DNxHD (SMPTE VC-3) encoder
[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 X @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 @item AMV @tab @tab X @tab Used in Chinese MP3 players.
235 @end multitable
236
237 @code{X} means that encoding (resp. decoding) is supported.
238
239 @section Audio Codecs
240
241 @multitable @columnfractions .4 .1 .1 .1 .7
242 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
243 @item MPEG audio layer 2 @tab IX @tab IX
244 @item MPEG audio layer 1/3 @tab IX @tab IX
245 @tab MP3 encoding is supported through the external library LAME.
246 @item AC3 @tab IX @tab IX
247 @tab liba52 is used internally for decoding.
248 @item Vorbis @tab X @tab X
249 @item WMA V1/V2 @tab X @tab X
250 @item AAC @tab X @tab X
251 @tab Supported through the external library libfaac/libfaad.
252 @item Microsoft ADPCM @tab X @tab X
253 @item AMV IMA ADPCM @tab @tab X
254 @tab Used in AMV files
255 @item MS IMA ADPCM @tab X @tab X
256 @item QT IMA ADPCM @tab @tab X
257 @item 4X IMA ADPCM @tab @tab X
258 @item G.726 ADPCM @tab X @tab X
259 @item Duck DK3 IMA ADPCM @tab @tab X
260 @tab Used in some Sega Saturn console games.
261 @item Duck DK4 IMA ADPCM @tab @tab X
262 @tab Used in some Sega Saturn console games.
263 @item Westwood Studios IMA ADPCM @tab @tab X
264 @tab Used in Westwood Studios games like Command and Conquer.
265 @item SMJPEG IMA ADPCM @tab @tab X
266 @tab Used in certain Loki game ports.
267 @item CD-ROM XA ADPCM @tab @tab X
268 @item CRI ADX ADPCM @tab X @tab X
269 @tab Used in Sega Dreamcast games.
270 @item Electronic Arts ADPCM @tab @tab X
271 @tab Used in various EA titles.
272 @item Creative ADPCM @tab @tab X
273 @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
274 @item THP ADPCM @tab @tab X
275 @tab Used on the Nintendo GameCube.
276 @item RA144 @tab @tab X
277 @tab Real 14400 bit/s codec
278 @item RA288 @tab @tab X
279 @tab Real 28800 bit/s codec
280 @item RADnet @tab X @tab IX
281 @tab Real low bitrate AC3 codec, liba52 is used for decoding.
282 @item AMR-NB @tab X @tab X
283 @tab Supported through an external library.
284 @item AMR-WB @tab X @tab X
285 @tab Supported through an external library.
286 @item DV audio @tab @tab X
287 @item Id RoQ DPCM @tab X @tab X
288 @tab Used in Quake III, Jedi Knight 2, other computer games.
289 @item Interplay MVE DPCM @tab @tab X
290 @tab Used in various Interplay computer games.
291 @item Xan DPCM @tab @tab X
292 @tab Used in Origin's Wing Commander IV AVI files.
293 @item Sierra Online DPCM @tab @tab X
294 @tab Used in Sierra Online game audio files.
295 @item Apple MACE 3 @tab @tab X
296 @item Apple MACE 6 @tab @tab X
297 @item FLAC lossless audio @tab X @tab X
298 @item Shorten lossless audio @tab @tab X
299 @item Apple lossless audio @tab @tab X
300 @tab QuickTime fourcc 'alac'
301 @item FFmpeg Sonic @tab X @tab X
302 @tab experimental lossy/lossless codec
303 @item Qdesign QDM2 @tab @tab X
304 @tab there are still some distortions
305 @item Real COOK @tab @tab X
306 @tab All versions except 5.1 are supported
307 @item DSP Group TrueSpeech @tab @tab X
308 @item True Audio (TTA) @tab @tab X
309 @item Smacker Audio @tab @tab X
310 @item WavPack Audio @tab @tab X
311 @item Cin Audio @tab @tab X
312 @tab Codec used in Delphine Software games.
313 @item Intel Music Coder @tab @tab X
314 @item Musepack @tab @tab X
315 @tab Only SV7 is supported
316 @item DT$ Coherent Audio @tab @tab X
317 @item ATRAC 3 @tab @tab X
318 @item Monkey's Audio @tab @tab X @tab Only versions 3.97-3.99 are supported
319 @end multitable
320
321 @code{X} means that encoding (resp. decoding) is supported.
322
323 @code{I} means that an integer-only version is available, too (ensures high
324 performance on systems without hardware floating point support).
325
326 @chapter Platform Specific information
327
328 @section BSD
329
330 BSD make will not build FFmpeg, you need to install and use GNU Make
331 (@file{gmake}).
332
333 @section Windows
334
335 To get help and instructions for using FFmpeg under Windows, check out
336 the FFmpeg Windows Help Forum at
337 @url{http://arrozcru.no-ip.org/ffmpeg/}.
338
339 @subsection Native Windows compilation
340
341 @itemize
342 @item Install the current versions of MSYS and MinGW from
343 @url{http://www.mingw.org/}. You can find detailed installation
344 instructions in the download section and the FAQ.
345
346 NOTE: Use at least bash 3.1. Older versions are known to be failing on the
347 configure script.
348
349 @item If you want to test the FFplay, also download
350 the MinGW development library of SDL 1.2.x
351 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
352 @url{http://www.libsdl.org}. Unpack it in a temporary directory, and
353 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
354 directory. Edit the @file{sdl-config} script so that it gives the
355 correct SDL directory when invoked.
356
357 @item If you want to use vhooks, you must have a POSIX compliant libdl in your
358 MinGW system. Get dlfcn-win32 from @url{http://code.google.com/p/dlfcn-win32}.
359
360 @item Extract the current version of FFmpeg.
361
362 @item Start the MSYS shell (file @file{msys.bat}).
363
364 @item Change to the FFmpeg directory and follow
365 the instructions of how to compile FFmpeg (file
366 @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
367 suffices. If you have problems using SDL, verify that
368 @file{sdl-config} can be launched from the MSYS command line.
369
370 @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
371 @file{make install}. Do not forget to copy @file{SDL.dll} to the place
372 you launch @file{ffplay} from.
373
374 @end itemize
375
376 Notes:
377 @itemize
378
379 @item The target @file{make wininstaller} can be used to create a
380 Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
381 must be copied to the FFmpeg directory in order to build the
382 installer.
383
384 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
385 you can build @file{avcodec.dll} and @file{avformat.dll}. With
386 @code{make install} you install the FFmpeg DLLs and the associated
387 headers in @file{Program Files/FFmpeg}.
388
389 @item Visual C++ compatibility: If you used @code{./configure --enable-shared}
390 when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
391 C++ @code{lib} tool to build @code{avcodec.lib} and
392 @code{avformat.lib}. With these libraries you can link your Visual C++
393 code directly with the FFmpeg DLLs (see below).
394
395 @end itemize
396
397 @subsection Visual C++ compatibility
398
399 FFmpeg will not compile under Visual C++ -- and it has too many
400 dependencies on the GCC compiler to make a port viable. However,
401 if you want to use the FFmpeg libraries in your own applications,
402 you can still compile those applications using Visual C++. An
403 important restriction to this is that you have to use the
404 dynamically linked versions of the FFmpeg libraries (i.e. the
405 DLLs), and you have to make sure that Visual-C++-compatible
406 import libraries are created during the FFmpeg build process.
407
408 This description of how to use the FFmpeg libraries with Visual C++ is
409 based on Visual C++ 2005 Express Edition Beta 2. If you have a different
410 version, you might have to modify the procedures slightly.
411
412 Here are the step-by-step instructions for building the FFmpeg libraries
413 so they can be used with Visual C++:
414
415 @enumerate
416
417 @item Install Visual C++ (if you have not done so already).
418
419 @item Install MinGW and MSYS as described above.
420
421 @item Add a call to @file{vcvars32.bat} (which sets up the environment
422 variables for the Visual C++ tools) as the first line of
423 @file{msys.bat}. The standard location for @file{vcvars32.bat} is
424 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
425 and the standard location for @file{msys.bat} is
426 @file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
427 following line as the first line of @file{msys.bat}:
428
429 @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
430
431 @item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
432 If you get a help message with the command line options of @code{link.exe},
433 this means your environment variables are set up correctly, the
434 Microsoft linker is on the path and will be used by FFmpeg to
435 create Visual-C++-compatible import libraries.
436
437 @item Extract the current version of FFmpeg and change to the FFmpeg directory.
438
439 @item Type the command
440 @code{./configure --enable-shared --disable-static --enable-memalign-hack}
441 to configure and, if that did not produce any errors,
442 type @code{make} to build FFmpeg.
443
444 @item The subdirectories @file{libavformat}, @file{libavcodec}, and
445 @file{libavutil} should now contain the files @file{avformat.dll},
446 @file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
447 @file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
448 DLLs to your System32 directory (typically @file{C:\Windows\System32}).
449
450 @end enumerate
451
452 And here is how to use these libraries with Visual C++:
453
454 @enumerate
455
456 @item Create a new console application ("File / New / Project") and then
457 select "Win32 Console Application". On the appropriate page of the
458 Application Wizard, uncheck the "Precompiled headers" option.
459
460 @item Write the source code for your application, or, for testing, just
461 copy the code from an existing sample application into the source file
462 that Visual C++ has already created for you. (Note that your source
463 filehas to have a @code{.cpp} extension; otherwise, Visual C++ will not
464 compile the FFmpeg headers correctly because in C mode, it does not
465 recognize the @code{inline} keyword.) For example, you can copy
466 @file{output_example.c} from the FFmpeg distribution (but you will
467 have to make minor modifications so the code will compile under
468 C++, see below).
469
470 @item Open the "Project / Properties" dialog box. In the "Configuration"
471 combo box, select "All Configurations" so that the changes you make will
472 affect both debug and release builds. In the tree view on the left hand
473 side, select "C/C++ / General", then edit the "Additional Include
474 Directories" setting to contain the complete paths to the
475 @file{libavformat}, @file{libavcodec}, and @file{libavutil}
476 subdirectories of your FFmpeg directory. Note that the directories have
477 to be separated using semicolons. Now select "Linker / General" from the
478 tree view and edit the "Additional Library Directories" setting to
479 contain the same three directories.
480
481 @item Still in the "Project / Properties" dialog box, select "Linker / Input"
482 from the tree view, then add the files @file{avformat.lib},
483 @file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
484 Dependencies". Note that the names of the libraries have to be separated
485 using spaces.
486
487 @item Now, select "C/C++ / Code Generation" from the tree view. Select
488 "Debug" in the "Configuration" combo box. Make sure that "Runtime
489 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
490 the "Configuration" combo box and make sure that "Runtime Library" is
491 set to "Multi-threaded DLL".
492
493 @item Click "OK" to close the "Project / Properties" dialog box and build
494 the application. Hopefully, it should compile and run cleanly. If you
495 used @file{output_example.c} as your sample application, you will get a
496 few compiler errors, but they are easy to fix. The first type of error
497 occurs because Visual C++ does not allow an @code{int} to be converted to
498 an @code{enum} without a cast. To solve the problem, insert the required
499 casts (this error occurs once for a @code{CodecID} and once for a
500 @code{CodecType}). The second type of error occurs because C++ requires
501 the return value of @code{malloc} to be cast to the exact type of the
502 pointer it is being assigned to. Visual C++ will complain that, for
503 example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
504 an explicit cast. So insert an explicit cast in these places to silence
505 the compiler. The third type of error occurs because the @code{snprintf}
506 library function is called @code{_snprintf} under Visual C++. So just
507 add an underscore to fix the problem. With these changes,
508 @file{output_example.c} should compile under Visual C++, and the
509 resulting executable should produce valid video files.
510
511 @end enumerate
512
513 @subsection Cross compilation for Windows with Linux
514
515 You must use the MinGW cross compilation tools available at
516 @url{http://www.mingw.org/}.
517
518 Then configure FFmpeg with the following options:
519 @example
520 ./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
521 @end example
522 (you can change the cross-prefix according to the prefix chosen for the
523 MinGW tools).
524
525 Then you can easily test FFmpeg with Wine
526 (@url{http://www.winehq.com/}).
527
528 @subsection Compilation under Cygwin
529
530 Cygwin works very much like Unix.
531
532 Just install your Cygwin with all the "Base" packages, plus the
533 following "Devel" ones:
534 @example
535 binutils, gcc-core, make, subversion
536 @end example
537
538 Do not install binutils-20060709-1 (they are buggy on shared builds);
539 use binutils-20050610-1 instead.
540
541 Then run
542
543 @example
544 ./configure --enable-static --disable-shared
545 @end example
546
547 to make a static build or
548
549 @example
550 ./configure --enable-shared --disable-static
551 @end example
552
553 to build shared libraries.
554
555 If you want to build FFmpeg with additional libraries, download Cygwin
556 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
557 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
558 (@url{http://cygwinports.dotsrc.org/}).
559
560 @subsection Crosscompilation for Windows under Cygwin
561
562 With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
563
564 Just install your Cygwin as explained before, plus these additional
565 "Devel" packages:
566 @example
567 gcc-mingw-core, mingw-runtime, mingw-zlib
568 @end example
569
570 and add some special flags to your configure invocation.
571
572 For a static build run
573 @example
574 ./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
575 @end example
576
577 and for a build with shared libraries
578 @example
579 ./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
580 @end example
581
582 @section BeOS
583
584 BeOS support is broken in mysterious ways.
585
586 @chapter Developers Guide
587
588 @section API
589 @itemize @bullet
590 @item libavcodec is the library containing the codecs (both encoding and
591 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
592
593 @item libavformat is the library containing the file format handling (mux and
594 demux code for several formats). Look at @file{ffplay.c} to use it in a
595 player. See @file{output_example.c} to use it to generate audio or video
596 streams.
597
598 @end itemize
599
600 @section Integrating libavcodec or libavformat in your program
601
602 You can integrate all the source code of the libraries to link them
603 statically to avoid any version problem. All you need is to provide a
604 'config.mak' and a 'config.h' in the parent directory. See the defines
605 generated by ./configure to understand what is needed.
606
607 You can use libavcodec or libavformat in your commercial program, but
608 @emph{any patch you make must be published}. The best way to proceed is
609 to send your patches to the FFmpeg mailing list.
610
611 @node Coding Rules
612 @section Coding Rules
613
614 FFmpeg is programmed in the ISO C90 language with a few additional
615 features from ISO C99, namely:
616 @itemize @bullet
617 @item
618 the @samp{inline} keyword;
619 @item
620 @samp{//} comments;
621 @item
622 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
623 @item
624 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
625 @end itemize
626
627 These features are supported by all compilers we care about, so we will not
628 accept patches to remove their use unless they absolutely do not impair
629 clarity and performance.
630
631 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
632 compiles with several other compilers, such as the Compaq ccc compiler
633 or Sun Studio 9, and we would like to keep it that way unless it would
634 be exceedingly involved. To ensure compatibility, please do not use any
635 additional C99 features or GCC extensions. Especially watch out for:
636 @itemize @bullet
637 @item
638 mixing statements and declarations;
639 @item
640 @samp{long long} (use @samp{int64_t} instead);
641 @item
642 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
643 @item
644 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
645 @end itemize
646
647 Indent size is 4.
648 The presentation is the one specified by 'indent -i4 -kr -nut'.
649 The TAB character is forbidden outside of Makefiles as is any
650 form of trailing whitespace. Commits containing either will be
651 rejected by the Subversion repository.
652
653 The main priority in FFmpeg is simplicity and small code size in order to
654 minimize the bug count.
655
656 Comments: Use the JavaDoc/Doxygen
657 format (see examples below) so that code documentation
658 can be generated automatically. All nontrivial functions should have a comment
659 above them explaining what the function does, even if it is just one sentence.
660 All structures and their member variables should be documented, too.
661 @example
662 /**
663 * @@file mpeg.c
664 * MPEG codec.
665 * @@author ...
666 */
667
668 /**
669 * Summary sentence.
670 * more text ...
671 * ...
672 */
673 typedef struct Foobar@{
674 int var1; /**< var1 description */
675 int var2; ///< var2 description
676 /** var3 description */
677 int var3;
678 @} Foobar;
679
680 /**
681 * Summary sentence.
682 * more text ...
683 * ...
684 * @@param my_parameter description of my_parameter
685 * @@return return value description
686 */
687 int myfunc(int my_parameter)
688 ...
689 @end example
690
691 fprintf and printf are forbidden in libavformat and libavcodec,
692 please use av_log() instead.
693
694 Casts should be used only when necessary. Unneeded parentheses
695 should also be avoided if they don't make the code easier to understand.
696
697 @section Development Policy
698
699 @enumerate
700 @item
701 Contributions should be licensed under the LGPL 2.1, including an
702 "or any later version" clause, or the MIT license. GPL 2 including
703 an "or any later version" clause is also acceptable, but LGPL is
704 preferred.
705 @item
706 You must not commit code which breaks FFmpeg! (Meaning unfinished but
707 enabled code which breaks compilation or compiles but does not work or
708 breaks the regression tests)
709 You can commit unfinished stuff (for testing etc), but it must be disabled
710 (#ifdef etc) by default so it does not interfere with other developers'
711 work.
712 @item
713 You do not have to over-test things. If it works for you, and you think it
714 should work for others, then commit. If your code has problems
715 (portability, triggers compiler bugs, unusual environment etc) they will be
716 reported and eventually fixed.
717 @item
718 Do not commit unrelated changes together, split them into self-contained
719 pieces. Also do not forget that if part B depends on part A, but A does not
720 depend on B, then A can and should be committed first and separate from B.
721 Keeping changes well split into self-contained parts makes reviewing and
722 understanding them on the commit log mailing list easier. This also helps
723 in case of debugging later on.
724 Also if you have doubts about splitting or not splitting, do not hesitate to
725 ask/discuss it on the developer mailing list.
726 @item
727 Do not change behavior of the program (renaming options etc) without
728 first discussing it on the ffmpeg-devel mailing list. Do not remove
729 functionality from the code. Just improve!
730
731 Note: Redundant code can be removed.
732 @item
733 Do not commit changes to the build system (Makefiles, configure script)
734 which change behavior, defaults etc, without asking first. The same
735 applies to compiler warning fixes, trivial looking fixes and to code
736 maintained by other developers. We usually have a reason for doing things
737 the way we do. Send your changes as patches to the ffmpeg-devel mailing
738 list, and if the code maintainers say OK, you may commit. This does not
739 apply to files you wrote and/or maintain.
740 @item
741 We refuse source indentation and other cosmetic changes if they are mixed
742 with functional changes, such commits will be rejected and removed. Every
743 developer has his own indentation style, you should not change it. Of course
744 if you (re)write something, you can use your own style, even though we would
745 prefer if the indentation throughout FFmpeg was consistent (Many projects
746 force a given indentation style - we do not.). If you really need to make
747 indentation changes (try to avoid this), separate them strictly from real
748 changes.
749
750 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
751 then either do NOT change the indentation of the inner part within (do not
752 move it to the right)! or do so in a separate commit
753 @item
754 Always fill out the commit log message. Describe in a few lines what you
755 changed and why. You can refer to mailing list postings if you fix a
756 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
757 @item
758 If you apply a patch by someone else, include the name and email address in
759 the log message. Since the ffmpeg-cvslog mailing list is publicly
760 archived you should add some SPAM protection to the email address. Send an
761 answer to ffmpeg-devel (or wherever you got the patch from) saying that
762 you applied the patch.
763 @item
764 When applying patches that have been discussed (at length) on the mailing
765 list, reference the thread in the log message.
766 @item
767 Do NOT commit to code actively maintained by others without permission.
768 Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
769 timeframe (12h for build failures and security fixes, 3 days small changes,
770 1 week for big patches) then commit your patch if you think it is OK.
771 Also note, the maintainer can simply ask for more time to review!
772 @item
773 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
774 are sent there and reviewed by all the other developers. Bugs and possible
775 improvements or general questions regarding commits are discussed there. We
776 expect you to react if problems with your code are uncovered.
777 @item
778 Update the documentation if you change behavior or add features. If you are
779 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
780 maintainer(s) will review and commit your stuff.
781 @item
782 Try to keep important discussions and requests (also) on the public
783 developer mailing list, so that all developers can benefit from them.
784 @item
785 Never write to unallocated memory, never write over the end of arrays,
786 always check values read from some untrusted source before using them
787 as array index or other risky things.
788 @item
789 Remember to check if you need to bump versions for the specific libav
790 parts (libavutil, libavcodec, libavformat) you are changing. You need
791 to change the version integer and the version string.
792 Incrementing the first component means no backward compatibility to
793 previous versions (e.g. removal of a function from the public API).
794 Incrementing the second component means backward compatible change
795 (e.g. addition of a function to the public API).
796 Incrementing the third component means a noteworthy binary compatible
797 change (e.g. encoder bug fix that matters for the decoder).
798 @item
799 If you add a new codec, remember to update the changelog, add it to
800 the supported codecs table in the documentation and bump the second
801 component of the @file{libavcodec} version number appropriately. If
802 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
803 is only a decoder.
804 @item
805 Do not change code to hide warnings without ensuring that the underlying
806 logic is correct and thus the warning was inappropriate.
807 @item
808 If you add a new file, give it a proper license header. Do not copy and
809 paste it from a random place, use an existing file as template.
810 @end enumerate
811
812 We think our rules are not too hard. If you have comments, contact us.
813
814 Note, these rules are mostly borrowed from the MPlayer project.
815
816 @section Submitting patches
817
818 First, (@pxref{Coding Rules}) above if you did not yet.
819
820 When you submit your patch, try to send a unified diff (diff '-up'
821 option). We cannot read other diffs :-)
822
823 Also please do not submit a patch which contains several unrelated changes.
824 Split it into separate, self-contained pieces. This does not mean splitting
825 file by file. Instead, make the patch as small as possible while still
826 keeping it as a logical unit that contains an individual change, even
827 if it spans multiple files. This makes reviewing your patches much easier
828 for us and greatly increases your chances of getting your patch applied.
829
830 Run the regression tests before submitting a patch so that you can
831 verify that there are no big problems.
832
833 Patches should be posted as base64 encoded attachments (or any other
834 encoding which ensures that the patch will not be trashed during
835 transmission) to the ffmpeg-devel mailing list, see
836 @url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
837
838 It also helps quite a bit if you tell us what the patch does (for example
839 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
840 and has no lrint()')
841
842 Also please if you send several patches, send each patch as a separate mail,
843 do not attach several unrelated patches to the same mail.
844
845 @section patch submission checklist
846
847 @enumerate
848 @item
849 Do the regression tests pass with the patch applied?
850 @item
851 Is the patch a unified diff?
852 @item
853 Is the patch against latest FFmpeg SVN?
854 @item
855 Are you subscribed to ffmpeg-dev?
856 (the list is subscribers only due to spam)
857 @item
858 Have you checked that the changes are minimal, so that the same cannot be
859 achieved with a smaller patch and/or simpler final code?
860 @item
861 If the change is to speed critical code, did you benchmark it?
862 @item
863 If you did any benchmarks, did you provide them in the mail?
864 @item
865 Have you checked that the patch does not introduce buffer overflows or
866 other security issues?
867 @item
868 Is the patch created from the root of the source tree, so it can be
869 applied with @code{patch -p0}?
870 @item
871 Does the patch not mix functional and cosmetic changes?
872 @item
873 Did you add tabs or trailing whitespace to the code? Both are forbidden.
874 @item
875 Is the patch attached to the email you send?
876 @item
877 Is the mime type of the patch correct? It should be text/x-diff or
878 text/x-patch or at least text/plain and not application/octet-stream.
879 @item
880 If the patch fixes a bug, did you provide a verbose analysis of the bug?
881 @item
882 If the patch fixes a bug, did you provide enough information, including
883 a sample, so the bug can be reproduced and the fix can be verified?
884 Note please do not attach samples >100k to mails but rather provide a
885 URL, you can upload to ftp://upload.mplayerhq.hu
886 @item
887 Did you provide a verbose summary about what the patch does change?
888 @item
889 Did you provide a verbose explanation why it changes things like it does?
890 @item
891 Did you provide a verbose summary of the user visible advantages and
892 disadvantages if the patch is applied?
893 @item
894 Did you provide an example so we can verify the new feature added by the
895 patch easily?
896 @item
897 If you added a new file, did you insert a license header? It should be
898 taken from FFmpeg, not randomly copied and pasted from somewhere else.
899 @item
900 You should maintain alphabetical order in alphabetically ordered lists as
901 long as doing so does not break API/ABI compatibility.
902 @item
903 Lines with similar content should be aligned vertically when doing so
904 improves readability.
905 @item
906 Did you provide a suggestion for a clear commit log message?
907 @end enumerate
908
909 @section Patch review process
910
911 All patches posted to ffmpeg-devel will be reviewed, unless they contain a
912 clear note that the patch is not for SVN.
913 Reviews and comments will be posted as replies to the patch on the
914 mailing list. The patch submitter then has to take care of every comment,
915 that can be by resubmitting a changed patch or by discussion. Resubmitted
916 patches will themselves be reviewed like any other patch. If at some point
917 a patch passes review with no comments then it is approved, that can for
918 simple and small patches happen immediately while large patches will generally
919 have to be changed and reviewed many times before they are approved.
920 After a patch is approved it will be committed to the repository.
921
922 We will review all submitted patches, but sometimes we are quite busy so
923 especially for large patches this can take several weeks.
924
925 When resubmitting patches, please do not make any significant changes
926 not related to the comments received during review. Such patches will
927 be rejected. Instead, submit significant changes or new features as
928 separate patches.
929
930 @section Regression tests
931
932 Before submitting a patch (or committing to the repository), you should at least
933 test that you did not break anything.
934
935 The regression tests build a synthetic video stream and a synthetic
936 audio stream. These are then encoded and decoded with all codecs or
937 formats. The CRC (or MD5) of each generated file is recorded in a
938 result file. A 'diff' is launched to compare the reference results and
939 the result file.
940
941 The regression tests then go on to test the FFserver code with a
942 limited set of streams. It is important that this step runs correctly
943 as well.
944
945 Run 'make test' to test all the codecs and formats.
946
947 Run 'make fulltest' to test all the codecs, formats and FFserver.
948
949 [Of course, some patches may change the results of the regression tests. In
950 this case, the reference results of the regression tests shall be modified
951 accordingly].
952
953 @bye