ffmpeg-doc.texi

arm平台下的H264编码和解码源代码

@item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support
@item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
@item JPEG         @tab X @tab X @tab Progressive JPEG is not supported
@item .Y.U.V       @tab X @tab X @tab One raw file per component
@item Animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated
@item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet
@item SGI          @tab X @tab X @tab SGI RGB image format
@end multitable

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

@section Video Codecs

@multitable @columnfractions .4 .1 .1 .7
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
@item MPEG1 video            @tab  X  @tab  X
@item MPEG2 video            @tab  X  @tab  X 
@item MPEG4                  @tab  X  @tab  X @tab Also known as DIVX4/5
@item MSMPEG4 V1             @tab  X  @tab  X
@item MSMPEG4 V2             @tab  X  @tab  X
@item MSMPEG4 V3             @tab  X  @tab  X @tab Also known as DIVX3
@item WMV7                   @tab  X  @tab  X
@item WMV8                   @tab  X  @tab  X @tab Not completely working
@item H263(+)                @tab  X  @tab  X @tab Also known as Real Video 1.0
@item MJPEG                  @tab  X  @tab  X 
@item Lossless MJPEG         @tab  X  @tab  X
@item Apple MJPEG-B          @tab     @tab  X
@item Sunplus MJPEG          @tab     @tab  X @tab fourcc: SP5X
@item DV                     @tab  X  @tab  X 
@item Huff YUV               @tab  X  @tab  X
@item FFmpeg Video 1         @tab  X  @tab  X @tab Lossless codec (fourcc: FFV1)
@item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1
@item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2
@item Creative YUV           @tab     @tab  X @tab fourcc: CYUV
@item H.264                  @tab     @tab  X
@item Sorenson Video 1       @tab     @tab  X @tab fourcc: SVQ1
@item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3
@item On2 VP3                @tab     @tab  X @tab still experimental
@item Theora                 @tab     @tab  X @tab still experimental
@item Intel Indeo 3          @tab     @tab  X @tab only works on i386 right now
@item FLV                    @tab  X  @tab  X @tab Flash H263 variant
@item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1
@item ATI VCR2               @tab     @tab  X @tab fourcc: VCR2
@item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR
@item 4X Video               @tab     @tab  X @tab used in certain computer games
@item Sony Playstation MDEC  @tab     @tab  X 
@item Id RoQ                 @tab     @tab  X @tab used in Quake III, Jedi Knight 2, other computer games
@item Xan/WC3                @tab     @tab  X @tab used in Wing Commander III .MVE files
@item Interplay Video        @tab     @tab  X @tab used in Interplay .MVE files
@item Apple Animation        @tab     @tab  X @tab fourcc: 'rle '
@item Apple Graphics         @tab     @tab  X @tab fourcc: 'smc '
@item Apple Video            @tab     @tab  X @tab fourcc: rpza
@item Cinepak                @tab     @tab  X
@item Microsoft RLE          @tab     @tab  X
@item Microsoft Video-1      @tab     @tab  X
@item Westwood VQA           @tab     @tab  X
@item Id Cinematic Video     @tab     @tab  X @tab used in Quake II
@item Planar RGB             @tab     @tab  X @tab fourcc: 8BPS
@item FLIC video             @tab     @tab  X
@item Duck TrueMotion v1     @tab     @tab  X @tab fourcc: DUCK
@item VMD Video              @tab     @tab  X @tab used in Sierra VMD files
@item MSZH                   @tab     @tab  X @tab Part of LCL
@item ZLIB                   @tab  X  @tab  X @tab Part of LCL, encoder experimental
@end multitable

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

Check at @url{http://www.mplayerhq.hu/~michael/codec-features.html} to
get a precise comparison of FFmpeg MPEG4 codec compared to the other
solutions.

@section Audio Codecs

@multitable @columnfractions .4 .1 .1 .1 .7
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
@item MPEG audio layer 2     @tab  IX  @tab  IX 
@item MPEG audio layer 1/3   @tab IX   @tab  IX
@tab MP3 encoding is supported through the external library LAME
@item AC3                    @tab  IX  @tab  X
@tab liba52 is used internally for decoding
@item Vorbis                 @tab  X   @tab  X
@tab supported through the external library libvorbis
@item WMA V1/V2              @tab      @tab X
@item Microsoft ADPCM        @tab X    @tab X
@item MS IMA ADPCM           @tab X    @tab X
@item QT IMA ADPCM           @tab      @tab X
@item 4X IMA ADPCM           @tab      @tab X
@item G.726  ADPCM           @tab X    @tab X
@item Duck DK3 IMA ADPCM     @tab      @tab X
@tab used in some Sega Saturn console games
@item Duck DK4 IMA ADPCM     @tab      @tab X
@tab used in some Sega Saturn console games
@item Westwood Studios IMA ADPCM @tab      @tab X
@tab used in Westwood Studios games like Command and Conquer
@item SMJPEG IMA ADPCM       @tab      @tab X
@tab used in certain Loki game ports
@item CD-ROM XA ADPCM        @tab      @tab X
@item CRI ADX ADPCM          @tab X    @tab X
@tab used in Sega Dreamcast games
@item Electronic Arts ADPCM  @tab      @tab X
@tab used in various EA titles
@item RA144                  @tab      @tab X
@tab Real 14400 bit/s codec
@item RA288                  @tab      @tab X
@tab Real 28800 bit/s codec
@item AMR-NB                 @tab X    @tab X
@tab supported through an external library
@item AMR-WB                 @tab X    @tab X
@tab supported through an external library
@item DV audio               @tab      @tab X
@item Id RoQ DPCM            @tab      @tab X
@tab used in Quake III, Jedi Knight 2, other computer games
@item Interplay MVE DPCM     @tab      @tab X
@tab used in various Interplay computer games
@item Xan DPCM               @tab      @tab X
@tab used in Origin's Wing Commander IV AVI files
@item Apple MACE 3           @tab      @tab X
@item Apple MACE 6           @tab      @tab X
@item FLAC                   @tab      @tab X
@end multitable

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

@code{I} means that an integer only version is available too (ensures highest
performances on systems without hardware floating point support).

@chapter Platform Specific information

@section Linux

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

@section BSD

@section Windows

@subsection Native Windows compilation

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

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

@item Extract the current version of FFmpeg (the latest release version or the current CVS snapshot whichever is recommended).
 
@item Start the MSYS shell (file @file{msys.bat}).

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

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

@end itemize

Notes: 
@itemize

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

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

@item Visual C++ compatibility: if you used @code{./configure --enable-shared} 
when configuring FFmpeg, then FFmpeg tries to use the Microsoft Visual
C++ @code{lib} tool to build @code{avcodec.lib} and
@code{avformat.lib}. With these libraries, you can link your Visual C++
code directly with the FFmpeg DLLs.

@end itemize

@subsection Cross compilation for Windows with Linux

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

Then configure ffmpeg with the following options:
@example
./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
@end example
(you can change the cross-prefix according to the prefix choosen for the
MinGW tools).

Then you can easily test ffmpeg with wine
(@url{http://www.winehq.com/}).

@section MacOS X

@section BeOS

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

Old stuff:

Fran鏾is Revol - revol at free dot fr - April 2002

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

ffserver is broken (needs poll() implementation).

There is still issues with errno codes, which are negative in BeOs, and
that ffmpeg negates when returning. This ends up turning errors into 
valid results, then crashes.
(To be fixed)

@chapter Developers Guide

@section API
@itemize
@item libavcodec is the library containing the codecs (both encoding and
  decoding). See @file{libavcodec/apiexample.c} to see how to use it.

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

@end itemize

@section Integrating libavcodec or libavformat in your program

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

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

@section Coding Rules

ffmpeg is programmed in the ISO C90 language with a few additional
features from ISO C99, namely:
@itemize @bullet
@item
the @samp{inline} keyword;
@item
@samp{//} comments;
@item
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
@item
compound literals (@samp{x = (struct s) { 17, 23 @};})
@end itemize

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

All code must compile with gcc 2.95 and gcc 3.3. Currently, ffmpeg also
compiles with several other compilers, such as the Compaq ccc compiler
or Sun Studio 9, and we would like to keep it that way unless it would
be exceedingly involved. To ensure compatibility, please don't use any
additional C99 features or gcc extensions. Watch out especially for:
@itemize @bullet
@item
mixing statements and declarations;
@item
@samp{long long} (use @samp{int64_t} instead);
@item
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
@item
gcc statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
@end itemize

Indent size is 4. The TAB character should not be used.
The presentation is the one specified by 'indent -i4 -kr'.

Main priority in ffmpeg is simplicity and small code size (=less
bugs).

Comments: for functions visible from other modules, use the JavaDoc
format (see examples in @file{libav/utils.c}) so that a documentation
can be generated automatically.

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

@section Submitting patches

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

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

Patches should be posted as base64 encoded attachments (or any other
encoding which ensures that the patch wont be trashed during 
transmission) to the ffmpeg-devel mailinglist, see 
@url{http://lists.sourceforge.net/lists/listinfo/ffmpeg-devel}

It also helps quite a bit if you tell us what the patch does (for example
'replaces lrint by lrintf') , and why (for example '*bsd isnt c99 compliant
and has no lrint()')

@section Regression tests

Before submitting a patch (or committing with CVS), you should at least
test that you did not break anything.

The regression test build a synthetic video stream and a synthetic
audio stream. Then these are encoded then decoded with all codecs or
formats. The CRC (or MD5) of each generated file is recorded in a
result file. Then a 'diff' is launched with the reference results and
the result file.

The regression test then goes on to test the ffserver code with a 
limited set of streams. It is important that this step runs correctly
as well.

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

Run 'make fulltest' to test all the codecs, formats and ffserver.

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

@bye