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[libav.git] / doc / general.texi
1\input texinfo @c -*- texinfo -*-
3@settitle General Documentation
5@sp 7
6@center @titlefont{General Documentation}
7@sp 3
8@end titlepage
11@chapter external libraries
13FFmpeg can be hooked up with a number of external libraries to add support
14for more formats. None of them are used by default, their use has to be
15explicitly requested by passing the appropriate flags to @file{./configure}.
17@section AMR
19AMR comes in two different flavors, WB and NB. FFmpeg can make use of the
20AMR WB (floating-point mode) and the AMR NB (floating-point mode) reference
21decoders and encoders.
23Go to @url{} and follow the instructions for
24installing the libraries. Then pass @code{--enable-libamr-nb} and/or
25@code{--enable-libamr-wb} to configure to enable the libraries.
28@chapter Supported File Formats and Codecs
30You can use the @code{-formats} option to have an exhaustive list.
32@section File Formats
34FFmpeg supports the following file formats through the @code{libavformat}
37@multitable @columnfractions .4 .1 .1 .4
38@item Supported File Format @tab Encoding @tab Decoding @tab Comments
39@item MPEG audio @tab X @tab X
40@item MPEG-1 systems @tab X @tab X
41@tab muxed audio and video
42@item MPEG-2 PS @tab X @tab X
43@tab also known as @code{VOB} file
44@item MPEG-2 TS @tab @tab X
45@tab also known as DVB Transport Stream
46@item ASF@tab X @tab X
47@item AVI@tab X @tab X
48@item WAV@tab X @tab X
49@item Macromedia Flash@tab X @tab X
50@tab Only embedded audio is decoded.
51@item FLV @tab X @tab X
52@tab Macromedia Flash video files
53@item Real Audio and Video @tab X @tab X
54@item Raw AC3 @tab X @tab X
55@item Raw MJPEG @tab X @tab X
56@item Raw MPEG video @tab X @tab X
57@item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
58@item Raw CRI ADX audio @tab X @tab X
59@item Raw Shorten audio @tab @tab X
60@item SUN AU format @tab X @tab X
61@item NUT @tab X @tab X @tab NUT Open Container Format
62@item QuickTime @tab X @tab X
63@item MPEG-4 @tab X @tab X
64@tab MPEG-4 is a variant of QuickTime.
65@item Raw MPEG4 video @tab X @tab X
66@item DV @tab X @tab X
67@item 4xm @tab @tab X
68@tab 4X Technologies format, used in some games.
69@item Playstation STR @tab @tab X
70@item Id RoQ @tab X @tab X
71@tab Used in Quake III, Jedi Knight 2, other computer games.
72@item Interplay MVE @tab @tab X
73@tab Format used in various Interplay computer games.
74@item WC3 Movie @tab @tab X
75@tab Multimedia format used in Origin's Wing Commander III computer game.
76@item Sega FILM/CPK @tab @tab X
77@tab Used in many Sega Saturn console games.
78@item Westwood Studios VQA/AUD @tab @tab X
79@tab Multimedia formats used in Westwood Studios games.
80@item Id Cinematic (.cin) @tab @tab X
81@tab Used in Quake II.
82@item FLIC format @tab @tab X
83@tab .fli/.flc files
84@item Sierra VMD @tab @tab X
85@tab Used in Sierra CD-ROM games.
86@item Sierra Online @tab @tab X
87@tab .sol files used in Sierra Online games.
e09f7d61 88@item Matroska @tab X @tab X
89@item Electronic Arts Multimedia @tab @tab X
90@tab Used in various EA games; files have extensions like WVE and UV2.
91@item Nullsoft Video (NSV) format @tab @tab X
92@item ADTS AAC audio @tab X @tab X
93@item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
94@item American Laser Games MM @tab @tab X
95@tab Multimedia format used in games like Mad Dog McCree
96@item AVS @tab @tab X
97@tab Multimedia format used by the Creature Shock game.
98@item Smacker @tab @tab X
99@tab Multimedia format used by many games.
100@item GXF @tab X @tab X
101@tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
102@item CIN @tab @tab X
103@tab Multimedia format used by Delphine Software games.
104@item MXF @tab @tab X
105@tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
106@item SEQ @tab @tab X
107@tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
108@item DXA @tab @tab X
109@tab This format is used in non-Windows version of Feeble Files game and
110different game cutscenes repacked for use with ScummVM.
111@item THP @tab @tab X
112@tab Used on the Nintendo GameCube.
113@item C93 @tab @tab X
114@tab Used in the game Cyberia from Interplay.
115@item Bethsoft VID @tab @tab X
116@tab Used in some games from Bethesda Softworks.
117@item CRYO APC @tab @tab X
118@tab Audio format used in some games by CRYO Interactive Entertainment.
bf4a1f17 119@item Monkey's Audio @tab @tab X
120@item SIFF @tab @tab X
121@tab Audio and video format used in some games by Beam Software
122@end multitable
124@code{X} means that encoding (resp. decoding) is supported.
126@section Image Formats
128FFmpeg can read and write images for each frame of a video sequence. The
129following image formats are supported:
131@multitable @columnfractions .4 .1 .1 .4
132@item Supported Image Format @tab Encoding @tab Decoding @tab Comments
133@item PGM, PPM @tab X @tab X
134@item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support.
135@item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
136@item JPEG @tab X @tab X @tab Progressive JPEG is not supported.
137@item .Y.U.V @tab X @tab X @tab one raw file per component
138@item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
139@item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
140@item Targa @tab @tab X @tab Targa (.TGA) image format.
141@item TIFF @tab X @tab X @tab YUV, JPEG and some extension is not supported yet.
142@item SGI @tab X @tab X @tab SGI RGB image format
143@item PTX @tab @tab X @tab V.Flash PTX format
144@end multitable
146@code{X} means that encoding (resp. decoding) is supported.
148@section Video Codecs
150@multitable @columnfractions .4 .1 .1 .4
151@item Supported Codec @tab Encoding @tab Decoding @tab Comments
152@item MPEG-1 video @tab X @tab X
153@item MPEG-2 video @tab X @tab X
154@item MPEG-4 @tab X @tab X
155@item MSMPEG4 V1 @tab X @tab X
156@item MSMPEG4 V2 @tab X @tab X
157@item MSMPEG4 V3 @tab X @tab X
158@item WMV7 @tab X @tab X
159@item WMV8 @tab X @tab X @tab not completely working
160@item WMV9 @tab @tab X @tab not completely working
161@item VC1 @tab @tab X
162@item H.261 @tab X @tab X
163@item H.263(+) @tab X @tab X @tab also known as RealVideo 1.0
164@item H.264 @tab @tab X
165@item RealVideo 1.0 @tab X @tab X
166@item RealVideo 2.0 @tab X @tab X
167@item MJPEG @tab X @tab X
168@item lossless MJPEG @tab X @tab X
169@item JPEG-LS @tab X @tab X @tab fourcc: MJLS, lossless and near-lossless is supported
170@item Apple MJPEG-B @tab @tab X
171@item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
172@item DV @tab X @tab X
173@item HuffYUV @tab X @tab X
174@item FFmpeg Video 1 @tab X @tab X @tab experimental lossless codec (fourcc: FFV1)
175@item FFmpeg Snow @tab X @tab X @tab experimental wavelet codec (fourcc: SNOW)
176@item Asus v1 @tab X @tab X @tab fourcc: ASV1
177@item Asus v2 @tab X @tab X @tab fourcc: ASV2
178@item Creative YUV @tab @tab X @tab fourcc: CYUV
179@item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
180@item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
181@item On2 VP3 @tab @tab X @tab still experimental
182@item On2 VP5 @tab @tab X @tab fourcc: VP50
183@item On2 VP6 @tab @tab X @tab fourcc: VP60,VP61,VP62
184@item Theora @tab X @tab X @tab still experimental
185@item Intel Indeo 3 @tab @tab X
186@item FLV @tab X @tab X @tab Sorenson H.263 used in Flash
187@item Flash Screen Video @tab X @tab X @tab fourcc: FSV1
188@item ATI VCR1 @tab @tab X @tab fourcc: VCR1
189@item ATI VCR2 @tab @tab X @tab fourcc: VCR2
190@item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
191@item 4X Video @tab @tab X @tab Used in certain computer games.
192@item Sony Playstation MDEC @tab @tab X
193@item Id RoQ @tab X @tab X @tab Used in Quake III, Jedi Knight 2, other computer games.
194@item Xan/WC3 @tab @tab X @tab Used in Wing Commander III .MVE files.
195@item Interplay Video @tab @tab X @tab Used in Interplay .MVE files.
196@item Apple Animation @tab X @tab X @tab fourcc: 'rle '
197@item Apple Graphics @tab @tab X @tab fourcc: 'smc '
198@item Apple Video @tab @tab X @tab fourcc: rpza
199@item Apple QuickDraw @tab @tab X @tab fourcc: qdrw
200@item Cinepak @tab @tab X
201@item Microsoft RLE @tab @tab X
202@item Microsoft Video-1 @tab @tab X
203@item Westwood VQA @tab @tab X
204@item Id Cinematic Video @tab @tab X @tab Used in Quake II.
205@item Planar RGB @tab @tab X @tab fourcc: 8BPS
206@item FLIC video @tab @tab X
207@item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
208@item Duck TrueMotion v2 @tab @tab X @tab fourcc: TM20
209@item VMD Video @tab @tab X @tab Used in Sierra VMD files.
210@item MSZH @tab @tab X @tab Part of LCL
211@item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
212@item TechSmith Camtasia @tab @tab X @tab fourcc: TSCC
213@item IBM Ultimotion @tab @tab X @tab fourcc: ULTI
214@item Miro VideoXL @tab @tab X @tab fourcc: VIXL
215@item QPEG @tab @tab X @tab fourccs: QPEG, Q1.0, Q1.1
216@item LOCO @tab @tab X @tab
217@item Winnov WNV1 @tab @tab X @tab
218@item Autodesk Animator Studio Codec @tab @tab X @tab fourcc: AASC
219@item Fraps FPS1 @tab @tab X @tab
220@item CamStudio @tab @tab X @tab fourcc: CSCD
221@item American Laser Games Video @tab @tab X @tab Used in games like Mad Dog McCree
222@item ZMBV @tab X @tab X @tab Encoder works only on PAL8
223@item AVS Video @tab @tab X @tab Video encoding used by the Creature Shock game.
224@item Smacker Video @tab @tab X @tab Video encoding used in Smacker.
225@item RTjpeg @tab @tab X @tab Video encoding used in NuppelVideo files.
226@item KMVC @tab @tab X @tab Codec used in Worms games.
227@item VMware Video @tab @tab X @tab Codec used in videos captured by VMware.
228@item Cin Video @tab @tab X @tab Codec used in Delphine Software games.
229@item Tiertex Seq Video @tab @tab X @tab Codec used in DOS CDROM FlashBack game.
230@item DXA Video @tab @tab X @tab Codec originally used in Feeble Files game.
fc4cbc16 231@item AVID DNxHD @tab X @tab X @tab aka SMPTE VC3
232@item C93 Video @tab @tab X @tab Codec used in Cyberia game.
233@item THP @tab @tab X @tab Used on the Nintendo GameCube.
234@item Bethsoft VID @tab @tab X @tab Used in some games from Bethesda Softworks.
235@item Renderware TXD @tab @tab X @tab Texture dictionaries used by the Renderware Engine.
03b8e292 236@item AMV @tab @tab X @tab Used in Chinese MP3 players.
237@end multitable
239@code{X} means that encoding (resp. decoding) is supported.
241@section Audio Codecs
243@multitable @columnfractions .4 .1 .1 .1 .7
244@item Supported Codec @tab Encoding @tab Decoding @tab Comments
245@item MPEG audio layer 2 @tab IX @tab IX
246@item MPEG audio layer 1/3 @tab IX @tab IX
247@tab MP3 encoding is supported through the external library LAME.
248@item AC3 @tab IX @tab IX
249@tab liba52 is used internally for decoding.
250@item Vorbis @tab X @tab X
251@item WMA V1/V2 @tab X @tab X
252@item AAC @tab X @tab X
253@tab Supported through the external library libfaac/libfaad.
254@item Microsoft ADPCM @tab X @tab X
255@item AMV IMA ADPCM @tab @tab X
256@tab Used in AMV files
257@item MS IMA ADPCM @tab X @tab X
258@item QT IMA ADPCM @tab @tab X
259@item 4X IMA ADPCM @tab @tab X
260@item G.726 ADPCM @tab X @tab X
261@item Duck DK3 IMA ADPCM @tab @tab X
262@tab Used in some Sega Saturn console games.
263@item Duck DK4 IMA ADPCM @tab @tab X
264@tab Used in some Sega Saturn console games.
265@item Westwood Studios IMA ADPCM @tab @tab X
266@tab Used in Westwood Studios games like Command and Conquer.
267@item SMJPEG IMA ADPCM @tab @tab X
268@tab Used in certain Loki game ports.
269@item CD-ROM XA ADPCM @tab @tab X
270@item CRI ADX ADPCM @tab X @tab X
271@tab Used in Sega Dreamcast games.
272@item Electronic Arts ADPCM @tab @tab X
273@tab Used in various EA titles.
274@item Creative ADPCM @tab @tab X
275@tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
276@item THP ADPCM @tab @tab X
277@tab Used on the Nintendo GameCube.
278@item RA144 @tab @tab X
279@tab Real 14400 bit/s codec
280@item RA288 @tab @tab X
281@tab Real 28800 bit/s codec
282@item RADnet @tab X @tab IX
283@tab Real low bitrate AC3 codec, liba52 is used for decoding.
284@item AMR-NB @tab X @tab X
285@tab Supported through an external library.
286@item AMR-WB @tab X @tab X
287@tab Supported through an external library.
288@item DV audio @tab @tab X
289@item Id RoQ DPCM @tab X @tab X
290@tab Used in Quake III, Jedi Knight 2, other computer games.
291@item Interplay MVE DPCM @tab @tab X
292@tab Used in various Interplay computer games.
293@item Xan DPCM @tab @tab X
294@tab Used in Origin's Wing Commander IV AVI files.
295@item Sierra Online DPCM @tab @tab X
296@tab Used in Sierra Online game audio files.
297@item Apple MACE 3 @tab @tab X
298@item Apple MACE 6 @tab @tab X
299@item FLAC lossless audio @tab X @tab X
300@item Shorten lossless audio @tab @tab X
301@item Apple lossless audio @tab @tab X
302@tab QuickTime fourcc 'alac'
303@item FFmpeg Sonic @tab X @tab X
304@tab experimental lossy/lossless codec
305@item Qdesign QDM2 @tab @tab X
306@tab there are still some distortions
307@item Real COOK @tab @tab X
308@tab All versions except 5.1 are supported
309@item DSP Group TrueSpeech @tab @tab X
310@item True Audio (TTA) @tab @tab X
311@item Smacker Audio @tab @tab X
312@item WavPack Audio @tab @tab X
313@item Cin Audio @tab @tab X
314@tab Codec used in Delphine Software games.
315@item Intel Music Coder @tab @tab X
316@item Musepack @tab @tab X
317@tab Only SV7 is supported
318@item DT$ Coherent Audio @tab @tab X
319@item ATRAC 3 @tab @tab X
bf4a1f17 320@item Monkey's Audio @tab @tab X @tab Only versions 3.97-3.99 are supported
636b13c5 321@item Nellymoser ASAO @tab @tab X
322@end multitable
324@code{X} means that encoding (resp. decoding) is supported.
326@code{I} means that an integer-only version is available, too (ensures high
327performance on systems without hardware floating point support).
329@chapter Platform Specific information
331@section BSD
333BSD make will not build FFmpeg, you need to install and use GNU Make
336@section Windows
338To get help and instructions for using FFmpeg under Windows, check out
339the FFmpeg Windows Help Forum at
342@subsection Native Windows compilation
344FFmpeg can be built to run natively on Windows using the MinGW tools. Install
345the current versions of MSYS and MinGW from @url{}. Also
346install the coreutils package. You can find detailed installation
347instructions in the download section and the FAQ.
c1989552 349Within the MSYS shell, configure and make with:
d0e1cd3d 350
352./configure --enable-memalign-hack
354make install
355@end example
d0e1cd3d 356
357This will install @file{ffmpeg.exe} along with many other development files
358to @file{/usr/local}. You may specify another install path using the
359@code{--prefix} option in @file{configure}.
d0e1cd3d 360
c1989552 361Notes:
d0e1cd3d 362
c1989552 363@itemize
d0e1cd3d 364
365@item Use at least bash 3.1. Older versions are known to be fail on the
366configure script.
d0e1cd3d 367
368@item In order to compile vhooks, you must have a POSIX-compliant libdl in
369your MinGW system. Get dlfcn-win32 from
d0e1cd3d 371
372@item In order to compile FFplay, you must have the MinGW development library
373of SDL. Get it from @url{}.
374Edit the @file{bin/sdl-config} script so that it points to the correct prefix
375where SDL was installed. Verify that @file{sdl-config} can be launched from
376the MSYS command line.
d0e1cd3d 377
378@item The target @code{make wininstaller} can be used to create a
379Nullsoft-based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
380must be copied to the FFmpeg directory in order to build the
383@item By using @code{./configure --enable-shared} when configuring FFmpeg,
c1989552 384you can build libavutil, libavcodec and libavformat as DLLs.
386@end itemize
c1989552 388@subsection Microsoft Visual C++ compatibility
d0e1cd3d 389
390As stated in the FAQ, FFmpeg will not compile under MSVC++. However, if you
391want to use the libav* libraries in your own applications, you can still
392compile those applications using MSVC++. But the libav* libraries you link
393to @emph{must} be built with MinGW. However, you will not be able to debug
394inside the libav* libraries, since MSVC++ does not recognize the debug
395symbols generated by GCC.
396We strongly recommend you to move over from MSVC++ to MinGW tools.
d0e1cd3d 397
398This description of how to use the FFmpeg libraries with MSVC++ is based on
399Microsoft Visual C++ 2005 Express Edition. If you have a different version,
400you might have to modify the procedures slightly.
d0e1cd3d 401
c1989552 402@subsubsection Using static libraries
d0e1cd3d 403
c1989552 404Assuming you have just built and installed FFmpeg in @file{/usr/local}.
408@item Create a new console application ("File / New / Project") and then
409select "Win32 Console Application". On the appropriate page of the
410Application Wizard, uncheck the "Precompiled headers" option.
412@item Write the source code for your application, or, for testing, just
413copy the code from an existing sample application into the source file
414that MSVC++ has already created for you. For example, you can copy
415@file{output_example.c} from the FFmpeg distribution.
417@item Open the "Project / Properties" dialog box. In the "Configuration"
418combo box, select "All Configurations" so that the changes you make will
419affect both debug and release builds. In the tree view on the left hand
420side, select "C/C++ / General", then edit the "Additional Include
421Directories" setting to contain the path where the FFmpeg includes were
422installed (i.e. @file{c:\msys\1.0\local\include}).
424@item Still in the "Project / Properties" dialog box, select
425"Linker / General" from the tree view and edit the
426"Additional Library Directories" setting to contain the @file{lib}
427directory where FFmpeg was installed (i.e. @file{c:\msys\1.0\local\lib}),
428the directory where MinGW libs are installed (i.e. @file{c:\mingw\lib}),
429and the directory where MinGW's GCC libs are installed
430(i.e. @file{C:\mingw\lib\gcc\mingw32\4.2.1-sjlj}). Then select
431"Linker / Input" from the tree view, and add the files @file{libavformat.a},
432@file{libavcodec.a}, @file{libavutil.a}, @file{libmingwex.a},
433@file{libgcc.a}, and any other libraries you used (i.e. @file{libz.a})
434to the end of "Additional Dependencies".
436@item Now, select "C/C++ / Code Generation" from the tree view. Select
437"Debug" in the "Configuration" combo box. Make sure that "Runtime
438Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
439the "Configuration" combo box and make sure that "Runtime Library" is
440set to "Multi-threaded DLL".
442@item Click "OK" to close the "Project / Properties" dialog box.
444@item MSVC++ lacks some C99 header files that are fundamental for FFmpeg.
445Get msinttypes from @url{}
446and install it in MSVC++'s include directory
447(i.e. @file{C:\Program Files\Microsoft Visual Studio 8\VC\include}).
449@item MSVC++ also does not understand the @code{inline} keyword used by
450FFmpeg, so you must add this line before @code{#include}ing libav*:
452#define inline _inline
453@end example
455@item If you used @file{output_example.c} as your sample application,
456you will have to edit the @code{#include}s to point to the files which
457are under the @file{ffmpeg} directory (i.e. @code{<ffmpeg/avformat.h>}).
459@item Build your application, everything should work.
461@end enumerate
463@subsubsection Using shared libraries
465This is how to create DLL and LIB files that are compatible with MSVC++:
469@item Add a call to @file{vcvars32.bat} (which sets up the environment
470variables for the Visual C++ tools) as the first line of @file{msys.bat}.
471The standard location for @file{vcvars32.bat} is
472@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
473and the standard location for @file{msys.bat} is @file{C:\msys\1.0\msys.bat}.
474If this corresponds to your setup, add the following line as the first line
475of @file{msys.bat}:
478call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"
479@end example
481Alternatively, you may start the @file{Visual Studio 2005 Command Prompt},
482and run @file{c:\msys\1.0\msys.bat} from there.
484@item Within the MSYS shell, run @code{lib.exe}. If you get a help message
485from @file{Microsoft (R) Library Manager}, this means your environment
486variables are set up correctly, the @file{Microsoft (R) Library Manager}
487is on the path and will be used by FFmpeg to create
488MSVC++-compatible import libraries.
490@item Build FFmpeg with
493./configure --enable-shared --enable-memalign-hack
495make install
496@end example
498Your install path (@file{/usr/local/} by default) should now have the
499necessary DLL and LIB files under the @file{bin} directory.
501@end enumerate
503To use those files with MSVC++, do the same as you would do with
504the static libraries, as described above. But in Step 4,
505you should only need to add the directory where the LIB files are installed
506(i.e. @file{c:\msys\usr\local\bin}). This is not a typo, the LIB files are
507installed in the @file{bin} directory. And instead of adding @file{libxx.a}
508files, you should add @file{avcodec.lib}, @file{avformat.lib}, and
509@file{avutil.lib}. There should be no need for @file{libmingwex.a},
510@file{libgcc.a}, and @file{wsock32.lib}, nor any other external library
511statically linked into the DLLs. The @file{bin} directory contains a bunch
512of DLL files, but the ones that are actually used to run your application
513are the ones with a major version number in their filenames
514(i.e. @file{avcodec-51.dll}).
516@subsection Cross compilation for Windows with Linux
518You must use the MinGW cross compilation tools available at
521Then configure FFmpeg with the following options:
523./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
524@end example
525(you can change the cross-prefix according to the prefix chosen for the
526MinGW tools).
528Then you can easily test FFmpeg with Wine
531@subsection Compilation under Cygwin
533Cygwin works very much like Unix.
535Just install your Cygwin with all the "Base" packages, plus the
536following "Devel" ones:
538binutils, gcc-core, make, subversion
539@end example
541Do not install binutils-20060709-1 (they are buggy on shared builds);
542use binutils-20050610-1 instead.
544Then run
547./configure --enable-static --disable-shared
548@end example
550to make a static build or
553./configure --enable-shared --disable-static
554@end example
556to build shared libraries.
558If you want to build FFmpeg with additional libraries, download Cygwin
559"Devel" packages for Ogg and Vorbis from any Cygwin packages repository
560and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
563@subsection Crosscompilation for Windows under Cygwin
565With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
567Just install your Cygwin as explained before, plus these additional
568"Devel" packages:
570gcc-mingw-core, mingw-runtime, mingw-zlib
571@end example
573and add some special flags to your configure invocation.
575For a static build run
577./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
578@end example
580and for a build with shared libraries
582./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
583@end example
585@section BeOS
5f757b85 587BeOS support is broken in mysterious ways.
589@chapter Developers Guide
591@section API
592@itemize @bullet
593@item libavcodec is the library containing the codecs (both encoding and
594decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
596@item libavformat is the library containing the file format handling (mux and
597demux code for several formats). Look at @file{ffplay.c} to use it in a
598player. See @file{output_example.c} to use it to generate audio or video
601@end itemize
603@section Integrating libavcodec or libavformat in your program
605You can integrate all the source code of the libraries to link them
606statically to avoid any version problem. All you need is to provide a
607'config.mak' and a 'config.h' in the parent directory. See the defines
608generated by ./configure to understand what is needed.
610You can use libavcodec or libavformat in your commercial program, but
611@emph{any patch you make must be published}. The best way to proceed is
612to send your patches to the FFmpeg mailing list.
614@node Coding Rules
615@section Coding Rules
617FFmpeg is programmed in the ISO C90 language with a few additional
618features from ISO C99, namely:
619@itemize @bullet
621the @samp{inline} keyword;
623@samp{//} comments;
625designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
627compound literals (@samp{x = (struct s) @{ 17, 23 @};})
628@end itemize
630These features are supported by all compilers we care about, so we will not
631accept patches to remove their use unless they absolutely do not impair
632clarity and performance.
634All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
635compiles with several other compilers, such as the Compaq ccc compiler
636or Sun Studio 9, and we would like to keep it that way unless it would
637be exceedingly involved. To ensure compatibility, please do not use any
638additional C99 features or GCC extensions. Especially watch out for:
639@itemize @bullet
641mixing statements and declarations;
643@samp{long long} (use @samp{int64_t} instead);
645@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
647GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
648@end itemize
650Indent size is 4.
651The presentation is the one specified by 'indent -i4 -kr -nut'.
652The TAB character is forbidden outside of Makefiles as is any
653form of trailing whitespace. Commits containing either will be
654rejected by the Subversion repository.
656The main priority in FFmpeg is simplicity and small code size in order to
657minimize the bug count.
659Comments: Use the JavaDoc/Doxygen
660format (see examples below) so that code documentation
661can be generated automatically. All nontrivial functions should have a comment
662above them explaining what the function does, even if it is just one sentence.
663All structures and their member variables should be documented, too.
666 * @@file mpeg.c
667 * MPEG codec.
668 * @@author ...
669 */
672 * Summary sentence.
673 * more text ...
674 * ...
675 */
676typedef struct Foobar@{
677 int var1; /**< var1 description */
678 int var2; ///< var2 description
679 /** var3 description */
680 int var3;
681@} Foobar;
684 * Summary sentence.
685 * more text ...
686 * ...
687 * @@param my_parameter description of my_parameter
688 * @@return return value description
689 */
690int myfunc(int my_parameter)
692@end example
694fprintf and printf are forbidden in libavformat and libavcodec,
695please use av_log() instead.
697Casts should be used only when necessary. Unneeded parentheses
698should also be avoided if they don't make the code easier to understand.
700@section Development Policy
704 Contributions should be licensed under the LGPL 2.1, including an
705 "or any later version" clause, or the MIT license. GPL 2 including
706 an "or any later version" clause is also acceptable, but LGPL is
707 preferred.
709 You must not commit code which breaks FFmpeg! (Meaning unfinished but
710 enabled code which breaks compilation or compiles but does not work or
711 breaks the regression tests)
712 You can commit unfinished stuff (for testing etc), but it must be disabled
713 (#ifdef etc) by default so it does not interfere with other developers'
714 work.
716 You do not have to over-test things. If it works for you, and you think it
717 should work for others, then commit. If your code has problems
718 (portability, triggers compiler bugs, unusual environment etc) they will be
719 reported and eventually fixed.
721 Do not commit unrelated changes together, split them into self-contained
722 pieces. Also do not forget that if part B depends on part A, but A does not
723 depend on B, then A can and should be committed first and separate from B.
724 Keeping changes well split into self-contained parts makes reviewing and
725 understanding them on the commit log mailing list easier. This also helps
726 in case of debugging later on.
727 Also if you have doubts about splitting or not splitting, do not hesitate to
728 ask/discuss it on the developer mailing list.
730 Do not change behavior of the program (renaming options etc) without
731 first discussing it on the ffmpeg-devel mailing list. Do not remove
732 functionality from the code. Just improve!
734 Note: Redundant code can be removed.
736 Do not commit changes to the build system (Makefiles, configure script)
737 which change behavior, defaults etc, without asking first. The same
738 applies to compiler warning fixes, trivial looking fixes and to code
739 maintained by other developers. We usually have a reason for doing things
740 the way we do. Send your changes as patches to the ffmpeg-devel mailing
741 list, and if the code maintainers say OK, you may commit. This does not
742 apply to files you wrote and/or maintain.
744 We refuse source indentation and other cosmetic changes if they are mixed
745 with functional changes, such commits will be rejected and removed. Every
746 developer has his own indentation style, you should not change it. Of course
747 if you (re)write something, you can use your own style, even though we would
748 prefer if the indentation throughout FFmpeg was consistent (Many projects
749 force a given indentation style - we do not.). If you really need to make
750 indentation changes (try to avoid this), separate them strictly from real
751 changes.
753 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
754 then either do NOT change the indentation of the inner part within (do not
755 move it to the right)! or do so in a separate commit
757 Always fill out the commit log message. Describe in a few lines what you
758 changed and why. You can refer to mailing list postings if you fix a
759 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
761 If you apply a patch by someone else, include the name and email address in
762 the log message. Since the ffmpeg-cvslog mailing list is publicly
763 archived you should add some SPAM protection to the email address. Send an
764 answer to ffmpeg-devel (or wherever you got the patch from) saying that
765 you applied the patch.
767 When applying patches that have been discussed (at length) on the mailing
768 list, reference the thread in the log message.
770 Do NOT commit to code actively maintained by others without permission.
771 Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
772 timeframe (12h for build failures and security fixes, 3 days small changes,
773 1 week for big patches) then commit your patch if you think it is OK.
774 Also note, the maintainer can simply ask for more time to review!
776 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
777 are sent there and reviewed by all the other developers. Bugs and possible
778 improvements or general questions regarding commits are discussed there. We
779 expect you to react if problems with your code are uncovered.
781 Update the documentation if you change behavior or add features. If you are
782 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
783 maintainer(s) will review and commit your stuff.
785 Try to keep important discussions and requests (also) on the public
786 developer mailing list, so that all developers can benefit from them.
788 Never write to unallocated memory, never write over the end of arrays,
789 always check values read from some untrusted source before using them
790 as array index or other risky things.
792 Remember to check if you need to bump versions for the specific libav
793 parts (libavutil, libavcodec, libavformat) you are changing. You need
794 to change the version integer and the version string.
795 Incrementing the first component means no backward compatibility to
796 previous versions (e.g. removal of a function from the public API).
797 Incrementing the second component means backward compatible change
798 (e.g. addition of a function to the public API).
799 Incrementing the third component means a noteworthy binary compatible
800 change (e.g. encoder bug fix that matters for the decoder).
802 If you add a new codec, remember to update the changelog, add it to
803 the supported codecs table in the documentation and bump the second
804 component of the @file{libavcodec} version number appropriately. If
805 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
806 is only a decoder.
808 Do not change code to hide warnings without ensuring that the underlying
809 logic is correct and thus the warning was inappropriate.
811 If you add a new file, give it a proper license header. Do not copy and
812 paste it from a random place, use an existing file as template.
813@end enumerate
815We think our rules are not too hard. If you have comments, contact us.
817Note, these rules are mostly borrowed from the MPlayer project.
819@section Submitting patches
821First, (@pxref{Coding Rules}) above if you did not yet.
823When you submit your patch, try to send a unified diff (diff '-up'
824option). We cannot read other diffs :-)
826Also please do not submit a patch which contains several unrelated changes.
827Split it into separate, self-contained pieces. This does not mean splitting
828file by file. Instead, make the patch as small as possible while still
829keeping it as a logical unit that contains an individual change, even
830if it spans multiple files. This makes reviewing your patches much easier
831for us and greatly increases your chances of getting your patch applied.
833Run the regression tests before submitting a patch so that you can
834verify that there are no big problems.
836Patches should be posted as base64 encoded attachments (or any other
837encoding which ensures that the patch will not be trashed during
838transmission) to the ffmpeg-devel mailing list, see
841It also helps quite a bit if you tell us what the patch does (for example
842'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
843and has no lrint()')
845Also please if you send several patches, send each patch as a separate mail,
846do not attach several unrelated patches to the same mail.
848@section patch submission checklist
852 Do the regression tests pass with the patch applied?
854 Is the patch a unified diff?
856 Is the patch against latest FFmpeg SVN?
858 Are you subscribed to ffmpeg-dev?
859 (the list is subscribers only due to spam)
861 Have you checked that the changes are minimal, so that the same cannot be
862 achieved with a smaller patch and/or simpler final code?
864 If the change is to speed critical code, did you benchmark it?
866 If you did any benchmarks, did you provide them in the mail?
868 Have you checked that the patch does not introduce buffer overflows or
869 other security issues?
871 Is the patch created from the root of the source tree, so it can be
872 applied with @code{patch -p0}?
874 Does the patch not mix functional and cosmetic changes?
876 Did you add tabs or trailing whitespace to the code? Both are forbidden.
878 Is the patch attached to the email you send?
880 Is the mime type of the patch correct? It should be text/x-diff or
881 text/x-patch or at least text/plain and not application/octet-stream.
883 If the patch fixes a bug, did you provide a verbose analysis of the bug?
885 If the patch fixes a bug, did you provide enough information, including
886 a sample, so the bug can be reproduced and the fix can be verified?
887 Note please do not attach samples >100k to mails but rather provide a
888 URL, you can upload to
890 Did you provide a verbose summary about what the patch does change?
892 Did you provide a verbose explanation why it changes things like it does?
894 Did you provide a verbose summary of the user visible advantages and
895 disadvantages if the patch is applied?
897 Did you provide an example so we can verify the new feature added by the
898 patch easily?
900 If you added a new file, did you insert a license header? It should be
901 taken from FFmpeg, not randomly copied and pasted from somewhere else.
903 You should maintain alphabetical order in alphabetically ordered lists as
904 long as doing so does not break API/ABI compatibility.
906 Lines with similar content should be aligned vertically when doing so
907 improves readability.
909 Did you provide a suggestion for a clear commit log message?
910@end enumerate
912@section Patch review process
914All patches posted to ffmpeg-devel will be reviewed, unless they contain a
915clear note that the patch is not for SVN.
916Reviews and comments will be posted as replies to the patch on the
917mailing list. The patch submitter then has to take care of every comment,
918that can be by resubmitting a changed patch or by discussion. Resubmitted
919patches will themselves be reviewed like any other patch. If at some point
920a patch passes review with no comments then it is approved, that can for
921simple and small patches happen immediately while large patches will generally
922have to be changed and reviewed many times before they are approved.
923After a patch is approved it will be committed to the repository.
925We will review all submitted patches, but sometimes we are quite busy so
926especially for large patches this can take several weeks.
928When resubmitting patches, please do not make any significant changes
929not related to the comments received during review. Such patches will
930be rejected. Instead, submit significant changes or new features as
931separate patches.
933@section Regression tests
935Before submitting a patch (or committing to the repository), you should at least
936test that you did not break anything.
938The regression tests build a synthetic video stream and a synthetic
939audio stream. These are then encoded and decoded with all codecs or
940formats. The CRC (or MD5) of each generated file is recorded in a
941result file. A 'diff' is launched to compare the reference results and
942the result file.
944The regression tests then go on to test the FFserver code with a
945limited set of streams. It is important that this step runs correctly
946as well.
948Run 'make test' to test all the codecs and formats.
950Run 'make fulltest' to test all the codecs, formats and FFserver.
952[Of course, some patches may change the results of the regression tests. In
953this case, the reference results of the regression tests shall be modified