Statistics
| Branch: | Revision:

ffmpeg / doc / ffmpeg-doc.texi @ 5ce117c3

History | View | Annotate | Download (48.6 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 -track number
194
Set the track.
195

    
196
@item -year number
197
Set the year.
198

    
199
@item -target type
200
Specify target file type ("vcd", "svcd", "dvd", "dv", "pal-vcd",
201
"ntsc-svcd", ... ). All the format options (bitrate, codecs,
202
buffer sizes) are then set automatically. You can just type:
203

    
204
@example
205
ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
206
@end example
207

    
208
Nevertheless you can specify additional options as long as you know
209
they do not conflict with the standard, as in:
210

    
211
@example
212
ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
213
@end example
214

    
215
@item -hq
216
Activate high quality settings.
217

    
218
@item -itsoffset offset
219
Set the input time offset in seconds.
220
@code{[-]hh:mm:ss[.xxx]} syntax is also supported.
221
This option affects all the input files that follow it.
222
The offset is added to the timestamps of the input files.
223
Specifying a positive offset means that the corresponding
224
streams are delayed by 'offset' seconds.
225

    
226
@end table
227

    
228
@section Video Options
229

    
230
@table @option
231
@item -b bitrate
232
Set the video bitrate in kbit/s (default = 200 kb/s).
233
@item -r fps
234
Set frame rate (default = 25).
235
@item -s size
236
Set frame size. The format is @samp{wxh} (default = 160x128).
237
The following abbreviations are recognized:
238
@table @samp
239
@item sqcif
240
128x96
241
@item qcif
242
176x144
243
@item cif
244
352x288
245
@item 4cif
246
704x576
247
@end table
248

    
249
@item -aspect aspect
250
Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
251
@item -croptop size
252
Set top crop band size (in pixels).
253
@item -cropbottom size
254
Set bottom crop band size (in pixels).
255
@item -cropleft size
256
Set left crop band size (in pixels).
257
@item -cropright size
258
Set right crop band size (in pixels).
259
@item -padtop size
260
Set top pad band size (in pixels).
261
@item -padbottom size
262
Set bottom pad band size (in pixels).
263
@item -padleft size
264
Set left pad band size (in pixels).
265
@item -padright size
266
Set right pad band size (in pixels).
267
@item -padcolor (hex color)
268
Set color of padded bands. The value for padcolor is expressed
269
as a six digit hexadecimal number where the first two digits
270
represent red, the middle two digits green and last two digits
271
blue (default = 000000 (black)).
272
@item -vn
273
Disable video recording.
274
@item -bt tolerance
275
Set video bitrate tolerance (in kbit/s).
276
@item -maxrate bitrate
277
Set max video bitrate tolerance (in kbit/s).
278
@item -minrate bitrate
279
Set min video bitrate tolerance (in kbit/s).
280
@item -bufsize size
281
Set rate control buffer size (in kbit).
282
@item -vcodec codec
283
Force video codec to @var{codec}. Use the @code{copy} special value to
284
tell that the raw codec data must be copied as is.
285
@item -sameq
286
Use same video quality as source (implies VBR).
287

    
288
@item -pass n
289
Select the pass number (1 or 2). It is useful to do two pass
290
encoding. The statistics of the video are recorded in the first
291
pass and the video is generated at the exact requested bitrate
292
in the second pass.
293

    
294
@item -passlogfile file
295
Set two pass logfile name to @var{file}.
296

    
297
@end table
298

    
299
@section Advanced Video Options
300

    
301
@table @option
302
@item -g gop_size
303
Set the group of pictures size.
304
@item -intra
305
Use only intra frames.
306
@item -qscale q
307
Use fixed video quantiser scale (VBR).
308
@item -qmin q
309
minimum video quantiser scale (VBR)
310
@item -qmax q
311
maximum video quantiser scale (VBR)
312
@item -qdiff q
313
maximum difference between the quantiser scales (VBR)
314
@item -qblur blur
315
video quantiser scale blur (VBR)
316
@item -qcomp compression
317
video quantiser scale compression (VBR)
318

    
319
@item -rc_init_cplx complexity
320
initial complexity for single pass encoding
321
@item -b_qfactor factor
322
qp factor between P- and B-frames
323
@item -i_qfactor factor
324
qp factor between P- and I-frames
325
@item -b_qoffset offset
326
qp offset between P- and B-frames
327
@item -i_qoffset offset
328
qp offset between P- and I-frames
329
@item -rc_eq equation
330
Set rate control equation (@pxref{FFmpeg formula
331
evaluator}) (default = @code{tex^qComp}).
332
@item -rc_override override
333
rate control override for specific intervals
334
@item -me method
335
Set motion estimation method to @var{method}.
336
Available methods are (from lowest to best quality):
337
@table @samp
338
@item zero
339
Try just the (0, 0) vector.
340
@item phods
341
@item log
342
@item x1
343
@item epzs
344
(default method)
345
@item full
346
exhaustive search (slow and marginally better than epzs)
347
@end table
348

    
349
@item -dct_algo algo
350
Set DCT algorithm to @var{algo}. Available values are:
351
@table @samp
352
@item 0
353
FF_DCT_AUTO (default)
354
@item 1
355
FF_DCT_FASTINT
356
@item 2
357
FF_DCT_INT
358
@item 3
359
FF_DCT_MMX
360
@item 4
361
FF_DCT_MLIB
362
@item 5
363
FF_DCT_ALTIVEC
364
@end table
365

    
366
@item -idct_algo algo
367
Set IDCT algorithm to @var{algo}. Available values are:
368
@table @samp
369
@item 0
370
FF_IDCT_AUTO (default)
371
@item 1
372
FF_IDCT_INT
373
@item 2
374
FF_IDCT_SIMPLE
375
@item 3
376
FF_IDCT_SIMPLEMMX
377
@item 4
378
FF_IDCT_LIBMPEG2MMX
379
@item 5
380
FF_IDCT_PS2
381
@item 6
382
FF_IDCT_MLIB
383
@item 7
384
FF_IDCT_ARM
385
@item 8
386
FF_IDCT_ALTIVEC
387
@item 9
388
FF_IDCT_SH4
389
@item 10
390
FF_IDCT_SIMPLEARM
391
@end table
392

    
393
@item -er n
394
Set error resilience to @var{n}.
395
@table @samp
396
@item 1
397
FF_ER_CAREFUL (default)
398
@item 2
399
FF_ER_COMPLIANT
400
@item 3
401
FF_ER_AGGRESSIVE
402
@item 4
403
FF_ER_VERY_AGGRESSIVE
404
@end table
405

    
406
@item -ec bit_mask
407
Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
408
the following values:
409
@table @samp
410
@item 1
411
FF_EC_GUESS_MVS (default = enabled)
412
@item 2
413
FF_EC_DEBLOCK (default = enabled)
414
@end table
415

    
416
@item -bf frames
417
Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
418
@item -mbd mode
419
macroblock decision
420
@table @samp
421
@item 0
422
FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
423
@item 1
424
FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
425
@item 2
426
FF_MB_DECISION_RD: rate distortion
427
@end table
428

    
429
@item -4mv
430
Use four motion vector by macroblock (MPEG-4 only).
431
@item -part
432
Use data partitioning (MPEG-4 only).
433
@item -bug param
434
Work around encoder bugs that are not auto-detected.
435
@item -strict strictness
436
How strictly to follow the standards.
437
@item -aic
438
Enable Advanced intra coding (h263+).
439
@item -umv
440
Enable Unlimited Motion Vector (h263+)
441

    
442
@item -deinterlace
443
Deinterlace pictures.
444
@item -interlace
445
Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
446
Use this option if your input file is interlaced and you want
447
to keep the interlaced format for minimum losses.
448
The alternative is to deinterlace the input stream with
449
@option{-deinterlace}, but deinterlacing introduces losses.
450
@item -psnr
451
Calculate PSNR of compressed frames.
452
@item -vstats
453
Dump video coding statistics to @file{vstats_HHMMSS.log}.
454
@item -vhook module
455
Insert video processing @var{module}. @var{module} contains the module
456
name and its parameters separated by spaces.
457
@end table
458

    
459
@section Audio Options
460

    
461
@table @option
462
@item -ar freq
463
Set the audio sampling frequency (default = 44100 Hz).
464
@item -ab bitrate
465
Set the audio bitrate in kbit/s (default = 64).
466
@item -ac channels
467
Set the number of audio channels (default = 1).
468
@item -an
469
Disable audio recording.
470
@item -acodec codec
471
Force audio codec to @var{codec}. Use the @code{copy} special value to
472
specify that the raw codec data must be copied as is.
473
@end table
474

    
475
@section Audio/Video grab options
476

    
477
@table @option
478
@item -vd device
479
sEt video grab device (e.g. @file{/dev/video0}).
480
@item -vc channel
481
Set video grab channel (DV1394 only).
482
@item -tvstd standard
483
Set television standard (NTSC, PAL (SECAM)).
484
@item -dv1394
485
Set DV1394 grab.
486
@item -ad device
487
Set audio device (e.g. @file{/dev/dsp}).
488
@end table
489

    
490
@section Advanced options
491

    
492
@table @option
493
@item -map input stream id[:input stream id]
494
Set stream mapping from input streams to output streams.
495
Just enumerate the input streams in the order you want them in the output.
496
[input stream id] sets the (input) stream to sync against.
497
@item -debug
498
Print specific debug info.
499
@item -benchmark
500
Add timings for benchmarking.
501
@item -hex
502
Dump each input packet.
503
@item -bitexact
504
Only use bit exact algorithms (for codec testing).
505
@item -ps size
506
Set packet size in bits.
507
@item -re
508
Read input at native frame rate. Mainly used to simulate a grab device.
509
@item -loop
510
Loop over the input stream. Currently it works only for image
511
streams. This option is used for automatic FFserver testing.
512
@item -loop_output number_of_times
513
Repeatedly loop output for formats that support looping such as animated GIF
514
(0 will loop the output infinitely).
515
@item -vsync parameter
516
Video sync method. Video will be stretched/squeezed to match the timestamps,
517
it is done by duplicating and dropping frames. With -map you can select from
518
which stream the timestamps should be taken. You can leave either video or
519
audio unchanged and sync the remaining stream(s) to the unchanged one.
520
@item -async samples_per_second
521
Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
522
the parameter is the maximum samples per second by which the audio is changed.
523
-async 1 is a special case where only the start of the audio stream is corrected
524
without any later correction.
525
@end table
526

    
527
@node FFmpeg formula evaluator
528
@section FFmpeg formula evaluator
529

    
530
When evaluating a rate control string, FFmpeg uses an internal formula
531
evaluator.
532

    
533
The following binary operators are available: @code{+}, @code{-},
534
@code{*}, @code{/}, @code{^}.
535

    
536
The following unary operators are available: @code{+}, @code{-},
537
@code{(...)}.
538

    
539
The following functions are available:
540
@table @var
541
@item sinh(x)
542
@item cosh(x)
543
@item tanh(x)
544
@item sin(x)
545
@item cos(x)
546
@item tan(x)
547
@item exp(x)
548
@item log(x)
549
@item squish(x)
550
@item gauss(x)
551
@item abs(x)
552
@item max(x, y)
553
@item min(x, y)
554
@item gt(x, y)
555
@item lt(x, y)
556
@item eq(x, y)
557
@item bits2qp(bits)
558
@item qp2bits(qp)
559
@end table
560

    
561
The following constants are available:
562
@table @var
563
@item PI
564
@item E
565
@item iTex
566
@item pTex
567
@item tex
568
@item mv
569
@item fCode
570
@item iCount
571
@item mcVar
572
@item var
573
@item isI
574
@item isP
575
@item isB
576
@item avgQP
577
@item qComp
578
@item avgIITex
579
@item avgPITex
580
@item avgPPTex
581
@item avgBPTex
582
@item avgTex
583
@end table
584

    
585
@c man end
586

    
587
@ignore
588

    
589
@setfilename ffmpeg
590
@settitle FFmpeg video converter
591

    
592
@c man begin SEEALSO
593
ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
594
@c man end
595

    
596
@c man begin AUTHOR
597
Fabrice Bellard
598
@c man end
599

    
600
@end ignore
601

    
602
@section Protocols
603

    
604
The filename can be @file{-} to read from standard input or to write
605
to standard output.
606

    
607
FFmpeg also handles many protocols specified with an URL syntax.
608

    
609
Use 'ffmpeg -formats' to see a list of the supported protocols.
610

    
611
The protocol @code{http:} is currently used only to communicate with
612
FFserver (see the FFserver documentation). When FFmpeg will be a
613
video player it will also be used for streaming :-)
614

    
615
@chapter Tips
616

    
617
@itemize
618
@item For streaming at very low bitrate application, use a low frame rate
619
and a small GOP size. This is especially true for RealVideo where
620
the Linux player does not seem to be very fast, so it can miss
621
frames. An example is:
622

    
623
@example
624
ffmpeg -g 3 -r 3 -t 10 -b 50 -s qcif -f rv10 /tmp/b.rm
625
@end example
626

    
627
@item  The parameter 'q' which is displayed while encoding is the current
628
quantizer. The value 1 indicates that a very good quality could
629
be achieved. The value 31 indicates the worst quality. If q=31 appears
630
too often, it means that the encoder cannot compress enough to meet
631
your bitrate. You must either increase the bitrate, decrease the
632
frame rate or decrease the frame size.
633

    
634
@item If your computer is not fast enough, you can speed up the
635
compression at the expense of the compression ratio. You can use
636
'-me zero' to speed up motion estimation, and '-intra' to disable
637
motion estimation completely (you have only I-frames, which means it
638
is about as good as JPEG compression).
639

    
640
@item To have very low audio bitrates, reduce the sampling frequency
641
(down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
642

    
643
@item To have a constant quality (but a variable bitrate), use the option
644
'-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
645
quality).
646

    
647
@item When converting video files, you can use the '-sameq' option which
648
uses the same quality factor in the encoder as in the decoder.
649
It allows almost lossless encoding.
650

    
651
@end itemize
652

    
653
@chapter Supported File Formats and Codecs
654

    
655
You can use the @code{-formats} option to have an exhaustive list.
656

    
657
@section File Formats
658

    
659
FFmpeg supports the following file formats through the @code{libavformat}
660
library:
661

    
662
@multitable @columnfractions .4 .1 .1 .4
663
@item Supported File Format @tab Encoding @tab Decoding @tab Comments
664
@item MPEG audio @tab X @tab X
665
@item MPEG-1 systems @tab X  @tab  X
666
@tab muxed audio and video
667
@item MPEG-2 PS @tab X  @tab  X
668
@tab also known as @code{VOB} file
669
@item MPEG-2 TS @tab    @tab  X
670
@tab also known as DVB Transport Stream
671
@item ASF@tab X @tab X
672
@item AVI@tab X @tab X
673
@item WAV@tab X @tab X
674
@item Macromedia Flash@tab X @tab X
675
@tab Only embedded audio is decoded.
676
@item FLV              @tab  X @tab X
677
@tab Macromedia Flash video files
678
@item Real Audio and Video @tab X @tab X
679
@item Raw AC3 @tab X  @tab  X
680
@item Raw MJPEG @tab X  @tab  X
681
@item Raw MPEG video @tab X  @tab  X
682
@item Raw PCM8/16 bits, mulaw/Alaw@tab X  @tab  X
683
@item Raw CRI ADX audio @tab X  @tab  X
684
@item Raw Shorten audio @tab    @tab  X
685
@item SUN AU format @tab X  @tab  X
686
@item NUT @tab X @tab X @tab NUT Open Container Format
687
@item QuickTime        @tab X @tab  X
688
@item MPEG-4           @tab X @tab  X
689
@tab MPEG-4 is a variant of QuickTime.
690
@item Raw MPEG4 video  @tab  X @tab  X
691
@item DV               @tab  X @tab  X
692
@item 4xm              @tab    @tab X
693
@tab 4X Technologies format, used in some games.
694
@item Playstation STR  @tab    @tab X
695
@item Id RoQ           @tab    @tab X
696
@tab Used in Quake III, Jedi Knight 2, other computer games.
697
@item Interplay MVE    @tab    @tab X
698
@tab Format used in various Interplay computer games.
699
@item WC3 Movie        @tab    @tab X
700
@tab Multimedia format used in Origin's Wing Commander III computer game.
701
@item Sega FILM/CPK    @tab    @tab X
702
@tab Used in many Sega Saturn console games.
703
@item Westwood Studios VQA/AUD  @tab    @tab X
704
@tab Multimedia formats used in Westwood Studios games.
705
@item Id Cinematic (.cin) @tab    @tab X
706
@tab Used in Quake II.
707
@item FLIC format      @tab    @tab X
708
@tab .fli/.flc files
709
@item Sierra VMD       @tab    @tab X
710
@tab Used in Sierra CD-ROM games.
711
@item Sierra Online    @tab    @tab X
712
@tab .sol files used in Sierra Online games.
713
@item Matroska         @tab    @tab X
714
@item Electronic Arts Multimedia    @tab    @tab X
715
@tab Used in various EA games; files have extensions like WVE and UV2.
716
@item Nullsoft Video (NSV) format @tab    @tab X
717
@item ADTS AAC audio @tab X @tab X
718
@item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
719
@item American Laser Games MM  @tab    @tab X
720
@tab Multimedia format used in games like Mad Dog McCree
721
@item AVS @tab    @tab X
722
@tab Multimedia format used by the Creature Shock game.
723
@item Smacker @tab    @tab X
724
@tab Multimedia format used by many games.
725
@item GXF @tab    @tab X
726
@end multitable
727

    
728
@code{X} means that encoding (resp. decoding) is supported.
729

    
730
@section Image Formats
731

    
732
FFmpeg can read and write images for each frame of a video sequence. The
733
following image formats are supported:
734

    
735
@multitable @columnfractions .4 .1 .1 .4
736
@item Supported Image Format @tab Encoding @tab Decoding @tab Comments
737
@item PGM, PPM     @tab X @tab X
738
@item PAM          @tab X @tab X @tab PAM is a PNM extension with alpha support.
739
@item PGMYUV       @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
740
@item JPEG         @tab X @tab X @tab Progressive JPEG is not supported.
741
@item .Y.U.V       @tab X @tab X @tab one raw file per component
742
@item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
743
@item PNG          @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
744
@item SGI          @tab X @tab X @tab SGI RGB image format
745
@end multitable
746

    
747
@code{X} means that encoding (resp. decoding) is supported.
748

    
749
@section Video Codecs
750

    
751
@multitable @columnfractions .4 .1 .1 .4
752
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
753
@item MPEG-1 video           @tab  X  @tab  X
754
@item MPEG-2 video           @tab  X  @tab  X
755
@item MPEG-4                 @tab  X  @tab  X @tab also known as DivX4/5
756
@item MSMPEG4 V1             @tab  X  @tab  X
757
@item MSMPEG4 V2             @tab  X  @tab  X
758
@item MSMPEG4 V3             @tab  X  @tab  X @tab also known as DivX3
759
@item WMV7                   @tab  X  @tab  X
760
@item WMV8                   @tab  X  @tab  X @tab not completely working
761
@item H.261                  @tab  X  @tab  X
762
@item H.263(+)               @tab  X  @tab  X @tab also known as RealVideo 1.0
763
@item H.264                  @tab     @tab  X
764
@item RealVideo 1.0          @tab  X  @tab  X
765
@item RealVideo 2.0          @tab  X  @tab  X
766
@item MJPEG                  @tab  X  @tab  X
767
@item lossless MJPEG         @tab  X  @tab  X
768
@item JPEG-LS                @tab  X  @tab  X @tab fourcc: MJLS, lossless and near-lossless is supported
769
@item Apple MJPEG-B          @tab     @tab  X
770
@item Sunplus MJPEG          @tab     @tab  X @tab fourcc: SP5X
771
@item DV                     @tab  X  @tab  X
772
@item HuffYUV                @tab  X  @tab  X
773
@item FFmpeg Video 1         @tab  X  @tab  X @tab experimental lossless codec (fourcc: FFV1)
774
@item FFmpeg Snow            @tab  X  @tab  X @tab experimental wavelet codec (fourcc: SNOW)
775
@item Asus v1                @tab  X  @tab  X @tab fourcc: ASV1
776
@item Asus v2                @tab  X  @tab  X @tab fourcc: ASV2
777
@item Creative YUV           @tab     @tab  X @tab fourcc: CYUV
778
@item Sorenson Video 1       @tab  X  @tab  X @tab fourcc: SVQ1
779
@item Sorenson Video 3       @tab     @tab  X @tab fourcc: SVQ3
780
@item On2 VP3                @tab     @tab  X @tab still experimental
781
@item On2 VP5                @tab     @tab  X @tab fourcc: VP50
782
@item On2 VP6                @tab     @tab  X @tab fourcc: VP62
783
@item Theora                 @tab     @tab  X @tab still experimental
784
@item Intel Indeo 3          @tab     @tab  X
785
@item FLV                    @tab  X  @tab  X @tab Sorenson H.263 used in Flash
786
@item Flash Screen Video     @tab     @tab  X @tab fourcc: FSV1
787
@item ATI VCR1               @tab     @tab  X @tab fourcc: VCR1
788
@item ATI VCR2               @tab     @tab  X @tab fourcc: VCR2
789
@item Cirrus Logic AccuPak   @tab     @tab  X @tab fourcc: CLJR
790
@item 4X Video               @tab     @tab  X @tab Used in certain computer games.
791
@item Sony Playstation MDEC  @tab     @tab  X
792
@item Id RoQ                 @tab     @tab  X @tab Used in Quake III, Jedi Knight 2, other computer games.
793
@item Xan/WC3                @tab     @tab  X @tab Used in Wing Commander III .MVE files.
794
@item Interplay Video        @tab     @tab  X @tab Used in Interplay .MVE files.
795
@item Apple Animation        @tab     @tab  X @tab fourcc: 'rle '
796
@item Apple Graphics         @tab     @tab  X @tab fourcc: 'smc '
797
@item Apple Video            @tab     @tab  X @tab fourcc: rpza
798
@item Apple QuickDraw        @tab     @tab  X @tab fourcc: qdrw
799
@item Cinepak                @tab     @tab  X
800
@item Microsoft RLE          @tab     @tab  X
801
@item Microsoft Video-1      @tab     @tab  X
802
@item Westwood VQA           @tab     @tab  X
803
@item Id Cinematic Video     @tab     @tab  X @tab Used in Quake II.
804
@item Planar RGB             @tab     @tab  X @tab fourcc: 8BPS
805
@item FLIC video             @tab     @tab  X
806
@item Duck TrueMotion v1     @tab     @tab  X @tab fourcc: DUCK
807
@item Duck TrueMotion v2     @tab     @tab  X @tab fourcc: TM20
808
@item VMD Video              @tab     @tab  X @tab Used in Sierra VMD files.
809
@item MSZH                   @tab     @tab  X @tab Part of LCL
810
@item ZLIB                   @tab  X  @tab  X @tab Part of LCL, encoder experimental
811
@item TechSmith Camtasia     @tab     @tab  X @tab fourcc: TSCC
812
@item IBM Ultimotion         @tab     @tab  X @tab fourcc: ULTI
813
@item Miro VideoXL           @tab     @tab  X @tab fourcc: VIXL
814
@item QPEG                   @tab     @tab  X @tab fourccs: QPEG, Q1.0, Q1.1
815
@item LOCO                   @tab     @tab  X @tab
816
@item Winnov WNV1            @tab     @tab  X @tab
817
@item Autodesk Animator Studio Codec  @tab     @tab  X @tab fourcc: AASC
818
@item Fraps FPS1             @tab     @tab  X @tab
819
@item CamStudio              @tab     @tab  X @tab fourcc: CSCD
820
@item American Laser Games Video  @tab    @tab X @tab Used in games like Mad Dog McCree
821
@item ZMBV                   @tab     @tab  X @tab
822
@item AVS Video              @tab     @tab  X @tab Video encoding used by the Creature Shock game.
823
@item Smacker Video          @tab     @tab  X @tab Video encoding used in Smacker.
824
@item RTjpeg                 @tab     @tab  X @tab Video encoding used in NuppelVideo files.
825
@item KMVC                   @tab     @tab  X @tab Codec used in Worms games.
826
@item VMware Video           @tab     @tab  X @tab Codec used in videos captured by VMware.
827
@end multitable
828

    
829
@code{X} means that encoding (resp. decoding) is supported.
830

    
831
See @url{http://mplayerhq.hu/~michael/codec-features.html} to
832
get a precise comparison of the FFmpeg MPEG-4 codec compared to
833
other implementations.
834

    
835
@section Audio Codecs
836

    
837
@multitable @columnfractions .4 .1 .1 .1 .7
838
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
839
@item MPEG audio layer 2     @tab  IX  @tab  IX
840
@item MPEG audio layer 1/3   @tab IX   @tab  IX
841
@tab MP3 encoding is supported through the external library LAME.
842
@item AC3                    @tab  IX  @tab  IX
843
@tab liba52 is used internally for decoding.
844
@item Vorbis                 @tab  X   @tab  X
845
@tab Supported through the external library libvorbis.
846
@item WMA V1/V2              @tab      @tab X
847
@item AAC                    @tab X    @tab X
848
@tab Supported through the external library libfaac/libfaad.
849
@item Microsoft ADPCM        @tab X    @tab X
850
@item MS IMA ADPCM           @tab X    @tab X
851
@item QT IMA ADPCM           @tab      @tab X
852
@item 4X IMA ADPCM           @tab      @tab X
853
@item G.726  ADPCM           @tab X    @tab X
854
@item Duck DK3 IMA ADPCM     @tab      @tab X
855
@tab Used in some Sega Saturn console games.
856
@item Duck DK4 IMA ADPCM     @tab      @tab X
857
@tab Used in some Sega Saturn console games.
858
@item Westwood Studios IMA ADPCM @tab      @tab X
859
@tab Used in Westwood Studios games like Command and Conquer.
860
@item SMJPEG IMA ADPCM       @tab      @tab X
861
@tab Used in certain Loki game ports.
862
@item CD-ROM XA ADPCM        @tab      @tab X
863
@item CRI ADX ADPCM          @tab X    @tab X
864
@tab Used in Sega Dreamcast games.
865
@item Electronic Arts ADPCM  @tab      @tab X
866
@tab Used in various EA titles.
867
@item Creative ADPCM         @tab      @tab X
868
@tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
869
@item RA144                  @tab      @tab X
870
@tab Real 14400 bit/s codec
871
@item RA288                  @tab      @tab X
872
@tab Real 28800 bit/s codec
873
@item RADnet                 @tab X    @tab IX
874
@tab Real low bitrate AC3 codec, liba52 is used for decoding.
875
@item AMR-NB                 @tab X    @tab X
876
@tab Supported through an external library.
877
@item AMR-WB                 @tab X    @tab X
878
@tab Supported through an external library.
879
@item DV audio               @tab      @tab X
880
@item Id RoQ DPCM            @tab      @tab X
881
@tab Used in Quake III, Jedi Knight 2, other computer games.
882
@item Interplay MVE DPCM     @tab      @tab X
883
@tab Used in various Interplay computer games.
884
@item Xan DPCM               @tab      @tab X
885
@tab Used in Origin's Wing Commander IV AVI files.
886
@item Sierra Online DPCM     @tab      @tab X
887
@tab Used in Sierra Online game audio files.
888
@item Apple MACE 3           @tab      @tab X
889
@item Apple MACE 6           @tab      @tab X
890
@item FLAC lossless audio    @tab      @tab X
891
@item Shorten lossless audio @tab      @tab X
892
@item Apple lossless audio   @tab      @tab X
893
@tab QuickTime fourcc 'alac'
894
@item FFmpeg Sonic           @tab X    @tab X
895
@tab experimental lossy/lossless codec
896
@item Qdesign QDM2           @tab      @tab X
897
@tab there are still some distortions
898
@item Real COOK              @tab      @tab X
899
@tab All versions except 5.1 are supported
900
@item DSP Group TrueSpeech   @tab      @tab X
901
@item True Audio (TTA)       @tab      @tab X
902
@item Smacker Audio          @tab      @tab X
903
@end multitable
904

    
905
@code{X} means that encoding (resp. decoding) is supported.
906

    
907
@code{I} means that an integer-only version is available, too (ensures high
908
performance on systems without hardware floating point support).
909

    
910
@chapter Platform Specific information
911

    
912
@section Linux
913

    
914
FFmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
915
preferred compiler now for FFmpeg. All future optimizations will depend on
916
features only found in GCC 3.2.
917

    
918
@section BSD
919

    
920
BSD make will not build FFmpeg, you need to install and use GNU Make
921
(@file{gmake}).
922

    
923
@section Windows
924

    
925
@subsection Native Windows compilation
926

    
927
@itemize
928
@item Install the current versions of MSYS and MinGW from
929
@url{http://www.mingw.org/}. You can find detailed installation
930
instructions in the download section and the FAQ.
931

    
932
@item If you want to test the FFplay, also download
933
the MinGW development library of SDL 1.2.x
934
(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
935
@url{http://www.libsdl.org}. Unpack it in a temporary directory, and
936
unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
937
directory. Edit the @file{sdl-config} script so that it gives the
938
correct SDL directory when invoked.
939

    
940
@item Extract the current version of FFmpeg.
941

    
942
@item Start the MSYS shell (file @file{msys.bat}).
943

    
944
@item Change to the FFmpeg directory and follow
945
 the instructions of how to compile FFmpeg (file
946
@file{INSTALL}). Usually, launching @file{./configure} and @file{make}
947
suffices. If you have problems using SDL, verify that
948
@file{sdl-config} can be launched from the MSYS command line.
949

    
950
@item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
951
@file{make install}. Don't forget to copy @file{SDL.dll} to the place
952
you launch @file{ffplay} from.
953

    
954
@end itemize
955

    
956
Notes:
957
@itemize
958

    
959
@item The target @file{make wininstaller} can be used to create a
960
Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
961
must be copied to the FFmpeg directory in order to build the
962
installer.
963

    
964
@item By using @code{./configure --enable-shared} when configuring FFmpeg,
965
you can build @file{avcodec.dll} and @file{avformat.dll}. With
966
@code{make install} you install the FFmpeg DLLs and the associated
967
headers in @file{Program Files/FFmpeg}.
968

    
969
@item Visual C++ compatibility: If you used @code{./configure --enable-shared}
970
when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
971
C++ @code{lib} tool to build @code{avcodec.lib} and
972
@code{avformat.lib}. With these libraries you can link your Visual C++
973
code directly with the FFmpeg DLLs (see below).
974

    
975
@end itemize
976

    
977
@subsection Visual C++ compatibility
978

    
979
FFmpeg will not compile under Visual C++ -- and it has too many
980
dependencies on the GCC compiler to make a port viable. However,
981
if you want to use the FFmpeg libraries in your own applications,
982
you can still compile those applications using Visual C++. An
983
important restriction to this is that you have to use the
984
dynamically linked versions of the FFmpeg libraries (i.e. the
985
DLLs), and you have to make sure that Visual-C++-compatible
986
import libraries are created during the FFmpeg build process.
987

    
988
This description of how to use the FFmpeg libraries with Visual C++ is
989
based on Visual C++ 2005 Express Edition Beta 2. If you have a different
990
version, you might have to modify the procedures slightly.
991

    
992
Here are the step-by-step instructions for building the FFmpeg libraries
993
so they can be used with Visual C++:
994

    
995
@enumerate
996

    
997
@item Install Visual C++ (if you haven't done so already).
998

    
999
@item Install MinGW and MSYS as described above.
1000

    
1001
@item Add a call to @file{vcvars32.bat} (which sets up the environment
1002
variables for the Visual C++ tools) as the first line of
1003
@file{msys.bat}. The standard location for @file{vcvars32.bat} is
1004
@file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
1005
and the standard location for @file{msys.bat} is
1006
@file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
1007
following line as the first line of @file{msys.bat}:
1008

    
1009
@code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
1010

    
1011
@item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
1012
If you get a help message with the command line options of @code{link.exe},
1013
this means your environment variables are set up correctly, the
1014
Microsoft linker is on the path and will be used by FFmpeg to
1015
create Visual-C++-compatible import libraries.
1016

    
1017
@item Extract the current version of FFmpeg and change to the FFmpeg directory.
1018

    
1019
@item Type the command
1020
@code{./configure --enable-shared --disable-static --enable-memalign-hack}
1021
to configure and, if that didn't produce any errors,
1022
type @code{make} to build FFmpeg.
1023

    
1024
@item The subdirectories @file{libavformat}, @file{libavcodec}, and
1025
@file{libavutil} should now contain the files @file{avformat.dll},
1026
@file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1027
@file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1028
DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1029

    
1030
@end enumerate
1031

    
1032
And here is how to use these libraries with Visual C++:
1033

    
1034
@enumerate
1035

    
1036
@item Create a new console application ("File / New / Project") and then
1037
select "Win32 Console Application". On the appropriate page of the
1038
Application Wizard, uncheck the "Precompiled headers" option.
1039

    
1040
@item Write the source code for your application, or, for testing, just
1041
copy the code from an existing sample application into the source file
1042
that Visual C++ has already created for you. (Note that your source
1043
filehas to have a @code{.cpp} extension; otherwise, Visual C++ won't
1044
compile the FFmpeg headers correctly because in C mode, it doesn't
1045
recognize the @code{inline} keyword.)  For example, you can copy
1046
@file{output_example.c} from the FFmpeg distribution (but you will
1047
have to make minor modifications so the code will compile under
1048
C++, see below).
1049

    
1050
@item Open the "Project / Properties" dialog box. In the "Configuration"
1051
combo box, select "All Configurations" so that the changes you make will
1052
affect both debug and release builds. In the tree view on the left hand
1053
side, select "C/C++ / General", then edit the "Additional Include
1054
Directories" setting to contain the complete paths to the
1055
@file{libavformat}, @file{libavcodec}, and @file{libavutil}
1056
subdirectories of your FFmpeg directory. Note that the directories have
1057
to be separated using semicolons. Now select "Linker / General" from the
1058
tree view and edit the "Additional Library Directories" setting to
1059
contain the same three directories.
1060

    
1061
@item Still in the "Project / Properties" dialog box, select "Linker / Input"
1062
from the tree view, then add the files @file{avformat.lib},
1063
@file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1064
Dependencies". Note that the names of the libraries have to be separated
1065
using spaces.
1066

    
1067
@item Now, select "C/C++ / Code Generation" from the tree view. Select
1068
"Debug" in the "Configuration" combo box. Make sure that "Runtime
1069
Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1070
the "Configuration" combo box and make sure that "Runtime Library" is
1071
set to "Multi-threaded DLL".
1072

    
1073
@item Click "OK" to close the "Project / Properties" dialog box and build
1074
the application. Hopefully, it should compile and run cleanly. If you
1075
used @file{output_example.c} as your sample application, you will get a
1076
few compiler errors, but they are easy to fix. The first type of error
1077
occurs because Visual C++ doesn't allow an @code{int} to be converted to
1078
an @code{enum} without a cast. To solve the problem, insert the required
1079
casts (this error occurs once for a @code{CodecID} and once for a
1080
@code{CodecType}).  The second type of error occurs because C++ requires
1081
the return value of @code{malloc} to be cast to the exact type of the
1082
pointer it is being assigned to. Visual C++ will complain that, for
1083
example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1084
an explicit cast. So insert an explicit cast in these places to silence
1085
the compiler. The third type of error occurs because the @code{snprintf}
1086
library function is called @code{_snprintf} under Visual C++.  So just
1087
add an underscore to fix the problem. With these changes,
1088
@file{output_example.c} should compile under Visual C++, and the
1089
resulting executable should produce valid video files.
1090

    
1091
@end enumerate
1092

    
1093
@subsection Cross compilation for Windows with Linux
1094

    
1095
You must use the MinGW cross compilation tools available at
1096
@url{http://www.mingw.org/}.
1097

    
1098
Then configure FFmpeg with the following options:
1099
@example
1100
./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
1101
@end example
1102
(you can change the cross-prefix according to the prefix chosen for the
1103
MinGW tools).
1104

    
1105
Then you can easily test FFmpeg with Wine
1106
(@url{http://www.winehq.com/}).
1107

    
1108
@subsection Compilation under Cygwin
1109

    
1110
Cygwin works very much like Unix.
1111

    
1112
Just install your Cygwin with all the "Base" packages, plus the
1113
following "Devel" ones:
1114
@example
1115
binutils, gcc-core, make, subversion
1116
@end example
1117

    
1118
Do not install binutils-20060709-1 (they are buggy on shared builds);
1119
use binutils-20050610-1 instead.
1120

    
1121
Then run
1122

    
1123
@example
1124
./configure --enable-static --disable-shared
1125
@end example
1126

    
1127
to make a static build or
1128

    
1129
@example
1130
./configure --enable-shared --disable-static
1131
@end example
1132

    
1133
to build shared libraries.
1134

    
1135
If you want to build FFmpeg with additional libraries, download Cygwin
1136
"Devel" packages for Ogg and Vorbis from any Cygwin packages repository
1137
and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
1138
(@url{http://cygwinports.dotsrc.org/}).
1139

    
1140
@subsection Crosscompilation for Windows under Cygwin
1141

    
1142
With Cygwin you can create Windows binaries that don't need the cygwin1.dll.
1143

    
1144
Just install your Cygwin as explained before, plus these additional
1145
"Devel" packages:
1146
@example
1147
gcc-mingw-core, mingw-runtime, mingw-zlib
1148
@end example
1149

    
1150
and add some special flags to your configure invocation.
1151

    
1152
For a static build run
1153
@example
1154
./configure --enable-mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1155
@end example
1156

    
1157
and for a build with shared libraries
1158
@example
1159
./configure --enable-mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1160
@end example
1161

    
1162
@section Mac OS X
1163

    
1164
@section BeOS
1165

    
1166
The configure script should guess the configuration itself.
1167
Networking support is currently not finished.
1168
errno issues fixed by Andrew Bachmann.
1169

    
1170
Old stuff:
1171

    
1172
Fran├žois Revol - revol at free dot fr - April 2002
1173

    
1174
The configure script should guess the configuration itself,
1175
however I still didn't test building on the net_server version of BeOS.
1176

    
1177
FFserver is broken (needs poll() implementation).
1178

    
1179
There are still issues with errno codes, which are negative in BeOS, and
1180
that FFmpeg negates when returning. This ends up turning errors into
1181
valid results, then crashes.
1182
(To be fixed)
1183

    
1184
@chapter Developers Guide
1185

    
1186
@section API
1187
@itemize @bullet
1188
@item libavcodec is the library containing the codecs (both encoding and
1189
decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1190

    
1191
@item libavformat is the library containing the file format handling (mux and
1192
demux code for several formats). Look at @file{ffplay.c} to use it in a
1193
player. See @file{output_example.c} to use it to generate audio or video
1194
streams.
1195

    
1196
@end itemize
1197

    
1198
@section Integrating libavcodec or libavformat in your program
1199

    
1200
You can integrate all the source code of the libraries to link them
1201
statically to avoid any version problem. All you need is to provide a
1202
'config.mak' and a 'config.h' in the parent directory. See the defines
1203
generated by ./configure to understand what is needed.
1204

    
1205
You can use libavcodec or libavformat in your commercial program, but
1206
@emph{any patch you make must be published}. The best way to proceed is
1207
to send your patches to the FFmpeg mailing list.
1208

    
1209
@node Coding Rules
1210
@section Coding Rules
1211

    
1212
FFmpeg is programmed in the ISO C90 language with a few additional
1213
features from ISO C99, namely:
1214
@itemize @bullet
1215
@item
1216
the @samp{inline} keyword;
1217
@item
1218
@samp{//} comments;
1219
@item
1220
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1221
@item
1222
compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1223
@end itemize
1224

    
1225
These features are supported by all compilers we care about, so we won't
1226
accept patches to remove their use unless they absolutely don't impair
1227
clarity and performance.
1228

    
1229
All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1230
compiles with several other compilers, such as the Compaq ccc compiler
1231
or Sun Studio 9, and we would like to keep it that way unless it would
1232
be exceedingly involved. To ensure compatibility, please don't use any
1233
additional C99 features or GCC extensions. Especially watch out for:
1234
@itemize @bullet
1235
@item
1236
mixing statements and declarations;
1237
@item
1238
@samp{long long} (use @samp{int64_t} instead);
1239
@item
1240
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1241
@item
1242
GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1243
@end itemize
1244

    
1245
Indent size is 4.
1246
The presentation is the one specified by 'indent -i4 -kr -nut'.
1247
The TAB character is forbidden outside of Makefiles as is any
1248
form of trailing whitespace. Commits containing either will be
1249
rejected by the Subversion repository.
1250

    
1251
Main priority in FFmpeg is simplicity and small code size (=less
1252
bugs).
1253

    
1254
Comments: Use the JavaDoc/Doxygen
1255
format (see examples below) so that code documentation
1256
can be generated automatically. All nontrivial functions should have a comment
1257
above them explaining what the function does, even if it's just one sentence.
1258
All structures and their member variables should be documented, too.
1259
@example
1260
/**
1261
 * @@file mpeg.c
1262
 * MPEG codec.
1263
 * @@author ...
1264
 */
1265

    
1266
/**
1267
 * Summary sentence.
1268
 * more text ...
1269
 * ...
1270
 */
1271
typedef struct Foobar@{
1272
    int var1; /**< var1 description */
1273
    int var2; ///< var2 description
1274
    /** var3 description */
1275
    int var3;
1276
@} Foobar;
1277

    
1278
/**
1279
 * Summary sentence.
1280
 * more text ...
1281
 * ...
1282
 * @@param my_parameter description of my_parameter
1283
 * @@return return value description
1284
 */
1285
int myfunc(int my_parameter)
1286
...
1287
@end example
1288

    
1289
fprintf and printf are forbidden in libavformat and libavcodec,
1290
please use av_log() instead.
1291

    
1292
@section Development Policy
1293

    
1294
@enumerate
1295
@item
1296
   You must not commit code which breaks FFmpeg! (Meaning unfinished but
1297
   enabled code which breaks compilation or compiles but does not work or
1298
   breaks the regression tests)
1299
   You can commit unfinished stuff (for testing etc), but it must be disabled
1300
   (#ifdef etc) by default so it does not interfere with other developers'
1301
   work.
1302
@item
1303
   You don't have to over-test things. If it works for you, and you think it
1304
   should work for others, then commit. If your code has problems
1305
   (portability, triggers compiler bugs, unusual environment etc) they will be
1306
   reported and eventually fixed.
1307
@item
1308
   Do not commit unrelated changes together, split them into self-contained
1309
   pieces.
1310
@item
1311
   Do not change behavior of the program (renaming options etc) without
1312
   first discussing it on the ffmpeg-devel mailing list. Do not remove
1313
   functionality from the code. Just improve!
1314

    
1315
   Note: Redundant code can be removed.
1316
@item
1317
   Do not commit changes to the build system (Makefiles, configure script)
1318
   which change behavior, defaults etc, without asking first. The same
1319
   applies to compiler warning fixes, trivial looking fixes and to code
1320
   maintained by other developers. We usually have a reason for doing things
1321
   the way we do. Send your changes as patches to the ffmpeg-devel mailing
1322
   list, and if the code maintainers say OK, you may commit. This does not
1323
   apply to files you wrote and/or maintain.
1324
@item
1325
   We refuse source indentation and other cosmetic changes if they are mixed
1326
   with functional changes, such commits will be rejected and removed. Every
1327
   developer has his own indentation style, you should not change it. Of course
1328
   if you (re)write something, you can use your own style, even though we would
1329
   prefer if the indentation throughout FFmpeg was consistent (Many projects
1330
   force a given indentation style - we don't.). If you really need to make
1331
   indentation changes (try to avoid this), separate them strictly from real
1332
   changes.
1333

    
1334
   NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1335
   then either do NOT change the indentation of the inner part within (don't
1336
   move it to the right)! or do so in a separate commit
1337
@item
1338
   Always fill out the commit log message. Describe in a few lines what you
1339
   changed and why. You can refer to mailing list postings if you fix a
1340
   particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1341
@item
1342
   If you apply a patch by someone else, include the name and email address in
1343
   the log message. Since the ffmpeg-cvslog mailing list is publicly
1344
   archived you should add some SPAM protection to the email address. Send an
1345
   answer to ffmpeg-devel (or wherever you got the patch from) saying that
1346
   you applied the patch.
1347
@item
1348
    Do NOT commit to code actively maintained by others without permission.
1349
    Send a patch to ffmpeg-devel instead. If noone answers within a reasonable
1350
    timeframe (12h for build failures and security fixes, 3 days small changes,
1351
    1 week for big patches) then commit your patch if you think it's OK.
1352
    Also note, the maintainer can simply ask for more time to review!
1353
@item
1354
    Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1355
    are sent there and reviewed by all the other developers. Bugs and possible
1356
    improvements or general questions regarding commits are discussed there. We
1357
    expect you to react if problems with your code are uncovered.
1358
@item
1359
    Update the documentation if you change behavior or add features. If you are
1360
    unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1361
    maintainer(s) will review and commit your stuff.
1362
@item
1363
    Never write to unallocated memory, never write over the end of arrays,
1364
    always check values read from some untrusted source before using them
1365
    as array index or other risky things.
1366
@item
1367
    Remember to check if you need to bump versions for the specific libav
1368
    parts (libavutil, libavcodec, libavformat) you are changing. You need
1369
    to change the version integer and the version string.
1370
    Incrementing the first component means no backward compatibility to
1371
    previous versions (e.g. removal of a function from the public API).
1372
    Incrementing the second component means backward compatible change
1373
    (e.g. addition of a function to the public API).
1374
    Incrementing the third component means a noteworthy binary compatible
1375
    change (e.g. encoder bug fix that matters for the decoder).
1376
@item
1377
    If you add a new codec, remember to update the changelog, add it to
1378
    the supported codecs table in the documentation and bump the second
1379
    component of the @file{libavcodec} version number appropriately. If
1380
    it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1381
    is only a decoder.
1382
@end enumerate
1383

    
1384
We think our rules are not too hard. If you have comments, contact us.
1385

    
1386
Note, these rules are mostly borrowed from the MPlayer project.
1387

    
1388
@section Submitting patches
1389

    
1390
First, (@pxref{Coding Rules}) above if you didn't yet.
1391

    
1392
When you submit your patch, try to send a unified diff (diff '-up'
1393
option). I cannot read other diffs :-)
1394

    
1395
Also please do not submit patches which contain several unrelated changes.
1396
Split them into individual self-contained patches; this makes reviewing
1397
them much easier.
1398

    
1399
Run the regression tests before submitting a patch so that you can
1400
verify that there are no big problems.
1401

    
1402
Patches should be posted as base64 encoded attachments (or any other
1403
encoding which ensures that the patch won't be trashed during
1404
transmission) to the ffmpeg-devel mailing list, see
1405
@url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1406

    
1407
It also helps quite a bit if you tell us what the patch does (for example
1408
'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1409
and has no lrint()')
1410

    
1411
We reply to all submitted patches and either apply or reject with some
1412
explanation why, but sometimes we are quite busy so it can take a week or two.
1413

    
1414
@section Regression tests
1415

    
1416
Before submitting a patch (or committing to the repository), you should at least
1417
test that you did not break anything.
1418

    
1419
The regression tests build a synthetic video stream and a synthetic
1420
audio stream. These are then encoded and decoded with all codecs or
1421
formats. The CRC (or MD5) of each generated file is recorded in a
1422
result file. A 'diff' is launched to compare the reference results and
1423
the result file.
1424

    
1425
The regression tests then go on to test the FFserver code with a
1426
limited set of streams. It is important that this step runs correctly
1427
as well.
1428

    
1429
Run 'make test' to test all the codecs and formats.
1430

    
1431
Run 'make fulltest' to test all the codecs, formats and FFserver.
1432

    
1433
[Of course, some patches may change the results of the regression tests. In
1434
this case, the reference results of the regression tests shall be modified
1435
accordingly].
1436

    
1437
@bye