Add small OS/2 section with a link to further information.
[libav.git] / doc / general.texi
1 \input texinfo @c -*- texinfo -*-
3 @settitle General Documentation
4 @titlepage
5 @sp 7
6 @center @titlefont{General Documentation}
7 @sp 3
8 @end titlepage
11 @chapter external libraries
13 FFmpeg can be hooked up with a number of external libraries to add support
14 for more formats. None of them are used by default, their use has to be
15 explicitly requested by passing the appropriate flags to @file{./configure}.
17 @section AMR
19 AMR comes in two different flavors, WB and NB. FFmpeg can make use of the
20 AMR WB (floating-point mode) and the AMR NB (floating-point mode) reference
21 decoders and encoders.
23 Go to @url{} and follow the instructions for
24 installing 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
30 You can use the @code{-formats} option to have an exhaustive list.
32 @section File Formats
34 FFmpeg supports the following file formats through the @code{libavformat}
35 library:
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.
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
110 different 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.
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
128 FFmpeg can read and write images for each frame of a video sequence. The
129 following 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.
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.
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 X @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 SV7 and SV8 are supported
318 @item DT$ Coherent Audio @tab @tab X
319 @item ATRAC 3 @tab @tab X
320 @item Monkey's Audio @tab @tab X @tab Only versions 3.97-3.99 are supported
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
327 performance on systems without hardware floating point support).
329 @chapter Platform Specific information
331 @section BSD
333 BSD make will not build FFmpeg, you need to install and use GNU Make
334 (@file{gmake}).
336 @section Windows
338 To get help and instructions for building FFmpeg under Windows, check out
339 the FFmpeg Windows Help Forum at
340 @url{}.
342 @subsection Native Windows compilation
344 FFmpeg can be built to run natively on Windows using the MinGW tools. Install
345 the current versions of MSYS and MinGW from @url{}. Also
346 install the coreutils package. You can find detailed installation
347 instructions in the download section and the FAQ.
349 Within the MSYS shell, configure and make with:
351 @example
352 ./configure --enable-memalign-hack
353 make
354 make install
355 @end example
357 This will install @file{ffmpeg.exe} along with many other development files
358 to @file{/usr/local}. You may specify another install path using the
359 @code{--prefix} option in @file{configure}.
361 Notes:
363 @itemize
365 @item Use at least bash 3.1. Older versions are known to be fail on the
366 configure script.
368 @item In order to compile vhooks, you must have a POSIX-compliant libdl in
369 your MinGW system. Get dlfcn-win32 from
370 @url{}.
372 @item In order to compile FFplay, you must have the MinGW development library
373 of SDL. Get it from @url{}.
374 Edit the @file{bin/sdl-config} script so that it points to the correct prefix
375 where SDL was installed. Verify that @file{sdl-config} can be launched from
376 the MSYS command line.
378 @item The target @code{make wininstaller} can be used to create a
379 Nullsoft-based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
380 must be copied to the FFmpeg directory in order to build the
381 installer.
383 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
384 you can build libavutil, libavcodec and libavformat as DLLs.
386 @end itemize
388 @subsection Microsoft Visual C++ compatibility
390 As stated in the FAQ, FFmpeg will not compile under MSVC++. However, if you
391 want to use the libav* libraries in your own applications, you can still
392 compile those applications using MSVC++. But the libav* libraries you link
393 to @emph{must} be built with MinGW. However, you will not be able to debug
394 inside the libav* libraries, since MSVC++ does not recognize the debug
395 symbols generated by GCC.
396 We strongly recommend you to move over from MSVC++ to MinGW tools.
398 This description of how to use the FFmpeg libraries with MSVC++ is based on
399 Microsoft Visual C++ 2005 Express Edition. If you have a different version,
400 you might have to modify the procedures slightly.
402 @subsubsection Using static libraries
404 Assuming you have just built and installed FFmpeg in @file{/usr/local}.
406 @enumerate
408 @item Create a new console application ("File / New / Project") and then
409 select "Win32 Console Application". On the appropriate page of the
410 Application Wizard, uncheck the "Precompiled headers" option.
412 @item Write the source code for your application, or, for testing, just
413 copy the code from an existing sample application into the source file
414 that 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"
418 combo box, select "All Configurations" so that the changes you make will
419 affect both debug and release builds. In the tree view on the left hand
420 side, select "C/C++ / General", then edit the "Additional Include
421 Directories" setting to contain the path where the FFmpeg includes were
422 installed (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}
427 directory where FFmpeg was installed (i.e. @file{c:\msys\1.0\local\lib}),
428 the directory where MinGW libs are installed (i.e. @file{c:\mingw\lib}),
429 and 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})
434 to 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
438 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
439 the "Configuration" combo box and make sure that "Runtime Library" is
440 set 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.
445 Get msinttypes from @url{}
446 and 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
450 FFmpeg, so you must add this line before @code{#include}ing libav*:
451 @example
452 #define inline _inline
453 @end example
455 @item If you used @file{output_example.c} as your sample application,
456 you will have to edit the @code{#include}s to point to the files which
457 are 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
465 This is how to create DLL and LIB files that are compatible with MSVC++:
467 @enumerate
469 @item Add a call to @file{vcvars32.bat} (which sets up the environment
470 variables for the Visual C++ tools) as the first line of @file{msys.bat}.
471 The standard location for @file{vcvars32.bat} is
472 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
473 and the standard location for @file{msys.bat} is @file{C:\msys\1.0\msys.bat}.
474 If this corresponds to your setup, add the following line as the first line
475 of @file{msys.bat}:
477 @example
478 call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"
479 @end example
481 Alternatively, you may start the @file{Visual Studio 2005 Command Prompt},
482 and 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
485 from @file{Microsoft (R) Library Manager}, this means your environment
486 variables are set up correctly, the @file{Microsoft (R) Library Manager}
487 is on the path and will be used by FFmpeg to create
488 MSVC++-compatible import libraries.
490 @item Build FFmpeg with
492 @example
493 ./configure --enable-shared --enable-memalign-hack
494 make
495 make install
496 @end example
498 Your install path (@file{/usr/local/} by default) should now have the
499 necessary DLL and LIB files under the @file{bin} directory.
501 @end enumerate
503 To use those files with MSVC++, do the same as you would do with
504 the static libraries, as described above. But in Step 4,
505 you 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
507 installed in the @file{bin} directory. And instead of adding @file{libxx.a}
508 files, 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
511 statically linked into the DLLs. The @file{bin} directory contains a bunch
512 of DLL files, but the ones that are actually used to run your application
513 are 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
518 You must use the MinGW cross compilation tools available at
519 @url{}.
521 Then configure FFmpeg with the following options:
522 @example
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
526 MinGW tools).
528 Then you can easily test FFmpeg with Wine
529 (@url{}).
531 @subsection Compilation under Cygwin
533 The main issue with Cygwin is that newlib, its C library, does not
534 contain llrint(). However, it is possible to leverage the
535 implementation in MinGW.
537 Just install your Cygwin with all the "Base" packages, plus the
538 following "Devel" ones:
539 @example
540 binutils, gcc-core, make, subversion, mingw-runtime
541 @end example
543 Do not install binutils-20060709-1 (they are buggy on shared builds);
544 use binutils-20050610-1 instead.
546 Then create a small library that just contains llrint():
548 @example
549 ar x /usr/lib/mingw/libmingwex.a llrint.o
550 ar cq /usr/local/lib/libllrint.a llrint.o
551 @end example
553 Then run
555 @example
556 ./configure --enable-static --disable-shared --extra-ldflags='-L /usr/local/lib' --extra-libs='-l llrint'
557 @end example
559 to make a static build or
561 @example
562 ./configure --enable-shared --disable-static --extra-ldflags='-L /usr/local/lib' --extra-libs='-l llrint'
563 @end example
565 to build shared libraries.
567 If you want to build FFmpeg with additional libraries, download Cygwin
568 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
569 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
570 (@url{}).
572 @subsection Crosscompilation for Windows under Cygwin
574 With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
576 Just install your Cygwin as explained before, plus these additional
577 "Devel" packages:
578 @example
579 gcc-mingw-core, mingw-runtime, mingw-zlib
580 @end example
582 and add some special flags to your configure invocation.
584 For a static build run
585 @example
586 ./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
587 @end example
589 and for a build with shared libraries
590 @example
591 ./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
592 @end example
594 @section BeOS
596 BeOS support is broken in mysterious ways.
598 @section OS/2
600 For information about compiling FFmpeg on OS/2 see
601 @url{}.
603 @chapter Developers Guide
605 @section API
606 @itemize @bullet
607 @item libavcodec is the library containing the codecs (both encoding and
608 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
610 @item libavformat is the library containing the file format handling (mux and
611 demux code for several formats). Look at @file{ffplay.c} to use it in a
612 player. See @file{output_example.c} to use it to generate audio or video
613 streams.
615 @end itemize
617 @section Integrating libavcodec or libavformat in your program
619 You can integrate all the source code of the libraries to link them
620 statically to avoid any version problem. All you need is to provide a
621 'config.mak' and a 'config.h' in the parent directory. See the defines
622 generated by ./configure to understand what is needed.
624 You can use libavcodec or libavformat in your commercial program, but
625 @emph{any patch you make must be published}. The best way to proceed is
626 to send your patches to the FFmpeg mailing list.
628 @node Coding Rules
629 @section Coding Rules
631 FFmpeg is programmed in the ISO C90 language with a few additional
632 features from ISO C99, namely:
633 @itemize @bullet
634 @item
635 the @samp{inline} keyword;
636 @item
637 @samp{//} comments;
638 @item
639 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
640 @item
641 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
642 @end itemize
644 These features are supported by all compilers we care about, so we will not
645 accept patches to remove their use unless they absolutely do not impair
646 clarity and performance.
648 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
649 compiles with several other compilers, such as the Compaq ccc compiler
650 or Sun Studio 9, and we would like to keep it that way unless it would
651 be exceedingly involved. To ensure compatibility, please do not use any
652 additional C99 features or GCC extensions. Especially watch out for:
653 @itemize @bullet
654 @item
655 mixing statements and declarations;
656 @item
657 @samp{long long} (use @samp{int64_t} instead);
658 @item
659 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
660 @item
661 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
662 @end itemize
664 Indent size is 4.
665 The presentation is the one specified by 'indent -i4 -kr -nut'.
666 The TAB character is forbidden outside of Makefiles as is any
667 form of trailing whitespace. Commits containing either will be
668 rejected by the Subversion repository.
670 The main priority in FFmpeg is simplicity and small code size in order to
671 minimize the bug count.
673 Comments: Use the JavaDoc/Doxygen
674 format (see examples below) so that code documentation
675 can be generated automatically. All nontrivial functions should have a comment
676 above them explaining what the function does, even if it is just one sentence.
677 All structures and their member variables should be documented, too.
678 @example
679 /**
680 * @@file mpeg.c
681 * MPEG codec.
682 * @@author ...
683 */
685 /**
686 * Summary sentence.
687 * more text ...
688 * ...
689 */
690 typedef struct Foobar@{
691 int var1; /**< var1 description */
692 int var2; ///< var2 description
693 /** var3 description */
694 int var3;
695 @} Foobar;
697 /**
698 * Summary sentence.
699 * more text ...
700 * ...
701 * @@param my_parameter description of my_parameter
702 * @@return return value description
703 */
704 int myfunc(int my_parameter)
705 ...
706 @end example
708 fprintf and printf are forbidden in libavformat and libavcodec,
709 please use av_log() instead.
711 Casts should be used only when necessary. Unneeded parentheses
712 should also be avoided if they don't make the code easier to understand.
714 @section Development Policy
716 @enumerate
717 @item
718 Contributions should be licensed under the LGPL 2.1, including an
719 "or any later version" clause, or the MIT license. GPL 2 including
720 an "or any later version" clause is also acceptable, but LGPL is
721 preferred.
722 @item
723 You must not commit code which breaks FFmpeg! (Meaning unfinished but
724 enabled code which breaks compilation or compiles but does not work or
725 breaks the regression tests)
726 You can commit unfinished stuff (for testing etc), but it must be disabled
727 (#ifdef etc) by default so it does not interfere with other developers'
728 work.
729 @item
730 You do not have to over-test things. If it works for you, and you think it
731 should work for others, then commit. If your code has problems
732 (portability, triggers compiler bugs, unusual environment etc) they will be
733 reported and eventually fixed.
734 @item
735 Do not commit unrelated changes together, split them into self-contained
736 pieces. Also do not forget that if part B depends on part A, but A does not
737 depend on B, then A can and should be committed first and separate from B.
738 Keeping changes well split into self-contained parts makes reviewing and
739 understanding them on the commit log mailing list easier. This also helps
740 in case of debugging later on.
741 Also if you have doubts about splitting or not splitting, do not hesitate to
742 ask/discuss it on the developer mailing list.
743 @item
744 Do not change behavior of the program (renaming options etc) without
745 first discussing it on the ffmpeg-devel mailing list. Do not remove
746 functionality from the code. Just improve!
748 Note: Redundant code can be removed.
749 @item
750 Do not commit changes to the build system (Makefiles, configure script)
751 which change behavior, defaults etc, without asking first. The same
752 applies to compiler warning fixes, trivial looking fixes and to code
753 maintained by other developers. We usually have a reason for doing things
754 the way we do. Send your changes as patches to the ffmpeg-devel mailing
755 list, and if the code maintainers say OK, you may commit. This does not
756 apply to files you wrote and/or maintain.
757 @item
758 We refuse source indentation and other cosmetic changes if they are mixed
759 with functional changes, such commits will be rejected and removed. Every
760 developer has his own indentation style, you should not change it. Of course
761 if you (re)write something, you can use your own style, even though we would
762 prefer if the indentation throughout FFmpeg was consistent (Many projects
763 force a given indentation style - we do not.). If you really need to make
764 indentation changes (try to avoid this), separate them strictly from real
765 changes.
767 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
768 then either do NOT change the indentation of the inner part within (do not
769 move it to the right)! or do so in a separate commit
770 @item
771 Always fill out the commit log message. Describe in a few lines what you
772 changed and why. You can refer to mailing list postings if you fix a
773 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
774 @item
775 If you apply a patch by someone else, include the name and email address in
776 the log message. Since the ffmpeg-cvslog mailing list is publicly
777 archived you should add some SPAM protection to the email address. Send an
778 answer to ffmpeg-devel (or wherever you got the patch from) saying that
779 you applied the patch.
780 @item
781 When applying patches that have been discussed (at length) on the mailing
782 list, reference the thread in the log message.
783 @item
784 Do NOT commit to code actively maintained by others without permission.
785 Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
786 timeframe (12h for build failures and security fixes, 3 days small changes,
787 1 week for big patches) then commit your patch if you think it is OK.
788 Also note, the maintainer can simply ask for more time to review!
789 @item
790 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
791 are sent there and reviewed by all the other developers. Bugs and possible
792 improvements or general questions regarding commits are discussed there. We
793 expect you to react if problems with your code are uncovered.
794 @item
795 Update the documentation if you change behavior or add features. If you are
796 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
797 maintainer(s) will review and commit your stuff.
798 @item
799 Try to keep important discussions and requests (also) on the public
800 developer mailing list, so that all developers can benefit from them.
801 @item
802 Never write to unallocated memory, never write over the end of arrays,
803 always check values read from some untrusted source before using them
804 as array index or other risky things.
805 @item
806 Remember to check if you need to bump versions for the specific libav
807 parts (libavutil, libavcodec, libavformat) you are changing. You need
808 to change the version integer and the version string.
809 Incrementing the first component means no backward compatibility to
810 previous versions (e.g. removal of a function from the public API).
811 Incrementing the second component means backward compatible change
812 (e.g. addition of a function to the public API).
813 Incrementing the third component means a noteworthy binary compatible
814 change (e.g. encoder bug fix that matters for the decoder).
815 @item
816 If you add a new codec, remember to update the changelog, add it to
817 the supported codecs table in the documentation and bump the second
818 component of the @file{libavcodec} version number appropriately. If
819 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
820 is only a decoder.
821 @item
822 Do not change code to hide warnings without ensuring that the underlying
823 logic is correct and thus the warning was inappropriate.
824 @item
825 If you add a new file, give it a proper license header. Do not copy and
826 paste it from a random place, use an existing file as template.
827 @end enumerate
829 We think our rules are not too hard. If you have comments, contact us.
831 Note, these rules are mostly borrowed from the MPlayer project.
833 @section Submitting patches
835 First, (@pxref{Coding Rules}) above if you did not yet.
837 When you submit your patch, try to send a unified diff (diff '-up'
838 option). We cannot read other diffs :-)
840 Also please do not submit a patch which contains several unrelated changes.
841 Split it into separate, self-contained pieces. This does not mean splitting
842 file by file. Instead, make the patch as small as possible while still
843 keeping it as a logical unit that contains an individual change, even
844 if it spans multiple files. This makes reviewing your patches much easier
845 for us and greatly increases your chances of getting your patch applied.
847 Run the regression tests before submitting a patch so that you can
848 verify that there are no big problems.
850 Patches should be posted as base64 encoded attachments (or any other
851 encoding which ensures that the patch will not be trashed during
852 transmission) to the ffmpeg-devel mailing list, see
853 @url{}
855 It also helps quite a bit if you tell us what the patch does (for example
856 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
857 and has no lrint()')
859 Also please if you send several patches, send each patch as a separate mail,
860 do not attach several unrelated patches to the same mail.
862 @section patch submission checklist
864 @enumerate
865 @item
866 Do the regression tests pass with the patch applied?
867 @item
868 Is the patch a unified diff?
869 @item
870 Is the patch against latest FFmpeg SVN?
871 @item
872 Are you subscribed to ffmpeg-dev?
873 (the list is subscribers only due to spam)
874 @item
875 Have you checked that the changes are minimal, so that the same cannot be
876 achieved with a smaller patch and/or simpler final code?
877 @item
878 If the change is to speed critical code, did you benchmark it?
879 @item
880 If you did any benchmarks, did you provide them in the mail?
881 @item
882 Have you checked that the patch does not introduce buffer overflows or
883 other security issues?
884 @item
885 Is the patch created from the root of the source tree, so it can be
886 applied with @code{patch -p0}?
887 @item
888 Does the patch not mix functional and cosmetic changes?
889 @item
890 Did you add tabs or trailing whitespace to the code? Both are forbidden.
891 @item
892 Is the patch attached to the email you send?
893 @item
894 Is the mime type of the patch correct? It should be text/x-diff or
895 text/x-patch or at least text/plain and not application/octet-stream.
896 @item
897 If the patch fixes a bug, did you provide a verbose analysis of the bug?
898 @item
899 If the patch fixes a bug, did you provide enough information, including
900 a sample, so the bug can be reproduced and the fix can be verified?
901 Note please do not attach samples >100k to mails but rather provide a
902 URL, you can upload to
903 @item
904 Did you provide a verbose summary about what the patch does change?
905 @item
906 Did you provide a verbose explanation why it changes things like it does?
907 @item
908 Did you provide a verbose summary of the user visible advantages and
909 disadvantages if the patch is applied?
910 @item
911 Did you provide an example so we can verify the new feature added by the
912 patch easily?
913 @item
914 If you added a new file, did you insert a license header? It should be
915 taken from FFmpeg, not randomly copied and pasted from somewhere else.
916 @item
917 You should maintain alphabetical order in alphabetically ordered lists as
918 long as doing so does not break API/ABI compatibility.
919 @item
920 Lines with similar content should be aligned vertically when doing so
921 improves readability.
922 @item
923 Did you provide a suggestion for a clear commit log message?
924 @end enumerate
926 @section Patch review process
928 All patches posted to ffmpeg-devel will be reviewed, unless they contain a
929 clear note that the patch is not for SVN.
930 Reviews and comments will be posted as replies to the patch on the
931 mailing list. The patch submitter then has to take care of every comment,
932 that can be by resubmitting a changed patch or by discussion. Resubmitted
933 patches will themselves be reviewed like any other patch. If at some point
934 a patch passes review with no comments then it is approved, that can for
935 simple and small patches happen immediately while large patches will generally
936 have to be changed and reviewed many times before they are approved.
937 After a patch is approved it will be committed to the repository.
939 We will review all submitted patches, but sometimes we are quite busy so
940 especially for large patches this can take several weeks.
942 When resubmitting patches, please do not make any significant changes
943 not related to the comments received during review. Such patches will
944 be rejected. Instead, submit significant changes or new features as
945 separate patches.
947 @section Regression tests
949 Before submitting a patch (or committing to the repository), you should at least
950 test that you did not break anything.
952 The regression tests build a synthetic video stream and a synthetic
953 audio stream. These are then encoded and decoded with all codecs or
954 formats. The CRC (or MD5) of each generated file is recorded in a
955 result file. A 'diff' is launched to compare the reference results and
956 the result file.
958 The regression tests then go on to test the FFserver code with a
959 limited set of streams. It is important that this step runs correctly
960 as well.
962 Run 'make test' to test all the codecs and formats.
964 Run 'make fulltest' to test all the codecs, formats and FFserver.
966 [Of course, some patches may change the results of the regression tests. In
967 this case, the reference results of the regression tests shall be modified
968 accordingly].
970 @bye