7f65afa61fa935ef50b3b98129cabcd67d3a4636
[libav.git] / doc / ffmpeg-doc.texi
1 \input texinfo @c -*- texinfo -*-
2
3 @settitle FFmpeg Documentation
4 @titlepage
5 @sp 7
6 @center @titlefont{FFmpeg Documentation}
7 @sp 3
8 @end titlepage
9
10
11 @chapter Introduction
12
13 FFmpeg is a very fast video and audio converter. It can also grab from
14 a live audio/video source.
15
16 The command line interface is designed to be intuitive, in the sense
17 that FFmpeg tries to figure out all parameters that can possibly be
18 derived automatically. You usually only have to specify the target
19 bitrate you want.
20
21 FFmpeg can also convert from any sample rate to any other, and resize
22 video on the fly with a high quality polyphase filter.
23
24 @chapter Quick Start
25
26 @c man begin EXAMPLES
27 @section Video and Audio grabbing
28
29 FFmpeg can grab video and audio from devices given that you specify the input
30 format and device.
31
32 @example
33 ffmpeg -f audio_device -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
34 @end example
35
36 Note that you must activate the right video source and channel before
37 launching FFmpeg with any TV viewer such as xawtv
38 (@url{http://bytesex.org/xawtv/}) by Gerd Knorr. You also
39 have to set the audio recording levels correctly with a
40 standard mixer.
41
42 @section X11 grabbing
43
44 FFmpeg can grab the X11 display.
45
46 @example
47 ffmpeg -f x11grab -s cif -i :0.0 /tmp/out.mpg
48 @end example
49
50 0.0 is display.screen number of your X11 server, same as
51 the DISPLAY environment variable.
52
53 @example
54 ffmpeg -f x11grab -s cif -i :0.0+10,20 /tmp/out.mpg
55 @end example
56
57 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
58 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
59
60 @section Video and Audio file format conversion
61
62 * FFmpeg can use any supported file format and protocol as input:
63
64 Examples:
65
66 * You can use YUV files as input:
67
68 @example
69 ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
70 @end example
71
72 It will use the files:
73 @example
74 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
75 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
76 @end example
77
78 The Y files use twice the resolution of the U and V files. They are
79 raw files, without header. They can be generated by all decent video
80 decoders. You must specify the size of the image with the @option{-s} option
81 if FFmpeg cannot guess it.
82
83 * You can input from a raw YUV420P file:
84
85 @example
86 ffmpeg -i /tmp/test.yuv /tmp/out.avi
87 @end example
88
89 test.yuv is a file containing raw YUV planar data. Each frame is composed
90 of the Y plane followed by the U and V planes at half vertical and
91 horizontal resolution.
92
93 * You can output to a raw YUV420P file:
94
95 @example
96 ffmpeg -i mydivx.avi hugefile.yuv
97 @end example
98
99 * You can set several input files and output files:
100
101 @example
102 ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
103 @end example
104
105 Converts the audio file a.wav and the raw YUV video file a.yuv
106 to MPEG file a.mpg.
107
108 * You can also do audio and video conversions at the same time:
109
110 @example
111 ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
112 @end example
113
114 Converts a.wav to MPEG audio at 22050Hz sample rate.
115
116 * You can encode to several formats at the same time and define a
117 mapping from input stream to output streams:
118
119 @example
120 ffmpeg -i /tmp/a.wav -ab 64k /tmp/a.mp2 -ab 128k /tmp/b.mp2 -map 0:0 -map 0:0
121 @end example
122
123 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
124 file:index' specifies which input stream is used for each output
125 stream, in the order of the definition of output streams.
126
127 * You can transcode decrypted VOBs
128
129 @example
130 ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800k -g 300 -bf 2 -acodec libmp3lame -ab 128k snatch.avi
131 @end example
132
133 This is a typical DVD ripping example; the input is a VOB file, the
134 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
135 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
136 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
137 input video. Furthermore, the audio stream is MP3-encoded so you need
138 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
139 The mapping is particularly useful for DVD transcoding
140 to get the desired audio language.
141
142 NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
143 @c man end
144
145 @chapter Invocation
146
147 @section Syntax
148
149 The generic syntax is:
150
151 @example
152 @c man begin SYNOPSIS
153 ffmpeg [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
154 @c man end
155 @end example
156 @c man begin DESCRIPTION
157 As a general rule, options are applied to the next specified
158 file. Therefore, order is important, and you can have the same
159 option on the command line multiple times. Each occurrence is
160 then applied to the next input or output file.
161
162 * To set the video bitrate of the output file to 64kbit/s:
163 @example
164 ffmpeg -i input.avi -b 64k output.avi
165 @end example
166
167 * To force the frame rate of the input and output file to 24 fps:
168 @example
169 ffmpeg -r 24 -i input.avi output.avi
170 @end example
171
172 * To force the frame rate of the output file to 24 fps:
173 @example
174 ffmpeg -i input.avi -r 24 output.avi
175 @end example
176
177 * To force the frame rate of input file to 1 fps and the output file to 24 fps:
178 @example
179 ffmpeg -r 1 -i input.avi -r 24 output.avi
180 @end example
181
182 The format option may be needed for raw input files.
183
184 By default, FFmpeg tries to convert as losslessly as possible: It
185 uses the same audio and video parameters for the outputs as the one
186 specified for the inputs.
187 @c man end
188
189 @c man begin OPTIONS
190 @section Main options
191
192 @table @option
193 @item -L
194 Show license.
195
196 @item -h
197 Show help.
198
199 @item -version
200 Show version.
201
202 @item -formats
203 Show available formats, codecs, protocols, ...
204
205 @item -f fmt
206 Force format.
207
208 @item -i filename
209 input filename
210
211 @item -y
212 Overwrite output files.
213
214 @item -t duration
215 Restrict the transcoded/captured video sequence
216 to the duration specified in seconds.
217 @code{hh:mm:ss[.xxx]} syntax is also supported.
218
219 @item -fs limit_size
220 Set the file size limit.
221
222 @item -ss position
223 Seek to given time position in seconds.
224 @code{hh:mm:ss[.xxx]} syntax is also supported.
225
226 @item -itsoffset offset
227 Set the input time offset in seconds.
228 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
229 This option affects all the input files that follow it.
230 The offset is added to the timestamps of the input files.
231 Specifying a positive offset means that the corresponding
232 streams are delayed by 'offset' seconds.
233
234 @item -title string
235 Set the title.
236
237 @item -timestamp time
238 Set the timestamp.
239
240 @item -author string
241 Set the author.
242
243 @item -copyright string
244 Set the copyright.
245
246 @item -comment string
247 Set the comment.
248
249 @item -album string
250 Set the album.
251
252 @item -track number
253 Set the track.
254
255 @item -year number
256 Set the year.
257
258 @item -v verbose
259 Control amount of logging.
260
261 @item -target type
262 Specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "pal-vcd",
263 "ntsc-svcd", ... ). All the format options (bitrate, codecs,
264 buffer sizes) are then set automatically. You can just type:
265
266 @example
267 ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
268 @end example
269
270 Nevertheless you can specify additional options as long as you know
271 they do not conflict with the standard, as in:
272
273 @example
274 ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
275 @end example
276
277 @item -dframes number
278 Set the number of data frames to record.
279
280 @item -scodec codec
281 Force subtitle codec ('copy' to copy stream).
282
283 @item -newsubtitle
284 Add a new subtitle stream to the current output stream.
285
286 @item -slang code
287 Set the ISO 639 language code (3 letters) of the current subtitle stream.
288
289 @end table
290
291 @section Video Options
292
293 @table @option
294 @item -b bitrate
295 Set the video bitrate in bit/s (default = 200 kb/s).
296 @item -vframes number
297 Set the number of video frames to record.
298 @item -r fps
299 Set frame rate (Hz value, fraction or abbreviation), (default = 25).
300 @item -s size
301 Set frame size. The format is @samp{wxh} (ffserver default = 160x128, ffmpeg default = same as source).
302 The following abbreviations are recognized:
303 @table @samp
304 @item sqcif
305 128x96
306 @item qcif
307 176x144
308 @item cif
309 352x288
310 @item 4cif
311 704x576
312 @item qqvga
313 160x120
314 @item qvga
315 320x240
316 @item vga
317 640x480
318 @item svga
319 800x600
320 @item xga
321 1024x768
322 @item uxga
323 1600x1200
324 @item qxga
325 2048x1536
326 @item sxga
327 1280x1024
328 @item qsxga
329 2560x2048
330 @item hsxga
331 5120x4096
332 @item wvga
333 852x480
334 @item wxga
335 1366x768
336 @item wsxga
337 1600x1024
338 @item wuxga
339 1920x1200
340 @item woxga
341 2560x1600
342 @item wqsxga
343 3200x2048
344 @item wquxga
345 3840x2400
346 @item whsxga
347 6400x4096
348 @item whuxga
349 7680x4800
350 @item cga
351 320x200
352 @item ega
353 640x350
354 @item hd480
355 852x480
356 @item hd720
357 1280x720
358 @item hd1080
359 1920x1080
360 @end table
361
362 @item -aspect aspect
363 Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
364 @item -croptop size
365 Set top crop band size (in pixels).
366 @item -cropbottom size
367 Set bottom crop band size (in pixels).
368 @item -cropleft size
369 Set left crop band size (in pixels).
370 @item -cropright size
371 Set right crop band size (in pixels).
372 @item -padtop size
373 Set top pad band size (in pixels).
374 @item -padbottom size
375 Set bottom pad band size (in pixels).
376 @item -padleft size
377 Set left pad band size (in pixels).
378 @item -padright size
379 Set right pad band size (in pixels).
380 @item -padcolor (hex color)
381 Set color of padded bands. The value for padcolor is expressed
382 as a six digit hexadecimal number where the first two digits
383 represent red, the middle two digits green and last two digits
384 blue (default = 000000 (black)).
385 @item -vn
386 Disable video recording.
387 @item -bt tolerance
388 Set video bitrate tolerance (in bit/s).
389 @item -maxrate bitrate
390 Set max video bitrate (in bit/s).
391 @item -minrate bitrate
392 Set min video bitrate (in bit/s).
393 @item -bufsize size
394 Set video buffer verifier buffer size (in bits).
395 @item -vcodec codec
396 Force video codec to @var{codec}. Use the @code{copy} special value to
397 tell that the raw codec data must be copied as is.
398 @item -sameq
399 Use same video quality as source (implies VBR).
400
401 @item -pass n
402 Select the pass number (1 or 2). It is useful to do two pass
403 encoding. The statistics of the video are recorded in the first
404 pass and the video is generated at the exact requested bitrate
405 in the second pass.
406
407 @item -passlogfile file
408 Set two pass logfile name to @var{file}.
409
410 @item -newvideo
411 Add a new video stream to the current output stream.
412
413 @end table
414
415 @section Advanced Video Options
416
417 @table @option
418 @item -pix_fmt format
419 Set pixel format. Use 'list' as parameter to show all the supported
420 pixel formats.
421 @item -sws_flags flags
422 Set SwScaler flags (only available when compiled with SwScaler support).
423 @item -g gop_size
424 Set the group of pictures size.
425 @item -intra
426 Use only intra frames.
427 @item -vdt n
428 Discard threshold.
429 @item -qscale q
430 Use fixed video quantizer scale (VBR).
431 @item -qmin q
432 minimum video quantizer scale (VBR)
433 @item -qmax q
434 maximum video quantizer scale (VBR)
435 @item -qdiff q
436 maximum difference between the quantizer scales (VBR)
437 @item -qblur blur
438 video quantizer scale blur (VBR)
439 @item -qcomp compression
440 video quantizer scale compression (VBR)
441
442 @item -lmin lambda
443 minimum video lagrange factor (VBR)
444 @item -lmax lambda
445 max video lagrange factor (VBR)
446 @item -mblmin lambda
447 minimum macroblock quantizer scale (VBR)
448 @item -mblmax lambda
449 maximum macroblock quantizer scale (VBR)
450
451 These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
452 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
453 @example
454 ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
455 @end example
456
457 @item -rc_init_cplx complexity
458 initial complexity for single pass encoding
459 @item -b_qfactor factor
460 qp factor between P- and B-frames
461 @item -i_qfactor factor
462 qp factor between P- and I-frames
463 @item -b_qoffset offset
464 qp offset between P- and B-frames
465 @item -i_qoffset offset
466 qp offset between P- and I-frames
467 @item -rc_eq equation
468 Set rate control equation (@pxref{FFmpeg formula
469 evaluator}) (default = @code{tex^qComp}).
470 @item -rc_override override
471 rate control override for specific intervals
472 @item -me_method method
473 Set motion estimation method to @var{method}.
474 Available methods are (from lowest to best quality):
475 @table @samp
476 @item zero
477 Try just the (0, 0) vector.
478 @item phods
479 @item log
480 @item x1
481 @item hex
482 @item umh
483 @item epzs
484 (default method)
485 @item full
486 exhaustive search (slow and marginally better than epzs)
487 @end table
488
489 @item -dct_algo algo
490 Set DCT algorithm to @var{algo}. Available values are:
491 @table @samp
492 @item 0
493 FF_DCT_AUTO (default)
494 @item 1
495 FF_DCT_FASTINT
496 @item 2
497 FF_DCT_INT
498 @item 3
499 FF_DCT_MMX
500 @item 4
501 FF_DCT_MLIB
502 @item 5
503 FF_DCT_ALTIVEC
504 @end table
505
506 @item -idct_algo algo
507 Set IDCT algorithm to @var{algo}. Available values are:
508 @table @samp
509 @item 0
510 FF_IDCT_AUTO (default)
511 @item 1
512 FF_IDCT_INT
513 @item 2
514 FF_IDCT_SIMPLE
515 @item 3
516 FF_IDCT_SIMPLEMMX
517 @item 4
518 FF_IDCT_LIBMPEG2MMX
519 @item 5
520 FF_IDCT_PS2
521 @item 6
522 FF_IDCT_MLIB
523 @item 7
524 FF_IDCT_ARM
525 @item 8
526 FF_IDCT_ALTIVEC
527 @item 9
528 FF_IDCT_SH4
529 @item 10
530 FF_IDCT_SIMPLEARM
531 @end table
532
533 @item -er n
534 Set error resilience to @var{n}.
535 @table @samp
536 @item 1
537 FF_ER_CAREFUL (default)
538 @item 2
539 FF_ER_COMPLIANT
540 @item 3
541 FF_ER_AGGRESSIVE
542 @item 4
543 FF_ER_VERY_AGGRESSIVE
544 @end table
545
546 @item -ec bit_mask
547 Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
548 the following values:
549 @table @samp
550 @item 1
551 FF_EC_GUESS_MVS (default = enabled)
552 @item 2
553 FF_EC_DEBLOCK (default = enabled)
554 @end table
555
556 @item -bf frames
557 Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
558 @item -mbd mode
559 macroblock decision
560 @table @samp
561 @item 0
562 FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
563 @item 1
564 FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
565 @item 2
566 FF_MB_DECISION_RD: rate distortion
567 @end table
568
569 @item -4mv
570 Use four motion vector by macroblock (MPEG-4 only).
571 @item -part
572 Use data partitioning (MPEG-4 only).
573 @item -bug param
574 Work around encoder bugs that are not auto-detected.
575 @item -strict strictness
576 How strictly to follow the standards.
577 @item -aic
578 Enable Advanced intra coding (h263+).
579 @item -umv
580 Enable Unlimited Motion Vector (h263+)
581
582 @item -deinterlace
583 Deinterlace pictures.
584 @item -ilme
585 Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
586 Use this option if your input file is interlaced and you want
587 to keep the interlaced format for minimum losses.
588 The alternative is to deinterlace the input stream with
589 @option{-deinterlace}, but deinterlacing introduces losses.
590 @item -psnr
591 Calculate PSNR of compressed frames.
592 @item -vstats
593 Dump video coding statistics to @file{vstats_HHMMSS.log}.
594 @item -vstats_file file
595 Dump video coding statistics to @var{file}.
596 @item -vhook module
597 Insert video processing @var{module}. @var{module} contains the module
598 name and its parameters separated by spaces.
599 @item -top n
600 top=1/bottom=0/auto=-1 field first
601 @item -dc precision
602 Intra_dc_precision.
603 @item -vtag fourcc/tag
604 Force video tag/fourcc.
605 @item -qphist
606 Show QP histogram.
607 @item -vbsf bitstream filter
608 Bitstream filters available are "dump_extra", "remove_extra", "noise".
609 @end table
610
611 @section Audio Options
612
613 @table @option
614 @item -aframes number
615 Set the number of audio frames to record.
616 @item -ar freq
617 Set the audio sampling frequency (default = 44100 Hz).
618 @item -ab bitrate
619 Set the audio bitrate in bit/s (default = 64k).
620 @item -ac channels
621 Set the number of audio channels (default = 1).
622 @item -an
623 Disable audio recording.
624 @item -acodec codec
625 Force audio codec to @var{codec}. Use the @code{copy} special value to
626 specify that the raw codec data must be copied as is.
627 @item -newaudio
628 Add a new audio track to the output file. If you want to specify parameters,
629 do so before @code{-newaudio} (@code{-acodec}, @code{-ab}, etc..).
630
631 Mapping will be done automatically, if the number of output streams is equal to
632 the number of input streams, else it will pick the first one that matches. You
633 can override the mapping using @code{-map} as usual.
634
635 Example:
636 @example
637 ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384k test.mpg -acodec mp2 -ab 192k -newaudio
638 @end example
639 @item -alang code
640 Set the ISO 639 language code (3 letters) of the current audio stream.
641 @end table
642
643 @section Advanced Audio options:
644
645 @table @option
646 @item -atag fourcc/tag
647 Force audio tag/fourcc.
648 @item -absf bitstream filter
649 Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
650 @end table
651
652 @section Subtitle options:
653
654 @table @option
655 @item -scodec codec
656 Force subtitle codec ('copy' to copy stream).
657 @item -newsubtitle
658 Add a new subtitle stream to the current output stream.
659 @item -slang code
660 Set the ISO 639 language code (3 letters) of the current subtitle stream.
661 @end table
662
663 @section Audio/Video grab options
664
665 @table @option
666 @item -vc channel
667 Set video grab channel (DV1394 only).
668 @item -tvstd standard
669 Set television standard (NTSC, PAL (SECAM)).
670 @item -isync
671 Synchronize read on input.
672 @end table
673
674 @section Advanced options
675
676 @table @option
677 @item -map input stream id[:input stream id]
678 Set stream mapping from input streams to output streams.
679 Just enumerate the input streams in the order you want them in the output.
680 [input stream id] sets the (input) stream to sync against.
681 @item -map_meta_data outfile:infile
682 Set meta data information of outfile from infile.
683 @item -debug
684 Print specific debug info.
685 @item -benchmark
686 Add timings for benchmarking.
687 @item -dump
688 Dump each input packet.
689 @item -hex
690 When dumping packets, also dump the payload.
691 @item -bitexact
692 Only use bit exact algorithms (for codec testing).
693 @item -ps size
694 Set packet size in bits.
695 @item -re
696 Read input at native frame rate. Mainly used to simulate a grab device.
697 @item -loop_input
698 Loop over the input stream. Currently it works only for image
699 streams. This option is used for automatic FFserver testing.
700 @item -loop_output number_of_times
701 Repeatedly loop output for formats that support looping such as animated GIF
702 (0 will loop the output infinitely).
703 @item -threads count
704 Thread count.
705 @item -vsync parameter
706 Video sync method. Video will be stretched/squeezed to match the timestamps,
707 it is done by duplicating and dropping frames. With -map you can select from
708 which stream the timestamps should be taken. You can leave either video or
709 audio unchanged and sync the remaining stream(s) to the unchanged one.
710 @item -async samples_per_second
711 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
712 the parameter is the maximum samples per second by which the audio is changed.
713 -async 1 is a special case where only the start of the audio stream is corrected
714 without any later correction.
715 @item -copyts
716 Copy timestamps from input to output.
717 @item -shortest
718 Finish encoding when the shortest input stream ends.
719 @item -dts_delta_threshold
720 Timestamp discontinuity delta threshold.
721 @item -muxdelay seconds
722 Set the maximum demux-decode delay.
723 @item -muxpreload seconds
724 Set the initial demux-decode delay.
725 @end table
726
727 @node FFmpeg formula evaluator
728 @section FFmpeg formula evaluator
729
730 When evaluating a rate control string, FFmpeg uses an internal formula
731 evaluator.
732
733 The following binary operators are available: @code{+}, @code{-},
734 @code{*}, @code{/}, @code{^}.
735
736 The following unary operators are available: @code{+}, @code{-},
737 @code{(...)}.
738
739 The following functions are available:
740 @table @var
741 @item sinh(x)
742 @item cosh(x)
743 @item tanh(x)
744 @item sin(x)
745 @item cos(x)
746 @item tan(x)
747 @item exp(x)
748 @item log(x)
749 @item squish(x)
750 @item gauss(x)
751 @item abs(x)
752 @item max(x, y)
753 @item min(x, y)
754 @item gt(x, y)
755 @item lt(x, y)
756 @item eq(x, y)
757 @item bits2qp(bits)
758 @item qp2bits(qp)
759 @end table
760
761 The following constants are available:
762 @table @var
763 @item PI
764 @item E
765 @item iTex
766 @item pTex
767 @item tex
768 @item mv
769 @item fCode
770 @item iCount
771 @item mcVar
772 @item var
773 @item isI
774 @item isP
775 @item isB
776 @item avgQP
777 @item qComp
778 @item avgIITex
779 @item avgPITex
780 @item avgPPTex
781 @item avgBPTex
782 @item avgTex
783 @end table
784
785 @c man end
786
787 @ignore
788
789 @setfilename ffmpeg
790 @settitle FFmpeg video converter
791
792 @c man begin SEEALSO
793 ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
794 @c man end
795
796 @c man begin AUTHOR
797 Fabrice Bellard
798 @c man end
799
800 @end ignore
801
802 @section Protocols
803
804 The filename can be @file{-} to read from standard input or to write
805 to standard output.
806
807 FFmpeg also handles many protocols specified with an URL syntax.
808
809 Use 'ffmpeg -formats' to see a list of the supported protocols.
810
811 The protocol @code{http:} is currently used only to communicate with
812 FFserver (see the FFserver documentation). When FFmpeg will be a
813 video player it will also be used for streaming :-)
814
815 @chapter Tips
816
817 @itemize
818 @item For streaming at very low bitrate application, use a low frame rate
819 and a small GOP size. This is especially true for RealVideo where
820 the Linux player does not seem to be very fast, so it can miss
821 frames. An example is:
822
823 @example
824 ffmpeg -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
825 @end example
826
827 @item The parameter 'q' which is displayed while encoding is the current
828 quantizer. The value 1 indicates that a very good quality could
829 be achieved. The value 31 indicates the worst quality. If q=31 appears
830 too often, it means that the encoder cannot compress enough to meet
831 your bitrate. You must either increase the bitrate, decrease the
832 frame rate or decrease the frame size.
833
834 @item If your computer is not fast enough, you can speed up the
835 compression at the expense of the compression ratio. You can use
836 '-me zero' to speed up motion estimation, and '-intra' to disable
837 motion estimation completely (you have only I-frames, which means it
838 is about as good as JPEG compression).
839
840 @item To have very low audio bitrates, reduce the sampling frequency
841 (down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
842
843 @item To have a constant quality (but a variable bitrate), use the option
844 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
845 quality).
846
847 @item When converting video files, you can use the '-sameq' option which
848 uses the same quality factor in the encoder as in the decoder.
849 It allows almost lossless encoding.
850
851 @end itemize
852
853
854 @chapter external libraries
855
856 FFmpeg can be hooked up with a number of external libraries to add support
857 for more formats. None of them are used by default, their use has to be
858 explicitly requested by passing the appropriate flags to @file{./configure}.
859
860 @section AMR
861
862 AMR comes in two different flavors, WB and NB. FFmpeg can make use of the
863 AMR WB (floating-point mode) and the AMR NB (floating-point mode) reference
864 decoders and encoders.
865
866 Go to @url{http://www.penguin.cz/~utx/amr} and follow the instructions for
867 installing the libraries. Then pass @code{--enable-libamr-nb} and/or
868 @code{--enable-libamr-wb} to configure to enable the libraries.
869
870
871 @chapter Supported File Formats and Codecs
872
873 You can use the @code{-formats} option to have an exhaustive list.
874
875 @section File Formats
876
877 FFmpeg supports the following file formats through the @code{libavformat}
878 library:
879
880 @multitable @columnfractions .4 .1 .1 .4
881 @item Supported File Format @tab Encoding @tab Decoding @tab Comments
882 @item MPEG audio @tab X @tab X
883 @item MPEG-1 systems @tab X @tab X
884 @tab muxed audio and video
885 @item MPEG-2 PS @tab X @tab X
886 @tab also known as @code{VOB} file
887 @item MPEG-2 TS @tab @tab X
888 @tab also known as DVB Transport Stream
889 @item ASF@tab X @tab X
890 @item AVI@tab X @tab X
891 @item WAV@tab X @tab X
892 @item Macromedia Flash@tab X @tab X
893 @tab Only embedded audio is decoded.
894 @item FLV @tab X @tab X
895 @tab Macromedia Flash video files
896 @item Real Audio and Video @tab X @tab X
897 @item Raw AC3 @tab X @tab X
898 @item Raw MJPEG @tab X @tab X
899 @item Raw MPEG video @tab X @tab X
900 @item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
901 @item Raw CRI ADX audio @tab X @tab X
902 @item Raw Shorten audio @tab @tab X
903 @item SUN AU format @tab X @tab X
904 @item NUT @tab X @tab X @tab NUT Open Container Format
905 @item QuickTime @tab X @tab X
906 @item MPEG-4 @tab X @tab X
907 @tab MPEG-4 is a variant of QuickTime.
908 @item Raw MPEG4 video @tab X @tab X
909 @item DV @tab X @tab X
910 @item 4xm @tab @tab X
911 @tab 4X Technologies format, used in some games.
912 @item Playstation STR @tab @tab X
913 @item Id RoQ @tab X @tab X
914 @tab Used in Quake III, Jedi Knight 2, other computer games.
915 @item Interplay MVE @tab @tab X
916 @tab Format used in various Interplay computer games.
917 @item WC3 Movie @tab @tab X
918 @tab Multimedia format used in Origin's Wing Commander III computer game.
919 @item Sega FILM/CPK @tab @tab X
920 @tab Used in many Sega Saturn console games.
921 @item Westwood Studios VQA/AUD @tab @tab X
922 @tab Multimedia formats used in Westwood Studios games.
923 @item Id Cinematic (.cin) @tab @tab X
924 @tab Used in Quake II.
925 @item FLIC format @tab @tab X
926 @tab .fli/.flc files
927 @item Sierra VMD @tab @tab X
928 @tab Used in Sierra CD-ROM games.
929 @item Sierra Online @tab @tab X
930 @tab .sol files used in Sierra Online games.
931 @item Matroska @tab @tab X
932 @item Electronic Arts Multimedia @tab @tab X
933 @tab Used in various EA games; files have extensions like WVE and UV2.
934 @item Nullsoft Video (NSV) format @tab @tab X
935 @item ADTS AAC audio @tab X @tab X
936 @item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
937 @item American Laser Games MM @tab @tab X
938 @tab Multimedia format used in games like Mad Dog McCree
939 @item AVS @tab @tab X
940 @tab Multimedia format used by the Creature Shock game.
941 @item Smacker @tab @tab X
942 @tab Multimedia format used by many games.
943 @item GXF @tab X @tab X
944 @tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
945 @item CIN @tab @tab X
946 @tab Multimedia format used by Delphine Software games.
947 @item MXF @tab @tab X
948 @tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
949 @item SEQ @tab @tab X
950 @tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
951 @item DXA @tab @tab X
952 @tab This format is used in non-Windows version of Feeble Files game and
953 different game cutscenes repacked for use with ScummVM.
954 @item THP @tab @tab X
955 @tab Used on the Nintendo GameCube.
956 @item C93 @tab @tab X
957 @tab Used in the game Cyberia from Interplay.
958 @item Bethsoft VID @tab @tab X
959 @tab Used in some games from Bethesda Softworks.
960 @item CRYO APC @tab @tab X
961 @tab Audio format used in some games by CRYO Interactive Entertainment.
962 @end multitable
963
964 @code{X} means that encoding (resp. decoding) is supported.
965
966 @section Image Formats
967
968 FFmpeg can read and write images for each frame of a video sequence. The
969 following image formats are supported:
970
971 @multitable @columnfractions .4 .1 .1 .4
972 @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
973 @item PGM, PPM @tab X @tab X
974 @item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support.
975 @item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
976 @item JPEG @tab X @tab X @tab Progressive JPEG is not supported.
977 @item .Y.U.V @tab X @tab X @tab one raw file per component
978 @item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
979 @item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
980 @item Targa @tab @tab X @tab Targa (.TGA) image format.
981 @item TIFF @tab X @tab X @tab YUV, JPEG and some extension is not supported yet.
982 @item SGI @tab X @tab X @tab SGI RGB image format
983 @item PTX @tab @tab X @tab V.Flash PTX format
984 @end multitable
985
986 @code{X} means that encoding (resp. decoding) is supported.
987
988 @section Video Codecs
989
990 @multitable @columnfractions .4 .1 .1 .4
991 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
992 @item MPEG-1 video @tab X @tab X
993 @item MPEG-2 video @tab X @tab X
994 @item MPEG-4 @tab X @tab X
995 @item MSMPEG4 V1 @tab X @tab X
996 @item MSMPEG4 V2 @tab X @tab X
997 @item MSMPEG4 V3 @tab X @tab X
998 @item WMV7 @tab X @tab X
999 @item WMV8 @tab X @tab X @tab not completely working
1000 @item WMV9 @tab @tab X @tab not completely working
1001 @item VC1 @tab @tab X
1002 @item H.261 @tab X @tab X
1003 @item H.263(+) @tab X @tab X @tab also known as RealVideo 1.0
1004 @item H.264 @tab @tab X
1005 @item RealVideo 1.0 @tab X @tab X
1006 @item RealVideo 2.0 @tab X @tab X
1007 @item MJPEG @tab X @tab X
1008 @item lossless MJPEG @tab X @tab X
1009 @item JPEG-LS @tab X @tab X @tab fourcc: MJLS, lossless and near-lossless is supported
1010 @item Apple MJPEG-B @tab @tab X
1011 @item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
1012 @item DV @tab X @tab X
1013 @item HuffYUV @tab X @tab X
1014 @item FFmpeg Video 1 @tab X @tab X @tab experimental lossless codec (fourcc: FFV1)
1015 @item FFmpeg Snow @tab X @tab X @tab experimental wavelet codec (fourcc: SNOW)
1016 @item Asus v1 @tab X @tab X @tab fourcc: ASV1
1017 @item Asus v2 @tab X @tab X @tab fourcc: ASV2
1018 @item Creative YUV @tab @tab X @tab fourcc: CYUV
1019 @item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
1020 @item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
1021 @item On2 VP3 @tab @tab X @tab still experimental
1022 @item On2 VP5 @tab @tab X @tab fourcc: VP50
1023 @item On2 VP6 @tab @tab X @tab fourcc: VP60,VP61,VP62
1024 @item Theora @tab X @tab X @tab still experimental
1025 @item Intel Indeo 3 @tab @tab X
1026 @item FLV @tab X @tab X @tab Sorenson H.263 used in Flash
1027 @item Flash Screen Video @tab X @tab X @tab fourcc: FSV1
1028 @item ATI VCR1 @tab @tab X @tab fourcc: VCR1
1029 @item ATI VCR2 @tab @tab X @tab fourcc: VCR2
1030 @item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
1031 @item 4X Video @tab @tab X @tab Used in certain computer games.
1032 @item Sony Playstation MDEC @tab @tab X
1033 @item Id RoQ @tab X @tab X @tab Used in Quake III, Jedi Knight 2, other computer games.
1034 @item Xan/WC3 @tab @tab X @tab Used in Wing Commander III .MVE files.
1035 @item Interplay Video @tab @tab X @tab Used in Interplay .MVE files.
1036 @item Apple Animation @tab X @tab X @tab fourcc: 'rle '
1037 @item Apple Graphics @tab @tab X @tab fourcc: 'smc '
1038 @item Apple Video @tab @tab X @tab fourcc: rpza
1039 @item Apple QuickDraw @tab @tab X @tab fourcc: qdrw
1040 @item Cinepak @tab @tab X
1041 @item Microsoft RLE @tab @tab X
1042 @item Microsoft Video-1 @tab @tab X
1043 @item Westwood VQA @tab @tab X
1044 @item Id Cinematic Video @tab @tab X @tab Used in Quake II.
1045 @item Planar RGB @tab @tab X @tab fourcc: 8BPS
1046 @item FLIC video @tab @tab X
1047 @item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
1048 @item Duck TrueMotion v2 @tab @tab X @tab fourcc: TM20
1049 @item VMD Video @tab @tab X @tab Used in Sierra VMD files.
1050 @item MSZH @tab @tab X @tab Part of LCL
1051 @item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
1052 @item TechSmith Camtasia @tab @tab X @tab fourcc: TSCC
1053 @item IBM Ultimotion @tab @tab X @tab fourcc: ULTI
1054 @item Miro VideoXL @tab @tab X @tab fourcc: VIXL
1055 @item QPEG @tab @tab X @tab fourccs: QPEG, Q1.0, Q1.1
1056 @item LOCO @tab @tab X @tab
1057 @item Winnov WNV1 @tab @tab X @tab
1058 @item Autodesk Animator Studio Codec @tab @tab X @tab fourcc: AASC
1059 @item Fraps FPS1 @tab @tab X @tab
1060 @item CamStudio @tab @tab X @tab fourcc: CSCD
1061 @item American Laser Games Video @tab @tab X @tab Used in games like Mad Dog McCree
1062 @item ZMBV @tab X @tab X @tab Encoder works only on PAL8
1063 @item AVS Video @tab @tab X @tab Video encoding used by the Creature Shock game.
1064 @item Smacker Video @tab @tab X @tab Video encoding used in Smacker.
1065 @item RTjpeg @tab @tab X @tab Video encoding used in NuppelVideo files.
1066 @item KMVC @tab @tab X @tab Codec used in Worms games.
1067 @item VMware Video @tab @tab X @tab Codec used in videos captured by VMware.
1068 @item Cin Video @tab @tab X @tab Codec used in Delphine Software games.
1069 @item Tiertex Seq Video @tab @tab X @tab Codec used in DOS CDROM FlashBack game.
1070 @item DXA Video @tab @tab X @tab Codec originally used in Feeble Files game.
1071 @item AVID DNxHD @tab @tab X @tab aka SMPTE VC3
1072 @item C93 Video @tab @tab X @tab Codec used in Cyberia game.
1073 @item THP @tab @tab X @tab Used on the Nintendo GameCube.
1074 @item Bethsoft VID @tab @tab X @tab Used in some games from Bethesda Softworks.
1075 @item Renderware TXD @tab @tab X @tab Texture dictionaries used by the Renderware Engine.
1076 @end multitable
1077
1078 @code{X} means that encoding (resp. decoding) is supported.
1079
1080 @section Audio Codecs
1081
1082 @multitable @columnfractions .4 .1 .1 .1 .7
1083 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
1084 @item MPEG audio layer 2 @tab IX @tab IX
1085 @item MPEG audio layer 1/3 @tab IX @tab IX
1086 @tab MP3 encoding is supported through the external library LAME.
1087 @item AC3 @tab IX @tab IX
1088 @tab liba52 is used internally for decoding.
1089 @item Vorbis @tab X @tab X
1090 @item WMA V1/V2 @tab X @tab X
1091 @item AAC @tab X @tab X
1092 @tab Supported through the external library libfaac/libfaad.
1093 @item Microsoft ADPCM @tab X @tab X
1094 @item MS IMA ADPCM @tab X @tab X
1095 @item QT IMA ADPCM @tab @tab X
1096 @item 4X IMA ADPCM @tab @tab X
1097 @item G.726 ADPCM @tab X @tab X
1098 @item Duck DK3 IMA ADPCM @tab @tab X
1099 @tab Used in some Sega Saturn console games.
1100 @item Duck DK4 IMA ADPCM @tab @tab X
1101 @tab Used in some Sega Saturn console games.
1102 @item Westwood Studios IMA ADPCM @tab @tab X
1103 @tab Used in Westwood Studios games like Command and Conquer.
1104 @item SMJPEG IMA ADPCM @tab @tab X
1105 @tab Used in certain Loki game ports.
1106 @item CD-ROM XA ADPCM @tab @tab X
1107 @item CRI ADX ADPCM @tab X @tab X
1108 @tab Used in Sega Dreamcast games.
1109 @item Electronic Arts ADPCM @tab @tab X
1110 @tab Used in various EA titles.
1111 @item Creative ADPCM @tab @tab X
1112 @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
1113 @item THP ADPCM @tab @tab X
1114 @tab Used on the Nintendo GameCube.
1115 @item RA144 @tab @tab X
1116 @tab Real 14400 bit/s codec
1117 @item RA288 @tab @tab X
1118 @tab Real 28800 bit/s codec
1119 @item RADnet @tab X @tab IX
1120 @tab Real low bitrate AC3 codec, liba52 is used for decoding.
1121 @item AMR-NB @tab X @tab X
1122 @tab Supported through an external library.
1123 @item AMR-WB @tab X @tab X
1124 @tab Supported through an external library.
1125 @item DV audio @tab @tab X
1126 @item Id RoQ DPCM @tab X @tab X
1127 @tab Used in Quake III, Jedi Knight 2, other computer games.
1128 @item Interplay MVE DPCM @tab @tab X
1129 @tab Used in various Interplay computer games.
1130 @item Xan DPCM @tab @tab X
1131 @tab Used in Origin's Wing Commander IV AVI files.
1132 @item Sierra Online DPCM @tab @tab X
1133 @tab Used in Sierra Online game audio files.
1134 @item Apple MACE 3 @tab @tab X
1135 @item Apple MACE 6 @tab @tab X
1136 @item FLAC lossless audio @tab X @tab X
1137 @item Shorten lossless audio @tab @tab X
1138 @item Apple lossless audio @tab @tab X
1139 @tab QuickTime fourcc 'alac'
1140 @item FFmpeg Sonic @tab X @tab X
1141 @tab experimental lossy/lossless codec
1142 @item Qdesign QDM2 @tab @tab X
1143 @tab there are still some distortions
1144 @item Real COOK @tab @tab X
1145 @tab All versions except 5.1 are supported
1146 @item DSP Group TrueSpeech @tab @tab X
1147 @item True Audio (TTA) @tab @tab X
1148 @item Smacker Audio @tab @tab X
1149 @item WavPack Audio @tab @tab X
1150 @item Cin Audio @tab @tab X
1151 @tab Codec used in Delphine Software games.
1152 @item Intel Music Coder @tab @tab X
1153 @item Musepack @tab @tab X
1154 @tab Only SV7 is supported
1155 @item DT$ Coherent Audio @tab @tab X
1156 @item ATRAC 3 @tab @tab X
1157 @end multitable
1158
1159 @code{X} means that encoding (resp. decoding) is supported.
1160
1161 @code{I} means that an integer-only version is available, too (ensures high
1162 performance on systems without hardware floating point support).
1163
1164 @chapter Platform Specific information
1165
1166 @section BSD
1167
1168 BSD make will not build FFmpeg, you need to install and use GNU Make
1169 (@file{gmake}).
1170
1171 @section Windows
1172
1173 To get help and instructions for using FFmpeg under Windows, check out
1174 the FFmpeg Windows Help Forum at
1175 @url{http://arrozcru.no-ip.org/ffmpeg/}.
1176
1177 @subsection Native Windows compilation
1178
1179 @itemize
1180 @item Install the current versions of MSYS and MinGW from
1181 @url{http://www.mingw.org/}. You can find detailed installation
1182 instructions in the download section and the FAQ.
1183
1184 NOTE: Use at least bash 3.1. Older versions are known to be failing on the
1185 configure script.
1186
1187 @item If you want to test the FFplay, also download
1188 the MinGW development library of SDL 1.2.x
1189 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
1190 @url{http://www.libsdl.org}. Unpack it in a temporary directory, and
1191 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
1192 directory. Edit the @file{sdl-config} script so that it gives the
1193 correct SDL directory when invoked.
1194
1195 @item If you want to use vhooks, you must have a POSIX compliant libdl in your
1196 MinGW system. Get dlfcn-win32 from @url{http://code.google.com/p/dlfcn-win32}.
1197
1198 @item Extract the current version of FFmpeg.
1199
1200 @item Start the MSYS shell (file @file{msys.bat}).
1201
1202 @item Change to the FFmpeg directory and follow
1203 the instructions of how to compile FFmpeg (file
1204 @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
1205 suffices. If you have problems using SDL, verify that
1206 @file{sdl-config} can be launched from the MSYS command line.
1207
1208 @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
1209 @file{make install}. Do not forget to copy @file{SDL.dll} to the place
1210 you launch @file{ffplay} from.
1211
1212 @end itemize
1213
1214 Notes:
1215 @itemize
1216
1217 @item The target @file{make wininstaller} can be used to create a
1218 Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
1219 must be copied to the FFmpeg directory in order to build the
1220 installer.
1221
1222 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
1223 you can build @file{avcodec.dll} and @file{avformat.dll}. With
1224 @code{make install} you install the FFmpeg DLLs and the associated
1225 headers in @file{Program Files/FFmpeg}.
1226
1227 @item Visual C++ compatibility: If you used @code{./configure --enable-shared}
1228 when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
1229 C++ @code{lib} tool to build @code{avcodec.lib} and
1230 @code{avformat.lib}. With these libraries you can link your Visual C++
1231 code directly with the FFmpeg DLLs (see below).
1232
1233 @end itemize
1234
1235 @subsection Visual C++ compatibility
1236
1237 FFmpeg will not compile under Visual C++ -- and it has too many
1238 dependencies on the GCC compiler to make a port viable. However,
1239 if you want to use the FFmpeg libraries in your own applications,
1240 you can still compile those applications using Visual C++. An
1241 important restriction to this is that you have to use the
1242 dynamically linked versions of the FFmpeg libraries (i.e. the
1243 DLLs), and you have to make sure that Visual-C++-compatible
1244 import libraries are created during the FFmpeg build process.
1245
1246 This description of how to use the FFmpeg libraries with Visual C++ is
1247 based on Visual C++ 2005 Express Edition Beta 2. If you have a different
1248 version, you might have to modify the procedures slightly.
1249
1250 Here are the step-by-step instructions for building the FFmpeg libraries
1251 so they can be used with Visual C++:
1252
1253 @enumerate
1254
1255 @item Install Visual C++ (if you have not done so already).
1256
1257 @item Install MinGW and MSYS as described above.
1258
1259 @item Add a call to @file{vcvars32.bat} (which sets up the environment
1260 variables for the Visual C++ tools) as the first line of
1261 @file{msys.bat}. The standard location for @file{vcvars32.bat} is
1262 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
1263 and the standard location for @file{msys.bat} is
1264 @file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
1265 following line as the first line of @file{msys.bat}:
1266
1267 @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
1268
1269 @item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
1270 If you get a help message with the command line options of @code{link.exe},
1271 this means your environment variables are set up correctly, the
1272 Microsoft linker is on the path and will be used by FFmpeg to
1273 create Visual-C++-compatible import libraries.
1274
1275 @item Extract the current version of FFmpeg and change to the FFmpeg directory.
1276
1277 @item Type the command
1278 @code{./configure --enable-shared --disable-static --enable-memalign-hack}
1279 to configure and, if that did not produce any errors,
1280 type @code{make} to build FFmpeg.
1281
1282 @item The subdirectories @file{libavformat}, @file{libavcodec}, and
1283 @file{libavutil} should now contain the files @file{avformat.dll},
1284 @file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1285 @file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1286 DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1287
1288 @end enumerate
1289
1290 And here is how to use these libraries with Visual C++:
1291
1292 @enumerate
1293
1294 @item Create a new console application ("File / New / Project") and then
1295 select "Win32 Console Application". On the appropriate page of the
1296 Application Wizard, uncheck the "Precompiled headers" option.
1297
1298 @item Write the source code for your application, or, for testing, just
1299 copy the code from an existing sample application into the source file
1300 that Visual C++ has already created for you. (Note that your source
1301 filehas to have a @code{.cpp} extension; otherwise, Visual C++ will not
1302 compile the FFmpeg headers correctly because in C mode, it does not
1303 recognize the @code{inline} keyword.) For example, you can copy
1304 @file{output_example.c} from the FFmpeg distribution (but you will
1305 have to make minor modifications so the code will compile under
1306 C++, see below).
1307
1308 @item Open the "Project / Properties" dialog box. In the "Configuration"
1309 combo box, select "All Configurations" so that the changes you make will
1310 affect both debug and release builds. In the tree view on the left hand
1311 side, select "C/C++ / General", then edit the "Additional Include
1312 Directories" setting to contain the complete paths to the
1313 @file{libavformat}, @file{libavcodec}, and @file{libavutil}
1314 subdirectories of your FFmpeg directory. Note that the directories have
1315 to be separated using semicolons. Now select "Linker / General" from the
1316 tree view and edit the "Additional Library Directories" setting to
1317 contain the same three directories.
1318
1319 @item Still in the "Project / Properties" dialog box, select "Linker / Input"
1320 from the tree view, then add the files @file{avformat.lib},
1321 @file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1322 Dependencies". Note that the names of the libraries have to be separated
1323 using spaces.
1324
1325 @item Now, select "C/C++ / Code Generation" from the tree view. Select
1326 "Debug" in the "Configuration" combo box. Make sure that "Runtime
1327 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1328 the "Configuration" combo box and make sure that "Runtime Library" is
1329 set to "Multi-threaded DLL".
1330
1331 @item Click "OK" to close the "Project / Properties" dialog box and build
1332 the application. Hopefully, it should compile and run cleanly. If you
1333 used @file{output_example.c} as your sample application, you will get a
1334 few compiler errors, but they are easy to fix. The first type of error
1335 occurs because Visual C++ does not allow an @code{int} to be converted to
1336 an @code{enum} without a cast. To solve the problem, insert the required
1337 casts (this error occurs once for a @code{CodecID} and once for a
1338 @code{CodecType}). The second type of error occurs because C++ requires
1339 the return value of @code{malloc} to be cast to the exact type of the
1340 pointer it is being assigned to. Visual C++ will complain that, for
1341 example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1342 an explicit cast. So insert an explicit cast in these places to silence
1343 the compiler. The third type of error occurs because the @code{snprintf}
1344 library function is called @code{_snprintf} under Visual C++. So just
1345 add an underscore to fix the problem. With these changes,
1346 @file{output_example.c} should compile under Visual C++, and the
1347 resulting executable should produce valid video files.
1348
1349 @end enumerate
1350
1351 @subsection Cross compilation for Windows with Linux
1352
1353 You must use the MinGW cross compilation tools available at
1354 @url{http://www.mingw.org/}.
1355
1356 Then configure FFmpeg with the following options:
1357 @example
1358 ./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
1359 @end example
1360 (you can change the cross-prefix according to the prefix chosen for the
1361 MinGW tools).
1362
1363 Then you can easily test FFmpeg with Wine
1364 (@url{http://www.winehq.com/}).
1365
1366 @subsection Compilation under Cygwin
1367
1368 Cygwin works very much like Unix.
1369
1370 Just install your Cygwin with all the "Base" packages, plus the
1371 following "Devel" ones:
1372 @example
1373 binutils, gcc-core, make, subversion
1374 @end example
1375
1376 Do not install binutils-20060709-1 (they are buggy on shared builds);
1377 use binutils-20050610-1 instead.
1378
1379 Then run
1380
1381 @example
1382 ./configure --enable-static --disable-shared
1383 @end example
1384
1385 to make a static build or
1386
1387 @example
1388 ./configure --enable-shared --disable-static
1389 @end example
1390
1391 to build shared libraries.
1392
1393 If you want to build FFmpeg with additional libraries, download Cygwin
1394 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
1395 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
1396 (@url{http://cygwinports.dotsrc.org/}).
1397
1398 @subsection Crosscompilation for Windows under Cygwin
1399
1400 With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
1401
1402 Just install your Cygwin as explained before, plus these additional
1403 "Devel" packages:
1404 @example
1405 gcc-mingw-core, mingw-runtime, mingw-zlib
1406 @end example
1407
1408 and add some special flags to your configure invocation.
1409
1410 For a static build run
1411 @example
1412 ./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1413 @end example
1414
1415 and for a build with shared libraries
1416 @example
1417 ./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1418 @end example
1419
1420 @section BeOS
1421
1422 The configure script should guess the configuration itself.
1423 Networking support is currently not finished.
1424 errno issues fixed by Andrew Bachmann.
1425
1426 Old stuff:
1427
1428 Fran├žois Revol - revol at free dot fr - April 2002
1429
1430 The configure script should guess the configuration itself,
1431 however I still did not test building on the net_server version of BeOS.
1432
1433 FFserver is broken (needs poll() implementation).
1434
1435 There are still issues with errno codes, which are negative in BeOS, and
1436 that FFmpeg negates when returning. This ends up turning errors into
1437 valid results, then crashes.
1438 (To be fixed)
1439
1440 @chapter Developers Guide
1441
1442 @section API
1443 @itemize @bullet
1444 @item libavcodec is the library containing the codecs (both encoding and
1445 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1446
1447 @item libavformat is the library containing the file format handling (mux and
1448 demux code for several formats). Look at @file{ffplay.c} to use it in a
1449 player. See @file{output_example.c} to use it to generate audio or video
1450 streams.
1451
1452 @end itemize
1453
1454 @section Integrating libavcodec or libavformat in your program
1455
1456 You can integrate all the source code of the libraries to link them
1457 statically to avoid any version problem. All you need is to provide a
1458 'config.mak' and a 'config.h' in the parent directory. See the defines
1459 generated by ./configure to understand what is needed.
1460
1461 You can use libavcodec or libavformat in your commercial program, but
1462 @emph{any patch you make must be published}. The best way to proceed is
1463 to send your patches to the FFmpeg mailing list.
1464
1465 @node Coding Rules
1466 @section Coding Rules
1467
1468 FFmpeg is programmed in the ISO C90 language with a few additional
1469 features from ISO C99, namely:
1470 @itemize @bullet
1471 @item
1472 the @samp{inline} keyword;
1473 @item
1474 @samp{//} comments;
1475 @item
1476 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1477 @item
1478 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1479 @end itemize
1480
1481 These features are supported by all compilers we care about, so we will not
1482 accept patches to remove their use unless they absolutely do not impair
1483 clarity and performance.
1484
1485 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1486 compiles with several other compilers, such as the Compaq ccc compiler
1487 or Sun Studio 9, and we would like to keep it that way unless it would
1488 be exceedingly involved. To ensure compatibility, please do not use any
1489 additional C99 features or GCC extensions. Especially watch out for:
1490 @itemize @bullet
1491 @item
1492 mixing statements and declarations;
1493 @item
1494 @samp{long long} (use @samp{int64_t} instead);
1495 @item
1496 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1497 @item
1498 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1499 @end itemize
1500
1501 Indent size is 4.
1502 The presentation is the one specified by 'indent -i4 -kr -nut'.
1503 The TAB character is forbidden outside of Makefiles as is any
1504 form of trailing whitespace. Commits containing either will be
1505 rejected by the Subversion repository.
1506
1507 The main priority in FFmpeg is simplicity and small code size in order to
1508 minimize the bug count.
1509
1510 Comments: Use the JavaDoc/Doxygen
1511 format (see examples below) so that code documentation
1512 can be generated automatically. All nontrivial functions should have a comment
1513 above them explaining what the function does, even if it is just one sentence.
1514 All structures and their member variables should be documented, too.
1515 @example
1516 /**
1517 * @@file mpeg.c
1518 * MPEG codec.
1519 * @@author ...
1520 */
1521
1522 /**
1523 * Summary sentence.
1524 * more text ...
1525 * ...
1526 */
1527 typedef struct Foobar@{
1528 int var1; /**< var1 description */
1529 int var2; ///< var2 description
1530 /** var3 description */
1531 int var3;
1532 @} Foobar;
1533
1534 /**
1535 * Summary sentence.
1536 * more text ...
1537 * ...
1538 * @@param my_parameter description of my_parameter
1539 * @@return return value description
1540 */
1541 int myfunc(int my_parameter)
1542 ...
1543 @end example
1544
1545 fprintf and printf are forbidden in libavformat and libavcodec,
1546 please use av_log() instead.
1547
1548 Casts should be used only when necessary. Unneeded parentheses
1549 should also be avoided if they don't make the code easier to understand.
1550
1551 @section Development Policy
1552
1553 @enumerate
1554 @item
1555 Contributions should be licensed under the LGPL 2.1, including an
1556 "or any later version" clause, or the MIT license. GPL 2 including
1557 an "or any later version" clause is also acceptable, but LGPL is
1558 preferred.
1559 @item
1560 You must not commit code which breaks FFmpeg! (Meaning unfinished but
1561 enabled code which breaks compilation or compiles but does not work or
1562 breaks the regression tests)
1563 You can commit unfinished stuff (for testing etc), but it must be disabled
1564 (#ifdef etc) by default so it does not interfere with other developers'
1565 work.
1566 @item
1567 You do not have to over-test things. If it works for you, and you think it
1568 should work for others, then commit. If your code has problems
1569 (portability, triggers compiler bugs, unusual environment etc) they will be
1570 reported and eventually fixed.
1571 @item
1572 Do not commit unrelated changes together, split them into self-contained
1573 pieces. Also do not forget that if part B depends on part A, but A does not
1574 depend on B, then A can and should be committed first and separate from B.
1575 Keeping changes well split into self-contained parts makes reviewing and
1576 understanding them on the commit log mailing list easier. This also helps
1577 in case of debugging later on.
1578 Also if you have doubts about splitting or not splitting, do not hesitate to
1579 ask/discuss it on the developer mailing list.
1580 @item
1581 Do not change behavior of the program (renaming options etc) without
1582 first discussing it on the ffmpeg-devel mailing list. Do not remove
1583 functionality from the code. Just improve!
1584
1585 Note: Redundant code can be removed.
1586 @item
1587 Do not commit changes to the build system (Makefiles, configure script)
1588 which change behavior, defaults etc, without asking first. The same
1589 applies to compiler warning fixes, trivial looking fixes and to code
1590 maintained by other developers. We usually have a reason for doing things
1591 the way we do. Send your changes as patches to the ffmpeg-devel mailing
1592 list, and if the code maintainers say OK, you may commit. This does not
1593 apply to files you wrote and/or maintain.
1594 @item
1595 We refuse source indentation and other cosmetic changes if they are mixed
1596 with functional changes, such commits will be rejected and removed. Every
1597 developer has his own indentation style, you should not change it. Of course
1598 if you (re)write something, you can use your own style, even though we would
1599 prefer if the indentation throughout FFmpeg was consistent (Many projects
1600 force a given indentation style - we do not.). If you really need to make
1601 indentation changes (try to avoid this), separate them strictly from real
1602 changes.
1603
1604 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1605 then either do NOT change the indentation of the inner part within (do not
1606 move it to the right)! or do so in a separate commit
1607 @item
1608 Always fill out the commit log message. Describe in a few lines what you
1609 changed and why. You can refer to mailing list postings if you fix a
1610 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1611 @item
1612 If you apply a patch by someone else, include the name and email address in
1613 the log message. Since the ffmpeg-cvslog mailing list is publicly
1614 archived you should add some SPAM protection to the email address. Send an
1615 answer to ffmpeg-devel (or wherever you got the patch from) saying that
1616 you applied the patch.
1617 @item
1618 When applying patches that have been discussed (at length) on the mailing
1619 list, reference the thread in the log message.
1620 @item
1621 Do NOT commit to code actively maintained by others without permission.
1622 Send a patch to ffmpeg-devel instead. If no one answers within a reasonable
1623 timeframe (12h for build failures and security fixes, 3 days small changes,
1624 1 week for big patches) then commit your patch if you think it is OK.
1625 Also note, the maintainer can simply ask for more time to review!
1626 @item
1627 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1628 are sent there and reviewed by all the other developers. Bugs and possible
1629 improvements or general questions regarding commits are discussed there. We
1630 expect you to react if problems with your code are uncovered.
1631 @item
1632 Update the documentation if you change behavior or add features. If you are
1633 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1634 maintainer(s) will review and commit your stuff.
1635 @item
1636 Try to keep important discussions and requests (also) on the public
1637 developer mailing list, so that all developers can benefit from them.
1638 @item
1639 Never write to unallocated memory, never write over the end of arrays,
1640 always check values read from some untrusted source before using them
1641 as array index or other risky things.
1642 @item
1643 Remember to check if you need to bump versions for the specific libav
1644 parts (libavutil, libavcodec, libavformat) you are changing. You need
1645 to change the version integer and the version string.
1646 Incrementing the first component means no backward compatibility to
1647 previous versions (e.g. removal of a function from the public API).
1648 Incrementing the second component means backward compatible change
1649 (e.g. addition of a function to the public API).
1650 Incrementing the third component means a noteworthy binary compatible
1651 change (e.g. encoder bug fix that matters for the decoder).
1652 @item
1653 If you add a new codec, remember to update the changelog, add it to
1654 the supported codecs table in the documentation and bump the second
1655 component of the @file{libavcodec} version number appropriately. If
1656 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1657 is only a decoder.
1658 @item
1659 Do not change code to hide warnings without ensuring that the underlying
1660 logic is correct and thus the warning was inappropriate.
1661 @item
1662 If you add a new file, give it a proper license header. Do not copy and
1663 paste it from a random place, use an existing file as template.
1664 @end enumerate
1665
1666 We think our rules are not too hard. If you have comments, contact us.
1667
1668 Note, these rules are mostly borrowed from the MPlayer project.
1669
1670 @section Submitting patches
1671
1672 First, (@pxref{Coding Rules}) above if you did not yet.
1673
1674 When you submit your patch, try to send a unified diff (diff '-up'
1675 option). We cannot read other diffs :-)
1676
1677 Also please do not submit a patch which contains several unrelated changes.
1678 Split it into separate, self-contained pieces. This does not mean splitting
1679 file by file. Instead, make the patch as small as possible while still
1680 keeping it as a logical unit that contains an individual change, even
1681 if it spans multiple files. This makes reviewing your patches much easier
1682 for us and greatly increases your chances of getting your patch applied.
1683
1684 Run the regression tests before submitting a patch so that you can
1685 verify that there are no big problems.
1686
1687 Patches should be posted as base64 encoded attachments (or any other
1688 encoding which ensures that the patch will not be trashed during
1689 transmission) to the ffmpeg-devel mailing list, see
1690 @url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1691
1692 It also helps quite a bit if you tell us what the patch does (for example
1693 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1694 and has no lrint()')
1695
1696 Also please if you send several patches, send each patch as a separate mail,
1697 do not attach several unrelated patches to the same mail.
1698
1699 @section patch submission checklist
1700
1701 @enumerate
1702 @item
1703 Do the regression tests pass with the patch applied?
1704 @item
1705 Is the patch a unified diff?
1706 @item
1707 Is the patch against latest FFmpeg SVN?
1708 @item
1709 Are you subscribed to ffmpeg-dev?
1710 (the list is subscribers only due to spam)
1711 @item
1712 Have you checked that the changes are minimal, so that the same cannot be
1713 achieved with a smaller patch and/or simpler final code?
1714 @item
1715 If the change is to speed critical code, did you benchmark it?
1716 @item
1717 If you did any benchmarks, did you provide them in the mail?
1718 @item
1719 Have you checked that the patch does not introduce buffer overflows or
1720 other security issues?
1721 @item
1722 Is the patch created from the root of the source tree, so it can be
1723 applied with @code{patch -p0}?
1724 @item
1725 Does the patch not mix functional and cosmetic changes?
1726 @item
1727 Did you add tabs or trailing whitespace to the code? Both are forbidden.
1728 @item
1729 Is the patch attached to the email you send?
1730 @item
1731 Is the mime type of the patch correct? It should be text/x-diff or
1732 text/x-patch or at least text/plain and not application/octet-stream.
1733 @item
1734 If the patch fixes a bug, did you provide a verbose analysis of the bug?
1735 @item
1736 If the patch fixes a bug, did you provide enough information, including
1737 a sample, so the bug can be reproduced and the fix can be verified?
1738 Note please do not attach samples >100k to mails but rather provide a
1739 URL, you can upload to ftp://upload.mplayerhq.hu
1740 @item
1741 Did you provide a verbose summary about what the patch does change?
1742 @item
1743 Did you provide a verbose explanation why it changes things like it does?
1744 @item
1745 Did you provide a verbose summary of the user visible advantages and
1746 disadvantages if the patch is applied?
1747 @item
1748 Did you provide an example so we can verify the new feature added by the
1749 patch easily?
1750 @item
1751 If you added a new file, did you insert a license header? It should be
1752 taken from FFmpeg, not randomly copied and pasted from somewhere else.
1753 @item
1754 You should maintain alphabetical order in alphabetically ordered lists as
1755 long as doing so does not break API/ABI compatibility.
1756 @item
1757 Lines with similar content should be aligned vertically when doing so
1758 improves readability.
1759 @item
1760 Did you provide a suggestion for a clear commit log message?
1761 @end enumerate
1762
1763 @section Patch review process
1764
1765 All patches posted to ffmpeg-devel will be reviewed, unless they contain a
1766 clear note that the patch is not for SVN.
1767 Reviews and comments will be posted as replies to the patch on the
1768 mailing list. The patch submitter then has to take care of every comment,
1769 that can be by resubmitting a changed patch or by discussion. Resubmitted
1770 patches will themselves be reviewed like any other patch. If at some point
1771 a patch passes review with no comments then it is approved, that can for
1772 simple and small patches happen immediately while large patches will generally
1773 have to be changed and reviewed many times before they are approved.
1774 After a patch is approved it will be committed to the repository.
1775
1776 We will review all submitted patches, but sometimes we are quite busy so
1777 especially for large patches this can take several weeks.
1778
1779 When resubmitting patches, please do not make any significant changes
1780 not related to the comments received during review. Such patches will
1781 be rejected. Instead, submit significant changes or new features as
1782 separate patches.
1783
1784 @section Regression tests
1785
1786 Before submitting a patch (or committing to the repository), you should at least
1787 test that you did not break anything.
1788
1789 The regression tests build a synthetic video stream and a synthetic
1790 audio stream. These are then encoded and decoded with all codecs or
1791 formats. The CRC (or MD5) of each generated file is recorded in a
1792 result file. A 'diff' is launched to compare the reference results and
1793 the result file.
1794
1795 The regression tests then go on to test the FFserver code with a
1796 limited set of streams. It is important that this step runs correctly
1797 as well.
1798
1799 Run 'make test' to test all the codecs and formats.
1800
1801 Run 'make fulltest' to test all the codecs, formats and FFserver.
1802
1803 [Of course, some patches may change the results of the regression tests. In
1804 this case, the reference results of the regression tests shall be modified
1805 accordingly].
1806
1807 @bye