[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{http://bytesex.org/xawtv/}) 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 800k -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 64k} 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 -version
162 Show version.
164 @item -formats
165 Show available formats, codecs, protocols, ...
167 @item -f fmt
168 Force format.
170 @item -i filename
171 input filename
173 @item -y
174 Overwrite output files.
176 @item -t duration
177 Set the recording time in seconds.
178 @code{hh:mm:ss[.xxx]} syntax is also supported.
180 @item -fs limit_size
181 Set the file size limit.
183 @item -ss position
184 Seek to given time position in seconds.
185 @code{hh:mm:ss[.xxx]} syntax is also supported.
187 @item -itsoffset offset
188 Set the input time offset in seconds.
189 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
190 This option affects all the input files that follow it.
191 The offset is added to the timestamps of the input files.
192 Specifying a positive offset means that the corresponding
193 streams are delayed by 'offset' seconds.
195 @item -title string
196 Set the title.
198 @item -timestamp time
199 Set the timestamp.
201 @item -author string
202 Set the author.
204 @item -copyright string
205 Set the copyright.
207 @item -comment string
208 Set the comment.
210 @item -album string
211 Set the album.
213 @item -track number
214 Set the track.
216 @item -year number
217 Set the year.
219 @item -v verbose
220 Control amount of logging.
222 @item -target type
223 Specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "pal-vcd",
224 "ntsc-svcd", ... ). All the format options (bitrate, codecs,
225 buffer sizes) are then set automatically. You can just type:
227 @example
228 ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
229 @end example
231 Nevertheless you can specify additional options as long as you know
232 they do not conflict with the standard, as in:
234 @example
235 ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
236 @end example
238 @item -dframes number
239 Set the number of data frames to record.
241 @item -scodec codec
242 Force subtitle codec ('copy' to copy stream).
244 @item -newsubtitle
245 Add a new subtitle stream to the current output stream.
247 @item -slang code
248 Set the ISO 639 language code (3 letters) of the current subtitle stream.
250 @end table
252 @section Video Options
254 @table @option
255 @item -b bitrate
256 Set the video bitrate in bit/s (default = 200 kb/s).
257 @item -vframes number
258 Set the number of video frames to record.
259 @item -r fps
260 Set frame rate (Hz value, fraction or abbreviation), (default = 25).
261 @item -s size
262 Set frame size. The format is @samp{wxh} (default = 160x128).
263 The following abbreviations are recognized:
264 @table @samp
265 @item sqcif
266 128x96
267 @item qcif
268 176x144
269 @item cif
270 352x288
271 @item 4cif
272 704x576
273 @end table
275 @item -aspect aspect
276 Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
277 @item -croptop size
278 Set top crop band size (in pixels).
279 @item -cropbottom size
280 Set bottom crop band size (in pixels).
281 @item -cropleft size
282 Set left crop band size (in pixels).
283 @item -cropright size
284 Set right crop band size (in pixels).
285 @item -padtop size
286 Set top pad band size (in pixels).
287 @item -padbottom size
288 Set bottom pad band size (in pixels).
289 @item -padleft size
290 Set left pad band size (in pixels).
291 @item -padright size
292 Set right pad band size (in pixels).
293 @item -padcolor (hex color)
294 Set color of padded bands. The value for padcolor is expressed
295 as a six digit hexadecimal number where the first two digits
296 represent red, the middle two digits green and last two digits
297 blue (default = 000000 (black)).
298 @item -vn
299 Disable video recording.
300 @item -bt tolerance
301 Set video bitrate tolerance (in bit/s).
302 @item -maxrate bitrate
303 Set max video bitrate tolerance (in bit/s).
304 @item -minrate bitrate
305 Set min video bitrate tolerance (in bit/s).
306 @item -bufsize size
307 Set rate control buffer size (in bits).
308 @item -vcodec codec
309 Force video codec to @var{codec}. Use the @code{copy} special value to
310 tell that the raw codec data must be copied as is.
311 @item -sameq
312 Use same video quality as source (implies VBR).
314 @item -pass n
315 Select the pass number (1 or 2). It is useful to do two pass
316 encoding. The statistics of the video are recorded in the first
317 pass and the video is generated at the exact requested bitrate
318 in the second pass.
320 @item -passlogfile file
321 Set two pass logfile name to @var{file}.
323 @item -newvideo
324 Add a new video stream to the current output stream.
326 @end table
328 @section Advanced Video Options
330 @table @option
331 @item -pix_fmt format
332 Set pixel format.
333 @item -g gop_size
334 Set the group of pictures size.
335 @item -intra
336 Use only intra frames.
337 @item -vdt n
338 Discard threshold.
339 @item -qscale q
340 Use fixed video quantizer scale (VBR).
341 @item -qmin q
342 minimum video quantizer scale (VBR)
343 @item -qmax q
344 maximum video quantizer scale (VBR)
345 @item -qdiff q
346 maximum difference between the quantizer scales (VBR)
347 @item -qblur blur
348 video quantizer scale blur (VBR)
349 @item -qcomp compression
350 video quantizer scale compression (VBR)
352 @item -lmin lambda
353 minimum video lagrange factor (VBR)
354 @item -lmax lambda
355 max video lagrange factor (VBR)
356 @item -mblmin lambda
357 minimum macroblock quantizer scale (VBR)
358 @item -mblmax lambda
359 maximum macroblock quantizer scale (VBR)
361 These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
362 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
363 @example
364 ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
365 @end example
367 @item -rc_init_cplx complexity
368 initial complexity for single pass encoding
369 @item -b_qfactor factor
370 qp factor between P- and B-frames
371 @item -i_qfactor factor
372 qp factor between P- and I-frames
373 @item -b_qoffset offset
374 qp offset between P- and B-frames
375 @item -i_qoffset offset
376 qp offset between P- and I-frames
377 @item -rc_eq equation
378 Set rate control equation (@pxref{FFmpeg formula
379 evaluator}) (default = @code{tex^qComp}).
380 @item -rc_override override
381 rate control override for specific intervals
382 @item -me method
383 Set motion estimation method to @var{method}.
384 Available methods are (from lowest to best quality):
385 @table @samp
386 @item zero
387 Try just the (0, 0) vector.
388 @item phods
389 @item log
390 @item x1
391 @item epzs
392 (default method)
393 @item full
394 exhaustive search (slow and marginally better than epzs)
395 @end table
397 @item -dct_algo algo
398 Set DCT algorithm to @var{algo}. Available values are:
399 @table @samp
400 @item 0
401 FF_DCT_AUTO (default)
402 @item 1
404 @item 2
406 @item 3
408 @item 4
410 @item 5
412 @end table
414 @item -idct_algo algo
415 Set IDCT algorithm to @var{algo}. Available values are:
416 @table @samp
417 @item 0
418 FF_IDCT_AUTO (default)
419 @item 1
421 @item 2
423 @item 3
425 @item 4
427 @item 5
429 @item 6
431 @item 7
433 @item 8
435 @item 9
437 @item 10
439 @end table
441 @item -er n
442 Set error resilience to @var{n}.
443 @table @samp
444 @item 1
445 FF_ER_CAREFUL (default)
446 @item 2
448 @item 3
450 @item 4
452 @end table
454 @item -ec bit_mask
455 Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
456 the following values:
457 @table @samp
458 @item 1
459 FF_EC_GUESS_MVS (default = enabled)
460 @item 2
461 FF_EC_DEBLOCK (default = enabled)
462 @end table
464 @item -bf frames
465 Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
466 @item -mbd mode
467 macroblock decision
468 @table @samp
469 @item 0
470 FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
471 @item 1
472 FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
473 @item 2
474 FF_MB_DECISION_RD: rate distortion
475 @end table
477 @item -4mv
478 Use four motion vector by macroblock (MPEG-4 only).
479 @item -part
480 Use data partitioning (MPEG-4 only).
481 @item -bug param
482 Work around encoder bugs that are not auto-detected.
483 @item -strict strictness
484 How strictly to follow the standards.
485 @item -aic
486 Enable Advanced intra coding (h263+).
487 @item -umv
488 Enable Unlimited Motion Vector (h263+)
490 @item -deinterlace
491 Deinterlace pictures.
492 @item -ilme
493 Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
494 Use this option if your input file is interlaced and you want
495 to keep the interlaced format for minimum losses.
496 The alternative is to deinterlace the input stream with
497 @option{-deinterlace}, but deinterlacing introduces losses.
498 @item -psnr
499 Calculate PSNR of compressed frames.
500 @item -vstats
501 Dump video coding statistics to @file{vstats_HHMMSS.log}.
502 @item -vhook module
503 Insert video processing @var{module}. @var{module} contains the module
504 name and its parameters separated by spaces.
505 @item -top n
506 top=1/bottom=0/auto=-1 field first
507 @item -dc precision
508 Intra_dc_precision.
509 @item -vtag fourcc/tag
510 Force video tag/fourcc.
511 @item -qphist
512 Show QP histogram.
513 @item -vbsf bitstream filter
514 Bitstream filters available are "dump_extra", "remove_extra", "noise".
515 @end table
517 @section Audio Options
519 @table @option
520 @item -aframes number
521 Set the number of audio frames to record.
522 @item -ar freq
523 Set the audio sampling frequency (default = 44100 Hz).
524 @item -ab bitrate
525 Set the audio bitrate in kbit/s (default = 64).
526 @item -ac channels
527 Set the number of audio channels (default = 1).
528 @item -an
529 Disable audio recording.
530 @item -acodec codec
531 Force audio codec to @var{codec}. Use the @code{copy} special value to
532 specify that the raw codec data must be copied as is.
533 @item -newaudio
534 Add a new audio track to the output file. If you want to specify parameters,
535 do so before @code{-newaudio} (@code{-acodec}, @code{-ab}, etc..).
537 Mapping will be done automatically, if the number of output streams is equal to
538 the number of input streams, else it will pick the first one that matches. You
539 can override the mapping using @code{-map} as usual.
541 Example:
542 @example
543 ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384 test.mpg -acodec mp2 -ab 192 -newaudio
544 @end example
545 @item -alang code
546 Set the ISO 639 language code (3 letters) of the current audio stream.
547 @end table
549 @section Advanced Audio options:
551 @table @option
552 @item -atag fourcc/tag
553 Force audio tag/fourcc.
554 @item -absf bitstream filter
555 Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
556 @end table
558 @section Subtitle options:
560 @table @option
561 @item -scodec codec
562 Force subtitle codec ('copy' to copy stream).
563 @item -newsubtitle
564 Add a new subtitle stream to the current output stream.
565 @item -slang code
566 Set the ISO 639 language code (3 letters) of the current subtitle stream.
567 @end table
569 @section Audio/Video grab options
571 @table @option
572 @item -vd device
573 sEt video grab device (e.g. @file{/dev/video0}).
574 @item -vc channel
575 Set video grab channel (DV1394 only).
576 @item -tvstd standard
577 Set television standard (NTSC, PAL (SECAM)).
578 @item -dv1394
579 Set DV1394 grab.
580 @item -ad device
581 Set audio device (e.g. @file{/dev/dsp}).
582 @item -grab format
583 Request grabbing using.
584 @item -gd device
585 Set grab device.
586 @end table
588 @section Advanced options
590 @table @option
591 @item -map input stream id[:input stream id]
592 Set stream mapping from input streams to output streams.
593 Just enumerate the input streams in the order you want them in the output.
594 [input stream id] sets the (input) stream to sync against.
595 @item -map_meta_data outfile:infile
596 Set meta data information of outfile from infile.
597 @item -debug
598 Print specific debug info.
599 @item -benchmark
600 Add timings for benchmarking.
601 @item -dump
602 Dump each input packet.
603 @item -hex
604 When dumping packets, also dump the payload.
605 @item -bitexact
606 Only use bit exact algorithms (for codec testing).
607 @item -ps size
608 Set packet size in bits.
609 @item -re
610 Read input at native frame rate. Mainly used to simulate a grab device.
611 @item -loop_input
612 Loop over the input stream. Currently it works only for image
613 streams. This option is used for automatic FFserver testing.
614 @item -loop_output number_of_times
615 Repeatedly loop output for formats that support looping such as animated GIF
616 (0 will loop the output infinitely).
617 @item -threads count
618 Thread count.
619 @item -vsync parameter
620 Video sync method. Video will be stretched/squeezed to match the timestamps,
621 it is done by duplicating and dropping frames. With -map you can select from
622 which stream the timestamps should be taken. You can leave either video or
623 audio unchanged and sync the remaining stream(s) to the unchanged one.
624 @item -async samples_per_second
625 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
626 the parameter is the maximum samples per second by which the audio is changed.
627 -async 1 is a special case where only the start of the audio stream is corrected
628 without any later correction.
629 @end table
631 @node FFmpeg formula evaluator
632 @section FFmpeg formula evaluator
634 When evaluating a rate control string, FFmpeg uses an internal formula
635 evaluator.
637 The following binary operators are available: @code{+}, @code{-},
638 @code{*}, @code{/}, @code{^}.
640 The following unary operators are available: @code{+}, @code{-},
641 @code{(...)}.
643 The following functions are available:
644 @table @var
645 @item sinh(x)
646 @item cosh(x)
647 @item tanh(x)
648 @item sin(x)
649 @item cos(x)
650 @item tan(x)
651 @item exp(x)
652 @item log(x)
653 @item squish(x)
654 @item gauss(x)
655 @item abs(x)
656 @item max(x, y)
657 @item min(x, y)
658 @item gt(x, y)
659 @item lt(x, y)
660 @item eq(x, y)
661 @item bits2qp(bits)
662 @item qp2bits(qp)
663 @end table
665 The following constants are available:
666 @table @var
667 @item PI
668 @item E
669 @item iTex
670 @item pTex
671 @item tex
672 @item mv
673 @item fCode
674 @item iCount
675 @item mcVar
676 @item var
677 @item isI
678 @item isP
679 @item isB
680 @item avgQP
681 @item qComp
682 @item avgIITex
683 @item avgPITex
684 @item avgPPTex
685 @item avgBPTex
686 @item avgTex
687 @end table
689 @c man end
691 @ignore
693 @setfilename ffmpeg
694 @settitle FFmpeg video converter
696 @c man begin SEEALSO
697 ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
698 @c man end
700 @c man begin AUTHOR
701 Fabrice Bellard
702 @c man end
704 @end ignore
706 @section Protocols
708 The filename can be @file{-} to read from standard input or to write
709 to standard output.
711 FFmpeg also handles many protocols specified with an URL syntax.
713 Use 'ffmpeg -formats' to see a list of the supported protocols.
715 The protocol @code{http:} is currently used only to communicate with
716 FFserver (see the FFserver documentation). When FFmpeg will be a
717 video player it will also be used for streaming :-)
719 @chapter Tips
721 @itemize
722 @item For streaming at very low bitrate application, use a low frame rate
723 and a small GOP size. This is especially true for RealVideo where
724 the Linux player does not seem to be very fast, so it can miss
725 frames. An example is:
727 @example
728 ffmpeg -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
729 @end example
731 @item The parameter 'q' which is displayed while encoding is the current
732 quantizer. The value 1 indicates that a very good quality could
733 be achieved. The value 31 indicates the worst quality. If q=31 appears
734 too often, it means that the encoder cannot compress enough to meet
735 your bitrate. You must either increase the bitrate, decrease the
736 frame rate or decrease the frame size.
738 @item If your computer is not fast enough, you can speed up the
739 compression at the expense of the compression ratio. You can use
740 '-me zero' to speed up motion estimation, and '-intra' to disable
741 motion estimation completely (you have only I-frames, which means it
742 is about as good as JPEG compression).
744 @item To have very low audio bitrates, reduce the sampling frequency
745 (down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
747 @item To have a constant quality (but a variable bitrate), use the option
748 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
749 quality).
751 @item When converting video files, you can use the '-sameq' option which
752 uses the same quality factor in the encoder as in the decoder.
753 It allows almost lossless encoding.
755 @end itemize
757 @chapter Supported File Formats and Codecs
759 You can use the @code{-formats} option to have an exhaustive list.
761 @section File Formats
763 FFmpeg supports the following file formats through the @code{libavformat}
764 library:
766 @multitable @columnfractions .4 .1 .1 .4
767 @item Supported File Format @tab Encoding @tab Decoding @tab Comments
768 @item MPEG audio @tab X @tab X
769 @item MPEG-1 systems @tab X @tab X
770 @tab muxed audio and video
771 @item MPEG-2 PS @tab X @tab X
772 @tab also known as @code{VOB} file
773 @item MPEG-2 TS @tab @tab X
774 @tab also known as DVB Transport Stream
775 @item ASF@tab X @tab X
776 @item AVI@tab X @tab X
777 @item WAV@tab X @tab X
778 @item Macromedia Flash@tab X @tab X
779 @tab Only embedded audio is decoded.
780 @item FLV @tab X @tab X
781 @tab Macromedia Flash video files
782 @item Real Audio and Video @tab X @tab X
783 @item Raw AC3 @tab X @tab X
784 @item Raw MJPEG @tab X @tab X
785 @item Raw MPEG video @tab X @tab X
786 @item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
787 @item Raw CRI ADX audio @tab X @tab X
788 @item Raw Shorten audio @tab @tab X
789 @item SUN AU format @tab X @tab X
790 @item NUT @tab X @tab X @tab NUT Open Container Format
791 @item QuickTime @tab X @tab X
792 @item MPEG-4 @tab X @tab X
793 @tab MPEG-4 is a variant of QuickTime.
794 @item Raw MPEG4 video @tab X @tab X
795 @item DV @tab X @tab X
796 @item 4xm @tab @tab X
797 @tab 4X Technologies format, used in some games.
798 @item Playstation STR @tab @tab X
799 @item Id RoQ @tab @tab X
800 @tab Used in Quake III, Jedi Knight 2, other computer games.
801 @item Interplay MVE @tab @tab X
802 @tab Format used in various Interplay computer games.
803 @item WC3 Movie @tab @tab X
804 @tab Multimedia format used in Origin's Wing Commander III computer game.
805 @item Sega FILM/CPK @tab @tab X
806 @tab Used in many Sega Saturn console games.
807 @item Westwood Studios VQA/AUD @tab @tab X
808 @tab Multimedia formats used in Westwood Studios games.
809 @item Id Cinematic (.cin) @tab @tab X
810 @tab Used in Quake II.
811 @item FLIC format @tab @tab X
812 @tab .fli/.flc files
813 @item Sierra VMD @tab @tab X
814 @tab Used in Sierra CD-ROM games.
815 @item Sierra Online @tab @tab X
816 @tab .sol files used in Sierra Online games.
817 @item Matroska @tab @tab X
818 @item Electronic Arts Multimedia @tab @tab X
819 @tab Used in various EA games; files have extensions like WVE and UV2.
820 @item Nullsoft Video (NSV) format @tab @tab X
821 @item ADTS AAC audio @tab X @tab X
822 @item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
823 @item American Laser Games MM @tab @tab X
824 @tab Multimedia format used in games like Mad Dog McCree
825 @item AVS @tab @tab X
826 @tab Multimedia format used by the Creature Shock game.
827 @item Smacker @tab @tab X
828 @tab Multimedia format used by many games.
829 @item GXF @tab X @tab X
830 @tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
831 @item CIN @tab @tab X
832 @tab Multimedia format used by Delphine Software games.
833 @item MXF @tab @tab X
834 @tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
835 @item SEQ @tab @tab X
836 @tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
837 @end multitable
839 @code{X} means that encoding (resp. decoding) is supported.
841 @section Image Formats
843 FFmpeg can read and write images for each frame of a video sequence. The
844 following image formats are supported:
846 @multitable @columnfractions .4 .1 .1 .4
847 @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
848 @item PGM, PPM @tab X @tab X
849 @item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support.
850 @item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
851 @item JPEG @tab X @tab X @tab Progressive JPEG is not supported.
852 @item .Y.U.V @tab X @tab X @tab one raw file per component
853 @item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
854 @item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
855 @item Targa @tab @tab X @tab Targa (.TGA) image format.
856 @item TIFF @tab @tab X @tab Only 24 bit/pixel images are supported.
857 @item SGI @tab X @tab X @tab SGI RGB image format
858 @end multitable
860 @code{X} means that encoding (resp. decoding) is supported.
862 @section Video Codecs
864 @multitable @columnfractions .4 .1 .1 .4
865 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
866 @item MPEG-1 video @tab X @tab X
867 @item MPEG-2 video @tab X @tab X
868 @item MPEG-4 @tab X @tab X
869 @item MSMPEG4 V1 @tab X @tab X
870 @item MSMPEG4 V2 @tab X @tab X
871 @item MSMPEG4 V3 @tab X @tab X
872 @item WMV7 @tab X @tab X
873 @item WMV8 @tab X @tab X @tab not completely working
874 @item WMV9 @tab @tab X @tab not completely working
875 @item VC1 @tab @tab X
876 @item H.261 @tab X @tab X
877 @item H.263(+) @tab X @tab X @tab also known as RealVideo 1.0
878 @item H.264 @tab @tab X
879 @item RealVideo 1.0 @tab X @tab X
880 @item RealVideo 2.0 @tab X @tab X
881 @item MJPEG @tab X @tab X
882 @item lossless MJPEG @tab X @tab X
883 @item JPEG-LS @tab X @tab X @tab fourcc: MJLS, lossless and near-lossless is supported
884 @item Apple MJPEG-B @tab @tab X
885 @item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
886 @item DV @tab X @tab X
887 @item HuffYUV @tab X @tab X
888 @item FFmpeg Video 1 @tab X @tab X @tab experimental lossless codec (fourcc: FFV1)
889 @item FFmpeg Snow @tab X @tab X @tab experimental wavelet codec (fourcc: SNOW)
890 @item Asus v1 @tab X @tab X @tab fourcc: ASV1
891 @item Asus v2 @tab X @tab X @tab fourcc: ASV2
892 @item Creative YUV @tab @tab X @tab fourcc: CYUV
893 @item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
894 @item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
895 @item On2 VP3 @tab @tab X @tab still experimental
896 @item On2 VP5 @tab @tab X @tab fourcc: VP50
897 @item On2 VP6 @tab @tab X @tab fourcc: VP62
898 @item Theora @tab @tab X @tab still experimental
899 @item Intel Indeo 3 @tab @tab X
900 @item FLV @tab X @tab X @tab Sorenson H.263 used in Flash
901 @item Flash Screen Video @tab @tab X @tab fourcc: FSV1
902 @item ATI VCR1 @tab @tab X @tab fourcc: VCR1
903 @item ATI VCR2 @tab @tab X @tab fourcc: VCR2
904 @item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
905 @item 4X Video @tab @tab X @tab Used in certain computer games.
906 @item Sony Playstation MDEC @tab @tab X
907 @item Id RoQ @tab @tab X @tab Used in Quake III, Jedi Knight 2, other computer games.
908 @item Xan/WC3 @tab @tab X @tab Used in Wing Commander III .MVE files.
909 @item Interplay Video @tab @tab X @tab Used in Interplay .MVE files.
910 @item Apple Animation @tab @tab X @tab fourcc: 'rle '
911 @item Apple Graphics @tab @tab X @tab fourcc: 'smc '
912 @item Apple Video @tab @tab X @tab fourcc: rpza
913 @item Apple QuickDraw @tab @tab X @tab fourcc: qdrw
914 @item Cinepak @tab @tab X
915 @item Microsoft RLE @tab @tab X
916 @item Microsoft Video-1 @tab @tab X
917 @item Westwood VQA @tab @tab X
918 @item Id Cinematic Video @tab @tab X @tab Used in Quake II.
919 @item Planar RGB @tab @tab X @tab fourcc: 8BPS
920 @item FLIC video @tab @tab X
921 @item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
922 @item Duck TrueMotion v2 @tab @tab X @tab fourcc: TM20
923 @item VMD Video @tab @tab X @tab Used in Sierra VMD files.
924 @item MSZH @tab @tab X @tab Part of LCL
925 @item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
926 @item TechSmith Camtasia @tab @tab X @tab fourcc: TSCC
927 @item IBM Ultimotion @tab @tab X @tab fourcc: ULTI
928 @item Miro VideoXL @tab @tab X @tab fourcc: VIXL
929 @item QPEG @tab @tab X @tab fourccs: QPEG, Q1.0, Q1.1
930 @item LOCO @tab @tab X @tab
931 @item Winnov WNV1 @tab @tab X @tab
932 @item Autodesk Animator Studio Codec @tab @tab X @tab fourcc: AASC
933 @item Fraps FPS1 @tab @tab X @tab
934 @item CamStudio @tab @tab X @tab fourcc: CSCD
935 @item American Laser Games Video @tab @tab X @tab Used in games like Mad Dog McCree
936 @item ZMBV @tab @tab X @tab
937 @item AVS Video @tab @tab X @tab Video encoding used by the Creature Shock game.
938 @item Smacker Video @tab @tab X @tab Video encoding used in Smacker.
939 @item RTjpeg @tab @tab X @tab Video encoding used in NuppelVideo files.
940 @item KMVC @tab @tab X @tab Codec used in Worms games.
941 @item VMware Video @tab @tab X @tab Codec used in videos captured by VMware.
942 @item Cin Video @tab @tab X @tab Codec used in Delphine Software games.
943 @item Tiertex Seq Video @tab @tab X @tab Codec used in DOS CDROM FlashBack game.
944 @end multitable
946 @code{X} means that encoding (resp. decoding) is supported.
948 @section Audio Codecs
950 @multitable @columnfractions .4 .1 .1 .1 .7
951 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
952 @item MPEG audio layer 2 @tab IX @tab IX
953 @item MPEG audio layer 1/3 @tab IX @tab IX
954 @tab MP3 encoding is supported through the external library LAME.
955 @item AC3 @tab IX @tab IX
956 @tab liba52 is used internally for decoding.
957 @item Vorbis @tab X @tab X
958 @item WMA V1/V2 @tab @tab X
959 @item AAC @tab X @tab X
960 @tab Supported through the external library libfaac/libfaad.
961 @item Microsoft ADPCM @tab X @tab X
962 @item MS IMA ADPCM @tab X @tab X
963 @item QT IMA ADPCM @tab @tab X
964 @item 4X IMA ADPCM @tab @tab X
965 @item G.726 ADPCM @tab X @tab X
966 @item Duck DK3 IMA ADPCM @tab @tab X
967 @tab Used in some Sega Saturn console games.
968 @item Duck DK4 IMA ADPCM @tab @tab X
969 @tab Used in some Sega Saturn console games.
970 @item Westwood Studios IMA ADPCM @tab @tab X
971 @tab Used in Westwood Studios games like Command and Conquer.
972 @item SMJPEG IMA ADPCM @tab @tab X
973 @tab Used in certain Loki game ports.
974 @item CD-ROM XA ADPCM @tab @tab X
975 @item CRI ADX ADPCM @tab X @tab X
976 @tab Used in Sega Dreamcast games.
977 @item Electronic Arts ADPCM @tab @tab X
978 @tab Used in various EA titles.
979 @item Creative ADPCM @tab @tab X
980 @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
981 @item RA144 @tab @tab X
982 @tab Real 14400 bit/s codec
983 @item RA288 @tab @tab X
984 @tab Real 28800 bit/s codec
985 @item RADnet @tab X @tab IX
986 @tab Real low bitrate AC3 codec, liba52 is used for decoding.
987 @item AMR-NB @tab X @tab X
988 @tab Supported through an external library.
989 @item AMR-WB @tab X @tab X
990 @tab Supported through an external library.
991 @item DV audio @tab @tab X
992 @item Id RoQ DPCM @tab @tab X
993 @tab Used in Quake III, Jedi Knight 2, other computer games.
994 @item Interplay MVE DPCM @tab @tab X
995 @tab Used in various Interplay computer games.
996 @item Xan DPCM @tab @tab X
997 @tab Used in Origin's Wing Commander IV AVI files.
998 @item Sierra Online DPCM @tab @tab X
999 @tab Used in Sierra Online game audio files.
1000 @item Apple MACE 3 @tab @tab X
1001 @item Apple MACE 6 @tab @tab X
1002 @item FLAC lossless audio @tab @tab X
1003 @item Shorten lossless audio @tab @tab X
1004 @item Apple lossless audio @tab @tab X
1005 @tab QuickTime fourcc 'alac'
1006 @item FFmpeg Sonic @tab X @tab X
1007 @tab experimental lossy/lossless codec
1008 @item Qdesign QDM2 @tab @tab X
1009 @tab there are still some distortions
1010 @item Real COOK @tab @tab X
1011 @tab All versions except 5.1 are supported
1012 @item DSP Group TrueSpeech @tab @tab X
1013 @item True Audio (TTA) @tab @tab X
1014 @item Smacker Audio @tab @tab X
1015 @item WavPack Audio @tab @tab X
1016 @item Cin Audio @tab @tab X
1017 @tab Codec used in Delphine Software games.
1018 @item Intel Music Coder @tab @tab X
1019 @end multitable
1021 @code{X} means that encoding (resp. decoding) is supported.
1023 @code{I} means that an integer-only version is available, too (ensures high
1024 performance on systems without hardware floating point support).
1026 @chapter Platform Specific information
1028 @section Linux
1030 FFmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
1031 preferred compiler now for FFmpeg. All future optimizations will depend on
1032 features only found in GCC 3.2.
1034 @section BSD
1036 BSD make will not build FFmpeg, you need to install and use GNU Make
1037 (@file{gmake}).
1039 @section Windows
1041 @subsection Native Windows compilation
1043 @itemize
1044 @item Install the current versions of MSYS and MinGW from
1045 @url{http://www.mingw.org/}. You can find detailed installation
1046 instructions in the download section and the FAQ.
1048 @item If you want to test the FFplay, also download
1049 the MinGW development library of SDL 1.2.x
1050 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
1051 @url{http://www.libsdl.org}. Unpack it in a temporary directory, and
1052 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
1053 directory. Edit the @file{sdl-config} script so that it gives the
1054 correct SDL directory when invoked.
1056 @item Extract the current version of FFmpeg.
1058 @item Start the MSYS shell (file @file{msys.bat}).
1060 @item Change to the FFmpeg directory and follow
1061 the instructions of how to compile FFmpeg (file
1062 @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
1063 suffices. If you have problems using SDL, verify that
1064 @file{sdl-config} can be launched from the MSYS command line.
1066 @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
1067 @file{make install}. Don't forget to copy @file{SDL.dll} to the place
1068 you launch @file{ffplay} from.
1070 @end itemize
1072 Notes:
1073 @itemize
1075 @item The target @file{make wininstaller} can be used to create a
1076 Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
1077 must be copied to the FFmpeg directory in order to build the
1078 installer.
1080 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
1081 you can build @file{avcodec.dll} and @file{avformat.dll}. With
1082 @code{make install} you install the FFmpeg DLLs and the associated
1083 headers in @file{Program Files/FFmpeg}.
1085 @item Visual C++ compatibility: If you used @code{./configure --enable-shared}
1086 when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
1087 C++ @code{lib} tool to build @code{avcodec.lib} and
1088 @code{avformat.lib}. With these libraries you can link your Visual C++
1089 code directly with the FFmpeg DLLs (see below).
1091 @end itemize
1093 @subsection Visual C++ compatibility
1095 FFmpeg will not compile under Visual C++ -- and it has too many
1096 dependencies on the GCC compiler to make a port viable. However,
1097 if you want to use the FFmpeg libraries in your own applications,
1098 you can still compile those applications using Visual C++. An
1099 important restriction to this is that you have to use the
1100 dynamically linked versions of the FFmpeg libraries (i.e. the
1101 DLLs), and you have to make sure that Visual-C++-compatible
1102 import libraries are created during the FFmpeg build process.
1104 This description of how to use the FFmpeg libraries with Visual C++ is
1105 based on Visual C++ 2005 Express Edition Beta 2. If you have a different
1106 version, you might have to modify the procedures slightly.
1108 Here are the step-by-step instructions for building the FFmpeg libraries
1109 so they can be used with Visual C++:
1111 @enumerate
1113 @item Install Visual C++ (if you haven't done so already).
1115 @item Install MinGW and MSYS as described above.
1117 @item Add a call to @file{vcvars32.bat} (which sets up the environment
1118 variables for the Visual C++ tools) as the first line of
1119 @file{msys.bat}. The standard location for @file{vcvars32.bat} is
1120 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
1121 and the standard location for @file{msys.bat} is
1122 @file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
1123 following line as the first line of @file{msys.bat}:
1125 @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
1127 @item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
1128 If you get a help message with the command line options of @code{link.exe},
1129 this means your environment variables are set up correctly, the
1130 Microsoft linker is on the path and will be used by FFmpeg to
1131 create Visual-C++-compatible import libraries.
1133 @item Extract the current version of FFmpeg and change to the FFmpeg directory.
1135 @item Type the command
1136 @code{./configure --enable-shared --disable-static --enable-memalign-hack}
1137 to configure and, if that didn't produce any errors,
1138 type @code{make} to build FFmpeg.
1140 @item The subdirectories @file{libavformat}, @file{libavcodec}, and
1141 @file{libavutil} should now contain the files @file{avformat.dll},
1142 @file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1143 @file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1144 DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1146 @end enumerate
1148 And here is how to use these libraries with Visual C++:
1150 @enumerate
1152 @item Create a new console application ("File / New / Project") and then
1153 select "Win32 Console Application". On the appropriate page of the
1154 Application Wizard, uncheck the "Precompiled headers" option.
1156 @item Write the source code for your application, or, for testing, just
1157 copy the code from an existing sample application into the source file
1158 that Visual C++ has already created for you. (Note that your source
1159 filehas to have a @code{.cpp} extension; otherwise, Visual C++ won't
1160 compile the FFmpeg headers correctly because in C mode, it doesn't
1161 recognize the @code{inline} keyword.) For example, you can copy
1162 @file{output_example.c} from the FFmpeg distribution (but you will
1163 have to make minor modifications so the code will compile under
1164 C++, see below).
1166 @item Open the "Project / Properties" dialog box. In the "Configuration"
1167 combo box, select "All Configurations" so that the changes you make will
1168 affect both debug and release builds. In the tree view on the left hand
1169 side, select "C/C++ / General", then edit the "Additional Include
1170 Directories" setting to contain the complete paths to the
1171 @file{libavformat}, @file{libavcodec}, and @file{libavutil}
1172 subdirectories of your FFmpeg directory. Note that the directories have
1173 to be separated using semicolons. Now select "Linker / General" from the
1174 tree view and edit the "Additional Library Directories" setting to
1175 contain the same three directories.
1177 @item Still in the "Project / Properties" dialog box, select "Linker / Input"
1178 from the tree view, then add the files @file{avformat.lib},
1179 @file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1180 Dependencies". Note that the names of the libraries have to be separated
1181 using spaces.
1183 @item Now, select "C/C++ / Code Generation" from the tree view. Select
1184 "Debug" in the "Configuration" combo box. Make sure that "Runtime
1185 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1186 the "Configuration" combo box and make sure that "Runtime Library" is
1187 set to "Multi-threaded DLL".
1189 @item Click "OK" to close the "Project / Properties" dialog box and build
1190 the application. Hopefully, it should compile and run cleanly. If you
1191 used @file{output_example.c} as your sample application, you will get a
1192 few compiler errors, but they are easy to fix. The first type of error
1193 occurs because Visual C++ doesn't allow an @code{int} to be converted to
1194 an @code{enum} without a cast. To solve the problem, insert the required
1195 casts (this error occurs once for a @code{CodecID} and once for a
1196 @code{CodecType}). The second type of error occurs because C++ requires
1197 the return value of @code{malloc} to be cast to the exact type of the
1198 pointer it is being assigned to. Visual C++ will complain that, for
1199 example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1200 an explicit cast. So insert an explicit cast in these places to silence
1201 the compiler. The third type of error occurs because the @code{snprintf}
1202 library function is called @code{_snprintf} under Visual C++. So just
1203 add an underscore to fix the problem. With these changes,
1204 @file{output_example.c} should compile under Visual C++, and the
1205 resulting executable should produce valid video files.
1207 @end enumerate
1209 @subsection Cross compilation for Windows with Linux
1211 You must use the MinGW cross compilation tools available at
1212 @url{http://www.mingw.org/}.
1214 Then configure FFmpeg with the following options:
1215 @example
1216 ./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
1217 @end example
1218 (you can change the cross-prefix according to the prefix chosen for the
1219 MinGW tools).
1221 Then you can easily test FFmpeg with Wine
1222 (@url{http://www.winehq.com/}).
1224 @subsection Compilation under Cygwin
1226 Cygwin works very much like Unix.
1228 Just install your Cygwin with all the "Base" packages, plus the
1229 following "Devel" ones:
1230 @example
1231 binutils, gcc-core, make, subversion
1232 @end example
1234 Do not install binutils-20060709-1 (they are buggy on shared builds);
1235 use binutils-20050610-1 instead.
1237 Then run
1239 @example
1240 ./configure --enable-static --disable-shared
1241 @end example
1243 to make a static build or
1245 @example
1246 ./configure --enable-shared --disable-static
1247 @end example
1249 to build shared libraries.
1251 If you want to build FFmpeg with additional libraries, download Cygwin
1252 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
1253 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
1254 (@url{http://cygwinports.dotsrc.org/}).
1256 @subsection Crosscompilation for Windows under Cygwin
1258 With Cygwin you can create Windows binaries that don't need the cygwin1.dll.
1260 Just install your Cygwin as explained before, plus these additional
1261 "Devel" packages:
1262 @example
1263 gcc-mingw-core, mingw-runtime, mingw-zlib
1264 @end example
1266 and add some special flags to your configure invocation.
1268 For a static build run
1269 @example
1270 ./configure --enable-mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1271 @end example
1273 and for a build with shared libraries
1274 @example
1275 ./configure --enable-mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1276 @end example
1278 @section BeOS
1280 The configure script should guess the configuration itself.
1281 Networking support is currently not finished.
1282 errno issues fixed by Andrew Bachmann.
1284 Old stuff:
1286 Fran├žois Revol - revol at free dot fr - April 2002
1288 The configure script should guess the configuration itself,
1289 however I still didn't test building on the net_server version of BeOS.
1291 FFserver is broken (needs poll() implementation).
1293 There are still issues with errno codes, which are negative in BeOS, and
1294 that FFmpeg negates when returning. This ends up turning errors into
1295 valid results, then crashes.
1296 (To be fixed)
1298 @chapter Developers Guide
1300 @section API
1301 @itemize @bullet
1302 @item libavcodec is the library containing the codecs (both encoding and
1303 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1305 @item libavformat is the library containing the file format handling (mux and
1306 demux code for several formats). Look at @file{ffplay.c} to use it in a
1307 player. See @file{output_example.c} to use it to generate audio or video
1308 streams.
1310 @end itemize
1312 @section Integrating libavcodec or libavformat in your program
1314 You can integrate all the source code of the libraries to link them
1315 statically to avoid any version problem. All you need is to provide a
1316 'config.mak' and a 'config.h' in the parent directory. See the defines
1317 generated by ./configure to understand what is needed.
1319 You can use libavcodec or libavformat in your commercial program, but
1320 @emph{any patch you make must be published}. The best way to proceed is
1321 to send your patches to the FFmpeg mailing list.
1323 @node Coding Rules
1324 @section Coding Rules
1326 FFmpeg is programmed in the ISO C90 language with a few additional
1327 features from ISO C99, namely:
1328 @itemize @bullet
1329 @item
1330 the @samp{inline} keyword;
1331 @item
1332 @samp{//} comments;
1333 @item
1334 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1335 @item
1336 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1337 @end itemize
1339 These features are supported by all compilers we care about, so we won't
1340 accept patches to remove their use unless they absolutely don't impair
1341 clarity and performance.
1343 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1344 compiles with several other compilers, such as the Compaq ccc compiler
1345 or Sun Studio 9, and we would like to keep it that way unless it would
1346 be exceedingly involved. To ensure compatibility, please don't use any
1347 additional C99 features or GCC extensions. Especially watch out for:
1348 @itemize @bullet
1349 @item
1350 mixing statements and declarations;
1351 @item
1352 @samp{long long} (use @samp{int64_t} instead);
1353 @item
1354 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1355 @item
1356 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1357 @end itemize
1359 Indent size is 4.
1360 The presentation is the one specified by 'indent -i4 -kr -nut'.
1361 The TAB character is forbidden outside of Makefiles as is any
1362 form of trailing whitespace. Commits containing either will be
1363 rejected by the Subversion repository.
1365 Main priority in FFmpeg is simplicity and small code size (=less
1366 bugs).
1368 Comments: Use the JavaDoc/Doxygen
1369 format (see examples below) so that code documentation
1370 can be generated automatically. All nontrivial functions should have a comment
1371 above them explaining what the function does, even if it's just one sentence.
1372 All structures and their member variables should be documented, too.
1373 @example
1374 /**
1375 * @@file mpeg.c
1376 * MPEG codec.
1377 * @@author ...
1378 */
1380 /**
1381 * Summary sentence.
1382 * more text ...
1383 * ...
1384 */
1385 typedef struct Foobar@{
1386 int var1; /**< var1 description */
1387 int var2; ///< var2 description
1388 /** var3 description */
1389 int var3;
1390 @} Foobar;
1392 /**
1393 * Summary sentence.
1394 * more text ...
1395 * ...
1396 * @@param my_parameter description of my_parameter
1397 * @@return return value description
1398 */
1399 int myfunc(int my_parameter)
1400 ...
1401 @end example
1403 fprintf and printf are forbidden in libavformat and libavcodec,
1404 please use av_log() instead.
1406 @section Development Policy
1408 @enumerate
1409 @item
1410 You must not commit code which breaks FFmpeg! (Meaning unfinished but
1411 enabled code which breaks compilation or compiles but does not work or
1412 breaks the regression tests)
1413 You can commit unfinished stuff (for testing etc), but it must be disabled
1414 (#ifdef etc) by default so it does not interfere with other developers'
1415 work.
1416 @item
1417 You don't have to over-test things. If it works for you, and you think it
1418 should work for others, then commit. If your code has problems
1419 (portability, triggers compiler bugs, unusual environment etc) they will be
1420 reported and eventually fixed.
1421 @item
1422 Do not commit unrelated changes together, split them into self-contained
1423 pieces.
1424 @item
1425 Do not change behavior of the program (renaming options etc) without
1426 first discussing it on the ffmpeg-devel mailing list. Do not remove
1427 functionality from the code. Just improve!
1429 Note: Redundant code can be removed.
1430 @item
1431 Do not commit changes to the build system (Makefiles, configure script)
1432 which change behavior, defaults etc, without asking first. The same
1433 applies to compiler warning fixes, trivial looking fixes and to code
1434 maintained by other developers. We usually have a reason for doing things
1435 the way we do. Send your changes as patches to the ffmpeg-devel mailing
1436 list, and if the code maintainers say OK, you may commit. This does not
1437 apply to files you wrote and/or maintain.
1438 @item
1439 We refuse source indentation and other cosmetic changes if they are mixed
1440 with functional changes, such commits will be rejected and removed. Every
1441 developer has his own indentation style, you should not change it. Of course
1442 if you (re)write something, you can use your own style, even though we would
1443 prefer if the indentation throughout FFmpeg was consistent (Many projects
1444 force a given indentation style - we don't.). If you really need to make
1445 indentation changes (try to avoid this), separate them strictly from real
1446 changes.
1448 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1449 then either do NOT change the indentation of the inner part within (don't
1450 move it to the right)! or do so in a separate commit
1451 @item
1452 Always fill out the commit log message. Describe in a few lines what you
1453 changed and why. You can refer to mailing list postings if you fix a
1454 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1455 @item
1456 If you apply a patch by someone else, include the name and email address in
1457 the log message. Since the ffmpeg-cvslog mailing list is publicly
1458 archived you should add some SPAM protection to the email address. Send an
1459 answer to ffmpeg-devel (or wherever you got the patch from) saying that
1460 you applied the patch.
1461 @item
1462 Do NOT commit to code actively maintained by others without permission.
1463 Send a patch to ffmpeg-devel instead. If noone answers within a reasonable
1464 timeframe (12h for build failures and security fixes, 3 days small changes,
1465 1 week for big patches) then commit your patch if you think it's OK.
1466 Also note, the maintainer can simply ask for more time to review!
1467 @item
1468 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1469 are sent there and reviewed by all the other developers. Bugs and possible
1470 improvements or general questions regarding commits are discussed there. We
1471 expect you to react if problems with your code are uncovered.
1472 @item
1473 Update the documentation if you change behavior or add features. If you are
1474 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1475 maintainer(s) will review and commit your stuff.
1476 @item
1477 Never write to unallocated memory, never write over the end of arrays,
1478 always check values read from some untrusted source before using them
1479 as array index or other risky things.
1480 @item
1481 Remember to check if you need to bump versions for the specific libav
1482 parts (libavutil, libavcodec, libavformat) you are changing. You need
1483 to change the version integer and the version string.
1484 Incrementing the first component means no backward compatibility to
1485 previous versions (e.g. removal of a function from the public API).
1486 Incrementing the second component means backward compatible change
1487 (e.g. addition of a function to the public API).
1488 Incrementing the third component means a noteworthy binary compatible
1489 change (e.g. encoder bug fix that matters for the decoder).
1490 @item
1491 If you add a new codec, remember to update the changelog, add it to
1492 the supported codecs table in the documentation and bump the second
1493 component of the @file{libavcodec} version number appropriately. If
1494 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1495 is only a decoder.
1496 @end enumerate
1498 We think our rules are not too hard. If you have comments, contact us.
1500 Note, these rules are mostly borrowed from the MPlayer project.
1502 @section Submitting patches
1504 First, (@pxref{Coding Rules}) above if you didn't yet.
1506 When you submit your patch, try to send a unified diff (diff '-up'
1507 option). I cannot read other diffs :-)
1509 Also please do not submit patches which contain several unrelated changes.
1510 Split them into individual self-contained patches; this makes reviewing
1511 them much easier.
1513 Run the regression tests before submitting a patch so that you can
1514 verify that there are no big problems.
1516 Patches should be posted as base64 encoded attachments (or any other
1517 encoding which ensures that the patch won't be trashed during
1518 transmission) to the ffmpeg-devel mailing list, see
1519 @url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1521 It also helps quite a bit if you tell us what the patch does (for example
1522 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1523 and has no lrint()')
1525 We reply to all submitted patches and either apply or reject with some
1526 explanation why, but sometimes we are quite busy so it can take a week or two.
1528 @section Regression tests
1530 Before submitting a patch (or committing to the repository), you should at least
1531 test that you did not break anything.
1533 The regression tests build a synthetic video stream and a synthetic
1534 audio stream. These are then encoded and decoded with all codecs or
1535 formats. The CRC (or MD5) of each generated file is recorded in a
1536 result file. A 'diff' is launched to compare the reference results and
1537 the result file.
1539 The regression tests then go on to test the FFserver code with a
1540 limited set of streams. It is important that this step runs correctly
1541 as well.
1543 Run 'make test' to test all the codecs and formats.
1545 Run 'make fulltest' to test all the codecs, formats and FFserver.
1547 [Of course, some patches may change the results of the regression tests. In
1548 this case, the reference results of the regression tests shall be modified
1549 accordingly].
1551 @bye