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[libav.git] / doc / ffmpeg-doc.texi
1 \input texinfo @c -*- texinfo -*-
2
3 @settitle FFmpeg Documentation
4 @titlepage
5 @sp 7
6 @center @titlefont{FFmpeg Documentation}
7 @sp 3
8 @end titlepage
9
10
11 @chapter Introduction
12
13 FFmpeg is a very fast video and audio converter. It can also grab from
14 a live audio/video source.
15
16 The command line interface is designed to be intuitive, in the sense
17 that ffmpeg tries to figure out all the parameters, when
18 possible. You have usually to give only the target bitrate you want.
19
20 FFmpeg can also convert from any sample rate to any other, and resize
21 video on the fly with a high quality polyphase filter.
22
23 @chapter Quick Start
24
25 @section Video and Audio grabbing
26
27 FFmpeg can use a video4linux compatible video source and any Open Sound
28 System audio source:
29 @example
30 ffmpeg /tmp/out.mpg
31 @end example
32
33 Note that you must activate the right video source and channel
34 before launching ffmpeg. You can use any TV viewer such as xawtv by
35 Gerd Knorr which I find very good. You must also set correctly the
36 audio recording levels with a standard mixer.
37
38 @section Video and Audio file format convertion
39
40 * ffmpeg can use any supported file format and protocol as input:
41
42 Examples:
43
44 * You can input from YUV files:
45
46 @example
47 ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
48 @end example
49
50 It will use the files:
51 @example
52 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
53 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
54 @end example
55
56 The Y files use twice the resolution of the U and V files. They are
57 raw files, without header. They can be generated by all decent video
58 decoders. You must specify the size of the image with the '-s' option
59 if ffmpeg cannot guess it.
60
61 * You can input from a RAW YUV420P file:
62
63 @example
64 ffmpeg -i /tmp/test.yuv /tmp/out.avi
65 @end example
66
67 The RAW YUV420P is a file containing RAW YUV planar, for each frame first
68 come the Y plane followed by U and V planes, which are half vertical and
69 horizontal resolution.
70
71 * You can output to a RAW YUV420P file:
72
73 @example
74 ffmpeg -i mydivx.avi -o hugefile.yuv
75 @end example
76
77 * You can set several input files and output files:
78
79 @example
80 ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
81 @end example
82
83 Convert the audio file a.wav and the raw yuv video file a.yuv
84 to mpeg file a.mpg
85
86 * You can also do audio and video convertions at the same time:
87
88 @example
89 ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
90 @end example
91
92 Convert the sample rate of a.wav to 22050 Hz and encode it to MPEG audio.
93
94 * You can encode to several formats at the same time and define a
95 mapping from input stream to output streams:
96
97 @example
98 ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0
99 @end example
100
101 Convert a.wav to a.mp2 at 64 kbits and b.mp2 at 128 kbits. '-map
102 file:index' specify which input stream is used for each output
103 stream, in the order of the definition of output streams.
104
105 * You can transcode decrypted VOBs
106
107 @example
108 ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800 -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi
109 @end example
110
111 This is a typicall DVD ripper example, input from a VOB file, output
112 to an AVI file with MPEG-4 video and MP3 audio, note that in this
113 command we use B frames so the MPEG-4 stream is DivX5 compatible, GOP
114 size is 300 that means an INTRA frame every 10 seconds for 29.97 fps
115 input video. Also the audio stream is MP3 encoded so you need LAME
116 support which is enabled using @code{--enable-mp3lame} when
117 configuring. The mapping is particullary usefull for DVD transcoding
118 to get the desired audio language.
119
120 NOTE: to see the supported input formats, use @code{ffmpeg -formats}.
121
122 @chapter Invocation
123
124 @section Syntax
125
126 The generic syntax is:
127
128 @example
129 ffmpeg [[options][-i input_file]]... {[options] output_file}...
130 @end example
131 If no input file is given, audio/video grabbing is done.
132
133 As a general rule, options are applied to the next specified
134 file. For example, if you give the '-b 64' option, it sets the video
135 bitrate of the next file. Format option may be needed for raw input
136 files.
137
138 By default, ffmpeg tries to convert as losslessly as possible: it
139 uses the same audio and video parameter fors the outputs as the one
140 specified for the inputs.
141
142 @section Main options
143
144 @table @samp
145 @item -L
146 show license
147 @item -h
148 show help
149 @item -formats
150 show available formats, codecs, protocols, ...
151 @item -f fmt
152 force format
153 @item -i filename
154 input file name
155
156 @item -y
157 overwrite output files
158
159 @item -t duration
160 set the recording time in seconds. @code{hh:mm:ss[.xxx]} syntax is also
161 supported.
162
163 @item -title string
164 set the title
165
166 @item -author string
167 set the author
168
169 @item -copyright string
170 set the copyright
171
172 @item -comment string
173 set the comment
174
175 @item -b bitrate
176 set video bitrate (in kbit/s)
177 @end table
178
179 @section Video Options
180
181 @table @samp
182 @item -s size
183 set frame size [160x128]
184 @item -r fps
185 set frame rate [25]
186 @item -b bitrate
187 set the video bitrate in kbit/s [200]
188 @item -vn
189 disable video recording [no]
190 @item -bt tolerance
191 set video bitrate tolerance (in kbit/s)
192 @item -sameq
193 use same video quality as source (implies VBR)
194
195 @item -pass n
196 select the pass number (1 or 2). It is useful to do two pass encoding. The statistics of the video are recorded in the first pass and the video at the exact requested bit rate is generated in the second pass.
197
198 @item -passlogfile file
199 select two pass log file name
200
201 @end table
202
203 @section Audio Options
204
205 @table @samp
206 @item -ab bitrate
207 set audio bitrate (in kbit/s)
208 @item -ar freq
209 set the audio sampling freq [44100]
210 @item -ab bitrate
211 set the audio bitrate in kbit/s [64]
212 @item -ac channels
213 set the number of audio channels [1]
214 @item -an
215 disable audio recording [no]
216 @end table
217
218 @section Advanced options
219
220 @table @samp
221 @item -map file:stream
222 set input stream mapping
223 @item -g gop_size
224 set the group of picture size
225 @item -intra
226 use only intra frames
227 @item -qscale q
228 use fixed video quantiser scale (VBR)
229 @item -qmin q
230 min video quantiser scale (VBR)
231 @item -qmax q
232 max video quantiser scale (VBR)
233 @item -qdiff q
234 max difference between the quantiser scale (VBR)
235 @item -qblur blur
236 video quantiser scale blur (VBR)
237 @item -qcomp compression
238 video quantiser scale compression (VBR)
239 @item -vd device
240 set video device
241 @item -vcodec codec
242 force video codec
243 @item -me method
244 set motion estimation method
245 @item -bf frames
246 use 'frames' B frames (only MPEG-4)
247 @item -hq
248 activate high quality settings
249 @item -4mv
250 use four motion vector by macroblock (only MPEG-4)
251 @item -ad device
252 set audio device
253 @item -acodec codec
254 force audio codec
255 @item -deinterlace
256 deinterlace pictures
257 @item -benchmark
258 add timings for benchmarking
259 @item -hex
260 dump each input packet
261 @item -psnr
262 calculate PSNR of compressed frames
263 @item -vstats
264 dump video coding statistics to file
265 @end table
266
267 @section Protocols
268
269 The filename can be @file{-} to read from the standard input or to write
270 to the standard output.
271
272 ffmpeg handles also many protocols specified with the URL syntax.
273
274 Use 'ffmpeg -formats' to have a list of the supported protocols.
275
276 The protocol @code{http:} is currently used only to communicate with
277 ffserver (see the ffserver documentation). When ffmpeg will be a
278 video player it will also be used for streaming :-)
279
280 @chapter Tips
281
282 @itemize
283 @item For streaming at very low bit rate application, use a low frame rate
284 and a small gop size. This is especially true for real video where
285 the Linux player does not seem to be very fast, so it can miss
286 frames. An example is:
287
288 @example
289 ffmpeg -g 3 -r 3 -t 10 -b 50 -s qcif -f rv10 /tmp/b.rm
290 @end example
291
292 @item The parameter 'q' which is displayed while encoding is the current
293 quantizer. The value of 1 indicates that a very good quality could
294 be achieved. The value of 31 indicates the worst quality. If q=31
295 too often, it means that the encoder cannot compress enough to meet
296 your bit rate. You must either increase the bit rate, decrease the
297 frame rate or decrease the frame size.
298
299 @item If your computer is not fast enough, you can speed up the
300 compression at the expense of the compression ratio. You can use
301 '-me zero' to speed up motion estimation, and '-intra' to disable
302 completly motion estimation (you have only I frames, which means it
303 is about as good as JPEG compression).
304
305 @item To have very low bitrates in audio, reduce the sampling frequency
306 (down to 22050 kHz for mpeg audio, 22050 or 11025 for ac3).
307
308 @item To have a constant quality (but a variable bitrate), use the option
309 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
310 quality).
311
312 @item When converting video files, you can use the '-sameq' option which
313 uses in the encoder the same quality factor than in the decoder. It
314 allows to be almost lossless in encoding.
315
316 @end itemize
317
318 @chapter Supported File Formats and Codecs
319
320 You can use the @code{-formats} option to have an exhaustive list.
321
322 @section File Formats
323
324 FFmpeg supports the following file formats thru the @code{libavformat}
325 library.
326
327 @multitable @columnfractions .4 .1 .1
328 @item Supported File Format @tab Encoding @tab Decoding @tab Comments
329 @item MPEG audio @tab X @tab X
330 @item MPEG1 systems @tab X @tab X
331 @tab muxed audio and video
332 @item MPEG2 PS @tab X @tab X
333 @tab also known as @code{VOB} file
334 @item MPEG2 TS @tab @tab X
335 @tab also known as DVB Transport Stream
336 @item ASF@tab X @tab X
337 @item AVI@tab X @tab X
338 @item WAV@tab X @tab X
339 @item Macromedia Flash@tab X @tab X
340 @tab Only embedded audio is decoded
341 @item Real Audio and Video @tab X @tab X
342 @item PGM, YUV, PPM, JPEG images @tab X @tab X
343 @item Animated GIF @tab X @tab
344 @tab Only uncompressed GIFs are generated
345 @item Raw AC3 @tab X @tab X
346 @item Raw MJPEG @tab X @tab X
347 @item Raw MPEG video @tab X @tab X
348 @item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
349 @item SUN AU format @tab X @tab X
350 @item Quicktime @tab @tab X
351 @item MPEG4 @tab @tab X
352 @tab MPEG4 is a variant of Quicktime
353 @item Raw MPEG4 video @tab @tab X
354 @tab Only small files are supported.
355 @item DV @tab @tab X
356 @tab Only the video track is decoded.
357 @end multitable
358
359 @code{X} means that the encoding (resp. decoding) is supported.
360
361 @section Video Codecs
362
363 @multitable @columnfractions .4 .1 .1 .7
364 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
365 @item MPEG1 video @tab X @tab X
366 @item MPEG2 video @tab @tab X
367 @item MPEG4 @tab X @tab X @tab Also known as DIVX4/5
368 @item MSMPEG4 V1 @tab X @tab X
369 @item MSMPEG4 V2 @tab X @tab X
370 @item MSMPEG4 V3 @tab X @tab X @tab Also known as DIVX3
371 @item WMV7 @tab X @tab X
372 @item H263(+) @tab X @tab X @tab Also known as Real Video 1.0
373 @item MJPEG @tab X @tab X
374 @item DV @tab @tab X
375 @item Huff YUV @tab X @tab X
376 @end multitable
377
378 @code{X} means that the encoding (resp. decoding) is supported.
379
380 Check at @url{http://www.mplayerhq.hu/~michael/codec-features.html} to
381 get a precise comparison of FFmpeg MPEG4 codec compared to the other
382 solutions.
383
384 @section Audio Codecs
385
386 @multitable @columnfractions .4 .1 .1 .1 .7
387 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
388 @item MPEG audio layer 2 @tab IX @tab IX
389 @item MPEG audio layer 1/3 @tab IX @tab IX
390 @tab MP3 encoding is supported thru the external library LAME
391 @item AC3 @tab IX @tab X
392 @tab liba52 is used internally for decoding.
393 @item Vorbis @tab X @tab
394 @tab encoding is supported thru the external library libvorbis.
395 @item WMA V1/V2 @tab @tab X
396
397 @end multitable
398
399 @code{X} means that the encoding (resp. decoding) is supported.
400
401 @code{I} means that an integer only version is available too (ensures highest
402 performances on systems without hardware floating point support).
403
404 @chapter Platform Specific information
405
406 @section Linux
407
408 ffmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
409 prefered compiler now for ffmpeg. All futur optimizations will depend on
410 features only found in GCC 3.2.
411
412 @section BSD
413
414 @section Windows
415
416 @section MacOS X
417
418 @section BeOS
419
420 The configure script should guess the configuration itself.
421 Networking support is currently not finished.
422 errno issues fixed by Andrew Bachmann.
423
424 Old stuff:
425
426 Fran├žois Revol - revol at free dot fr - April 2002
427
428 The configure script should guess the configuration itself,
429 however I still didn't tested building on net_server version of BeOS.
430
431 ffserver is broken (needs poll() implementation).
432
433 There is still issues with errno codes, which are negative in BeOs, and
434 that ffmpeg negates when returning. This ends up turning errors into
435 valid results, then crashes.
436 (To be fixed)
437
438 @chapter Developpers Guide
439
440 @section API
441 @itemize
442 @item libavcodec is the library containing the codecs (both encoding and
443 decoding). See @file{libavcodec/apiexample.c} to see how to use it.
444
445 @item libavformat is the library containing the file formats handling (mux and
446 demux code for several formats). (no example yet, the API is likely to
447 evolve).
448 @end itemize
449
450 @section Integrating libavcodec or libavformat in your program
451
452 You can integrate all the source code of the libraries to link them
453 statically to avoid any version problem. All you need is to provide a
454 'config.mak' and a 'config.h' in the parent directory. See the defines
455 generated by ./configure to understand what is needed.
456
457 You can use libavcodec or libavformat in your commercial program, but
458 @emph{any patch you make must be published}. The best way to proceed is
459 to send your patches to the ffmpeg mailing list.
460
461 @section Coding Rules
462
463 ffmpeg is programmed in ANSI C language. GCC extensions are
464 tolerated. Indent size is 4. The TAB character should not be used.
465
466 The presentation is the one specified by 'indent -i4 -kr'.
467
468 Main priority in ffmpeg is simplicity and small code size (=less
469 bugs).
470
471 Comments: for functions visible from other modules, use the JavaDoc
472 format (see examples in @file{libav/utils.c}) so that a documentation
473 can be generated automatically.
474
475 @section Submitting patches
476
477 When you submit your patch, try to send a unified diff (diff '-u'
478 option). I cannot read other diffs :-)
479
480 Run the regression tests before submitting a patch so that you can
481 verify that there is no big problems.
482
483 Except if your patch is really big and adds an important feature, by
484 submitting it to me, you accept implicitely to put it under my
485 copyright. I prefer to do this to avoid potential problems if
486 licensing of ffmpeg changes.
487
488 Patches should be posted as base64 encoded attachments (or any other
489 encoding which ensures that the patch wont be trashed during
490 transmission) to the ffmpeg-devel mailinglist, see
491 @url{http://lists.sourceforge.net/lists/listinfo/ffmpeg-devel}
492
493 @section Regression tests
494
495 Before submitting a patch (or commiting with CVS), you should at least
496 test that you did not break anything.
497
498 The regression test build a synthetic video stream and a synthetic
499 audio stream. Then there are encoded then decoded with all codecs or
500 formats. The CRC (or MD5) of each generated file is recorded in a
501 result file. Then a 'diff' is launched with the reference results and
502 the result file.
503
504 Run 'make test' to test all the codecs.
505
506 Run 'make libavtest' to test all the codecs.
507
508 [Of course, some patches may change the regression tests results. In
509 this case, the regression tests reference results shall be modified
510 accordingly].
511
512 @bye