Statistics
| Branch: | Revision:

ffmpeg / doc / ffmpeg-doc.texi @ e839a994

History | View | Annotate | Download (44.6 KB)

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 parameters that can possibly be
18
derived automatically. You usually only have to specify the target
19
bitrate you want.
20

    
21
FFmpeg can also convert from any sample rate to any other, and resize
22
video on the fly with a high quality polyphase filter.
23

    
24
@chapter Quick Start
25

    
26
@c man begin EXAMPLES
27
@section Video and Audio grabbing
28

    
29
FFmpeg can use a video4linux compatible video source and any Open Sound
30
System audio source:
31

    
32
@example
33
ffmpeg /tmp/out.mpg
34
@end example
35

    
36
Note that you must activate the right video source and channel before
37
launching FFmpeg with any TV viewer such as xawtv
38
(@url{http://bytesex.org/xawtv/}) by Gerd Knorr. You also
39
have to set the audio recording levels correctly with a
40
standard mixer.
41

    
42
@section Video and Audio file format conversion
43

    
44
* FFmpeg can use any supported file format and protocol as input:
45

    
46
Examples:
47

    
48
* You can use YUV files as input:
49

    
50
@example
51
ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
52
@end example
53

    
54
It will use the files:
55
@example
56
/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
57
/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
58
@end example
59

    
60
The Y files use twice the resolution of the U and V files. They are
61
raw files, without header. They can be generated by all decent video
62
decoders. You must specify the size of the image with the @option{-s} option
63
if FFmpeg cannot guess it.
64

    
65
* You can input from a raw YUV420P file:
66

    
67
@example
68
ffmpeg -i /tmp/test.yuv /tmp/out.avi
69
@end example
70

    
71
test.yuv is a file containing raw YUV planar data. Each frame is composed
72
of the Y plane followed by the U and V planes at half vertical and
73
horizontal resolution.
74

    
75
* You can output to a raw YUV420P file:
76

    
77
@example
78
ffmpeg -i mydivx.avi hugefile.yuv
79
@end example
80

    
81
* You can set several input files and output files:
82

    
83
@example
84
ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
85
@end example
86

    
87
Converts the audio file a.wav and the raw YUV video file a.yuv
88
to MPEG file a.mpg.
89

    
90
* You can also do audio and video conversions at the same time:
91

    
92
@example
93
ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
94
@end example
95

    
96
Converts a.wav to MPEG audio at 22050Hz sample rate.
97

    
98
* You can encode to several formats at the same time and define a
99
mapping from input stream to output streams:
100

    
101
@example
102
ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0
103
@end example
104

    
105
Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
106
file:index' specifies which input stream is used for each output
107
stream, in the order of the definition of output streams.
108

    
109
* You can transcode decrypted VOBs
110

    
111
@example
112
ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800 -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi
113
@end example
114

    
115
This is a typical DVD ripping example; the input is a VOB file, the
116
output an AVI file with MPEG-4 video and MP3 audio. Note that in this
117
command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
118
GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
119
input video. Furthermore, the audio stream is MP3-encoded so you need
120
to enable LAME support by passing @code{--enable-mp3lame} to configure.
121
The mapping is particularly useful for DVD transcoding
122
to get the desired audio language.
123

    
124
NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
125
@c man end
126

    
127
@chapter Invocation
128

    
129
@section Syntax
130

    
131
The generic syntax is:
132

    
133
@example
134
@c man begin SYNOPSIS
135
ffmpeg [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
136
@c man end
137
@end example
138
@c man begin DESCRIPTION
139
If no input file is given, audio/video grabbing is done.
140

    
141
As a general rule, options are applied to the next specified
142
file. For example, if you give the @option{-b 64} option, it sets the video
143
bitrate of the next file. The format option may be needed for raw input
144
files.
145

    
146
By default, FFmpeg tries to convert as losslessly as possible: It
147
uses the same audio and video parameters for the outputs as the one
148
specified for the inputs.
149
@c man end
150

    
151
@c man begin OPTIONS
152
@section Main options
153

    
154
@table @option
155
@item -L
156
Show license.
157

    
158
@item -h
159
Show help.
160

    
161
@item -formats
162
Show available formats, codecs, protocols, ...
163

    
164
@item -f fmt
165
Force format.
166

    
167
@item -i filename
168
input filename
169

    
170
@item -y
171
Overwrite output files.
172

    
173
@item -t duration
174
Set the recording time in seconds.
175
@code{hh:mm:ss[.xxx]} syntax is also supported.
176

    
177
@item -ss position
178
Seek to given time position in seconds.
179
@code{hh:mm:ss[.xxx]} syntax is also supported.
180

    
181
@item -title string
182
Set the title.
183

    
184
@item -author string
185
Set the author.
186

    
187
@item -copyright string
188
Set the copyright.
189

    
190
@item -comment string
191
Set the comment.
192

    
193
@item -target type
194
Specify target file type ("vcd", "svcd", "dvd", "dv", "pal-vcd",
195
"ntsc-svcd", ... ). All the format options (bitrate, codecs,
196
buffer sizes) are then set automatically. You can just type:
197

    
198
@example
199
ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
200
@end example
201

    
202
Nevertheless you can specify additional options as long as you know
203
they do not conflict with the standard, as in:
204

    
205
@example
206
ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
207
@end example
208

    
209
@item -hq
210
Activate high quality settings.
211

    
212
@item -itsoffset offset
213
Set the input time offset in seconds.
214
@code{[-]hh:mm:ss[.xxx]} syntax is also supported.
215
This option affects all the input files that follow it.
216
The offset is added to the timestamps of the input files.
217
Specifying a positive offset means that the corresponding
218
streams are delayed by 'offset' seconds.
219

    
220
@end table
221

    
222
@section Video Options
223

    
224
@table @option
225
@item -b bitrate
226
Set the video bitrate in kbit/s (default = 200 kb/s).
227
@item -r fps
228
Set frame rate (default = 25).
229
@item -s size
230
Set frame size. The format is @samp{wxh} (default = 160x128).
231
The following abbreviations are recognized:
232
@table @samp
233
@item sqcif
234
128x96
235
@item qcif
236
176x144
237
@item cif
238
352x288
239
@item 4cif
240
704x576
241
@end table
242

    
243
@item -aspect aspect
244
Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
245
@item -croptop size
246
Set top crop band size (in pixels).
247
@item -cropbottom size
248
Set bottom crop band size (in pixels).
249
@item -cropleft size
250
Set left crop band size (in pixels).
251
@item -cropright size
252
Set right crop band size (in pixels).
253
@item -padtop size
254
Set top pad band size (in pixels).
255
@item -padbottom size
256
Set bottom pad band size (in pixels).
257
@item -padleft size
258
Set left pad band size (in pixels).
259
@item -padright size
260
Set right pad band size (in pixels).
261
@item -padcolor (hex color)
262
Set color of padded bands. The value for padcolor is expressed
263
as a six digit hexadecimal number where the first two digits
264
represent red, the middle two digits green and last two digits
265
blue (default = 000000 (black)).
266
@item -vn
267
Disable video recording.
268
@item -bt tolerance
269
Set video bitrate tolerance (in kbit/s).
270
@item -maxrate bitrate
271
Set max video bitrate tolerance (in kbit/s).
272
@item -minrate bitrate
273
Set min video bitrate tolerance (in kbit/s).
274
@item -bufsize size
275
Set rate control buffer size (in kbit).
276
@item -vcodec codec
277
Force video codec to @var{codec}. Use the @code{copy} special value to
278
tell that the raw codec data must be copied as is.
279
@item -sameq
280
Use same video quality as source (implies VBR).
281

    
282
@item -pass n
283
Select the pass number (1 or 2). It is useful to do two pass
284
encoding. The statistics of the video are recorded in the first
285
pass and the video is generated at the exact requested bitrate
286
in the second pass.
287

    
288
@item -passlogfile file
289
Set two pass logfile name to @var{file}.
290

    
291
@end table
292

    
293
@section Advanced Video Options
294

    
295
@table @option
296
@item -g gop_size
297
Set the group of pictures size.
298
@item -intra
299
Use only intra frames.
300
@item -qscale q
301
Use fixed video quantiser scale (VBR).
302
@item -qmin q
303
minimum video quantiser scale (VBR)
304
@item -qmax q
305
maximum video quantiser scale (VBR)
306
@item -qdiff q
307
maximum difference between the quantiser scales (VBR)
308
@item -qblur blur
309
video quantiser scale blur (VBR)
310
@item -qcomp compression
311
video quantiser scale compression (VBR)
312

    
313
@item -rc_init_cplx complexity
314
initial complexity for single pass encoding
315
@item -b_qfactor factor
316
qp factor between P- and B-frames
317
@item -i_qfactor factor
318
qp factor between P- and I-frames
319
@item -b_qoffset offset
320
qp offset between P- and B-frames
321
@item -i_qoffset offset
322
qp offset between P- and I-frames
323
@item -rc_eq equation
324
Set rate control equation (@pxref{FFmpeg formula
325
evaluator}) (default = @code{tex^qComp}).
326
@item -rc_override override
327
rate control override for specific intervals
328
@item -me method
329
Set motion estimation method to @var{method}.
330
Available methods are (from lowest to best quality):
331
@table @samp
332
@item zero
333
Try just the (0, 0) vector.
334
@item phods
335
@item log
336
@item x1
337
@item epzs
338
(default method)
339
@item full
340
exhaustive search (slow and marginally better than epzs)
341
@end table
342

    
343
@item -dct_algo algo
344
Set DCT algorithm to @var{algo}. Available values are:
345
@table @samp
346
@item 0
347
FF_DCT_AUTO (default)
348
@item 1
349
FF_DCT_FASTINT
350
@item 2
351
FF_DCT_INT
352
@item 3
353
FF_DCT_MMX
354
@item 4
355
FF_DCT_MLIB
356
@item 5
357
FF_DCT_ALTIVEC
358
@end table
359

    
360
@item -idct_algo algo
361
Set IDCT algorithm to @var{algo}. Available values are:
362
@table @samp
363
@item 0
364
FF_IDCT_AUTO (default)
365
@item 1
366
FF_IDCT_INT
367
@item 2
368
FF_IDCT_SIMPLE
369
@item 3
370
FF_IDCT_SIMPLEMMX
371
@item 4
372
FF_IDCT_LIBMPEG2MMX
373
@item 5
374
FF_IDCT_PS2
375
@item 6
376
FF_IDCT_MLIB
377
@item 7
378
FF_IDCT_ARM
379
@item 8
380
FF_IDCT_ALTIVEC
381
@item 9
382
FF_IDCT_SH4
383
@item 10
384
FF_IDCT_SIMPLEARM
385
@end table
386

    
387
@item -er n
388
Set error resilience to @var{n}.
389
@table @samp
390
@item 1
391
FF_ER_CAREFUL (default)
392
@item 2
393
FF_ER_COMPLIANT
394
@item 3
395
FF_ER_AGGRESSIVE
396
@item 4
397
FF_ER_VERY_AGGRESSIVE
398
@end table
399

    
400
@item -ec bit_mask
401
Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
402
the following values:
403
@table @samp
404
@item 1
405
FF_EC_GUESS_MVS (default = enabled)
406
@item 2
407
FF_EC_DEBLOCK (default = enabled)
408
@end table
409

    
410
@item -bf frames
411
Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
412
@item -mbd mode
413
macroblock decision
414
@table @samp
415
@item 0
416
FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
417
@item 1
418
FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
419
@item 2
420
FF_MB_DECISION_RD: rate distortion
421
@end table
422

    
423
@item -4mv
424
Use four motion vector by macroblock (MPEG-4 only).
425
@item -part
426
Use data partitioning (MPEG-4 only).
427
@item -bug param
428
Work around encoder bugs that are not auto-detected.
429
@item -strict strictness
430
How strictly to follow the standards.
431
@item -aic
432
Enable Advanced intra coding (h263+).
433
@item -umv
434
Enable Unlimited Motion Vector (h263+)
435

    
436
@item -deinterlace
437
Deinterlace pictures.
438
@item -interlace
439
Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
440
Use this option if your input file is interlaced and you want
441
to keep the interlaced format for minimum losses.
442
The alternative is to deinterlace the input stream with
443
@option{-deinterlace}, but deinterlacing introduces losses.
444
@item -psnr
445
Calculate PSNR of compressed frames.
446
@item -vstats
447
Dump video coding statistics to @file{vstats_HHMMSS.log}.
448
@item -vhook module
449
Insert video processing @var{module}. @var{module} contains the module
450
name and its parameters separated by spaces.
451
@end table
452

    
453
@section Audio Options
454

    
455
@table @option
456
@item -ar freq
457
Set the audio sampling frequency (default = 44100 Hz).
458
@item -ab bitrate
459
Set the audio bitrate in kbit/s (default = 64).
460
@item -ac channels
461
Set the number of audio channels (default = 1).
462
@item -an
463
Disable audio recording.
464
@item -acodec codec
465
Force audio codec to @var{codec}. Use the @code{copy} special value to
466
specify that the raw codec data must be copied as is.
467
@end table
468

    
469
@section Audio/Video grab options
470

    
471
@table @option
472
@item -vd device
473
sEt video grab device (e.g. @file{/dev/video0}).
474
@item -vc channel
475
Set video grab channel (DV1394 only).
476
@item -tvstd standard
477
Set television standard (NTSC, PAL (SECAM)).
478
@item -dv1394
479
Set DV1394 grab.
480
@item -ad device
481
Set audio device (e.g. @file{/dev/dsp}).
482
@end table
483

    
484
@section Advanced options
485

    
486
@table @option
487
@item -map file:stream
488
Set input stream mapping.
489
@item -debug
490
Print specific debug info.
491
@item -benchmark
492
Add timings for benchmarking.
493
@item -hex
494
Dump each input packet.
495
@item -bitexact
496
Only use bit exact algorithms (for codec testing).
497
@item -ps size
498
Set packet size in bits.
499
@item -re
500
Read input at native frame rate. Mainly used to simulate a grab device.
501
@item -loop
502
Loop over the input stream. Currently it works only for image
503
streams. This option is used for automatic FFserver testing.
504
@item -loop_output number_of_times
505
Repeatedly loop output for formats that support looping such as animated GIF
506
(0 will loop the output infinitely).
507
@end table
508

    
509
@node FFmpeg formula evaluator
510
@section FFmpeg formula evaluator
511

    
512
When evaluating a rate control string, FFmpeg uses an internal formula
513
evaluator.
514

    
515
The following binary operators are available: @code{+}, @code{-},
516
@code{*}, @code{/}, @code{^}.
517

    
518
The following unary operators are available: @code{+}, @code{-},
519
@code{(...)}.
520

    
521
The following functions are available:
522
@table @var
523
@item sinh(x)
524
@item cosh(x)
525
@item tanh(x)
526
@item sin(x)
527
@item cos(x)
528
@item tan(x)
529
@item exp(x)
530
@item log(x)
531
@item squish(x)
532
@item gauss(x)
533
@item abs(x)
534
@item max(x, y)
535
@item min(x, y)
536
@item gt(x, y)
537
@item lt(x, y)
538
@item eq(x, y)
539
@item bits2qp(bits)
540
@item qp2bits(qp)
541
@end table
542

    
543
The following constants are available:
544
@table @var
545
@item PI
546
@item E
547
@item iTex
548
@item pTex
549
@item tex
550
@item mv
551
@item fCode
552
@item iCount
553
@item mcVar
554
@item var
555
@item isI
556
@item isP
557
@item isB
558
@item avgQP
559
@item qComp
560
@item avgIITex
561
@item avgPITex
562
@item avgPPTex
563
@item avgBPTex
564
@item avgTex
565
@end table
566

    
567
@c man end
568

    
569
@ignore
570

    
571
@setfilename ffmpeg
572
@settitle FFmpeg video converter
573

    
574
@c man begin SEEALSO
575
ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
576
@c man end
577

    
578
@c man begin AUTHOR
579
Fabrice Bellard
580
@c man end
581

    
582
@end ignore
583

    
584
@section Protocols
585

    
586
The filename can be @file{-} to read from standard input or to write
587
to standard output.
588

    
589
FFmpeg also handles many protocols specified with an URL syntax.
590

    
591
Use 'ffmpeg -formats' to see a list of the supported protocols.
592

    
593
The protocol @code{http:} is currently used only to communicate with
594
FFserver (see the FFserver documentation). When FFmpeg will be a
595
video player it will also be used for streaming :-)
596

    
597
@chapter Tips
598

    
599
@itemize
600
@item For streaming at very low bitrate application, use a low frame rate
601
and a small GOP size. This is especially true for RealVideo where
602
the Linux player does not seem to be very fast, so it can miss
603
frames. An example is:
604

    
605
@example
606
ffmpeg -g 3 -r 3 -t 10 -b 50 -s qcif -f rv10 /tmp/b.rm
607
@end example
608

    
609
@item  The parameter 'q' which is displayed while encoding is the current
610
quantizer. The value 1 indicates that a very good quality could
611
be achieved. The value 31 indicates the worst quality. If q=31 appears
612
too often, it means that the encoder cannot compress enough to meet
613
your bitrate. You must either increase the bitrate, decrease the
614
frame rate or decrease the frame size.
615

    
616
@item If your computer is not fast enough, you can speed up the
617
compression at the expense of the compression ratio. You can use
618
'-me zero' to speed up motion estimation, and '-intra' to disable
619
motion estimation completely (you have only I-frames, which means it
620
is about as good as JPEG compression).
621

    
622
@item To have very low audio bitrates, reduce the sampling frequency
623
(down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
624

    
625
@item To have a constant quality (but a variable bitrate), use the option
626
'-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
627
quality).
628

    
629
@item When converting video files, you can use the '-sameq' option which
630
uses the same quality factor in the encoder as in the decoder.
631
It allows almost lossless encoding.
632

    
633
@end itemize
634

    
635
@chapter Supported File Formats and Codecs
636

    
637
You can use the @code{-formats} option to have an exhaustive list.
638

    
639
@section File Formats
640

    
641
FFmpeg supports the following file formats through the @code{libavformat}
642
library:
643

    
644
@multitable @columnfractions .4 .1 .1 .4
645
@item Supported File Format @tab Encoding @tab Decoding @tab Comments
646
@item MPEG audio @tab X @tab X
647
@item MPEG-1 systems @tab X  @tab  X
648
@tab muxed audio and video
649
@item MPEG-2 PS @tab X  @tab  X
650
@tab also known as @code{VOB} file
651
@item MPEG-2 TS @tab    @tab  X
652
@tab also known as DVB Transport Stream
653
@item ASF@tab X @tab X
654
@item AVI@tab X @tab X
655
@item WAV@tab X @tab X
656
@item Macromedia Flash@tab X @tab X
657
@tab Only embedded audio is decoded.
658
@item FLV              @tab  X @tab X
659
@tab Macromedia Flash video files
660
@item Real Audio and Video @tab X @tab X
661
@item Raw AC3 @tab X  @tab  X
662
@item Raw MJPEG @tab X  @tab  X
663
@item Raw MPEG video @tab X  @tab  X
664
@item Raw PCM8/16 bits, mulaw/Alaw@tab X  @tab  X
665
@item Raw CRI ADX audio @tab X  @tab  X
666
@item Raw Shorten audio @tab    @tab  X
667
@item SUN AU format @tab X  @tab  X
668
@item NUT @tab X @tab X @tab NUT Open Container Format
669
@item QuickTime        @tab X @tab  X
670
@item MPEG-4           @tab X @tab  X
671
@tab MPEG-4 is a variant of QuickTime.
672
@item Raw MPEG4 video  @tab  X @tab  X
673
@item DV               @tab  X @tab  X
674
@item 4xm              @tab    @tab X
675
@tab 4X Technologies format, used in some games.
676
@item Playstation STR  @tab    @tab X
677
@item Id RoQ           @tab    @tab X
678
@tab Used in Quake III, Jedi Knight 2, other computer games.
679
@item Interplay MVE    @tab    @tab X
680
@tab Format used in various Interplay computer games.
681
@item WC3 Movie        @tab    @tab X
682
@tab Multimedia format used in Origin's Wing Commander III computer game.
683
@item Sega FILM/CPK    @tab    @tab X
684
@tab Used in many Sega Saturn console games.
685
@item Westwood Studios VQA/AUD  @tab    @tab X
686
@tab Multimedia formats used in Westwood Studios games.
687
@item Id Cinematic (.cin) @tab    @tab X
688
@tab Used in Quake II.
689
@item FLIC format      @tab    @tab X
690
@tab .fli/.flc files
691
@item Sierra VMD       @tab    @tab X
692
@tab Used in Sierra CD-ROM games.
693
@item Sierra Online    @tab    @tab X
694
@tab .sol files used in Sierra Online games.
695
@item Matroska         @tab    @tab X
696
@item Electronic Arts Multimedia    @tab    @tab X
697
@tab Used in various EA games; files have extensions like WVE and UV2.
698
@item Nullsoft Video (NSV) format @tab    @tab X
699
@end multitable
700

    
701
@code{X} means that encoding (resp. decoding) is supported.
702

    
703
@section Image Formats
704

    
705
FFmpeg can read and write images for each frame of a video sequence. The
706
following image formats are supported:
707

    
708
@multitable @columnfractions .4 .1 .1 .4
709
@item Supported Image Format @tab Encoding @tab Decoding @tab Comments
710
@item PGM, PPM     @tab X @tab X
711
@item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support.
712
@item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
713
@item JPEG         @tab X @tab X @tab Progressive JPEG is not supported.
714
@item .Y.U.V       @tab X @tab X @tab one raw file per component
715
@item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
716
@item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
717
@item SGI          @tab X @tab X @tab SGI RGB image format
718
@end multitable
719

    
720
@code{X} means that encoding (resp. decoding) is supported.
721

    
722
@section Video Codecs
723

    
724
@multitable @columnfractions .4 .1 .1 .4
725
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
726
@item MPEG-1 video           @tab  X  @tab  X
727
@item MPEG-2 video           @tab  X  @tab  X
728
@item MPEG-4                 @tab  X  @tab  X @tab also known as DivX4/5
729
@item MSMPEG4 V1             @tab  X  @tab  X
730
@item MSMPEG4 V2             @tab  X  @tab  X
731
@item MSMPEG4 V3             @tab  X  @tab  X @tab also known as DivX3
732
@item WMV7                   @tab  X  @tab  X
733
@item WMV8                   @tab  X  @tab  X @tab not completely working
734
@item H.261                  @tab  X  @tab  X
735
@item H.263(+)               @tab  X  @tab  X @tab also known as RealVideo 1.0
736
@item H.264                  @tab     @tab  X
737
@item RealVideo 1.0          @tab  X  @tab  X
738
@item RealVideo 2.0          @tab  X  @tab  X
739
@item MJPEG                  @tab  X  @tab  X
740
@item lossless MJPEG         @tab  X  @tab  X
741
@item Apple MJPEG-B          @tab     @tab  X
742
@item Sunplus MJPEG          @tab     @tab  X @tab fourcc: SP5X
743
@item DV                     @tab  X  @tab  X
744
@item HuffYUV                @tab  X  @tab  X
745
@item FFmpeg Video 1         @tab  X  @tab  X @tab experimental lossless codec (fourcc: FFV1)
746
@item FFmpeg Snow            @tab  X  @tab  X @tab experimental wavelet codec (fourcc: SNOW)
747
@item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1
748
@item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2
749
@item Creative YUV           @tab     @tab  X @tab fourcc: CYUV
750
@item Sorenson Video 1       @tab  X  @tab  X @tab fourcc: SVQ1
751
@item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3
752
@item On2 VP3                @tab     @tab  X @tab still experimental
753
@item Theora                 @tab     @tab  X @tab still experimental
754
@item Intel Indeo 3          @tab     @tab  X
755
@item FLV                    @tab  X  @tab  X @tab Sorenson H.263 used in Flash
756
@item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1
757
@item ATI VCR2               @tab     @tab  X @tab fourcc: VCR2
758
@item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR
759
@item 4X Video               @tab     @tab  X @tab Used in certain computer games.
760
@item Sony Playstation MDEC  @tab     @tab  X
761
@item Id RoQ                 @tab     @tab  X @tab Used in Quake III, Jedi Knight 2, other computer games.
762
@item Xan/WC3                @tab     @tab  X @tab Used in Wing Commander III .MVE files.
763
@item Interplay Video        @tab     @tab  X @tab Used in Interplay .MVE files.
764
@item Apple Animation        @tab     @tab  X @tab fourcc: 'rle '
765
@item Apple Graphics         @tab     @tab  X @tab fourcc: 'smc '
766
@item Apple Video            @tab     @tab  X @tab fourcc: rpza
767
@item Apple QuickDraw        @tab     @tab  X @tab fourcc: qdrw
768
@item Cinepak                @tab     @tab  X
769
@item Microsoft RLE          @tab     @tab  X
770
@item Microsoft Video-1      @tab     @tab  X
771
@item Westwood VQA           @tab     @tab  X
772
@item Id Cinematic Video     @tab     @tab  X @tab Used in Quake II.
773
@item Planar RGB             @tab     @tab  X @tab fourcc: 8BPS
774
@item FLIC video             @tab     @tab  X
775
@item Duck TrueMotion v1     @tab     @tab  X @tab fourcc: DUCK
776
@item Duck TrueMotion v2     @tab     @tab  X @tab fourcc: TM20
777
@item VMD Video              @tab     @tab  X @tab Used in Sierra VMD files.
778
@item MSZH                   @tab     @tab  X @tab Part of LCL
779
@item ZLIB                   @tab  X  @tab  X @tab Part of LCL, encoder experimental
780
@item TechSmith Camtasia     @tab     @tab  X @tab fourcc: TSCC
781
@item IBM Ultimotion         @tab     @tab  X @tab fourcc: ULTI
782
@item Miro VideoXL           @tab     @tab  X @tab fourcc: VIXL
783
@item QPEG                   @tab     @tab  X @tab fourccs: QPEG, Q1.0, Q1.1
784
@item LOCO                   @tab     @tab  X @tab
785
@item Winnov WNV1            @tab     @tab  X @tab
786
@item Autodesk Animator Studio Codec  @tab     @tab  X @tab fourcc: AASC
787
@item Fraps FPS1             @tab     @tab  X @tab
788
@end multitable
789

    
790
@code{X} means that encoding (resp. decoding) is supported.
791

    
792
See @url{http://www.mplayerhq.hu/~michael/codec-features.html} to
793
get a precise comparison of the FFmpeg MPEG-4 codec compared to
794
other implementations.
795

    
796
@section Audio Codecs
797

    
798
@multitable @columnfractions .4 .1 .1 .1 .7
799
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
800
@item MPEG audio layer 2     @tab  IX  @tab  IX
801
@item MPEG audio layer 1/3   @tab IX   @tab  IX
802
@tab MP3 encoding is supported through the external library LAME.
803
@item AC3                    @tab  IX  @tab  IX
804
@tab liba52 is used internally for decoding.
805
@item Vorbis                 @tab  X   @tab  X
806
@tab Supported through the external library libvorbis.
807
@item WMA V1/V2              @tab      @tab X
808
@item AAC                    @tab X    @tab X
809
@tab Supported through the external library libfaac/libfaad.
810
@item Microsoft ADPCM        @tab X    @tab X
811
@item MS IMA ADPCM           @tab X    @tab X
812
@item QT IMA ADPCM           @tab      @tab X
813
@item 4X IMA ADPCM           @tab      @tab X
814
@item G.726  ADPCM           @tab X    @tab X
815
@item Duck DK3 IMA ADPCM     @tab      @tab X
816
@tab Used in some Sega Saturn console games.
817
@item Duck DK4 IMA ADPCM     @tab      @tab X
818
@tab Used in some Sega Saturn console games.
819
@item Westwood Studios IMA ADPCM @tab      @tab X
820
@tab Used in Westwood Studios games like Command and Conquer.
821
@item SMJPEG IMA ADPCM       @tab      @tab X
822
@tab Used in certain Loki game ports.
823
@item CD-ROM XA ADPCM        @tab      @tab X
824
@item CRI ADX ADPCM          @tab X    @tab X
825
@tab Used in Sega Dreamcast games.
826
@item Electronic Arts ADPCM  @tab      @tab X
827
@tab Used in various EA titles.
828
@item Creative ADPCM         @tab      @tab X
829
@item RA144                  @tab      @tab X
830
@tab Real 14400 bit/s codec
831
@item RA288                  @tab      @tab X
832
@tab Real 28800 bit/s codec
833
@item RADnet                 @tab X    @tab IX
834
@tab Real low bitrate AC3 codec, liba52 is used for decoding.
835
@item AMR-NB                 @tab X    @tab X
836
@tab Supported through an external library.
837
@item AMR-WB                 @tab X    @tab X
838
@tab Supported through an external library.
839
@item DV audio               @tab      @tab X
840
@item Id RoQ DPCM            @tab      @tab X
841
@tab Used in Quake III, Jedi Knight 2, other computer games.
842
@item Interplay MVE DPCM     @tab      @tab X
843
@tab Used in various Interplay computer games.
844
@item Xan DPCM               @tab      @tab X
845
@tab Used in Origin's Wing Commander IV AVI files.
846
@item Sierra Online DPCM     @tab      @tab X
847
@tab Used in Sierra Online game audio files.
848
@item Apple MACE 3           @tab      @tab X
849
@item Apple MACE 6           @tab      @tab X
850
@item FLAC lossless audio    @tab      @tab X
851
@item Shorten lossless audio @tab      @tab X
852
@item Apple lossless audio   @tab      @tab X
853
@tab QuickTime fourcc 'alac'
854
@item FFmpeg Sonic           @tab X    @tab X
855
@tab experimental lossy/lossless codec
856
@item Qdesign QDM2           @tab      @tab X
857
@tab there are still some distortions
858
@item Real COOK              @tab      @tab X
859
@tab All versions except 5.1 are supported
860
@item DSP Group TrueSpeech   @tab      @tab X
861
@end multitable
862

    
863
@code{X} means that encoding (resp. decoding) is supported.
864

    
865
@code{I} means that an integer-only version is available, too (ensures high
866
performance on systems without hardware floating point support).
867

    
868
@chapter Platform Specific information
869

    
870
@section Linux
871

    
872
FFmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
873
preferred compiler now for FFmpeg. All future optimizations will depend on
874
features only found in GCC 3.2.
875

    
876
@section BSD
877

    
878
@section Windows
879

    
880
@subsection Native Windows compilation
881

    
882
@itemize
883
@item Install the current versions of MSYS and MinGW from
884
@url{http://www.mingw.org/}. You can find detailed installation
885
instructions in the download section and the FAQ.
886

    
887
@item If you want to test the FFplay, also download
888
the MinGW development library of SDL 1.2.x
889
(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
890
@url{http://www.libsdl.org}. Unpack it in a temporary directory, and
891
unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
892
directory. Edit the @file{sdl-config} script so that it gives the
893
correct SDL directory when invoked.
894

    
895
@item Extract the current version of FFmpeg.
896

    
897
@item Start the MSYS shell (file @file{msys.bat}).
898

    
899
@item Change to the FFmpeg directory and follow
900
 the instructions of how to compile FFmpeg (file
901
@file{INSTALL}). Usually, launching @file{./configure} and @file{make}
902
suffices. If you have problems using SDL, verify that
903
@file{sdl-config} can be launched from the MSYS command line.
904

    
905
@item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
906
@file{make install}. Don't forget to copy @file{SDL.dll} to the place
907
you launch @file{ffplay} from.
908

    
909
@end itemize
910

    
911
Notes:
912
@itemize
913

    
914
@item The target @file{make wininstaller} can be used to create a
915
Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
916
must be copied to the FFmpeg directory in order to build the
917
installer.
918

    
919
@item By using @code{./configure --enable-shared} when configuring FFmpeg,
920
you can build @file{avcodec.dll} and @file{avformat.dll}. With
921
@code{make install} you install the FFmpeg DLLs and the associated
922
headers in @file{Program Files/FFmpeg}.
923

    
924
@item Visual C++ compatibility: If you used @code{./configure --enable-shared}
925
when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
926
C++ @code{lib} tool to build @code{avcodec.lib} and
927
@code{avformat.lib}. With these libraries you can link your Visual C++
928
code directly with the FFmpeg DLLs (see below).
929

    
930
@end itemize
931

    
932
@subsection Visual C++ compatibility
933

    
934
FFmpeg will not compile under Visual C++ -- and it has too many
935
dependencies on the GCC compiler to make a port viable. However,
936
if you want to use the FFmpeg libraries in your own applications,
937
you can still compile those applications using Visual C++. An
938
important restriction to this is that you have to use the
939
dynamically linked versions of the FFmpeg libraries (i.e. the
940
DLLs), and you have to make sure that Visual-C++-compatible
941
import libraries are created during the FFmpeg build process.
942

    
943
This description of how to use the FFmpeg libraries with Visual C++ is
944
based on Visual C++ 2005 Express Edition Beta 2. If you have a different
945
version, you might have to modify the procedures slightly.
946

    
947
Here are the step-by-step instructions for building the FFmpeg libraries
948
so they can be used with Visual C++:
949

    
950
@enumerate
951

    
952
@item Install Visual C++ (if you haven't done so already).
953

    
954
@item Install MinGW and MSYS as described above.
955

    
956
@item Add a call to @file{vcvars32.bat} (which sets up the environment
957
variables for the Visual C++ tools) as the first line of
958
@file{msys.bat}. The standard location for @file{vcvars32.bat} is
959
@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
960
and the standard location for @file{msys.bat} is
961
@file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
962
following line as the first line of @file{msys.bat}:
963

    
964
@code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
965

    
966
@item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
967
If you get a help message with the command line options of @code{link.exe},
968
this means your environment variables are set up correctly, the
969
Microsoft linker is on the path and will be used by FFmpeg to
970
create Visual-C++-compatible import libraries.
971

    
972
@item Extract the current version of FFmpeg and change to the FFmpeg directory.
973

    
974
@item Type the command
975
@code{./configure --enable-shared --enable-memalign-hack} to configure and,
976
if that didn't produce any errors, type @code{make} to build FFmpeg.
977

    
978
@item The subdirectories @file{libavformat}, @file{libavcodec}, and
979
@file{libavutil} should now contain the files @file{avformat.dll},
980
@file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
981
@file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
982
DLLs to your System32 directory (typically @file{C:\Windows\System32}).
983

    
984
@end enumerate
985

    
986
And here is how to use these libraries with Visual C++:
987

    
988
@enumerate
989

    
990
@item Create a new console application ("File / New / Project") and then
991
select "Win32 Console Application". On the appropriate page of the
992
Application Wizard, uncheck the "Precompiled headers" option.
993

    
994
@item Write the source code for your application, or, for testing, just
995
copy the code from an existing sample application into the source file
996
that Visual C++ has already created for you. (Note that your source
997
filehas to have a @code{.cpp} extension; otherwise, Visual C++ won't
998
compile the FFmpeg headers correctly because in C mode, it doesn't
999
recognize the @code{inline} keyword.)  For example, you can copy
1000
@file{output_example.c} from the FFmpeg distribution (but you will
1001
have to make minor modifications so the code will compile under
1002
C++, see below).
1003

    
1004
@item Open the "Project / Properties" dialog box. In the "Configuration"
1005
combo box, select "All Configurations" so that the changes you make will
1006
affect both debug and release builds. In the tree view on the left hand
1007
side, select "C/C++ / General", then edit the "Additional Include
1008
Directories" setting to contain the complete paths to the
1009
@file{libavformat}, @file{libavcodec}, and @file{libavutil}
1010
subdirectories of your FFmpeg directory. Note that the directories have
1011
to be separated using semicolons. Now select "Linker / General" from the
1012
tree view and edit the "Additional Library Directories" setting to
1013
contain the same three directories.
1014

    
1015
@item Still in the "Project / Properties" dialog box, select "Linker / Input"
1016
from the tree view, then add the files @file{avformat.lib},
1017
@file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1018
Dependencies". Note that the names of the libraries have to be separated
1019
using spaces.
1020

    
1021
@item Now, select "C/C++ / Code Generation" from the tree view. Select
1022
"Debug" in the "Configuration" combo box. Make sure that "Runtime
1023
Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1024
the "Configuration" combo box and make sure that "Runtime Library" is
1025
set to "Multi-threaded DLL".
1026

    
1027
@item Click "OK" to close the "Project / Properties" dialog box and build
1028
the application. Hopefully, it should compile and run cleanly. If you
1029
used @file{output_example.c} as your sample application, you will get a
1030
few compiler errors, but they are easy to fix. The first type of error
1031
occurs because Visual C++ doesn't allow an @code{int} to be converted to
1032
an @code{enum} without a cast. To solve the problem, insert the required
1033
casts (this error occurs once for a @code{CodecID} and once for a
1034
@code{CodecType}).  The second type of error occurs because C++ requires
1035
the return value of @code{malloc} to be cast to the exact type of the
1036
pointer it is being assigned to. Visual C++ will complain that, for
1037
example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1038
an explicit cast. So insert an explicit cast in these places to silence
1039
the compiler. The third type of error occurs because the @code{snprintf}
1040
library function is called @code{_snprintf} under Visual C++.  So just
1041
add an underscore to fix the problem. With these changes,
1042
@file{output_example.c} should compile under Visual C++, and the
1043
resulting executable should produce valid video files.
1044

    
1045
@end enumerate
1046

    
1047
@subsection Cross compilation for Windows with Linux
1048

    
1049
You must use the MinGW cross compilation tools available at
1050
@url{http://www.mingw.org/}.
1051

    
1052
Then configure FFmpeg with the following options:
1053
@example
1054
./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
1055
@end example
1056
(you can change the cross-prefix according to the prefix chosen for the
1057
MinGW tools).
1058

    
1059
Then you can easily test FFmpeg with Wine
1060
(@url{http://www.winehq.com/}).
1061

    
1062
@section Mac OS X
1063

    
1064
@section BeOS
1065

    
1066
The configure script should guess the configuration itself.
1067
Networking support is currently not finished.
1068
errno issues fixed by Andrew Bachmann.
1069

    
1070
Old stuff:
1071

    
1072
Fran├žois Revol - revol at free dot fr - April 2002
1073

    
1074
The configure script should guess the configuration itself,
1075
however I still didn't test building on the net_server version of BeOS.
1076

    
1077
FFserver is broken (needs poll() implementation).
1078

    
1079
There are still issues with errno codes, which are negative in BeOS, and
1080
that FFmpeg negates when returning. This ends up turning errors into
1081
valid results, then crashes.
1082
(To be fixed)
1083

    
1084
@chapter Developers Guide
1085

    
1086
@section API
1087
@itemize
1088
@item libavcodec is the library containing the codecs (both encoding and
1089
decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1090

    
1091
@item libavformat is the library containing the file format handling (mux and
1092
demux code for several formats). Look at @file{ffplay.c} to use it in a
1093
player. See @file{output_example.c} to use it to generate audio or video
1094
streams.
1095

    
1096
@end itemize
1097

    
1098
@section Integrating libavcodec or libavformat in your program
1099

    
1100
You can integrate all the source code of the libraries to link them
1101
statically to avoid any version problem. All you need is to provide a
1102
'config.mak' and a 'config.h' in the parent directory. See the defines
1103
generated by ./configure to understand what is needed.
1104

    
1105
You can use libavcodec or libavformat in your commercial program, but
1106
@emph{any patch you make must be published}. The best way to proceed is
1107
to send your patches to the FFmpeg mailing list.
1108

    
1109
@node Coding Rules
1110
@section Coding Rules
1111

    
1112
FFmpeg is programmed in the ISO C90 language with a few additional
1113
features from ISO C99, namely:
1114
@itemize @bullet
1115
@item
1116
the @samp{inline} keyword;
1117
@item
1118
@samp{//} comments;
1119
@item
1120
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1121
@item
1122
compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1123
@end itemize
1124

    
1125
These features are supported by all compilers we care about, so we won't
1126
accept patches to remove their use unless they absolutely don't impair
1127
clarity and performance.
1128

    
1129
All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1130
compiles with several other compilers, such as the Compaq ccc compiler
1131
or Sun Studio 9, and we would like to keep it that way unless it would
1132
be exceedingly involved. To ensure compatibility, please don't use any
1133
additional C99 features or GCC extensions. Especially watch out for:
1134
@itemize @bullet
1135
@item
1136
mixing statements and declarations;
1137
@item
1138
@samp{long long} (use @samp{int64_t} instead);
1139
@item
1140
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1141
@item
1142
GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1143
@end itemize
1144

    
1145
Indent size is 4. The TAB character should not be used.
1146
The presentation is the one specified by 'indent -i4 -kr'.
1147

    
1148
Main priority in FFmpeg is simplicity and small code size (=less
1149
bugs).
1150

    
1151
Comments: Use the JavaDoc/Doxygen
1152
format (see examples below) so that code documentation
1153
can be generated automatically. All nontrivial functions should have a comment
1154
above them explaining what the function does, even if it's just one sentence.
1155
All structures and their member variables should be documented, too.
1156
@example
1157
/**
1158
 * @@file mpeg.c
1159
 * MPEG codec.
1160
 * @@author ...
1161
 */
1162

    
1163
/**
1164
 * Summary sentence.
1165
 * more text ...
1166
 * ...
1167
 */
1168
typedef struct Foobar@{
1169
    int var1; /**< var1 description */
1170
    int var2; ///< var2 description
1171
    /** var3 description */
1172
    int var3;
1173
@} Foobar;
1174

    
1175
/**
1176
 * Summary sentence.
1177
 * more text ...
1178
 * ...
1179
 * @@param my_parameter description of my_parameter
1180
 * @@return return value description
1181
 */
1182
int myfunc(int my_parameter)
1183
...
1184
@end example
1185

    
1186
fprintf and printf are forbidden in libavformat and libavcodec,
1187
please use av_log() instead.
1188

    
1189
@node CVS Policy
1190
@section CVS Policy
1191

    
1192
@enumerate
1193
@item
1194
   You must not commit code which breaks FFmpeg! (Meaning unfinished but
1195
   enabled code which breaks compilation or compiles but does not work or
1196
   breaks the regression tests)
1197
   You can commit unfinished stuff (for testing etc), but it must be disabled
1198
   (#ifdef etc) by default so it does not interfere with other developers'
1199
   work.
1200
@item
1201
   You don't have to over-test things. If it works for you, and you think it
1202
   should work for others, then commit. If your code has problems
1203
   (portability, triggers compiler bugs, unusual environment etc) they will be
1204
   reported and eventually fixed.
1205
@item
1206
   Do not commit unrelated changes together, split them into self-contained
1207
   pieces.
1208
@item
1209
   Do not change behavior of the program (renaming options etc) without
1210
   first discussing it on the ffmpeg-devel mailing list. Do not remove
1211
   functionality from the code. Just improve!
1212

    
1213
   Note: Redundant code can be removed.
1214
@item
1215
   Do not commit changes to the build system (Makefiles, configure script)
1216
   which change behavior, defaults etc, without asking first. The same
1217
   applies to compiler warning fixes, trivial looking fixes and to code
1218
   maintained by other developers. We usually have a reason for doing things
1219
   the way we do. Send your changes as patches to the ffmpeg-devel mailing
1220
   list, and if the code maintainers say OK, you may commit. This does not
1221
   apply to files you wrote and/or maintain.
1222
@item
1223
   We refuse source indentation and other cosmetic changes if they are mixed
1224
   with functional changes, such commits will be rejected and removed. Every
1225
   developer has his own indentation style, you should not change it. Of course
1226
   if you (re)write something, you can use your own style, even though we would
1227
   prefer if the indentation throughout FFmpeg was consistent (Many projects
1228
   force a given indentation style - we don't.). If you really need to make
1229
   indentation changes (try to avoid this), separate them strictly from real
1230
   changes.
1231

    
1232
   NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1233
   then either do NOT change the indentation of the inner part within (don't
1234
   move it to the right)! or do so in a separate commit
1235
@item
1236
   Always fill out the commit log message. Describe in a few lines what you
1237
   changed and why. You can refer to mailing list postings if you fix a
1238
   particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1239
@item
1240
   If you apply a patch by someone else, include the name and email address in
1241
   the CVS log message. Since the ffmpeg-cvslog mailing list is publicly
1242
   archived you should add some SPAM protection to the email address. Send an
1243
   answer to ffmpeg-devel (or wherever you got the patch from) saying that
1244
   you applied the patch.
1245
@item
1246
   Do NOT commit to code actively maintained by others without permission. Send
1247
   a patch to ffmpeg-devel instead.
1248
@item
1249
    Subscribe to the ffmpeg-cvslog mailing list. The diffs of all CVS commits
1250
    are sent there and reviewed by all the other developers. Bugs and possible
1251
    improvements or general questions regarding commits are discussed there. We
1252
    expect you to react if problems with your code are uncovered.
1253
@item
1254
    Update the documentation if you change behavior or add features. If you are
1255
    unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1256
    maintainer(s) will review and commit your stuff.
1257
@item
1258
    Revert a commit ONLY in case of a big blunder like committing something not
1259
    intended to be committed or committing a wrong file, the wrong version of a
1260
    patch, CVS policy violation or broken code and you are going to recommit the
1261
    right thing immediately.
1262

    
1263
    Never revert changes made a long time ago or buggy code. Fix it in the
1264
    normal way instead.
1265
@item
1266
    Never write to unallocated memory, never write over the end of arrays,
1267
    always check values read from some untrusted source before using them
1268
    as array index or other risky things.
1269
@item
1270
    Remember to check if you need to bump versions for the specific libav
1271
    parts (libavutil, libavcodec, libavformat) you are changing. You need
1272
    to change the version integer and the version string.
1273
    Incrementing the first component means no backward compatibility to
1274
    previous versions (e.g. removal of a function).
1275
    Incrementing the second component means backward compatible change
1276
    (e.g. addition of a function).
1277
    Incrementing the third component means a noteworthy binary compatible
1278
    change (e.g. encoder bug fix that matters for the decoder).
1279
@end enumerate
1280

    
1281
We think our rules are not too hard. If you have comments, contact us.
1282

    
1283
Note, these rules are mostly borrowed from the MPlayer project.
1284

    
1285
@subsection Renaming/moving files or content of files
1286
  You CANNOT do that. Post a request for such a change to the mailing list
1287
  Do NOT remove & readd a file - it will kill the changelog!!!!
1288

    
1289
@section Submitting patches
1290

    
1291
First, (@pxref{Coding Rules}) above if you didn't yet.
1292

    
1293
When you submit your patch, try to send a unified diff (diff '-up'
1294
option). I cannot read other diffs :-)
1295

    
1296
Also please do not submit patches which contain several unrelated changes.
1297
Split them into individual self-contained patches; this makes reviewing
1298
them much easier.
1299

    
1300
Run the regression tests before submitting a patch so that you can
1301
verify that there are no big problems.
1302

    
1303
Patches should be posted as base64 encoded attachments (or any other
1304
encoding which ensures that the patch won't be trashed during
1305
transmission) to the ffmpeg-devel mailing list, see
1306
@url{http://www1.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1307

    
1308
It also helps quite a bit if you tell us what the patch does (for example
1309
'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1310
and has no lrint()')
1311

    
1312
We reply to all submitted patches and either apply or reject with some
1313
explanation why, but sometimes we are quite busy so it can take a week or two.
1314

    
1315
@section Regression tests
1316

    
1317
Before submitting a patch (or committing to CVS), you should at least
1318
test that you did not break anything.
1319

    
1320
The regression tests build a synthetic video stream and a synthetic
1321
audio stream. These are then encoded and decoded with all codecs or
1322
formats. The CRC (or MD5) of each generated file is recorded in a
1323
result file. A 'diff' is launched to compare the reference results and
1324
the result file.
1325

    
1326
The regression tests then go on to test the FFserver code with a
1327
limited set of streams. It is important that this step runs correctly
1328
as well.
1329

    
1330
Run 'make test' to test all the codecs and formats.
1331

    
1332
Run 'make fulltest' to test all the codecs, formats and FFserver.
1333

    
1334
[Of course, some patches may change the results of the regression tests. In
1335
this case, the reference results of the regression tests shall be modified
1336
accordingly].
1337

    
1338
@bye