[libav.git] / doc / ffmpeg-doc.texi
1 \input texinfo @c -*- texinfo -*-
3 @settitle FFmpeg Documentation
4 @titlepage
5 @sp 7
6 @center @titlefont{FFmpeg Documentation}
7 @sp 3
8 @end titlepage
11 @chapter Introduction
13 FFmpeg is a very fast video and audio converter. It can also grab from
14 a live audio/video source.
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.
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.
24 @chapter Quick Start
26 @c man begin EXAMPLES
27 @section Video and Audio grabbing
29 FFmpeg can use a video4linux compatible video source and any Open Sound
30 System audio source:
32 @example
33 ffmpeg /tmp/out.mpg
34 @end example
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{}) by Gerd Knorr. You also
39 have to set the audio recording levels correctly with a
40 standard mixer.
42 @section Video and Audio file format conversion
44 * FFmpeg can use any supported file format and protocol as input:
46 Examples:
48 * You can use YUV files as input:
50 @example
51 ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
52 @end example
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
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.
65 * You can input from a raw YUV420P file:
67 @example
68 ffmpeg -i /tmp/test.yuv /tmp/out.avi
69 @end example
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.
75 * You can output to a raw YUV420P file:
77 @example
78 ffmpeg -i mydivx.avi hugefile.yuv
79 @end example
81 * You can set several input files and output files:
83 @example
84 ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
85 @end example
87 Converts the audio file a.wav and the raw YUV video file a.yuv
88 to MPEG file a.mpg.
90 * You can also do audio and video conversions at the same time:
92 @example
93 ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
94 @end example
96 Converts a.wav to MPEG audio at 22050Hz sample rate.
98 * You can encode to several formats at the same time and define a
99 mapping from input stream to output streams:
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
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.
109 * You can transcode decrypted VOBs
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
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.
124 NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
125 @c man end
127 @chapter Invocation
129 @section Syntax
131 The generic syntax is:
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.
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.
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
151 @c man begin OPTIONS
152 @section Main options
154 @table @option
155 @item -L
156 Show license.
158 @item -h
159 Show help.
161 @item -formats
162 Show available formats, codecs, protocols, ...
164 @item -f fmt
165 Force format.
167 @item -i filename
168 input filename
170 @item -y
171 Overwrite output files.
173 @item -t duration
174 Set the recording time in seconds.
175 @code{hh:mm:ss[.xxx]} syntax is also supported.
177 @item -ss position
178 Seek to given time position in seconds.
179 @code{hh:mm:ss[.xxx]} syntax is also supported.
181 @item -title string
182 Set the title.
184 @item -author string
185 Set the author.
187 @item -copyright string
188 Set the copyright.
190 @item -comment string
191 Set the comment.
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:
198 @example
199 ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
200 @end example
202 Nevertheless you can specify additional options as long as you know
203 they do not conflict with the standard, as in:
205 @example
206 ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
207 @end example
209 @item -hq
210 Activate high quality settings.
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.
220 @end table
222 @section Video Options
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
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).
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.
288 @item -passlogfile file
289 Set two pass logfile name to @var{file}.
291 @end table
293 @section Advanced Video Options
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)
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
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
350 @item 2
352 @item 3
354 @item 4
356 @item 5
358 @end table
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
367 @item 2
369 @item 3
371 @item 4
373 @item 5
375 @item 6
377 @item 7
379 @item 8
381 @item 9
383 @item 10
385 @end table
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
394 @item 3
396 @item 4
398 @end table
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
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
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+)
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
453 @section Audio Options
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
469 @section Audio/Video grab options
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
484 @section Advanced options
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 @item -vsync parameter
508 Video sync method. Video will be stretched/squeezed to match the timestamps,
509 it is done by duplicating and dropping frames. With -map you can select from
510 which stream the timestamps should be taken. You can leave either video or
511 audio unchanged and sync the remaining stream(s) to the unchanged one.
512 @item -async samples_per_second
513 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
514 the parameter is the maximum samples per second by which the audio is changed.
515 -async 1 is a special case where only the start of the audio stream is corrected
516 without any later correction.
517 @end table
519 @node FFmpeg formula evaluator
520 @section FFmpeg formula evaluator
522 When evaluating a rate control string, FFmpeg uses an internal formula
523 evaluator.
525 The following binary operators are available: @code{+}, @code{-},
526 @code{*}, @code{/}, @code{^}.
528 The following unary operators are available: @code{+}, @code{-},
529 @code{(...)}.
531 The following functions are available:
532 @table @var
533 @item sinh(x)
534 @item cosh(x)
535 @item tanh(x)
536 @item sin(x)
537 @item cos(x)
538 @item tan(x)
539 @item exp(x)
540 @item log(x)
541 @item squish(x)
542 @item gauss(x)
543 @item abs(x)
544 @item max(x, y)
545 @item min(x, y)
546 @item gt(x, y)
547 @item lt(x, y)
548 @item eq(x, y)
549 @item bits2qp(bits)
550 @item qp2bits(qp)
551 @end table
553 The following constants are available:
554 @table @var
555 @item PI
556 @item E
557 @item iTex
558 @item pTex
559 @item tex
560 @item mv
561 @item fCode
562 @item iCount
563 @item mcVar
564 @item var
565 @item isI
566 @item isP
567 @item isB
568 @item avgQP
569 @item qComp
570 @item avgIITex
571 @item avgPITex
572 @item avgPPTex
573 @item avgBPTex
574 @item avgTex
575 @end table
577 @c man end
579 @ignore
581 @setfilename ffmpeg
582 @settitle FFmpeg video converter
584 @c man begin SEEALSO
585 ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
586 @c man end
588 @c man begin AUTHOR
589 Fabrice Bellard
590 @c man end
592 @end ignore
594 @section Protocols
596 The filename can be @file{-} to read from standard input or to write
597 to standard output.
599 FFmpeg also handles many protocols specified with an URL syntax.
601 Use 'ffmpeg -formats' to see a list of the supported protocols.
603 The protocol @code{http:} is currently used only to communicate with
604 FFserver (see the FFserver documentation). When FFmpeg will be a
605 video player it will also be used for streaming :-)
607 @chapter Tips
609 @itemize
610 @item For streaming at very low bitrate application, use a low frame rate
611 and a small GOP size. This is especially true for RealVideo where
612 the Linux player does not seem to be very fast, so it can miss
613 frames. An example is:
615 @example
616 ffmpeg -g 3 -r 3 -t 10 -b 50 -s qcif -f rv10 /tmp/b.rm
617 @end example
619 @item The parameter 'q' which is displayed while encoding is the current
620 quantizer. The value 1 indicates that a very good quality could
621 be achieved. The value 31 indicates the worst quality. If q=31 appears
622 too often, it means that the encoder cannot compress enough to meet
623 your bitrate. You must either increase the bitrate, decrease the
624 frame rate or decrease the frame size.
626 @item If your computer is not fast enough, you can speed up the
627 compression at the expense of the compression ratio. You can use
628 '-me zero' to speed up motion estimation, and '-intra' to disable
629 motion estimation completely (you have only I-frames, which means it
630 is about as good as JPEG compression).
632 @item To have very low audio bitrates, reduce the sampling frequency
633 (down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
635 @item To have a constant quality (but a variable bitrate), use the option
636 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
637 quality).
639 @item When converting video files, you can use the '-sameq' option which
640 uses the same quality factor in the encoder as in the decoder.
641 It allows almost lossless encoding.
643 @end itemize
645 @chapter Supported File Formats and Codecs
647 You can use the @code{-formats} option to have an exhaustive list.
649 @section File Formats
651 FFmpeg supports the following file formats through the @code{libavformat}
652 library:
654 @multitable @columnfractions .4 .1 .1 .4
655 @item Supported File Format @tab Encoding @tab Decoding @tab Comments
656 @item MPEG audio @tab X @tab X
657 @item MPEG-1 systems @tab X @tab X
658 @tab muxed audio and video
659 @item MPEG-2 PS @tab X @tab X
660 @tab also known as @code{VOB} file
661 @item MPEG-2 TS @tab @tab X
662 @tab also known as DVB Transport Stream
663 @item ASF@tab X @tab X
664 @item AVI@tab X @tab X
665 @item WAV@tab X @tab X
666 @item Macromedia Flash@tab X @tab X
667 @tab Only embedded audio is decoded.
668 @item FLV @tab X @tab X
669 @tab Macromedia Flash video files
670 @item Real Audio and Video @tab X @tab X
671 @item Raw AC3 @tab X @tab X
672 @item Raw MJPEG @tab X @tab X
673 @item Raw MPEG video @tab X @tab X
674 @item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
675 @item Raw CRI ADX audio @tab X @tab X
676 @item Raw Shorten audio @tab @tab X
677 @item SUN AU format @tab X @tab X
678 @item NUT @tab X @tab X @tab NUT Open Container Format
679 @item QuickTime @tab X @tab X
680 @item MPEG-4 @tab X @tab X
681 @tab MPEG-4 is a variant of QuickTime.
682 @item Raw MPEG4 video @tab X @tab X
683 @item DV @tab X @tab X
684 @item 4xm @tab @tab X
685 @tab 4X Technologies format, used in some games.
686 @item Playstation STR @tab @tab X
687 @item Id RoQ @tab @tab X
688 @tab Used in Quake III, Jedi Knight 2, other computer games.
689 @item Interplay MVE @tab @tab X
690 @tab Format used in various Interplay computer games.
691 @item WC3 Movie @tab @tab X
692 @tab Multimedia format used in Origin's Wing Commander III computer game.
693 @item Sega FILM/CPK @tab @tab X
694 @tab Used in many Sega Saturn console games.
695 @item Westwood Studios VQA/AUD @tab @tab X
696 @tab Multimedia formats used in Westwood Studios games.
697 @item Id Cinematic (.cin) @tab @tab X
698 @tab Used in Quake II.
699 @item FLIC format @tab @tab X
700 @tab .fli/.flc files
701 @item Sierra VMD @tab @tab X
702 @tab Used in Sierra CD-ROM games.
703 @item Sierra Online @tab @tab X
704 @tab .sol files used in Sierra Online games.
705 @item Matroska @tab @tab X
706 @item Electronic Arts Multimedia @tab @tab X
707 @tab Used in various EA games; files have extensions like WVE and UV2.
708 @item Nullsoft Video (NSV) format @tab @tab X
709 @item ADTS AAC audio @tab X @tab X
710 @item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
711 @item American Laser Games MM @tab @tab X
712 @tab Multimedia format used in games like Mad Dog McCree
713 @item AVS @tab @tab X
714 @tab Multimedia format used by the Creature Shock game.
715 @item Smacker @tab @tab X
716 @tab Multimedia format used by many games.
717 @item GXF @tab @tab X
718 @end multitable
720 @code{X} means that encoding (resp. decoding) is supported.
722 @section Image Formats
724 FFmpeg can read and write images for each frame of a video sequence. The
725 following image formats are supported:
727 @multitable @columnfractions .4 .1 .1 .4
728 @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
729 @item PGM, PPM @tab X @tab X
730 @item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support.
731 @item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
732 @item JPEG @tab X @tab X @tab Progressive JPEG is not supported.
733 @item .Y.U.V @tab X @tab X @tab one raw file per component
734 @item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
735 @item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
736 @item SGI @tab X @tab X @tab SGI RGB image format
737 @end multitable
739 @code{X} means that encoding (resp. decoding) is supported.
741 @section Video Codecs
743 @multitable @columnfractions .4 .1 .1 .4
744 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
745 @item MPEG-1 video @tab X @tab X
746 @item MPEG-2 video @tab X @tab X
747 @item MPEG-4 @tab X @tab X @tab also known as DivX4/5
748 @item MSMPEG4 V1 @tab X @tab X
749 @item MSMPEG4 V2 @tab X @tab X
750 @item MSMPEG4 V3 @tab X @tab X @tab also known as DivX3
751 @item WMV7 @tab X @tab X
752 @item WMV8 @tab X @tab X @tab not completely working
753 @item H.261 @tab X @tab X
754 @item H.263(+) @tab X @tab X @tab also known as RealVideo 1.0
755 @item H.264 @tab @tab X
756 @item RealVideo 1.0 @tab X @tab X
757 @item RealVideo 2.0 @tab X @tab X
758 @item MJPEG @tab X @tab X
759 @item lossless MJPEG @tab X @tab X
760 @item JPEG-LS @tab X @tab X @tab fourcc: MJLS, lossless and near-lossless is supported
761 @item Apple MJPEG-B @tab @tab X
762 @item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
763 @item DV @tab X @tab X
764 @item HuffYUV @tab X @tab X
765 @item FFmpeg Video 1 @tab X @tab X @tab experimental lossless codec (fourcc: FFV1)
766 @item FFmpeg Snow @tab X @tab X @tab experimental wavelet codec (fourcc: SNOW)
767 @item Asus v1 @tab X @tab X @tab fourcc: ASV1
768 @item Asus v2 @tab X @tab X @tab fourcc: ASV2
769 @item Creative YUV @tab @tab X @tab fourcc: CYUV
770 @item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
771 @item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
772 @item On2 VP3 @tab @tab X @tab still experimental
773 @item Theora @tab @tab X @tab still experimental
774 @item Intel Indeo 3 @tab @tab X
775 @item FLV @tab X @tab X @tab Sorenson H.263 used in Flash
776 @item Flash Screen Video @tab @tab X @tab fourcc: FSV1
777 @item ATI VCR1 @tab @tab X @tab fourcc: VCR1
778 @item ATI VCR2 @tab @tab X @tab fourcc: VCR2
779 @item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
780 @item 4X Video @tab @tab X @tab Used in certain computer games.
781 @item Sony Playstation MDEC @tab @tab X
782 @item Id RoQ @tab @tab X @tab Used in Quake III, Jedi Knight 2, other computer games.
783 @item Xan/WC3 @tab @tab X @tab Used in Wing Commander III .MVE files.
784 @item Interplay Video @tab @tab X @tab Used in Interplay .MVE files.
785 @item Apple Animation @tab @tab X @tab fourcc: 'rle '
786 @item Apple Graphics @tab @tab X @tab fourcc: 'smc '
787 @item Apple Video @tab @tab X @tab fourcc: rpza
788 @item Apple QuickDraw @tab @tab X @tab fourcc: qdrw
789 @item Cinepak @tab @tab X
790 @item Microsoft RLE @tab @tab X
791 @item Microsoft Video-1 @tab @tab X
792 @item Westwood VQA @tab @tab X
793 @item Id Cinematic Video @tab @tab X @tab Used in Quake II.
794 @item Planar RGB @tab @tab X @tab fourcc: 8BPS
795 @item FLIC video @tab @tab X
796 @item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
797 @item Duck TrueMotion v2 @tab @tab X @tab fourcc: TM20
798 @item VMD Video @tab @tab X @tab Used in Sierra VMD files.
799 @item MSZH @tab @tab X @tab Part of LCL
800 @item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
801 @item TechSmith Camtasia @tab @tab X @tab fourcc: TSCC
802 @item IBM Ultimotion @tab @tab X @tab fourcc: ULTI
803 @item Miro VideoXL @tab @tab X @tab fourcc: VIXL
804 @item QPEG @tab @tab X @tab fourccs: QPEG, Q1.0, Q1.1
805 @item LOCO @tab @tab X @tab
806 @item Winnov WNV1 @tab @tab X @tab
807 @item Autodesk Animator Studio Codec @tab @tab X @tab fourcc: AASC
808 @item Fraps FPS1 @tab @tab X @tab
809 @item CamStudio @tab @tab X @tab fourcc: CSCD
810 @item American Laser Games Video @tab @tab X @tab Used in games like Mad Dog McCree
811 @item ZMBV @tab @tab X @tab
812 @item AVS Video @tab @tab X @tab Video encoding used by the Creature Shock game.
813 @item Smacker Video @tab @tab X @tab Video encoding used in Smacker.
814 @item RTjpeg @tab @tab X @tab Video encoding used in NuppelVideo files.
815 @item KMVC @tab @tab X @tab Codec used in Worms games.
816 @end multitable
818 @code{X} means that encoding (resp. decoding) is supported.
820 See @url{} to
821 get a precise comparison of the FFmpeg MPEG-4 codec compared to
822 other implementations.
824 @section Audio Codecs
826 @multitable @columnfractions .4 .1 .1 .1 .7
827 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
828 @item MPEG audio layer 2 @tab IX @tab IX
829 @item MPEG audio layer 1/3 @tab IX @tab IX
830 @tab MP3 encoding is supported through the external library LAME.
831 @item AC3 @tab IX @tab IX
832 @tab liba52 is used internally for decoding.
833 @item Vorbis @tab X @tab X
834 @tab Supported through the external library libvorbis.
835 @item WMA V1/V2 @tab @tab X
836 @item AAC @tab X @tab X
837 @tab Supported through the external library libfaac/libfaad.
838 @item Microsoft ADPCM @tab X @tab X
839 @item MS IMA ADPCM @tab X @tab X
840 @item QT IMA ADPCM @tab @tab X
841 @item 4X IMA ADPCM @tab @tab X
842 @item G.726 ADPCM @tab X @tab X
843 @item Duck DK3 IMA ADPCM @tab @tab X
844 @tab Used in some Sega Saturn console games.
845 @item Duck DK4 IMA ADPCM @tab @tab X
846 @tab Used in some Sega Saturn console games.
847 @item Westwood Studios IMA ADPCM @tab @tab X
848 @tab Used in Westwood Studios games like Command and Conquer.
849 @item SMJPEG IMA ADPCM @tab @tab X
850 @tab Used in certain Loki game ports.
851 @item CD-ROM XA ADPCM @tab @tab X
852 @item CRI ADX ADPCM @tab X @tab X
853 @tab Used in Sega Dreamcast games.
854 @item Electronic Arts ADPCM @tab @tab X
855 @tab Used in various EA titles.
856 @item Creative ADPCM @tab @tab X
857 @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
858 @item RA144 @tab @tab X
859 @tab Real 14400 bit/s codec
860 @item RA288 @tab @tab X
861 @tab Real 28800 bit/s codec
862 @item RADnet @tab X @tab IX
863 @tab Real low bitrate AC3 codec, liba52 is used for decoding.
864 @item AMR-NB @tab X @tab X
865 @tab Supported through an external library.
866 @item AMR-WB @tab X @tab X
867 @tab Supported through an external library.
868 @item DV audio @tab @tab X
869 @item Id RoQ DPCM @tab @tab X
870 @tab Used in Quake III, Jedi Knight 2, other computer games.
871 @item Interplay MVE DPCM @tab @tab X
872 @tab Used in various Interplay computer games.
873 @item Xan DPCM @tab @tab X
874 @tab Used in Origin's Wing Commander IV AVI files.
875 @item Sierra Online DPCM @tab @tab X
876 @tab Used in Sierra Online game audio files.
877 @item Apple MACE 3 @tab @tab X
878 @item Apple MACE 6 @tab @tab X
879 @item FLAC lossless audio @tab @tab X
880 @item Shorten lossless audio @tab @tab X
881 @item Apple lossless audio @tab @tab X
882 @tab QuickTime fourcc 'alac'
883 @item FFmpeg Sonic @tab X @tab X
884 @tab experimental lossy/lossless codec
885 @item Qdesign QDM2 @tab @tab X
886 @tab there are still some distortions
887 @item Real COOK @tab @tab X
888 @tab All versions except 5.1 are supported
889 @item DSP Group TrueSpeech @tab @tab X
890 @item True Audio (TTA) @tab @tab X
891 @item Smacker Audio @tab @tab X
892 @end multitable
894 @code{X} means that encoding (resp. decoding) is supported.
896 @code{I} means that an integer-only version is available, too (ensures high
897 performance on systems without hardware floating point support).
899 @chapter Platform Specific information
901 @section Linux
903 FFmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
904 preferred compiler now for FFmpeg. All future optimizations will depend on
905 features only found in GCC 3.2.
907 @section BSD
909 BSD make will not build FFmpeg, you need to install and use GNU Make
910 (@file{gmake}).
912 @section Windows
914 @subsection Native Windows compilation
916 @itemize
917 @item Install the current versions of MSYS and MinGW from
918 @url{}. You can find detailed installation
919 instructions in the download section and the FAQ.
921 @item If you want to test the FFplay, also download
922 the MinGW development library of SDL 1.2.x
923 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
924 @url{}. Unpack it in a temporary directory, and
925 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
926 directory. Edit the @file{sdl-config} script so that it gives the
927 correct SDL directory when invoked.
929 @item Extract the current version of FFmpeg.
931 @item Start the MSYS shell (file @file{msys.bat}).
933 @item Change to the FFmpeg directory and follow
934 the instructions of how to compile FFmpeg (file
935 @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
936 suffices. If you have problems using SDL, verify that
937 @file{sdl-config} can be launched from the MSYS command line.
939 @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
940 @file{make install}. Don't forget to copy @file{SDL.dll} to the place
941 you launch @file{ffplay} from.
943 @end itemize
945 Notes:
946 @itemize
948 @item The target @file{make wininstaller} can be used to create a
949 Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
950 must be copied to the FFmpeg directory in order to build the
951 installer.
953 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
954 you can build @file{avcodec.dll} and @file{avformat.dll}. With
955 @code{make install} you install the FFmpeg DLLs and the associated
956 headers in @file{Program Files/FFmpeg}.
958 @item Visual C++ compatibility: If you used @code{./configure --enable-shared}
959 when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
960 C++ @code{lib} tool to build @code{avcodec.lib} and
961 @code{avformat.lib}. With these libraries you can link your Visual C++
962 code directly with the FFmpeg DLLs (see below).
964 @end itemize
966 @subsection Visual C++ compatibility
968 FFmpeg will not compile under Visual C++ -- and it has too many
969 dependencies on the GCC compiler to make a port viable. However,
970 if you want to use the FFmpeg libraries in your own applications,
971 you can still compile those applications using Visual C++. An
972 important restriction to this is that you have to use the
973 dynamically linked versions of the FFmpeg libraries (i.e. the
974 DLLs), and you have to make sure that Visual-C++-compatible
975 import libraries are created during the FFmpeg build process.
977 This description of how to use the FFmpeg libraries with Visual C++ is
978 based on Visual C++ 2005 Express Edition Beta 2. If you have a different
979 version, you might have to modify the procedures slightly.
981 Here are the step-by-step instructions for building the FFmpeg libraries
982 so they can be used with Visual C++:
984 @enumerate
986 @item Install Visual C++ (if you haven't done so already).
988 @item Install MinGW and MSYS as described above.
990 @item Add a call to @file{vcvars32.bat} (which sets up the environment
991 variables for the Visual C++ tools) as the first line of
992 @file{msys.bat}. The standard location for @file{vcvars32.bat} is
993 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
994 and the standard location for @file{msys.bat} is
995 @file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
996 following line as the first line of @file{msys.bat}:
998 @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
1000 @item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
1001 If you get a help message with the command line options of @code{link.exe},
1002 this means your environment variables are set up correctly, the
1003 Microsoft linker is on the path and will be used by FFmpeg to
1004 create Visual-C++-compatible import libraries.
1006 @item Extract the current version of FFmpeg and change to the FFmpeg directory.
1008 @item Type the command
1009 @code{./configure --enable-shared --disable-static --enable-memalign-hack}
1010 to configure and, if that didn't produce any errors,
1011 type @code{make} to build FFmpeg.
1013 @item The subdirectories @file{libavformat}, @file{libavcodec}, and
1014 @file{libavutil} should now contain the files @file{avformat.dll},
1015 @file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1016 @file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1017 DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1019 @end enumerate
1021 And here is how to use these libraries with Visual C++:
1023 @enumerate
1025 @item Create a new console application ("File / New / Project") and then
1026 select "Win32 Console Application". On the appropriate page of the
1027 Application Wizard, uncheck the "Precompiled headers" option.
1029 @item Write the source code for your application, or, for testing, just
1030 copy the code from an existing sample application into the source file
1031 that Visual C++ has already created for you. (Note that your source
1032 filehas to have a @code{.cpp} extension; otherwise, Visual C++ won't
1033 compile the FFmpeg headers correctly because in C mode, it doesn't
1034 recognize the @code{inline} keyword.) For example, you can copy
1035 @file{output_example.c} from the FFmpeg distribution (but you will
1036 have to make minor modifications so the code will compile under
1037 C++, see below).
1039 @item Open the "Project / Properties" dialog box. In the "Configuration"
1040 combo box, select "All Configurations" so that the changes you make will
1041 affect both debug and release builds. In the tree view on the left hand
1042 side, select "C/C++ / General", then edit the "Additional Include
1043 Directories" setting to contain the complete paths to the
1044 @file{libavformat}, @file{libavcodec}, and @file{libavutil}
1045 subdirectories of your FFmpeg directory. Note that the directories have
1046 to be separated using semicolons. Now select "Linker / General" from the
1047 tree view and edit the "Additional Library Directories" setting to
1048 contain the same three directories.
1050 @item Still in the "Project / Properties" dialog box, select "Linker / Input"
1051 from the tree view, then add the files @file{avformat.lib},
1052 @file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1053 Dependencies". Note that the names of the libraries have to be separated
1054 using spaces.
1056 @item Now, select "C/C++ / Code Generation" from the tree view. Select
1057 "Debug" in the "Configuration" combo box. Make sure that "Runtime
1058 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1059 the "Configuration" combo box and make sure that "Runtime Library" is
1060 set to "Multi-threaded DLL".
1062 @item Click "OK" to close the "Project / Properties" dialog box and build
1063 the application. Hopefully, it should compile and run cleanly. If you
1064 used @file{output_example.c} as your sample application, you will get a
1065 few compiler errors, but they are easy to fix. The first type of error
1066 occurs because Visual C++ doesn't allow an @code{int} to be converted to
1067 an @code{enum} without a cast. To solve the problem, insert the required
1068 casts (this error occurs once for a @code{CodecID} and once for a
1069 @code{CodecType}). The second type of error occurs because C++ requires
1070 the return value of @code{malloc} to be cast to the exact type of the
1071 pointer it is being assigned to. Visual C++ will complain that, for
1072 example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1073 an explicit cast. So insert an explicit cast in these places to silence
1074 the compiler. The third type of error occurs because the @code{snprintf}
1075 library function is called @code{_snprintf} under Visual C++. So just
1076 add an underscore to fix the problem. With these changes,
1077 @file{output_example.c} should compile under Visual C++, and the
1078 resulting executable should produce valid video files.
1080 @end enumerate
1082 @subsection Cross compilation for Windows with Linux
1084 You must use the MinGW cross compilation tools available at
1085 @url{}.
1087 Then configure FFmpeg with the following options:
1088 @example
1089 ./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
1090 @end example
1091 (you can change the cross-prefix according to the prefix chosen for the
1092 MinGW tools).
1094 Then you can easily test FFmpeg with Wine
1095 (@url{}).
1097 @subsection Compilation under Cygwin
1099 Cygwin works very much like Unix.
1101 Just install your Cygwin with all the "Base" packages, plus the
1102 following "Devel" ones:
1103 @example
1104 binutils, gcc-core, make, subversion
1105 @end example
1107 Do not install binutils-20060709-1 (they are buggy on shared builds);
1108 use binutils-20050610-1 instead.
1110 Then run
1112 @example
1113 ./configure --enable-static --disable-shared
1114 @end example
1116 to make a static build or
1118 @example
1119 ./configure --enable-shared --disable-static
1120 @end example
1122 to build shared libraries.
1124 If you want to build FFmpeg with additional libraries, download Cygwin
1125 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
1126 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
1127 (@url{}).
1129 @subsection Crosscompilation for Windows under Cygwin
1131 With Cygwin you can create Windows binaries that don't need the cygwin1.dll.
1133 Just install your Cygwin as explained before, plus these additional
1134 "Devel" packages:
1135 @example
1136 gcc-mingw-core, mingw-runtime, mingw-zlib
1137 @end example
1139 and add some special flags to your configure invocation.
1141 For a static build run
1142 @example
1143 ./configure --enable-mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1144 @end example
1146 and for a build with shared libraries
1147 @example
1148 ./configure --enable-mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1149 @end example
1151 @section Mac OS X
1153 @section BeOS
1155 The configure script should guess the configuration itself.
1156 Networking support is currently not finished.
1157 errno issues fixed by Andrew Bachmann.
1159 Old stuff:
1161 Fran├žois Revol - revol at free dot fr - April 2002
1163 The configure script should guess the configuration itself,
1164 however I still didn't test building on the net_server version of BeOS.
1166 FFserver is broken (needs poll() implementation).
1168 There are still issues with errno codes, which are negative in BeOS, and
1169 that FFmpeg negates when returning. This ends up turning errors into
1170 valid results, then crashes.
1171 (To be fixed)
1173 @chapter Developers Guide
1175 @section API
1176 @itemize @bullet
1177 @item libavcodec is the library containing the codecs (both encoding and
1178 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1180 @item libavformat is the library containing the file format handling (mux and
1181 demux code for several formats). Look at @file{ffplay.c} to use it in a
1182 player. See @file{output_example.c} to use it to generate audio or video
1183 streams.
1185 @end itemize
1187 @section Integrating libavcodec or libavformat in your program
1189 You can integrate all the source code of the libraries to link them
1190 statically to avoid any version problem. All you need is to provide a
1191 'config.mak' and a 'config.h' in the parent directory. See the defines
1192 generated by ./configure to understand what is needed.
1194 You can use libavcodec or libavformat in your commercial program, but
1195 @emph{any patch you make must be published}. The best way to proceed is
1196 to send your patches to the FFmpeg mailing list.
1198 @node Coding Rules
1199 @section Coding Rules
1201 FFmpeg is programmed in the ISO C90 language with a few additional
1202 features from ISO C99, namely:
1203 @itemize @bullet
1204 @item
1205 the @samp{inline} keyword;
1206 @item
1207 @samp{//} comments;
1208 @item
1209 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1210 @item
1211 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1212 @end itemize
1214 These features are supported by all compilers we care about, so we won't
1215 accept patches to remove their use unless they absolutely don't impair
1216 clarity and performance.
1218 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1219 compiles with several other compilers, such as the Compaq ccc compiler
1220 or Sun Studio 9, and we would like to keep it that way unless it would
1221 be exceedingly involved. To ensure compatibility, please don't use any
1222 additional C99 features or GCC extensions. Especially watch out for:
1223 @itemize @bullet
1224 @item
1225 mixing statements and declarations;
1226 @item
1227 @samp{long long} (use @samp{int64_t} instead);
1228 @item
1229 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1230 @item
1231 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1232 @end itemize
1234 Indent size is 4.
1235 The presentation is the one specified by 'indent -i4 -kr -nut'.
1236 The TAB character is forbidden outside of Makefiles as is any
1237 form of trailing whitespace. Commits containing either will be
1238 rejected by the Subversion repository.
1240 Main priority in FFmpeg is simplicity and small code size (=less
1241 bugs).
1243 Comments: Use the JavaDoc/Doxygen
1244 format (see examples below) so that code documentation
1245 can be generated automatically. All nontrivial functions should have a comment
1246 above them explaining what the function does, even if it's just one sentence.
1247 All structures and their member variables should be documented, too.
1248 @example
1249 /**
1250 * @@file mpeg.c
1251 * MPEG codec.
1252 * @@author ...
1253 */
1255 /**
1256 * Summary sentence.
1257 * more text ...
1258 * ...
1259 */
1260 typedef struct Foobar@{
1261 int var1; /**< var1 description */
1262 int var2; ///< var2 description
1263 /** var3 description */
1264 int var3;
1265 @} Foobar;
1267 /**
1268 * Summary sentence.
1269 * more text ...
1270 * ...
1271 * @@param my_parameter description of my_parameter
1272 * @@return return value description
1273 */
1274 int myfunc(int my_parameter)
1275 ...
1276 @end example
1278 fprintf and printf are forbidden in libavformat and libavcodec,
1279 please use av_log() instead.
1281 @section Development Policy
1283 @enumerate
1284 @item
1285 You must not commit code which breaks FFmpeg! (Meaning unfinished but
1286 enabled code which breaks compilation or compiles but does not work or
1287 breaks the regression tests)
1288 You can commit unfinished stuff (for testing etc), but it must be disabled
1289 (#ifdef etc) by default so it does not interfere with other developers'
1290 work.
1291 @item
1292 You don't have to over-test things. If it works for you, and you think it
1293 should work for others, then commit. If your code has problems
1294 (portability, triggers compiler bugs, unusual environment etc) they will be
1295 reported and eventually fixed.
1296 @item
1297 Do not commit unrelated changes together, split them into self-contained
1298 pieces.
1299 @item
1300 Do not change behavior of the program (renaming options etc) without
1301 first discussing it on the ffmpeg-devel mailing list. Do not remove
1302 functionality from the code. Just improve!
1304 Note: Redundant code can be removed.
1305 @item
1306 Do not commit changes to the build system (Makefiles, configure script)
1307 which change behavior, defaults etc, without asking first. The same
1308 applies to compiler warning fixes, trivial looking fixes and to code
1309 maintained by other developers. We usually have a reason for doing things
1310 the way we do. Send your changes as patches to the ffmpeg-devel mailing
1311 list, and if the code maintainers say OK, you may commit. This does not
1312 apply to files you wrote and/or maintain.
1313 @item
1314 We refuse source indentation and other cosmetic changes if they are mixed
1315 with functional changes, such commits will be rejected and removed. Every
1316 developer has his own indentation style, you should not change it. Of course
1317 if you (re)write something, you can use your own style, even though we would
1318 prefer if the indentation throughout FFmpeg was consistent (Many projects
1319 force a given indentation style - we don't.). If you really need to make
1320 indentation changes (try to avoid this), separate them strictly from real
1321 changes.
1323 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1324 then either do NOT change the indentation of the inner part within (don't
1325 move it to the right)! or do so in a separate commit
1326 @item
1327 Always fill out the commit log message. Describe in a few lines what you
1328 changed and why. You can refer to mailing list postings if you fix a
1329 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1330 @item
1331 If you apply a patch by someone else, include the name and email address in
1332 the log message. Since the ffmpeg-cvslog mailing list is publicly
1333 archived you should add some SPAM protection to the email address. Send an
1334 answer to ffmpeg-devel (or wherever you got the patch from) saying that
1335 you applied the patch.
1336 @item
1337 Do NOT commit to code actively maintained by others without permission.
1338 Send a patch to ffmpeg-devel instead. If noone answers within a reasonable
1339 timeframe (12h for build failures and security fixes, 3 days small changes,
1340 1 week for big patches) then commit your patch if you think it's OK.
1341 Also note, the maintainer can simply ask for more time to review!
1342 @item
1343 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1344 are sent there and reviewed by all the other developers. Bugs and possible
1345 improvements or general questions regarding commits are discussed there. We
1346 expect you to react if problems with your code are uncovered.
1347 @item
1348 Update the documentation if you change behavior or add features. If you are
1349 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1350 maintainer(s) will review and commit your stuff.
1351 @item
1352 Never write to unallocated memory, never write over the end of arrays,
1353 always check values read from some untrusted source before using them
1354 as array index or other risky things.
1355 @item
1356 Remember to check if you need to bump versions for the specific libav
1357 parts (libavutil, libavcodec, libavformat) you are changing. You need
1358 to change the version integer and the version string.
1359 Incrementing the first component means no backward compatibility to
1360 previous versions (e.g. removal of a function from the public API).
1361 Incrementing the second component means backward compatible change
1362 (e.g. addition of a function to the public API).
1363 Incrementing the third component means a noteworthy binary compatible
1364 change (e.g. encoder bug fix that matters for the decoder).
1365 @item
1366 If you add a new codec, remember to update the changelog, add it to
1367 the supported codecs table in the documentation and bump the second
1368 component of the @file{libavcodec} version number appropriately. If
1369 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1370 is only a decoder.
1371 @end enumerate
1373 We think our rules are not too hard. If you have comments, contact us.
1375 Note, these rules are mostly borrowed from the MPlayer project.
1377 @section Submitting patches
1379 First, (@pxref{Coding Rules}) above if you didn't yet.
1381 When you submit your patch, try to send a unified diff (diff '-up'
1382 option). I cannot read other diffs :-)
1384 Also please do not submit patches which contain several unrelated changes.
1385 Split them into individual self-contained patches; this makes reviewing
1386 them much easier.
1388 Run the regression tests before submitting a patch so that you can
1389 verify that there are no big problems.
1391 Patches should be posted as base64 encoded attachments (or any other
1392 encoding which ensures that the patch won't be trashed during
1393 transmission) to the ffmpeg-devel mailing list, see
1394 @url{}
1396 It also helps quite a bit if you tell us what the patch does (for example
1397 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1398 and has no lrint()')
1400 We reply to all submitted patches and either apply or reject with some
1401 explanation why, but sometimes we are quite busy so it can take a week or two.
1403 @section Regression tests
1405 Before submitting a patch (or committing to the repository), you should at least
1406 test that you did not break anything.
1408 The regression tests build a synthetic video stream and a synthetic
1409 audio stream. These are then encoded and decoded with all codecs or
1410 formats. The CRC (or MD5) of each generated file is recorded in a
1411 result file. A 'diff' is launched to compare the reference results and
1412 the result file.
1414 The regression tests then go on to test the FFserver code with a
1415 limited set of streams. It is important that this step runs correctly
1416 as well.
1418 Run 'make test' to test all the codecs and formats.
1420 Run 'make fulltest' to test all the codecs, formats and FFserver.
1422 [Of course, some patches may change the results of the regression tests. In
1423 this case, the reference results of the regression tests shall be modified
1424 accordingly].
1426 @bye