Update policy entry about compiler warnings to reflect ml discussions.
[libav.git] / doc / general.texi
1 \input texinfo @c -*- texinfo -*-
2
3 @settitle General Documentation
4 @titlepage
5 @sp 7
6 @center @titlefont{General Documentation}
7 @sp 3
8 @end titlepage
9
10
11 @chapter external libraries
12
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}.
16
17 @section AMR
18
19 AMR comes in two different flavors, wideband and narrowband. FFmpeg can make
20 use of the AMR wideband (floating-point mode) and the AMR narrowband
21 (floating-point mode) reference decoders and encoders.
22
23 Go to @url{http://www.penguin.cz/~utx/amr} 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.
26
27 Note that libamr is copyrighted without any sort of license grant. This means
28 that you can use it if you legally obtained it but you are not allowed to
29 redistribute it in any way. @strong{Any FFmpeg binaries with libamr support
30 you create are non-free and unredistributable!}
31
32
33 @chapter Supported File Formats and Codecs
34
35 You can use the @code{-formats} option to have an exhaustive list.
36
37 @section File Formats
38
39 FFmpeg supports the following file formats through the @code{libavformat}
40 library:
41
42 @multitable @columnfractions .4 .1 .1 .4
43 @item Supported File Format @tab Encoding @tab Decoding @tab Comments
44 @item MPEG audio @tab X @tab X
45 @item MPEG-1 systems @tab X @tab X
46 @tab muxed audio and video
47 @item MPEG-2 PS @tab X @tab X
48 @tab also known as @code{VOB} file
49 @item MPEG-2 TS @tab @tab X
50 @tab also known as DVB Transport Stream
51 @item ASF@tab X @tab X
52 @item AVI@tab X @tab X
53 @item WAV@tab X @tab X
54 @item Macromedia Flash@tab X @tab X
55 @item AVM2 (Flash 9) @tab X @tab X
56 @tab Only embedded audio is decoded.
57 @item FLV @tab X @tab X
58 @tab Macromedia Flash video files
59 @item Real Audio and Video @tab X @tab X
60 @item Raw AC3 @tab X @tab X
61 @item Raw MJPEG @tab X @tab X
62 @item Raw MPEG video @tab X @tab X
63 @item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
64 @item Raw CRI ADX audio @tab X @tab X
65 @item Raw Shorten audio @tab @tab X
66 @item SUN AU format @tab X @tab X
67 @item NUT @tab X @tab X @tab NUT Open Container Format
68 @item QuickTime @tab X @tab X
69 @item MPEG-4 @tab X @tab X
70 @tab MPEG-4 is a variant of QuickTime.
71 @item Raw MPEG4 video @tab X @tab X
72 @item DV @tab X @tab X
73 @item 4xm @tab @tab X
74 @tab 4X Technologies format, used in some games.
75 @item Playstation STR @tab @tab X
76 @item Id RoQ @tab X @tab X
77 @tab Used in Quake III, Jedi Knight 2, other computer games.
78 @item Interplay MVE @tab @tab X
79 @tab Format used in various Interplay computer games.
80 @item WC3 Movie @tab @tab X
81 @tab Multimedia format used in Origin's Wing Commander III computer game.
82 @item Sega FILM/CPK @tab @tab X
83 @tab Used in many Sega Saturn console games.
84 @item Westwood Studios VQA/AUD @tab @tab X
85 @tab Multimedia formats used in Westwood Studios games.
86 @item Id Cinematic (.cin) @tab @tab X
87 @tab Used in Quake II.
88 @item FLIC format @tab @tab X
89 @tab .fli/.flc files
90 @item Sierra VMD @tab @tab X
91 @tab Used in Sierra CD-ROM games.
92 @item Sierra Online @tab @tab X
93 @tab .sol files used in Sierra Online games.
94 @item Matroska @tab X @tab X
95 @item Electronic Arts Multimedia @tab @tab X
96 @tab Used in various EA games; files have extensions like WVE and UV2.
97 @item Nullsoft Video (NSV) format @tab @tab X
98 @item ADTS AAC audio @tab X @tab X
99 @item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
100 @item American Laser Games MM @tab @tab X
101 @tab Multimedia format used in games like Mad Dog McCree
102 @item AVS @tab @tab X
103 @tab Multimedia format used by the Creature Shock game.
104 @item Smacker @tab @tab X
105 @tab Multimedia format used by many games.
106 @item GXF @tab X @tab X
107 @tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
108 @item CIN @tab @tab X
109 @tab Multimedia format used by Delphine Software games.
110 @item MXF @tab @tab X
111 @tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
112 @item SEQ @tab @tab X
113 @tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
114 @item DXA @tab @tab X
115 @tab This format is used in non-Windows version of Feeble Files game and
116 different game cutscenes repacked for use with ScummVM.
117 @item THP @tab @tab X
118 @tab Used on the Nintendo GameCube.
119 @item C93 @tab @tab X
120 @tab Used in the game Cyberia from Interplay.
121 @item Bethsoft VID @tab @tab X
122 @tab Used in some games from Bethesda Softworks.
123 @item CRYO APC @tab @tab X
124 @tab Audio format used in some games by CRYO Interactive Entertainment.
125 @item Monkey's Audio @tab @tab X
126 @item SIFF @tab @tab X
127 @tab Audio and video format used in some games by Beam Software
128 @end multitable
129
130 @code{X} means that encoding (resp. decoding) is supported.
131
132 @section Image Formats
133
134 FFmpeg can read and write images for each frame of a video sequence. The
135 following image formats are supported:
136
137 @multitable @columnfractions .4 .1 .1 .4
138 @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
139 @item PGM, PPM @tab X @tab X
140 @item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support.
141 @item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
142 @item JPEG @tab X @tab X @tab Progressive JPEG is not supported.
143 @item .Y.U.V @tab X @tab X @tab one raw file per component
144 @item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
145 @item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
146 @item Targa @tab @tab X @tab Targa (.TGA) image format.
147 @item TIFF @tab X @tab X @tab YUV, JPEG and some extension is not supported yet.
148 @item SGI @tab X @tab X @tab SGI RGB image format
149 @item PTX @tab @tab X @tab V.Flash PTX format
150 @end multitable
151
152 @code{X} means that encoding (resp. decoding) is supported.
153
154 @section Video Codecs
155
156 @multitable @columnfractions .4 .1 .1 .4
157 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
158 @item MPEG-1 video @tab X @tab X
159 @item MPEG-2 video @tab X @tab X
160 @item MPEG-4 @tab X @tab X
161 @item MSMPEG4 V1 @tab X @tab X
162 @item MSMPEG4 V2 @tab X @tab X
163 @item MSMPEG4 V3 @tab X @tab X
164 @item WMV7 @tab X @tab X
165 @item WMV8 @tab X @tab X @tab not completely working
166 @item WMV9 @tab @tab X @tab not completely working
167 @item VC1 @tab @tab X
168 @item H.261 @tab X @tab X
169 @item H.263(+) @tab X @tab X @tab also known as RealVideo 1.0
170 @item H.264 @tab @tab X
171 @item RealVideo 1.0 @tab X @tab X
172 @item RealVideo 2.0 @tab X @tab X
173 @item MJPEG @tab X @tab X
174 @item lossless MJPEG @tab X @tab X
175 @item JPEG-LS @tab X @tab X @tab fourcc: MJLS, lossless and near-lossless is supported
176 @item Apple MJPEG-B @tab @tab X
177 @item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
178 @item DV @tab X @tab X
179 @item HuffYUV @tab X @tab X
180 @item FFmpeg Video 1 @tab X @tab X @tab experimental lossless codec (fourcc: FFV1)
181 @item FFmpeg Snow @tab X @tab X @tab experimental wavelet codec (fourcc: SNOW)
182 @item Asus v1 @tab X @tab X @tab fourcc: ASV1
183 @item Asus v2 @tab X @tab X @tab fourcc: ASV2
184 @item Creative YUV @tab @tab X @tab fourcc: CYUV
185 @item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
186 @item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
187 @item On2 VP3 @tab @tab X @tab still experimental
188 @item On2 VP5 @tab @tab X @tab fourcc: VP50
189 @item On2 VP6 @tab @tab X @tab fourcc: VP60,VP61,VP62
190 @item Theora @tab X @tab X @tab still experimental
191 @item Intel Indeo 3 @tab @tab X
192 @item FLV @tab X @tab X @tab Sorenson H.263 used in Flash
193 @item Flash Screen Video @tab X @tab X @tab fourcc: FSV1
194 @item ATI VCR1 @tab @tab X @tab fourcc: VCR1
195 @item ATI VCR2 @tab @tab X @tab fourcc: VCR2
196 @item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
197 @item 4X Video @tab @tab X @tab Used in certain computer games.
198 @item Sony Playstation MDEC @tab @tab X
199 @item Id RoQ @tab X @tab X @tab Used in Quake III, Jedi Knight 2, other computer games.
200 @item Xan/WC3 @tab @tab X @tab Used in Wing Commander III .MVE files.
201 @item Interplay Video @tab @tab X @tab Used in Interplay .MVE files.
202 @item Apple Animation @tab X @tab X @tab fourcc: 'rle '
203 @item Apple Graphics @tab @tab X @tab fourcc: 'smc '
204 @item Apple Video @tab @tab X @tab fourcc: rpza
205 @item Apple QuickDraw @tab @tab X @tab fourcc: qdrw
206 @item Cinepak @tab @tab X
207 @item Microsoft RLE @tab @tab X
208 @item Microsoft Video-1 @tab @tab X
209 @item Westwood VQA @tab @tab X
210 @item Id Cinematic Video @tab @tab X @tab Used in Quake II.
211 @item Planar RGB @tab @tab X @tab fourcc: 8BPS
212 @item FLIC video @tab @tab X
213 @item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
214 @item Duck TrueMotion v2 @tab @tab X @tab fourcc: TM20
215 @item VMD Video @tab @tab X @tab Used in Sierra VMD files.
216 @item MSZH @tab @tab X @tab Part of LCL
217 @item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
218 @item TechSmith Camtasia @tab @tab X @tab fourcc: TSCC
219 @item IBM Ultimotion @tab @tab X @tab fourcc: ULTI
220 @item Miro VideoXL @tab @tab X @tab fourcc: VIXL
221 @item QPEG @tab @tab X @tab fourccs: QPEG, Q1.0, Q1.1
222 @item LOCO @tab @tab X @tab
223 @item Winnov WNV1 @tab @tab X @tab
224 @item Autodesk Animator Studio Codec @tab @tab X @tab fourcc: AASC
225 @item Fraps FPS1 @tab @tab X @tab
226 @item CamStudio @tab @tab X @tab fourcc: CSCD
227 @item American Laser Games Video @tab @tab X @tab Used in games like Mad Dog McCree
228 @item ZMBV @tab X @tab X @tab Encoder works only on PAL8
229 @item AVS Video @tab @tab X @tab Video encoding used by the Creature Shock game.
230 @item Smacker Video @tab @tab X @tab Video encoding used in Smacker.
231 @item RTjpeg @tab @tab X @tab Video encoding used in NuppelVideo files.
232 @item KMVC @tab @tab X @tab Codec used in Worms games.
233 @item VMware Video @tab @tab X @tab Codec used in videos captured by VMware.
234 @item Cin Video @tab @tab X @tab Codec used in Delphine Software games.
235 @item Tiertex Seq Video @tab @tab X @tab Codec used in DOS CDROM FlashBack game.
236 @item DXA Video @tab @tab X @tab Codec originally used in Feeble Files game.
237 @item AVID DNxHD @tab X @tab X @tab aka SMPTE VC3
238 @item C93 Video @tab @tab X @tab Codec used in Cyberia game.
239 @item THP @tab @tab X @tab Used on the Nintendo GameCube.
240 @item Bethsoft VID @tab @tab X @tab Used in some games from Bethesda Softworks.
241 @item Renderware TXD @tab @tab X @tab Texture dictionaries used by the Renderware Engine.
242 @item AMV @tab @tab X @tab Used in Chinese MP3 players.
243 @end multitable
244
245 @code{X} means that encoding (resp. decoding) is supported.
246
247 @section Audio Codecs
248
249 @multitable @columnfractions .4 .1 .1 .1 .7
250 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
251 @item MPEG audio layer 2 @tab IX @tab IX
252 @item MPEG audio layer 1/3 @tab X @tab IX
253 @tab MP3 encoding is supported through the external library LAME.
254 @item AC3 @tab IX @tab IX
255 @tab liba52 is used internally for decoding.
256 @item Vorbis @tab X @tab X
257 @item WMA V1/V2 @tab X @tab X
258 @item AAC @tab X @tab X
259 @tab Supported through the external library libfaac/libfaad.
260 @item Microsoft ADPCM @tab X @tab X
261 @item AMV IMA ADPCM @tab @tab X
262 @tab Used in AMV files
263 @item MS IMA ADPCM @tab X @tab X
264 @item QT IMA ADPCM @tab @tab X
265 @item 4X IMA ADPCM @tab @tab X
266 @item G.726 ADPCM @tab X @tab X
267 @item Duck DK3 IMA ADPCM @tab @tab X
268 @tab Used in some Sega Saturn console games.
269 @item Duck DK4 IMA ADPCM @tab @tab X
270 @tab Used in some Sega Saturn console games.
271 @item Westwood Studios IMA ADPCM @tab @tab X
272 @tab Used in Westwood Studios games like Command and Conquer.
273 @item SMJPEG IMA ADPCM @tab @tab X
274 @tab Used in certain Loki game ports.
275 @item CD-ROM XA ADPCM @tab @tab X
276 @item CRI ADX ADPCM @tab X @tab X
277 @tab Used in Sega Dreamcast games.
278 @item Electronic Arts ADPCM @tab @tab X
279 @tab Used in various EA titles.
280 @item Creative ADPCM @tab @tab X
281 @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
282 @item THP ADPCM @tab @tab X
283 @tab Used on the Nintendo GameCube.
284 @item RA144 @tab @tab X
285 @tab Real 14400 bit/s codec
286 @item RA288 @tab @tab X
287 @tab Real 28800 bit/s codec
288 @item RADnet @tab X @tab IX
289 @tab Real low bitrate AC3 codec, liba52 is used for decoding.
290 @item AMR-NB @tab X @tab X
291 @tab Supported through an external library.
292 @item AMR-WB @tab X @tab X
293 @tab Supported through an external library.
294 @item DV audio @tab @tab X
295 @item Id RoQ DPCM @tab X @tab X
296 @tab Used in Quake III, Jedi Knight 2, other computer games.
297 @item Interplay MVE DPCM @tab @tab X
298 @tab Used in various Interplay computer games.
299 @item Xan DPCM @tab @tab X
300 @tab Used in Origin's Wing Commander IV AVI files.
301 @item Sierra Online DPCM @tab @tab X
302 @tab Used in Sierra Online game audio files.
303 @item Apple MACE 3 @tab @tab X
304 @item Apple MACE 6 @tab @tab X
305 @item FLAC lossless audio @tab X @tab X
306 @item Shorten lossless audio @tab @tab X
307 @item Apple lossless audio @tab @tab X
308 @tab QuickTime fourcc 'alac'
309 @item FFmpeg Sonic @tab X @tab X
310 @tab experimental lossy/lossless codec
311 @item Qdesign QDM2 @tab @tab X
312 @tab there are still some distortions
313 @item Real COOK @tab @tab X
314 @tab All versions except 5.1 are supported
315 @item DSP Group TrueSpeech @tab @tab X
316 @item True Audio (TTA) @tab @tab X
317 @item Smacker Audio @tab @tab X
318 @item WavPack Audio @tab @tab X
319 @item Cin Audio @tab @tab X
320 @tab Codec used in Delphine Software games.
321 @item Intel Music Coder @tab @tab X
322 @item Musepack @tab @tab X
323 @tab SV7 and SV8 are supported
324 @item DT$ Coherent Audio @tab @tab X
325 @item ATRAC 3 @tab @tab X
326 @item Monkey's Audio @tab @tab X @tab Only versions 3.97-3.99 are supported
327 @item Nellymoser ASAO @tab @tab X
328 @end multitable
329
330 @code{X} means that encoding (resp. decoding) is supported.
331
332 @code{I} means that an integer-only version is available, too (ensures high
333 performance on systems without hardware floating point support).
334
335 @chapter Platform Specific information
336
337 @section BSD
338
339 BSD make will not build FFmpeg, you need to install and use GNU Make
340 (@file{gmake}).
341
342 @section Windows
343
344 To get help and instructions for building FFmpeg under Windows, check out
345 the FFmpeg Windows Help Forum at
346 @url{http://arrozcru.no-ip.org/ffmpeg/}.
347
348 @subsection Native Windows compilation
349
350 FFmpeg can be built to run natively on Windows using the MinGW tools. Install
351 the current versions of MSYS and MinGW from @url{http://www.mingw.org/}. Also
352 install the coreutils package. You can find detailed installation
353 instructions in the download section and the FAQ.
354
355 Within the MSYS shell, configure and make with:
356
357 @example
358 ./configure --enable-memalign-hack
359 make
360 make install
361 @end example
362
363 This will install @file{ffmpeg.exe} along with many other development files
364 to @file{/usr/local}. You may specify another install path using the
365 @code{--prefix} option in @file{configure}.
366
367 Notes:
368
369 @itemize
370
371 @item Use at least bash 3.1. Older versions are known to fail on the
372 configure script.
373
374 @item In order to compile vhooks, you must have a POSIX-compliant libdl in
375 your MinGW system. Get dlfcn-win32 from
376 @url{http://code.google.com/p/dlfcn-win32}.
377
378 @item In order to compile FFplay, you must have the MinGW development library
379 of SDL. Get it from @url{http://www.libsdl.org}.
380 Edit the @file{bin/sdl-config} script so that it points to the correct prefix
381 where SDL was installed. Verify that @file{sdl-config} can be launched from
382 the MSYS command line.
383
384 @item The target @code{make wininstaller} can be used to create a
385 Nullsoft-based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
386 must be copied to the FFmpeg directory in order to build the
387 installer.
388
389 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
390 you can build libavutil, libavcodec and libavformat as DLLs.
391
392 @end itemize
393
394 @subsection Microsoft Visual C++ compatibility
395
396 As stated in the FAQ, FFmpeg will not compile under MSVC++. However, if you
397 want to use the libav* libraries in your own applications, you can still
398 compile those applications using MSVC++. But the libav* libraries you link
399 to @emph{must} be built with MinGW. However, you will not be able to debug
400 inside the libav* libraries, since MSVC++ does not recognize the debug
401 symbols generated by GCC.
402 We strongly recommend you to move over from MSVC++ to MinGW tools.
403
404 This description of how to use the FFmpeg libraries with MSVC++ is based on
405 Microsoft Visual C++ 2005 Express Edition. If you have a different version,
406 you might have to modify the procedures slightly.
407
408 @subsubsection Using static libraries
409
410 Assuming you have just built and installed FFmpeg in @file{/usr/local}.
411
412 @enumerate
413
414 @item Create a new console application ("File / New / Project") and then
415 select "Win32 Console Application". On the appropriate page of the
416 Application Wizard, uncheck the "Precompiled headers" option.
417
418 @item Write the source code for your application, or, for testing, just
419 copy the code from an existing sample application into the source file
420 that MSVC++ has already created for you. For example, you can copy
421 @file{output_example.c} from the FFmpeg distribution.
422
423 @item Open the "Project / Properties" dialog box. In the "Configuration"
424 combo box, select "All Configurations" so that the changes you make will
425 affect both debug and release builds. In the tree view on the left hand
426 side, select "C/C++ / General", then edit the "Additional Include
427 Directories" setting to contain the path where the FFmpeg includes were
428 installed (i.e. @file{c:\msys\1.0\local\include}).
429
430 @item Still in the "Project / Properties" dialog box, select
431 "Linker / General" from the tree view and edit the
432 "Additional Library Directories" setting to contain the @file{lib}
433 directory where FFmpeg was installed (i.e. @file{c:\msys\1.0\local\lib}),
434 the directory where MinGW libs are installed (i.e. @file{c:\mingw\lib}),
435 and the directory where MinGW's GCC libs are installed
436 (i.e. @file{C:\mingw\lib\gcc\mingw32\4.2.1-sjlj}). Then select
437 "Linker / Input" from the tree view, and add the files @file{libavformat.a},
438 @file{libavcodec.a}, @file{libavutil.a}, @file{libmingwex.a},
439 @file{libgcc.a}, and any other libraries you used (i.e. @file{libz.a})
440 to the end of "Additional Dependencies".
441
442 @item Now, select "C/C++ / Code Generation" from the tree view. Select
443 "Debug" in the "Configuration" combo box. Make sure that "Runtime
444 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
445 the "Configuration" combo box and make sure that "Runtime Library" is
446 set to "Multi-threaded DLL".
447
448 @item Click "OK" to close the "Project / Properties" dialog box.
449
450 @item MSVC++ lacks some C99 header files that are fundamental for FFmpeg.
451 Get msinttypes from @url{http://code.google.com/p/msinttypes/downloads/list}
452 and install it in MSVC++'s include directory
453 (i.e. @file{C:\Program Files\Microsoft Visual Studio 8\VC\include}).
454
455 @item MSVC++ also does not understand the @code{inline} keyword used by
456 FFmpeg, so you must add this line before @code{#include}ing libav*:
457 @example
458 #define inline _inline
459 @end example
460
461 @item If you used @file{output_example.c} as your sample application,
462 you will have to edit the @code{#include}s to point to the files which
463 are under the @file{ffmpeg} directory (i.e. @code{<ffmpeg/avformat.h>}).
464
465 @item Build your application, everything should work.
466
467 @end enumerate
468
469 @subsubsection Using shared libraries
470
471 This is how to create DLL and LIB files that are compatible with MSVC++:
472
473 @enumerate
474
475 @item Add a call to @file{vcvars32.bat} (which sets up the environment
476 variables for the Visual C++ tools) as the first line of @file{msys.bat}.
477 The standard location for @file{vcvars32.bat} is
478 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
479 and the standard location for @file{msys.bat} is @file{C:\msys\1.0\msys.bat}.
480 If this corresponds to your setup, add the following line as the first line
481 of @file{msys.bat}:
482
483 @example
484 call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"
485 @end example
486
487 Alternatively, you may start the @file{Visual Studio 2005 Command Prompt},
488 and run @file{c:\msys\1.0\msys.bat} from there.
489
490 @item Within the MSYS shell, run @code{lib.exe}. If you get a help message
491 from @file{Microsoft (R) Library Manager}, this means your environment
492 variables are set up correctly, the @file{Microsoft (R) Library Manager}
493 is on the path and will be used by FFmpeg to create
494 MSVC++-compatible import libraries.
495
496 @item Build FFmpeg with
497
498 @example
499 ./configure --enable-shared --enable-memalign-hack
500 make
501 make install
502 @end example
503
504 Your install path (@file{/usr/local/} by default) should now have the
505 necessary DLL and LIB files under the @file{bin} directory.
506
507 @end enumerate
508
509 To use those files with MSVC++, do the same as you would do with
510 the static libraries, as described above. But in Step 4,
511 you should only need to add the directory where the LIB files are installed
512 (i.e. @file{c:\msys\usr\local\bin}). This is not a typo, the LIB files are
513 installed in the @file{bin} directory. And instead of adding @file{libxx.a}
514 files, you should add @file{avcodec.lib}, @file{avformat.lib}, and
515 @file{avutil.lib}. There should be no need for @file{libmingwex.a},
516 @file{libgcc.a}, and @file{wsock32.lib}, nor any other external library
517 statically linked into the DLLs. The @file{bin} directory contains a bunch
518 of DLL files, but the ones that are actually used to run your application
519 are the ones with a major version number in their filenames
520 (i.e. @file{avcodec-51.dll}).
521
522 @subsection Cross compilation for Windows with Linux
523
524 You must use the MinGW cross compilation tools available at
525 @url{http://www.mingw.org/}.
526
527 Then configure FFmpeg with the following options:
528 @example
529 ./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
530 @end example
531 (you can change the cross-prefix according to the prefix chosen for the
532 MinGW tools).
533
534 Then you can easily test FFmpeg with Wine
535 (@url{http://www.winehq.com/}).
536
537 @subsection Compilation under Cygwin
538
539 The main issue with Cygwin is that newlib, its C library, does not
540 contain llrint(). However, it is possible to leverage the
541 implementation in MinGW.
542
543 Just install your Cygwin with all the "Base" packages, plus the
544 following "Devel" ones:
545 @example
546 binutils, gcc-core, make, subversion, mingw-runtime
547 @end example
548
549 Do not install binutils-20060709-1 (they are buggy on shared builds);
550 use binutils-20050610-1 instead.
551
552 Then create a small library that just contains llrint():
553
554 @example
555 ar x /usr/lib/mingw/libmingwex.a llrint.o
556 ar cq /usr/local/lib/libllrint.a llrint.o
557 @end example
558
559 Then run
560
561 @example
562 ./configure --enable-static --disable-shared --extra-ldflags='-L /usr/local/lib' --extra-libs='-l llrint'
563 @end example
564
565 to make a static build or
566
567 @example
568 ./configure --enable-shared --disable-static --extra-ldflags='-L /usr/local/lib' --extra-libs='-l llrint'
569 @end example
570
571 to build shared libraries.
572
573 If you want to build FFmpeg with additional libraries, download Cygwin
574 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
575 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
576 (@url{http://cygwinports.dotsrc.org/}).
577
578 @subsection Crosscompilation for Windows under Cygwin
579
580 With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
581
582 Just install your Cygwin as explained before, plus these additional
583 "Devel" packages:
584 @example
585 gcc-mingw-core, mingw-runtime, mingw-zlib
586 @end example
587
588 and add some special flags to your configure invocation.
589
590 For a static build run
591 @example
592 ./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
593 @end example
594
595 and for a build with shared libraries
596 @example
597 ./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
598 @end example
599
600 @section BeOS
601
602 BeOS support is broken in mysterious ways.
603
604 @section OS/2
605
606 For information about compiling FFmpeg on OS/2 see
607 @url{http://www.edm2.com/index.php/FFmpeg}.
608
609 @chapter Developers Guide
610
611 @section API
612 @itemize @bullet
613 @item libavcodec is the library containing the codecs (both encoding and
614 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
615
616 @item libavformat is the library containing the file format handling (mux and
617 demux code for several formats). Look at @file{ffplay.c} to use it in a
618 player. See @file{output_example.c} to use it to generate audio or video
619 streams.
620
621 @end itemize
622
623 @section Integrating libavcodec or libavformat in your program
624
625 You can integrate all the source code of the libraries to link them
626 statically to avoid any version problem. All you need is to provide a
627 'config.mak' and a 'config.h' in the parent directory. See the defines
628 generated by ./configure to understand what is needed.
629
630 You can use libavcodec or libavformat in your commercial program, but
631 @emph{any patch you make must be published}. The best way to proceed is
632 to send your patches to the FFmpeg mailing list.
633
634 @node Coding Rules
635 @section Coding Rules
636
637 FFmpeg is programmed in the ISO C90 language with a few additional
638 features from ISO C99, namely:
639 @itemize @bullet
640 @item
641 the @samp{inline} keyword;
642 @item
643 @samp{//} comments;
644 @item
645 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
646 @item
647 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
648 @end itemize
649
650 These features are supported by all compilers we care about, so we will not
651 accept patches to remove their use unless they absolutely do not impair
652 clarity and performance.
653
654 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
655 compiles with several other compilers, such as the Compaq ccc compiler
656 or Sun Studio 9, and we would like to keep it that way unless it would
657 be exceedingly involved. To ensure compatibility, please do not use any
658 additional C99 features or GCC extensions. Especially watch out for:
659 @itemize @bullet
660 @item
661 mixing statements and declarations;
662 @item
663 @samp{long long} (use @samp{int64_t} instead);
664 @item
665 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
666 @item
667 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
668 @end itemize
669
670 Indent size is 4.
671 The presentation is the one specified by 'indent -i4 -kr -nut'.
672 The TAB character is forbidden outside of Makefiles as is any
673 form of trailing whitespace. Commits containing either will be
674 rejected by the Subversion repository.
675
676 The main priority in FFmpeg is simplicity and small code size in order to
677 minimize the bug count.
678
679 Comments: Use the JavaDoc/Doxygen
680 format (see examples below) so that code documentation
681 can be generated automatically. All nontrivial functions should have a comment
682 above them explaining what the function does, even if it is just one sentence.
683 All structures and their member variables should be documented, too.
684 @example
685 /**
686 * @@file mpeg.c
687 * MPEG codec.
688 * @@author ...
689 */
690
691 /**
692 * Summary sentence.
693 * more text ...
694 * ...
695 */
696 typedef struct Foobar@{
697 int var1; /**< var1 description */
698 int var2; ///< var2 description
699 /** var3 description */
700 int var3;
701 @} Foobar;
702
703 /**
704 * Summary sentence.
705 * more text ...
706 * ...
707 * @@param my_parameter description of my_parameter
708 * @@return return value description
709 */
710 int myfunc(int my_parameter)
711 ...
712 @end example
713
714 fprintf and printf are forbidden in libavformat and libavcodec,
715 please use av_log() instead.
716
717 Casts should be used only when necessary. Unneeded parentheses
718 should also be avoided if they don't make the code easier to understand.
719
720 @section Development Policy
721
722 @enumerate
723 @item
724 Contributions should be licensed under the LGPL 2.1, including an
725 "or any later version" clause, or the MIT license. GPL 2 including
726 an "or any later version" clause is also acceptable, but LGPL is
727 preferred.
728 @item
729 You must not commit code which breaks FFmpeg! (Meaning unfinished but
730 enabled code which breaks compilation or compiles but does not work or
731 breaks the regression tests)
732 You can commit unfinished stuff (for testing etc), but it must be disabled
733 (#ifdef etc) by default so it does not interfere with other developers'
734 work.
735 @item
736 You do not have to over-test things. If it works for you, and you think it
737 should work for others, then commit. If your code has problems
738 (portability, triggers compiler bugs, unusual environment etc) they will be
739 reported and eventually fixed.
740 @item
741 Do not commit unrelated changes together, split them into self-contained
742 pieces. Also do not forget that if part B depends on part A, but A does not
743 depend on B, then A can and should be committed first and separate from B.
744 Keeping changes well split into self-contained parts makes reviewing and
745 understanding them on the commit log mailing list easier. This also helps
746 in case of debugging later on.
747 Also if you have doubts about splitting or not splitting, do not hesitate to
748 ask/discuss it on the developer mailing list.
749 @item
750 Do not change behavior of the program (renaming options etc) without
751 first discussing it on the ffmpeg-devel mailing list. Do not remove
752 functionality from the code. Just improve!
753
754 Note: Redundant code can be removed.
755 @item
756 Do not commit changes to the build system (Makefiles, configure script)
757 which change behavior, defaults etc, without asking first. The same
758 applies to compiler warning fixes, trivial looking fixes and to code
759 maintained by other developers. We usually have a reason for doing things
760 the way we do. Send your changes as patches to the ffmpeg-devel mailing
761 list, and if the code maintainers say OK, you may commit. This does not
762 apply to files you wrote and/or maintain.
763 @item
764 We refuse source indentation and other cosmetic changes if they are mixed
765 with functional changes, such commits will be rejected and removed. Every
766 developer has his own indentation style, you should not change it. Of course
767 if you (re)write something, you can use your own style, even though we would
768 prefer if the indentation throughout FFmpeg was consistent (Many projects
769 force a given indentation style - we do not.). If you really need to make
770 indentation changes (try to avoid this), separate them strictly from real
771 changes.
772
773 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
774 then either do NOT change the indentation of the inner part within (do not
775 move it to the right)! or do so in a separate commit
776 @item
777 Always fill out the commit log message. Describe in a few lines what you
778 changed and why. You can refer to mailing list postings if you fix a
779 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
780 @item
781 If you apply a patch by someone else, include the name and email address in
782 the log message. Since the ffmpeg-cvslog mailing list is publicly
783 archived you should add some SPAM protection to the email address. Send an
784 answer to ffmpeg-devel (or wherever you got the patch from) saying that
785 you applied the patch.
786 @item
787 When applying patches that have been discussed (at length) on the mailing
788 list, reference the thread in the log message.
789 @item
790 Do NOT commit to code actively maintained by others without permission.
791 Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
792 timeframe (12h for build failures and security fixes, 3 days small changes,
793 1 week for big patches) then commit your patch if you think it is OK.
794 Also note, the maintainer can simply ask for more time to review!
795 @item
796 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
797 are sent there and reviewed by all the other developers. Bugs and possible
798 improvements or general questions regarding commits are discussed there. We
799 expect you to react if problems with your code are uncovered.
800 @item
801 Update the documentation if you change behavior or add features. If you are
802 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
803 maintainer(s) will review and commit your stuff.
804 @item
805 Try to keep important discussions and requests (also) on the public
806 developer mailing list, so that all developers can benefit from them.
807 @item
808 Never write to unallocated memory, never write over the end of arrays,
809 always check values read from some untrusted source before using them
810 as array index or other risky things.
811 @item
812 Remember to check if you need to bump versions for the specific libav
813 parts (libavutil, libavcodec, libavformat) you are changing. You need
814 to change the version integer and the version string.
815 Incrementing the first component means no backward compatibility to
816 previous versions (e.g. removal of a function from the public API).
817 Incrementing the second component means backward compatible change
818 (e.g. addition of a function to the public API).
819 Incrementing the third component means a noteworthy binary compatible
820 change (e.g. encoder bug fix that matters for the decoder).
821 @item
822 If you add a new codec, remember to update the changelog, add it to
823 the supported codecs table in the documentation and bump the second
824 component of the @file{libavcodec} version number appropriately. If
825 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
826 is only a decoder.
827 @item
828 Compiler warnings indicate bugs or code with bad style. If a type of
829 warning always points to correct and clean code, that warning should
830 be disabled, not the code changed.
831 Thus the remaining warnings can either be bugs or correct code.
832 If it is a bug, it has to be fixed. If it is not, the code should
833 be changed to not generate a warning unless that causes a slowdown
834 or obfuscates the code.
835 @item
836 If you add a new file, give it a proper license header. Do not copy and
837 paste it from a random place, use an existing file as template.
838 @end enumerate
839
840 We think our rules are not too hard. If you have comments, contact us.
841
842 Note, these rules are mostly borrowed from the MPlayer project.
843
844 @section Submitting patches
845
846 First, (@pxref{Coding Rules}) above if you did not yet.
847
848 When you submit your patch, try to send a unified diff (diff '-up'
849 option). We cannot read other diffs :-)
850
851 Also please do not submit a patch which contains several unrelated changes.
852 Split it into separate, self-contained pieces. This does not mean splitting
853 file by file. Instead, make the patch as small as possible while still
854 keeping it as a logical unit that contains an individual change, even
855 if it spans multiple files. This makes reviewing your patches much easier
856 for us and greatly increases your chances of getting your patch applied.
857
858 Run the regression tests before submitting a patch so that you can
859 verify that there are no big problems.
860
861 Patches should be posted as base64 encoded attachments (or any other
862 encoding which ensures that the patch will not be trashed during
863 transmission) to the ffmpeg-devel mailing list, see
864 @url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
865
866 It also helps quite a bit if you tell us what the patch does (for example
867 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
868 and has no lrint()')
869
870 Also please if you send several patches, send each patch as a separate mail,
871 do not attach several unrelated patches to the same mail.
872
873 @section patch submission checklist
874
875 @enumerate
876 @item
877 Do the regression tests pass with the patch applied?
878 @item
879 Is the patch a unified diff?
880 @item
881 Is the patch against latest FFmpeg SVN?
882 @item
883 Are you subscribed to ffmpeg-dev?
884 (the list is subscribers only due to spam)
885 @item
886 Have you checked that the changes are minimal, so that the same cannot be
887 achieved with a smaller patch and/or simpler final code?
888 @item
889 If the change is to speed critical code, did you benchmark it?
890 @item
891 If you did any benchmarks, did you provide them in the mail?
892 @item
893 Have you checked that the patch does not introduce buffer overflows or
894 other security issues?
895 @item
896 Is the patch created from the root of the source tree, so it can be
897 applied with @code{patch -p0}?
898 @item
899 Does the patch not mix functional and cosmetic changes?
900 @item
901 Did you add tabs or trailing whitespace to the code? Both are forbidden.
902 @item
903 Is the patch attached to the email you send?
904 @item
905 Is the mime type of the patch correct? It should be text/x-diff or
906 text/x-patch or at least text/plain and not application/octet-stream.
907 @item
908 If the patch fixes a bug, did you provide a verbose analysis of the bug?
909 @item
910 If the patch fixes a bug, did you provide enough information, including
911 a sample, so the bug can be reproduced and the fix can be verified?
912 Note please do not attach samples >100k to mails but rather provide a
913 URL, you can upload to ftp://upload.mplayerhq.hu
914 @item
915 Did you provide a verbose summary about what the patch does change?
916 @item
917 Did you provide a verbose explanation why it changes things like it does?
918 @item
919 Did you provide a verbose summary of the user visible advantages and
920 disadvantages if the patch is applied?
921 @item
922 Did you provide an example so we can verify the new feature added by the
923 patch easily?
924 @item
925 If you added a new file, did you insert a license header? It should be
926 taken from FFmpeg, not randomly copied and pasted from somewhere else.
927 @item
928 You should maintain alphabetical order in alphabetically ordered lists as
929 long as doing so does not break API/ABI compatibility.
930 @item
931 Lines with similar content should be aligned vertically when doing so
932 improves readability.
933 @item
934 Did you provide a suggestion for a clear commit log message?
935 @item
936 Did you test your decoder or demuxer against damaged data? If no, see
937 tools/trasher and the noise bitstream filter. Your decoder or demuxer
938 should not crash or end in a (near) infinite loop when fed damaged data.
939 @end enumerate
940
941 @section Patch review process
942
943 All patches posted to ffmpeg-devel will be reviewed, unless they contain a
944 clear note that the patch is not for SVN.
945 Reviews and comments will be posted as replies to the patch on the
946 mailing list. The patch submitter then has to take care of every comment,
947 that can be by resubmitting a changed patch or by discussion. Resubmitted
948 patches will themselves be reviewed like any other patch. If at some point
949 a patch passes review with no comments then it is approved, that can for
950 simple and small patches happen immediately while large patches will generally
951 have to be changed and reviewed many times before they are approved.
952 After a patch is approved it will be committed to the repository.
953
954 We will review all submitted patches, but sometimes we are quite busy so
955 especially for large patches this can take several weeks.
956
957 When resubmitting patches, please do not make any significant changes
958 not related to the comments received during review. Such patches will
959 be rejected. Instead, submit significant changes or new features as
960 separate patches.
961
962 @section Regression tests
963
964 Before submitting a patch (or committing to the repository), you should at least
965 test that you did not break anything.
966
967 The regression tests build a synthetic video stream and a synthetic
968 audio stream. These are then encoded and decoded with all codecs or
969 formats. The CRC (or MD5) of each generated file is recorded in a
970 result file. A 'diff' is launched to compare the reference results and
971 the result file.
972
973 The regression tests then go on to test the FFserver code with a
974 limited set of streams. It is important that this step runs correctly
975 as well.
976
977 Run 'make test' to test all the codecs and formats.
978
979 Run 'make fulltest' to test all the codecs, formats and FFserver.
980
981 [Of course, some patches may change the results of the regression tests. In
982 this case, the reference results of the regression tests shall be modified
983 accordingly].
984
985 @bye