should be licensed under the LGPL 2.1, including an
699
   "or any later version" clause, or the MIT license.  GPL 2 including
700
   an "or any later version" clause is also acceptable, but LGPL is
701
   preferred.
702
@item
703
   You must not commit code which breaks FFmpeg! (Meaning unfinished but
704
   enabled code which breaks compilation or compiles but does not work or
705
   breaks the regression tests)
706
   You can commit unfinished stuff (for testing etc), but it must be disabled
707
   (#ifdef etc) by default so it does not interfere with other developers'
708
   work.
709
@item
710
   You do not have to over-test things. If it works for you, and you think it
711
   should work for others, then commit. If your code has problems
712
   (portability, triggers compiler bugs, unusual environment etc) they will be
713
   reported and eventually fixed.
714
@item
715
   Do not commit unrelated changes together, split them into self-contained
716
   pieces. Also do not forget that if part B depends on part A, but A does not
717
   depend on B, then A can and should be committed first and separate from B.
718
   Keeping changes well split into self-contained parts makes reviewing and
719
   understanding them on the commit log mailing list easier. This also helps
720
   in case of debugging later on.
721
   Also if you have doubts about splitting or not splitting, do not hesitate to
722
   ask/discuss it on the developer mailing list.
723
@item
724
   Do not change behavior of the program (renaming options etc) without
725
   first discussing it on the ffmpeg-devel mailing list. Do not remove
726
   functionality from the code. Just improve!
727

    
728
   Note: Redundant code can be removed.
729
@item
730
   Do not commit changes to the build system (Makefiles, configure script)
731
   which change behavior, defaults etc, without asking first. The same
732
   applies to compiler warning fixes, trivial looking fixes and to code
733
   maintained by other developers. We usually have a reason for doing things
734
   the way we do. Send your changes as patches to the ffmpeg-devel mailing
735
   list, and if the code maintainers say OK, you may commit. This does not
736
   apply to files you wrote and/or maintain.
737
@item
738
   We refuse source indentation and other cosmetic changes if they are mixed
739
   with functional changes, such commits will be rejected and removed. Every
740
   developer has his own indentation style, you should not change it. Of course
741
   if you (re)write something, you can use your own style, even though we would
742
   prefer if the indentation throughout FFmpeg was consistent (Many projects
743
   force a given indentation style - we do not.). If you really need to make
744
   indentation changes (try to avoid this), separate them strictly from real
745
   changes.
746

    
747
   NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
748
   then either do NOT change the indentation of the inner part within (do not
749
   move it to the right)! or do so in a separate commit
750
@item
751
   Always fill out the commit log message. Describe in a few lines what you
752
   changed and why. You can refer to mailing list postings if you fix a
753
   particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
754
@item
755
   If you apply a patch by someone else, include the name and email address in
756
   the log message. Since the ffmpeg-cvslog mailing list is publicly
757
   archived you should add some SPAM protection to the email address. Send an
758
   answer to ffmpeg-devel (or wherever you got the patch from) saying that
759
   you applied the patch.
760
@item
761
   When applying patches that have been discussed (at length) on the mailing
762
   list, reference the thread in the log message.
763
@item
764
    Do NOT commit to code actively maintained by others without permission.
765
    Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
766
    timeframe (12h for build failures and security fixes, 3 days small changes,
767
    1 week for big patches) then commit your patch if you think it is OK.
768
    Also note, the maintainer can simply ask for more time to review!
769
@item
770
    Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
771
    are sent there and reviewed by all the other developers. Bugs and possible
772
    improvements or general questions regarding commits are discussed there. We
773
    expect you to react if problems with your code are uncovered.
774
@item
775
    Update the documentation if you change behavior or add features. If you are
776
    unsure how best to do this, send a patch to ffmpeg-devel, the documentation
777
    maintainer(s) will review and commit your stuff.
778
@item
779
    Try to keep important discussions and requests (also) on the public
780
    developer mailing list, so that all developers can benefit from them.
781
@item
782
    Never write to unallocated memory, never write over the end of arrays,
783
    always check values read from some untrusted source before using them
784
    as array index or other risky things.
785
@item
786
    Remember to check if you need to bump versions for the specific libav
787
    parts (libavutil, libavcodec, libavformat) you are changing. You need
788
    to change the version integer and the version string.
789
    Incrementing the first component means no backward compatibility to
790
    previous versions (e.g. removal of a function from the public API).
791
    Incrementing the second component means backward compatible change
792
    (e.g. addition of a function to the public API).
793
    Incrementing the third component means a noteworthy binary compatible
794
    change (e.g. encoder bug fix that matters for the decoder).
795
@item
796
    If you add a new codec, remember to update the changelog, add it to
797
    the supported codecs table in the documentation and bump the second
798
    component of the @file{libavcodec} version number appropriately. If
799
    it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
800
    is only a decoder.
801
@item
802
    Do not change code to hide warnings without ensuring that the underlying
803
    logic is correct and thus the warning was inappropriate.
804
@item
805
    If you add a new file, give it a proper license header. Do not copy and
806
    paste it from a random place, use an existing file as template.
807
@end enumerate
808

    
809
We think our rules are not too hard. If you have comments, contact us.
810

    
811
Note, these rules are mostly borrowed from the MPlayer project.
812

    
813
@section Submitting patches
814

    
815
First, (@pxref{Coding Rules}) above if you did not yet.
816

    
817
When you submit your patch, try to send a unified diff (diff '-up'
818
option). We cannot read other diffs :-)
819

    
820
Also please do not submit a patch which contains several unrelated changes.
821
Split it into separate, self-contained pieces. This does not mean splitting
822
file by file. Instead, make the patch as small as possible while still
823
keeping it as a logical unit that contains an individual change, even
824
if it spans multiple files. This makes reviewing your patches much easier
825
for us and greatly increases your chances of getting your patch applied.
826

    
827
Run the regression tests before submitting a patch so that you can
828
verify that there are no big problems.
829

    
830
Patches should be posted as base64 encoded attachments (or any other
831
encoding which ensures that the patch will not be trashed during
832
transmission) to the ffmpeg-devel mailing list, see
833
@url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
834

    
835
It also helps quite a bit if you tell us what the patch does (for example
836
'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
837
and has no lrint()')
838

    
839
Also please if you send several patches, send each patch as a separate mail,
840
do not attach several unrelated patches to the same mail.
841

    
842
@section patch submission checklist
843

    
844
@enumerate
845
@item
846
    Do the regression tests pass with the patch applied?
847
@item
848
    Is the patch a unified diff?
849
@item
850
    Is the patch against latest FFmpeg SVN?
851
@item
852
    Are you subscribed to ffmpeg-dev?
853
    (the list is subscribers only due to spam)
854
@item
855
    Have you checked that the changes are minimal, so that the same cannot be
856
    achieved with a smaller patch and/or simpler final code?
857
@item
858
    If the change is to speed critical code, did you benchmark it?
859
@item
860
    If you did any benchmarks, did you provide them in the mail?
861
@item
862
    Have you checked that the patch does not introduce buffer overflows or
863
    other security issues?
864
@item
865
    Is the patch created from the root of the source tree, so it can be
866
    applied with @code{patch -p0}?
867
@item
868
    Does the patch not mix functional and cosmetic changes?
869
@item
870
    Did you add tabs or trailing whitespace to the code? Both are forbidden.
871
@item
872
    Is the patch attached to the email you send?
873
@item
874
    Is the mime type of the patch correct? It should be text/x-diff or
875
    text/x-patch or at least text/plain and not application/octet-stream.
876
@item
877
    If the patch fixes a bug, did you provide a verbose analysis of the bug?
878
@item
879
    If the patch fixes a bug, did you provide enough information, including
880
    a sample, so the bug can be reproduced and the fix can be verified?
881
    Note please do not attach samples >100k to mails but rather provide a
882
    URL, you can upload to ftp://upload.mplayerhq.hu
883
@item
884
    Did you provide a verbose summary about what the patch does change?
885
@item
886
    Did you provide a verbose explanation why it changes things like it does?
887
@item
888
    Did you provide a verbose summary of the user visible advantages and
889
    disadvantages if the patch is applied?
890
@item
891
    Did you provide an example so we can verify the new feature added by the
892
    patch easily?
893
@item
894
    If you added a new file, did you insert a license header? It should be
895
    taken from FFmpeg, not randomly copied and pasted from somewhere else.
896
@item
897
    You should maintain alphabetical order in alphabetically ordered lists as
898
    long as doing so does not break API/ABI compatibility.
899
@item
900
    Lines with similar content should be aligned vertically when doing so
901
    improves readability.
902
@item
903
    Did you provide a suggestion for a clear commit log message?
904
@end enumerate
905

    
906
@section Patch review process
907

    
908
All patches posted to ffmpeg-devel will be reviewed, unless they contain a
909
clear note that the patch is not for SVN.
910
Reviews and comments will be posted as replies to the patch on the
911
mailing list. The patch submitter then has to take care of every comment,
912
that can be by resubmitting a changed patch or by discussion. Resubmitted
913
patches will themselves be reviewed like any other patch. If at some point
914
a patch passes review with no comments then it is approved, that can for
915
simple and small patches happen immediately while large patches will generally
916
have to be changed and reviewed many times before they are approved.
917
After a patch is approved it will be committed to the repository.
918

    
919
We will review all submitted patches, but sometimes we are quite busy so
920
especially for large patches this can take several weeks.
921

    
922
When resubmitting patches, please do not make any significant changes
923
not related to the comments received during review. Such patches will
924
be rejected. Instead, submit  significant changes or new features as
925
separate patches.
926

    
927
@section Regression tests
928

    
929
Before submitting a patch (or committing to the repository), you should at least
930
test that you did not break anything.
931

    
932
The regression tests build a synthetic video stream and a synthetic
933
audio stream. These are then encoded and decoded with all codecs or
934
formats. The CRC (or MD5) of each generated file is recorded in a
935
result file. A 'diff' is launched to compare the reference results and
936
the result file.
937

    
938
The regression tests then go on to test the FFserver code with a
939
limited set of streams. It is important that this step runs correctly
940
as well.
941

    
942
Run 'make test' to test all the codecs and formats.
943

    
944
Run 'make fulltest' to test all the codecs, formats and FFserver.
945

    
946
[Of course, some patches may change the results of the regression tests. In
947
this case, the reference results of the regression tests shall be modified
948
accordingly].
949

    
950
@bye