542233fbf685236c4c567498c924e78949740701
[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, 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.
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
28 @chapter Supported File Formats and Codecs
29
30 You can use the @code{-formats} option to have an exhaustive list.
31
32 @section File Formats
33
34 FFmpeg supports the following file formats through the @code{libavformat}
35 library:
36
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 @end multitable
121
122 @code{X} means that encoding (resp. decoding) is supported.
123
124 @section Image Formats
125
126 FFmpeg can read and write images for each frame of a video sequence. The
127 following image formats are supported:
128
129 @multitable @columnfractions .4 .1 .1 .4
130 @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
131 @item PGM, PPM @tab X @tab X
132 @item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support.
133 @item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
134 @item JPEG @tab X @tab X @tab Progressive JPEG is not supported.
135 @item .Y.U.V @tab X @tab X @tab one raw file per component
136 @item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
137 @item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
138 @item Targa @tab @tab X @tab Targa (.TGA) image format.
139 @item TIFF @tab X @tab X @tab YUV, JPEG and some extension is not supported yet.
140 @item SGI @tab X @tab X @tab SGI RGB image format
141 @item PTX @tab @tab X @tab V.Flash PTX format
142 @end multitable
143
144 @code{X} means that encoding (resp. decoding) is supported.
145
146 @section Video Codecs
147
148 @multitable @columnfractions .4 .1 .1 .4
149 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
150 @item MPEG-1 video @tab X @tab X
151 @item MPEG-2 video @tab X @tab X
152 @item MPEG-4 @tab X @tab X
153 @item MSMPEG4 V1 @tab X @tab X
154 @item MSMPEG4 V2 @tab X @tab X
155 @item MSMPEG4 V3 @tab X @tab X
156 @item WMV7 @tab X @tab X
157 @item WMV8 @tab X @tab X @tab not completely working
158 @item WMV9 @tab @tab X @tab not completely working
159 @item VC1 @tab @tab X
160 @item H.261 @tab X @tab X
161 @item H.263(+) @tab X @tab X @tab also known as RealVideo 1.0
162 @item H.264 @tab @tab X
163 @item RealVideo 1.0 @tab X @tab X
164 @item RealVideo 2.0 @tab X @tab X
165 @item MJPEG @tab X @tab X
166 @item lossless MJPEG @tab X @tab X
167 @item JPEG-LS @tab X @tab X @tab fourcc: MJLS, lossless and near-lossless is supported
168 @item Apple MJPEG-B @tab @tab X
169 @item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
170 @item DV @tab X @tab X
171 @item HuffYUV @tab X @tab X
172 @item FFmpeg Video 1 @tab X @tab X @tab experimental lossless codec (fourcc: FFV1)
173 @item FFmpeg Snow @tab X @tab X @tab experimental wavelet codec (fourcc: SNOW)
174 @item Asus v1 @tab X @tab X @tab fourcc: ASV1
175 @item Asus v2 @tab X @tab X @tab fourcc: ASV2
176 @item Creative YUV @tab @tab X @tab fourcc: CYUV
177 @item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
178 @item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
179 @item On2 VP3 @tab @tab X @tab still experimental
180 @item On2 VP5 @tab @tab X @tab fourcc: VP50
181 @item On2 VP6 @tab @tab X @tab fourcc: VP60,VP61,VP62
182 @item Theora @tab X @tab X @tab still experimental
183 @item Intel Indeo 3 @tab @tab X
184 @item FLV @tab X @tab X @tab Sorenson H.263 used in Flash
185 @item Flash Screen Video @tab X @tab X @tab fourcc: FSV1
186 @item ATI VCR1 @tab @tab X @tab fourcc: VCR1
187 @item ATI VCR2 @tab @tab X @tab fourcc: VCR2
188 @item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
189 @item 4X Video @tab @tab X @tab Used in certain computer games.
190 @item Sony Playstation MDEC @tab @tab X
191 @item Id RoQ @tab X @tab X @tab Used in Quake III, Jedi Knight 2, other computer games.
192 @item Xan/WC3 @tab @tab X @tab Used in Wing Commander III .MVE files.
193 @item Interplay Video @tab @tab X @tab Used in Interplay .MVE files.
194 @item Apple Animation @tab X @tab X @tab fourcc: 'rle '
195 @item Apple Graphics @tab @tab X @tab fourcc: 'smc '
196 @item Apple Video @tab @tab X @tab fourcc: rpza
197 @item Apple QuickDraw @tab @tab X @tab fourcc: qdrw
198 @item Cinepak @tab @tab X
199 @item Microsoft RLE @tab @tab X
200 @item Microsoft Video-1 @tab @tab X
201 @item Westwood VQA @tab @tab X
202 @item Id Cinematic Video @tab @tab X @tab Used in Quake II.
203 @item Planar RGB @tab @tab X @tab fourcc: 8BPS
204 @item FLIC video @tab @tab X
205 @item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
206 @item Duck TrueMotion v2 @tab @tab X @tab fourcc: TM20
207 @item VMD Video @tab @tab X @tab Used in Sierra VMD files.
208 @item MSZH @tab @tab X @tab Part of LCL
209 @item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
210 @item TechSmith Camtasia @tab @tab X @tab fourcc: TSCC
211 @item IBM Ultimotion @tab @tab X @tab fourcc: ULTI
212 @item Miro VideoXL @tab @tab X @tab fourcc: VIXL
213 @item QPEG @tab @tab X @tab fourccs: QPEG, Q1.0, Q1.1
214 @item LOCO @tab @tab X @tab
215 @item Winnov WNV1 @tab @tab X @tab
216 @item Autodesk Animator Studio Codec @tab @tab X @tab fourcc: AASC
217 @item Fraps FPS1 @tab @tab X @tab
218 @item CamStudio @tab @tab X @tab fourcc: CSCD
219 @item American Laser Games Video @tab @tab X @tab Used in games like Mad Dog McCree
220 @item ZMBV @tab X @tab X @tab Encoder works only on PAL8
221 @item AVS Video @tab @tab X @tab Video encoding used by the Creature Shock game.
222 @item Smacker Video @tab @tab X @tab Video encoding used in Smacker.
223 @item RTjpeg @tab @tab X @tab Video encoding used in NuppelVideo files.
224 @item KMVC @tab @tab X @tab Codec used in Worms games.
225 @item VMware Video @tab @tab X @tab Codec used in videos captured by VMware.
226 @item Cin Video @tab @tab X @tab Codec used in Delphine Software games.
227 @item Tiertex Seq Video @tab @tab X @tab Codec used in DOS CDROM FlashBack game.
228 @item DXA Video @tab @tab X @tab Codec originally used in Feeble Files game.
229 @item AVID DNxHD @tab @tab X @tab aka SMPTE VC3
230 @item C93 Video @tab @tab X @tab Codec used in Cyberia game.
231 @item THP @tab @tab X @tab Used on the Nintendo GameCube.
232 @item Bethsoft VID @tab @tab X @tab Used in some games from Bethesda Softworks.
233 @item Renderware TXD @tab @tab X @tab Texture dictionaries used by the Renderware Engine.
234 @end multitable
235
236 @code{X} means that encoding (resp. decoding) is supported.
237
238 @section Audio Codecs
239
240 @multitable @columnfractions .4 .1 .1 .1 .7
241 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
242 @item MPEG audio layer 2 @tab IX @tab IX
243 @item MPEG audio layer 1/3 @tab IX @tab IX
244 @tab MP3 encoding is supported through the external library LAME.
245 @item AC3 @tab IX @tab IX
246 @tab liba52 is used internally for decoding.
247 @item Vorbis @tab X @tab X
248 @item WMA V1/V2 @tab X @tab X
249 @item AAC @tab X @tab X
250 @tab Supported through the external library libfaac/libfaad.
251 @item Microsoft ADPCM @tab X @tab X
252 @item MS IMA ADPCM @tab X @tab X
253 @item QT IMA ADPCM @tab @tab X
254 @item 4X IMA ADPCM @tab @tab X
255 @item G.726 ADPCM @tab X @tab X
256 @item Duck DK3 IMA ADPCM @tab @tab X
257 @tab Used in some Sega Saturn console games.
258 @item Duck DK4 IMA ADPCM @tab @tab X
259 @tab Used in some Sega Saturn console games.
260 @item Westwood Studios IMA ADPCM @tab @tab X
261 @tab Used in Westwood Studios games like Command and Conquer.
262 @item SMJPEG IMA ADPCM @tab @tab X
263 @tab Used in certain Loki game ports.
264 @item CD-ROM XA ADPCM @tab @tab X
265 @item CRI ADX ADPCM @tab X @tab X
266 @tab Used in Sega Dreamcast games.
267 @item Electronic Arts ADPCM @tab @tab X
268 @tab Used in various EA titles.
269 @item Creative ADPCM @tab @tab X
270 @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
271 @item THP ADPCM @tab @tab X
272 @tab Used on the Nintendo GameCube.
273 @item RA144 @tab @tab X
274 @tab Real 14400 bit/s codec
275 @item RA288 @tab @tab X
276 @tab Real 28800 bit/s codec
277 @item RADnet @tab X @tab IX
278 @tab Real low bitrate AC3 codec, liba52 is used for decoding.
279 @item AMR-NB @tab X @tab X
280 @tab Supported through an external library.
281 @item AMR-WB @tab X @tab X
282 @tab Supported through an external library.
283 @item DV audio @tab @tab X
284 @item Id RoQ DPCM @tab X @tab X
285 @tab Used in Quake III, Jedi Knight 2, other computer games.
286 @item Interplay MVE DPCM @tab @tab X
287 @tab Used in various Interplay computer games.
288 @item Xan DPCM @tab @tab X
289 @tab Used in Origin's Wing Commander IV AVI files.
290 @item Sierra Online DPCM @tab @tab X
291 @tab Used in Sierra Online game audio files.
292 @item Apple MACE 3 @tab @tab X
293 @item Apple MACE 6 @tab @tab X
294 @item FLAC lossless audio @tab X @tab X
295 @item Shorten lossless audio @tab @tab X
296 @item Apple lossless audio @tab @tab X
297 @tab QuickTime fourcc 'alac'
298 @item FFmpeg Sonic @tab X @tab X
299 @tab experimental lossy/lossless codec
300 @item Qdesign QDM2 @tab @tab X
301 @tab there are still some distortions
302 @item Real COOK @tab @tab X
303 @tab All versions except 5.1 are supported
304 @item DSP Group TrueSpeech @tab @tab X
305 @item True Audio (TTA) @tab @tab X
306 @item Smacker Audio @tab @tab X
307 @item WavPack Audio @tab @tab X
308 @item Cin Audio @tab @tab X
309 @tab Codec used in Delphine Software games.
310 @item Intel Music Coder @tab @tab X
311 @item Musepack @tab @tab X
312 @tab Only SV7 is supported
313 @item DT$ Coherent Audio @tab @tab X
314 @item ATRAC 3 @tab @tab X
315 @item Monkey's Audio @tab @tab X @tab Only versions 3.97-3.99 are supported
316 @end multitable
317
318 @code{X} means that encoding (resp. decoding) is supported.
319
320 @code{I} means that an integer-only version is available, too (ensures high
321 performance on systems without hardware floating point support).
322
323 @chapter Platform Specific information
324
325 @section BSD
326
327 BSD make will not build FFmpeg, you need to install and use GNU Make
328 (@file{gmake}).
329
330 @section Windows
331
332 To get help and instructions for using FFmpeg under Windows, check out
333 the FFmpeg Windows Help Forum at
334 @url{http://arrozcru.no-ip.org/ffmpeg/}.
335
336 @subsection Native Windows compilation
337
338 @itemize
339 @item Install the current versions of MSYS and MinGW from
340 @url{http://www.mingw.org/}. You can find detailed installation
341 instructions in the download section and the FAQ.
342
343 NOTE: Use at least bash 3.1. Older versions are known to be failing on the
344 configure script.
345
346 @item If you want to test the FFplay, also download
347 the MinGW development library of SDL 1.2.x
348 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
349 @url{http://www.libsdl.org}. Unpack it in a temporary directory, and
350 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
351 directory. Edit the @file{sdl-config} script so that it gives the
352 correct SDL directory when invoked.
353
354 @item If you want to use vhooks, you must have a POSIX compliant libdl in your
355 MinGW system. Get dlfcn-win32 from @url{http://code.google.com/p/dlfcn-win32}.
356
357 @item Extract the current version of FFmpeg.
358
359 @item Start the MSYS shell (file @file{msys.bat}).
360
361 @item Change to the FFmpeg directory and follow
362 the instructions of how to compile FFmpeg (file
363 @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
364 suffices. If you have problems using SDL, verify that
365 @file{sdl-config} can be launched from the MSYS command line.
366
367 @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
368 @file{make install}. Do not forget to copy @file{SDL.dll} to the place
369 you launch @file{ffplay} from.
370
371 @end itemize
372
373 Notes:
374 @itemize
375
376 @item The target @file{make wininstaller} can be used to create a
377 Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
378 must be copied to the FFmpeg directory in order to build the
379 installer.
380
381 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
382 you can build @file{avcodec.dll} and @file{avformat.dll}. With
383 @code{make install} you install the FFmpeg DLLs and the associated
384 headers in @file{Program Files/FFmpeg}.
385
386 @item Visual C++ compatibility: If you used @code{./configure --enable-shared}
387 when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
388 C++ @code{lib} tool to build @code{avcodec.lib} and
389 @code{avformat.lib}. With these libraries you can link your Visual C++
390 code directly with the FFmpeg DLLs (see below).
391
392 @end itemize
393
394 @subsection Visual C++ compatibility
395
396 FFmpeg will not compile under Visual C++ -- and it has too many
397 dependencies on the GCC compiler to make a port viable. However,
398 if you want to use the FFmpeg libraries in your own applications,
399 you can still compile those applications using Visual C++. An
400 important restriction to this is that you have to use the
401 dynamically linked versions of the FFmpeg libraries (i.e. the
402 DLLs), and you have to make sure that Visual-C++-compatible
403 import libraries are created during the FFmpeg build process.
404
405 This description of how to use the FFmpeg libraries with Visual C++ is
406 based on Visual C++ 2005 Express Edition Beta 2. If you have a different
407 version, you might have to modify the procedures slightly.
408
409 Here are the step-by-step instructions for building the FFmpeg libraries
410 so they can be used with Visual C++:
411
412 @enumerate
413
414 @item Install Visual C++ (if you have not done so already).
415
416 @item Install MinGW and MSYS as described above.
417
418 @item Add a call to @file{vcvars32.bat} (which sets up the environment
419 variables for the Visual C++ tools) as the first line of
420 @file{msys.bat}. The standard location for @file{vcvars32.bat} is
421 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
422 and the standard location for @file{msys.bat} is
423 @file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
424 following line as the first line of @file{msys.bat}:
425
426 @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
427
428 @item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
429 If you get a help message with the command line options of @code{link.exe},
430 this means your environment variables are set up correctly, the
431 Microsoft linker is on the path and will be used by FFmpeg to
432 create Visual-C++-compatible import libraries.
433
434 @item Extract the current version of FFmpeg and change to the FFmpeg directory.
435
436 @item Type the command
437 @code{./configure --enable-shared --disable-static --enable-memalign-hack}
438 to configure and, if that did not produce any errors,
439 type @code{make} to build FFmpeg.
440
441 @item The subdirectories @file{libavformat}, @file{libavcodec}, and
442 @file{libavutil} should now contain the files @file{avformat.dll},
443 @file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
444 @file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
445 DLLs to your System32 directory (typically @file{C:\Windows\System32}).
446
447 @end enumerate
448
449 And here is how to use these libraries with Visual C++:
450
451 @enumerate
452
453 @item Create a new console application ("File / New / Project") and then
454 select "Win32 Console Application". On the appropriate page of the
455 Application Wizard, uncheck the "Precompiled headers" option.
456
457 @item Write the source code for your application, or, for testing, just
458 copy the code from an existing sample application into the source file
459 that Visual C++ has already created for you. (Note that your source
460 filehas to have a @code{.cpp} extension; otherwise, Visual C++ will not
461 compile the FFmpeg headers correctly because in C mode, it does not
462 recognize the @code{inline} keyword.) For example, you can copy
463 @file{output_example.c} from the FFmpeg distribution (but you will
464 have to make minor modifications so the code will compile under
465 C++, see below).
466
467 @item Open the "Project / Properties" dialog box. In the "Configuration"
468 combo box, select "All Configurations" so that the changes you make will
469 affect both debug and release builds. In the tree view on the left hand
470 side, select "C/C++ / General", then edit the "Additional Include
471 Directories" setting to contain the complete paths to the
472 @file{libavformat}, @file{libavcodec}, and @file{libavutil}
473 subdirectories of your FFmpeg directory. Note that the directories have
474 to be separated using semicolons. Now select "Linker / General" from the
475 tree view and edit the "Additional Library Directories" setting to
476 contain the same three directories.
477
478 @item Still in the "Project / Properties" dialog box, select "Linker / Input"
479 from the tree view, then add the files @file{avformat.lib},
480 @file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
481 Dependencies". Note that the names of the libraries have to be separated
482 using spaces.
483
484 @item Now, select "C/C++ / Code Generation" from the tree view. Select
485 "Debug" in the "Configuration" combo box. Make sure that "Runtime
486 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
487 the "Configuration" combo box and make sure that "Runtime Library" is
488 set to "Multi-threaded DLL".
489
490 @item Click "OK" to close the "Project / Properties" dialog box and build
491 the application. Hopefully, it should compile and run cleanly. If you
492 used @file{output_example.c} as your sample application, you will get a
493 few compiler errors, but they are easy to fix. The first type of error
494 occurs because Visual C++ does not allow an @code{int} to be converted to
495 an @code{enum} without a cast. To solve the problem, insert the required
496 casts (this error occurs once for a @code{CodecID} and once for a
497 @code{CodecType}). The second type of error occurs because C++ requires
498 the return value of @code{malloc} to be cast to the exact type of the
499 pointer it is being assigned to. Visual C++ will complain that, for
500 example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
501 an explicit cast. So insert an explicit cast in these places to silence
502 the compiler. The third type of error occurs because the @code{snprintf}
503 library function is called @code{_snprintf} under Visual C++. So just
504 add an underscore to fix the problem. With these changes,
505 @file{output_example.c} should compile under Visual C++, and the
506 resulting executable should produce valid video files.
507
508 @end enumerate
509
510 @subsection Cross compilation for Windows with Linux
511
512 You must use the MinGW cross compilation tools available at
513 @url{http://www.mingw.org/}.
514
515 Then configure FFmpeg with the following options:
516 @example
517 ./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
518 @end example
519 (you can change the cross-prefix according to the prefix chosen for the
520 MinGW tools).
521
522 Then you can easily test FFmpeg with Wine
523 (@url{http://www.winehq.com/}).
524
525 @subsection Compilation under Cygwin
526
527 Cygwin works very much like Unix.
528
529 Just install your Cygwin with all the "Base" packages, plus the
530 following "Devel" ones:
531 @example
532 binutils, gcc-core, make, subversion
533 @end example
534
535 Do not install binutils-20060709-1 (they are buggy on shared builds);
536 use binutils-20050610-1 instead.
537
538 Then run
539
540 @example
541 ./configure --enable-static --disable-shared
542 @end example
543
544 to make a static build or
545
546 @example
547 ./configure --enable-shared --disable-static
548 @end example
549
550 to build shared libraries.
551
552 If you want to build FFmpeg with additional libraries, download Cygwin
553 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
554 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
555 (@url{http://cygwinports.dotsrc.org/}).
556
557 @subsection Crosscompilation for Windows under Cygwin
558
559 With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
560
561 Just install your Cygwin as explained before, plus these additional
562 "Devel" packages:
563 @example
564 gcc-mingw-core, mingw-runtime, mingw-zlib
565 @end example
566
567 and add some special flags to your configure invocation.
568
569 For a static build run
570 @example
571 ./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
572 @end example
573
574 and for a build with shared libraries
575 @example
576 ./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
577 @end example
578
579 @section BeOS
580
581 BeOS support is broken in mysterious ways.
582
583 @chapter Developers Guide
584
585 @section API
586 @itemize @bullet
587 @item libavcodec is the library containing the codecs (both encoding and
588 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
589
590 @item libavformat is the library containing the file format handling (mux and
591 demux code for several formats). Look at @file{ffplay.c} to use it in a
592 player. See @file{output_example.c} to use it to generate audio or video
593 streams.
594
595 @end itemize
596
597 @section Integrating libavcodec or libavformat in your program
598
599 You can integrate all the source code of the libraries to link them
600 statically to avoid any version problem. All you need is to provide a
601 'config.mak' and a 'config.h' in the parent directory. See the defines
602 generated by ./configure to understand what is needed.
603
604 You can use libavcodec or libavformat in your commercial program, but
605 @emph{any patch you make must be published}. The best way to proceed is
606 to send your patches to the FFmpeg mailing list.
607
608 @node Coding Rules
609 @section Coding Rules
610
611 FFmpeg is programmed in the ISO C90 language with a few additional
612 features from ISO C99, namely:
613 @itemize @bullet
614 @item
615 the @samp{inline} keyword;
616 @item
617 @samp{//} comments;
618 @item
619 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
620 @item
621 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
622 @end itemize
623
624 These features are supported by all compilers we care about, so we will not
625 accept patches to remove their use unless they absolutely do not impair
626 clarity and performance.
627
628 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
629 compiles with several other compilers, such as the Compaq ccc compiler
630 or Sun Studio 9, and we would like to keep it that way unless it would
631 be exceedingly involved. To ensure compatibility, please do not use any
632 additional C99 features or GCC extensions. Especially watch out for:
633 @itemize @bullet
634 @item
635 mixing statements and declarations;
636 @item
637 @samp{long long} (use @samp{int64_t} instead);
638 @item
639 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
640 @item
641 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
642 @end itemize
643
644 Indent size is 4.
645 The presentation is the one specified by 'indent -i4 -kr -nut'.
646 The TAB character is forbidden outside of Makefiles as is any
647 form of trailing whitespace. Commits containing either will be
648 rejected by the Subversion repository.
649
650 The main priority in FFmpeg is simplicity and small code size in order to
651 minimize the bug count.
652
653 Comments: Use the JavaDoc/Doxygen
654 format (see examples below) so that code documentation
655 can be generated automatically. All nontrivial functions should have a comment
656 above them explaining what the function does, even if it is just one sentence.
657 All structures and their member variables should be documented, too.
658 @example
659 /**
660 * @@file mpeg.c
661 * MPEG codec.
662 * @@author ...
663 */
664
665 /**
666 * Summary sentence.
667 * more text ...
668 * ...
669 */
670 typedef struct Foobar@{
671 int var1; /**< var1 description */
672 int var2; ///< var2 description
673 /** var3 description */
674 int var3;
675 @} Foobar;
676
677 /**
678 * Summary sentence.
679 * more text ...
680 * ...
681 * @@param my_parameter description of my_parameter
682 * @@return return value description
683 */
684 int myfunc(int my_parameter)
685 ...
686 @end example
687
688 fprintf and printf are forbidden in libavformat and libavcodec,
689 please use av_log() instead.
690
691 Casts should be used only when necessary. Unneeded parentheses
692 should also be avoided if they don't make the code easier to understand.
693
694 @section Development Policy
695
696 @enumerate
697 @item
698 Contributions should be licensed under the LGPL 2.1, including an
699 "or any later version" clause, or the MIT license. GPL 2 including
700 an "or any later version" clause is also acceptable, but LGPL is
701 preferred.
702 @item
703 You must not commit code which breaks FFmpeg! (Meaning unfinished but
704 enabled code which breaks compilation or compiles but does not work or
705 breaks the regression tests)
706 You can commit unfinished stuff (for testing etc), but it must be disabled
707 (#ifdef etc) by default so it does not interfere with other developers'
708 work.
709 @item
710 You do not have to over-test things. If it works for you, and you think it
711 should work for others, then commit. If your code has problems
712 (portability, triggers compiler bugs, unusual environment etc) they will be
713 reported and eventually fixed.
714 @item
715 Do not commit unrelated changes together, split them into self-contained
716 pieces. Also do not forget that if part B depends on part A, but A does not
717 depend on B, then A can and should be committed first and separate from B.
718 Keeping changes well split into self-contained parts makes reviewing and
719 understanding them on the commit log mailing list easier. This also helps
720 in case of debugging later on.
721 Also if you have doubts about splitting or not splitting, do not hesitate to
722 ask/discuss it on the developer mailing list.
723 @item
724 Do not change behavior of the program (renaming options etc) without
725 first discussing it on the ffmpeg-devel mailing list. Do not remove
726 functionality from the code. Just improve!
727
728 Note: Redundant code can be removed.
729 @item
730 Do not commit changes to the build system (Makefiles, configure script)
731 which change behavior, defaults etc, without asking first. The same
732 applies to compiler warning fixes, trivial looking fixes and to code
733 maintained by other developers. We usually have a reason for doing things
734 the way we do. Send your changes as patches to the ffmpeg-devel mailing
735 list, and if the code maintainers say OK, you may commit. This does not
736 apply to files you wrote and/or maintain.
737 @item
738 We refuse source indentation and other cosmetic changes if they are mixed
739 with functional changes, such commits will be rejected and removed. Every
740 developer has his own indentation style, you should not change it. Of course
741 if you (re)write something, you can use your own style, even though we would
742 prefer if the indentation throughout FFmpeg was consistent (Many projects
743 force a given indentation style - we do not.). If you really need to make
744 indentation changes (try to avoid this), separate them strictly from real
745 changes.
746
747 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
748 then either do NOT change the indentation of the inner part within (do not
749 move it to the right)! or do so in a separate commit
750 @item
751 Always fill out the commit log message. Describe in a few lines what you
752 changed and why. You can refer to mailing list postings if you fix a
753 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
754 @item
755 If you apply a patch by someone else, include the name and email address in
756 the log message. Since the ffmpeg-cvslog mailing list is publicly
757 archived you should add some SPAM protection to the email address. Send an
758 answer to ffmpeg-devel (or wherever you got the patch from) saying that
759 you applied the patch.
760 @item
761 When applying patches that have been discussed (at length) on the mailing
762 list, reference the thread in the log message.
763 @item
764 Do NOT commit to code actively maintained by others without permission.
765 Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
766 timeframe (12h for build failures and security fixes, 3 days small changes,
767 1 week for big patches) then commit your patch if you think it is OK.
768 Also note, the maintainer can simply ask for more time to review!
769 @item
770 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
771 are sent there and reviewed by all the other developers. Bugs and possible
772 improvements or general questions regarding commits are discussed there. We
773 expect you to react if problems with your code are uncovered.
774 @item
775 Update the documentation if you change behavior or add features. If you are
776 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
777 maintainer(s) will review and commit your stuff.
778 @item
779 Try to keep important discussions and requests (also) on the public
780 developer mailing list, so that all developers can benefit from them.
781 @item
782 Never write to unallocated memory, never write over the end of arrays,
783 always check values read from some untrusted source before using them
784 as array index or other risky things.
785 @item
786 Remember to check if you need to bump versions for the specific libav
787 parts (libavutil, libavcodec, libavformat) you are changing. You need
788 to change the version integer and the version string.
789 Incrementing the first component means no backward compatibility to
790 previous versions (e.g. removal of a function from the public API).
791 Incrementing the second component means backward compatible change
792 (e.g. addition of a function to the public API).
793 Incrementing the third component means a noteworthy binary compatible
794 change (e.g. encoder bug fix that matters for the decoder).
795 @item
796 If you add a new codec, remember to update the changelog, add it to
797 the supported codecs table in the documentation and bump the second
798 component of the @file{libavcodec} version number appropriately. If
799 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
800 is only a decoder.
801 @item
802 Do not change code to hide warnings without ensuring that the underlying
803 logic is correct and thus the warning was inappropriate.
804 @item
805 If you add a new file, give it a proper license header. Do not copy and
806 paste it from a random place, use an existing file as template.
807 @end enumerate
808
809 We think our rules are not too hard. If you have comments, contact us.
810
811 Note, these rules are mostly borrowed from the MPlayer project.
812
813 @section Submitting patches
814
815 First, (@pxref{Coding Rules}) above if you did not yet.
816
817 When you submit your patch, try to send a unified diff (diff '-up'
818 option). We cannot read other diffs :-)
819
820 Also please do not submit a patch which contains several unrelated changes.
821 Split it into separate, self-contained pieces. This does not mean splitting
822 file by file. Instead, make the patch as small as possible while still
823 keeping it as a logical unit that contains an individual change, even
824 if it spans multiple files. This makes reviewing your patches much easier
825 for us and greatly increases your chances of getting your patch applied.
826
827 Run the regression tests before submitting a patch so that you can
828 verify that there are no big problems.
829
830 Patches should be posted as base64 encoded attachments (or any other
831 encoding which ensures that the patch will not be trashed during
832 transmission) to the ffmpeg-devel mailing list, see
833 @url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
834
835 It also helps quite a bit if you tell us what the patch does (for example
836 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
837 and has no lrint()')
838
839 Also please if you send several patches, send each patch as a separate mail,
840 do not attach several unrelated patches to the same mail.
841
842 @section patch submission checklist
843
844 @enumerate
845 @item
846 Do the regression tests pass with the patch applied?
847 @item
848 Is the patch a unified diff?
849 @item
850 Is the patch against latest FFmpeg SVN?
851 @item
852 Are you subscribed to ffmpeg-dev?
853 (the list is subscribers only due to spam)
854 @item
855 Have you checked that the changes are minimal, so that the same cannot be
856 achieved with a smaller patch and/or simpler final code?
857 @item
858 If the change is to speed critical code, did you benchmark it?
859 @item
860 If you did any benchmarks, did you provide them in the mail?
861 @item
862 Have you checked that the patch does not introduce buffer overflows or
863 other security issues?
864 @item
865 Is the patch created from the root of the source tree, so it can be
866 applied with @code{patch -p0}?
867 @item
868 Does the patch not mix functional and cosmetic changes?
869 @item
870 Did you add tabs or trailing whitespace to the code? Both are forbidden.
871 @item
872 Is the patch attached to the email you send?
873 @item
874 Is the mime type of the patch correct? It should be text/x-diff or
875 text/x-patch or at least text/plain and not application/octet-stream.
876 @item
877 If the patch fixes a bug, did you provide a verbose analysis of the bug?
878 @item
879 If the patch fixes a bug, did you provide enough information, including
880 a sample, so the bug can be reproduced and the fix can be verified?
881 Note please do not attach samples >100k to mails but rather provide a
882 URL, you can upload to ftp://upload.mplayerhq.hu
883 @item
884 Did you provide a verbose summary about what the patch does change?
885 @item
886 Did you provide a verbose explanation why it changes things like it does?
887 @item
888 Did you provide a verbose summary of the user visible advantages and
889 disadvantages if the patch is applied?
890 @item
891 Did you provide an example so we can verify the new feature added by the
892 patch easily?
893 @item
894 If you added a new file, did you insert a license header? It should be
895 taken from FFmpeg, not randomly copied and pasted from somewhere else.
896 @item
897 You should maintain alphabetical order in alphabetically ordered lists as
898 long as doing so does not break API/ABI compatibility.
899 @item
900 Lines with similar content should be aligned vertically when doing so
901 improves readability.
902 @item
903 Did you provide a suggestion for a clear commit log message?
904 @end enumerate
905
906 @section Patch review process
907
908 All patches posted to ffmpeg-devel will be reviewed, unless they contain a
909 clear note that the patch is not for SVN.
910 Reviews and comments will be posted as replies to the patch on the
911 mailing list. The patch submitter then has to take care of every comment,
912 that can be by resubmitting a changed patch or by discussion. Resubmitted
913 patches will themselves be reviewed like any other patch. If at some point
914 a patch passes review with no comments then it is approved, that can for
915 simple and small patches happen immediately while large patches will generally
916 have to be changed and reviewed many times before they are approved.
917 After a patch is approved it will be committed to the repository.
918
919 We will review all submitted patches, but sometimes we are quite busy so
920 especially for large patches this can take several weeks.
921
922 When resubmitting patches, please do not make any significant changes
923 not related to the comments received during review. Such patches will
924 be rejected. Instead, submit significant changes or new features as
925 separate patches.
926
927 @section Regression tests
928
929 Before submitting a patch (or committing to the repository), you should at least
930 test that you did not break anything.
931
932 The regression tests build a synthetic video stream and a synthetic
933 audio stream. These are then encoded and decoded with all codecs or
934 formats. The CRC (or MD5) of each generated file is recorded in a
935 result file. A 'diff' is launched to compare the reference results and
936 the result file.
937
938 The regression tests then go on to test the FFserver code with a
939 limited set of streams. It is important that this step runs correctly
940 as well.
941
942 Run 'make test' to test all the codecs and formats.
943
944 Run 'make fulltest' to test all the codecs, formats and FFserver.
945
946 [Of course, some patches may change the results of the regression tests. In
947 this case, the reference results of the regression tests shall be modified
948 accordingly].
949
950 @bye