1 \input texinfo @c -*- texinfo -*-
3 @settitle FFmpeg Documentation
6 @center @titlefont{FFmpeg Documentation}
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
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.
27 @section Video and Audio grabbing
29 FFmpeg can use a video4linux compatible video source and any Open Sound
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
44 FFmpeg can grab the X11 display.
47 ffmpeg -f x11grab -vd x11:0.0 /tmp/out.mpg
50 0.0 is display.screen number of your X11 server, same as
51 the DISPLAY environment variable.
54 ffmpeg -f x11grab -vd x11:0.0+10,20 /tmp/out.mpg
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.
60 @section Video and Audio file format conversion
62 * FFmpeg can use any supported file format and protocol as input:
66 * You can use YUV files as input:
69 ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
72 It will use the files:
74 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
75 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
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.
83 * You can input from a raw YUV420P file:
86 ffmpeg -i /tmp/test.yuv /tmp/out.avi
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.
93 * You can output to a raw YUV420P file:
96 ffmpeg -i mydivx.avi hugefile.yuv
99 * You can set several input files and output files:
102 ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
105 Converts the audio file a.wav and the raw YUV video file a.yuv
108 * You can also do audio and video conversions at the same time:
111 ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
114 Converts a.wav to MPEG audio at 22050Hz sample rate.
116 * You can encode to several formats at the same time and define a
117 mapping from input stream to output streams:
120 ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0
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.
127 * You can transcode decrypted VOBs
130 ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800k -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi
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-mp3lame} to configure.
139 The mapping is particularly useful for DVD transcoding
140 to get the desired audio language.
142 NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
149 The generic syntax is:
152 @c man begin SYNOPSIS
153 ffmpeg [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
156 @c man begin DESCRIPTION
157 If no input file is given, audio/video grabbing is done.
159 As a general rule, options are applied to the next specified
160 file. Therefore, order is important, and you can have the same
161 option on the command line multiple times. Each occurrence is
162 then applied to the next input or output file.
164 * To set the video bitrate of the output file to 64kbit/s:
166 ffmpeg -i input.avi -b 64k output.avi
169 * To force the frame rate of the input and output file to 24 fps:
171 ffmpeg -r 24 -i input.avi output.avi
174 * To force the frame rate of the output file to 24 fps:
176 ffmpeg -i input.avi -r 24 output.avi
179 * To force the frame rate of input file to 1 fps and the output file to 24 fps:
181 ffmpeg -r 1 -i input.avi -r 24 output.avi
184 The format option may be needed for raw input files.
186 By default, FFmpeg tries to convert as losslessly as possible: It
187 uses the same audio and video parameters for the outputs as the one
188 specified for the inputs.
192 @section Main options
205 Show available formats, codecs, protocols, ...
214 Overwrite output files.
217 Set the recording time in seconds.
218 @code{hh:mm:ss[.xxx]} syntax is also supported.
221 Set the file size limit.
224 Seek to given time position in seconds.
225 @code{hh:mm:ss[.xxx]} syntax is also supported.
227 @item -itsoffset offset
228 Set the input time offset in seconds.
229 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
230 This option affects all the input files that follow it.
231 The offset is added to the timestamps of the input files.
232 Specifying a positive offset means that the corresponding
233 streams are delayed by 'offset' seconds.
238 @item -timestamp time
244 @item -copyright string
247 @item -comment string
260 Control amount of logging.
263 Specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "pal-vcd",
264 "ntsc-svcd", ... ). All the format options (bitrate, codecs,
265 buffer sizes) are then set automatically. You can just type:
268 ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
271 Nevertheless you can specify additional options as long as you know
272 they do not conflict with the standard, as in:
275 ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
278 @item -dframes number
279 Set the number of data frames to record.
282 Force subtitle codec ('copy' to copy stream).
285 Add a new subtitle stream to the current output stream.
288 Set the ISO 639 language code (3 letters) of the current subtitle stream.
292 @section Video Options
296 Set the video bitrate in bit/s (default = 200 kb/s).
297 @item -vframes number
298 Set the number of video frames to record.
300 Set frame rate (Hz value, fraction or abbreviation), (default = 25).
302 Set frame size. The format is @samp{wxh} (ffserver default = 160x128, ffmpeg default = same as source).
303 The following abbreviations are recognized:
316 Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
318 Set top crop band size (in pixels).
319 @item -cropbottom size
320 Set bottom crop band size (in pixels).
322 Set left crop band size (in pixels).
323 @item -cropright size
324 Set right crop band size (in pixels).
326 Set top pad band size (in pixels).
327 @item -padbottom size
328 Set bottom pad band size (in pixels).
330 Set left pad band size (in pixels).
332 Set right pad band size (in pixels).
333 @item -padcolor (hex color)
334 Set color of padded bands. The value for padcolor is expressed
335 as a six digit hexadecimal number where the first two digits
336 represent red, the middle two digits green and last two digits
337 blue (default = 000000 (black)).
339 Disable video recording.
341 Set video bitrate tolerance (in bit/s).
342 @item -maxrate bitrate
343 Set max video bitrate tolerance (in bit/s).
344 @item -minrate bitrate
345 Set min video bitrate tolerance (in bit/s).
347 Set rate control buffer size (in bits).
349 Force video codec to @var{codec}. Use the @code{copy} special value to
350 tell that the raw codec data must be copied as is.
352 Use same video quality as source (implies VBR).
355 Select the pass number (1 or 2). It is useful to do two pass
356 encoding. The statistics of the video are recorded in the first
357 pass and the video is generated at the exact requested bitrate
360 @item -passlogfile file
361 Set two pass logfile name to @var{file}.
364 Add a new video stream to the current output stream.
368 @section Advanced Video Options
371 @item -pix_fmt format
374 Set the group of pictures size.
376 Use only intra frames.
380 Use fixed video quantizer scale (VBR).
382 minimum video quantizer scale (VBR)
384 maximum video quantizer scale (VBR)
386 maximum difference between the quantizer scales (VBR)
388 video quantizer scale blur (VBR)
389 @item -qcomp compression
390 video quantizer scale compression (VBR)
393 minimum video lagrange factor (VBR)
395 max video lagrange factor (VBR)
397 minimum macroblock quantizer scale (VBR)
399 maximum macroblock quantizer scale (VBR)
401 These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
402 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
404 ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
407 @item -rc_init_cplx complexity
408 initial complexity for single pass encoding
409 @item -b_qfactor factor
410 qp factor between P- and B-frames
411 @item -i_qfactor factor
412 qp factor between P- and I-frames
413 @item -b_qoffset offset
414 qp offset between P- and B-frames
415 @item -i_qoffset offset
416 qp offset between P- and I-frames
417 @item -rc_eq equation
418 Set rate control equation (@pxref{FFmpeg formula
419 evaluator}) (default = @code{tex^qComp}).
420 @item -rc_override override
421 rate control override for specific intervals
423 Set motion estimation method to @var{method}.
424 Available methods are (from lowest to best quality):
427 Try just the (0, 0) vector.
434 exhaustive search (slow and marginally better than epzs)
438 Set DCT algorithm to @var{algo}. Available values are:
441 FF_DCT_AUTO (default)
454 @item -idct_algo algo
455 Set IDCT algorithm to @var{algo}. Available values are:
458 FF_IDCT_AUTO (default)
482 Set error resilience to @var{n}.
485 FF_ER_CAREFUL (default)
491 FF_ER_VERY_AGGRESSIVE
495 Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
496 the following values:
499 FF_EC_GUESS_MVS (default = enabled)
501 FF_EC_DEBLOCK (default = enabled)
505 Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
510 FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
512 FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
514 FF_MB_DECISION_RD: rate distortion
518 Use four motion vector by macroblock (MPEG-4 only).
520 Use data partitioning (MPEG-4 only).
522 Work around encoder bugs that are not auto-detected.
523 @item -strict strictness
524 How strictly to follow the standards.
526 Enable Advanced intra coding (h263+).
528 Enable Unlimited Motion Vector (h263+)
531 Deinterlace pictures.
533 Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
534 Use this option if your input file is interlaced and you want
535 to keep the interlaced format for minimum losses.
536 The alternative is to deinterlace the input stream with
537 @option{-deinterlace}, but deinterlacing introduces losses.
539 Calculate PSNR of compressed frames.
541 Dump video coding statistics to @file{vstats_HHMMSS.log}.
543 Insert video processing @var{module}. @var{module} contains the module
544 name and its parameters separated by spaces.
546 top=1/bottom=0/auto=-1 field first
549 @item -vtag fourcc/tag
550 Force video tag/fourcc.
553 @item -vbsf bitstream filter
554 Bitstream filters available are "dump_extra", "remove_extra", "noise".
557 @section Audio Options
560 @item -aframes number
561 Set the number of audio frames to record.
563 Set the audio sampling frequency (default = 44100 Hz).
565 Set the audio bitrate in kbit/s (default = 64).
567 Set the number of audio channels (default = 1).
569 Disable audio recording.
571 Force audio codec to @var{codec}. Use the @code{copy} special value to
572 specify that the raw codec data must be copied as is.
574 Add a new audio track to the output file. If you want to specify parameters,
575 do so before @code{-newaudio} (@code{-acodec}, @code{-ab}, etc..).
577 Mapping will be done automatically, if the number of output streams is equal to
578 the number of input streams, else it will pick the first one that matches. You
579 can override the mapping using @code{-map} as usual.
583 ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384 test.mpg -acodec mp2 -ab 192 -newaudio
586 Set the ISO 639 language code (3 letters) of the current audio stream.
589 @section Advanced Audio options:
592 @item -atag fourcc/tag
593 Force audio tag/fourcc.
594 @item -absf bitstream filter
595 Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
598 @section Subtitle options:
602 Force subtitle codec ('copy' to copy stream).
604 Add a new subtitle stream to the current output stream.
606 Set the ISO 639 language code (3 letters) of the current subtitle stream.
609 @section Audio/Video grab options
613 sEt video grab device (e.g. @file{/dev/video0}).
615 Set video grab channel (DV1394 only).
616 @item -tvstd standard
617 Set television standard (NTSC, PAL (SECAM)).
621 Set audio device (e.g. @file{/dev/dsp}).
623 Request grabbing using.
628 @section Advanced options
631 @item -map input stream id[:input stream id]
632 Set stream mapping from input streams to output streams.
633 Just enumerate the input streams in the order you want them in the output.
634 [input stream id] sets the (input) stream to sync against.
635 @item -map_meta_data outfile:infile
636 Set meta data information of outfile from infile.
638 Print specific debug info.
640 Add timings for benchmarking.
642 Dump each input packet.
644 When dumping packets, also dump the payload.
646 Only use bit exact algorithms (for codec testing).
648 Set packet size in bits.
650 Read input at native frame rate. Mainly used to simulate a grab device.
652 Loop over the input stream. Currently it works only for image
653 streams. This option is used for automatic FFserver testing.
654 @item -loop_output number_of_times
655 Repeatedly loop output for formats that support looping such as animated GIF
656 (0 will loop the output infinitely).
659 @item -vsync parameter
660 Video sync method. Video will be stretched/squeezed to match the timestamps,
661 it is done by duplicating and dropping frames. With -map you can select from
662 which stream the timestamps should be taken. You can leave either video or
663 audio unchanged and sync the remaining stream(s) to the unchanged one.
664 @item -async samples_per_second
665 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
666 the parameter is the maximum samples per second by which the audio is changed.
667 -async 1 is a special case where only the start of the audio stream is corrected
668 without any later correction.
671 @node FFmpeg formula evaluator
672 @section FFmpeg formula evaluator
674 When evaluating a rate control string, FFmpeg uses an internal formula
677 The following binary operators are available: @code{+}, @code{-},
678 @code{*}, @code{/}, @code{^}.
680 The following unary operators are available: @code{+}, @code{-},
683 The following functions are available:
705 The following constants are available:
734 @settitle FFmpeg video converter
737 ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
748 The filename can be @file{-} to read from standard input or to write
751 FFmpeg also handles many protocols specified with an URL syntax.
753 Use 'ffmpeg -formats' to see a list of the supported protocols.
755 The protocol @code{http:} is currently used only to communicate with
756 FFserver (see the FFserver documentation). When FFmpeg will be a
757 video player it will also be used for streaming :-)
762 @item For streaming at very low bitrate application, use a low frame rate
763 and a small GOP size. This is especially true for RealVideo where
764 the Linux player does not seem to be very fast, so it can miss
765 frames. An example is:
768 ffmpeg -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
771 @item The parameter 'q' which is displayed while encoding is the current
772 quantizer. The value 1 indicates that a very good quality could
773 be achieved. The value 31 indicates the worst quality. If q=31 appears
774 too often, it means that the encoder cannot compress enough to meet
775 your bitrate. You must either increase the bitrate, decrease the
776 frame rate or decrease the frame size.
778 @item If your computer is not fast enough, you can speed up the
779 compression at the expense of the compression ratio. You can use
780 '-me zero' to speed up motion estimation, and '-intra' to disable
781 motion estimation completely (you have only I-frames, which means it
782 is about as good as JPEG compression).
784 @item To have very low audio bitrates, reduce the sampling frequency
785 (down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
787 @item To have a constant quality (but a variable bitrate), use the option
788 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
791 @item When converting video files, you can use the '-sameq' option which
792 uses the same quality factor in the encoder as in the decoder.
793 It allows almost lossless encoding.
798 @chapter external libraries
800 FFmpeg can be hooked up with a number of external libraries to add support
805 AMR comes in two different flavors, WB and NB. FFmpeg can make use of the
806 AMR WB (floating-point mode) and the AMR NB (both floating-point and
807 fixed-point mode) reference decoders and encoders.
811 @item For AMR WB floating-point download TS26.204 V5.1.0 from
812 @url{http://www.3gpp.org/ftp/Specs/archive/26_series/26.204/26204-510.zip}
813 and extract the source to @file{libavcodec/amrwb_float/}.
815 @item For AMR NB floating-point download TS26.104 REL-5 V5.1.0 from
816 @url{http://www.3gpp.org/ftp/Specs/archive/26_series/26.104/26104-510.zip}
817 and extract the source to @file{libavcodec/amr_float/}.
818 If you try this on Alpha, you may need to change @code{Word32} to
819 @code{int} in @file{amr/typedef.h}.
821 @item For AMR NB fixed-point download TS26.073 REL-5 V5.1.0 from
822 @url{http://www.3gpp.org/ftp/Specs/archive/26_series/26.073/26073-510.zip}
823 and extract the source to @file{libavcodec/amr}.
824 You must also add @code{-DMMS_IO} and remove @code{-pedantic-errors}
825 to/from @code{CFLAGS} in @file{libavcodec/amr/makefile}, i.e.
826 ``@code{CFLAGS = -Wall -I. \$(CFLAGS_\$(MODE)) -D\$(VAD) -DMMS_IO}''.
831 @chapter Supported File Formats and Codecs
833 You can use the @code{-formats} option to have an exhaustive list.
835 @section File Formats
837 FFmpeg supports the following file formats through the @code{libavformat}
840 @multitable @columnfractions .4 .1 .1 .4
841 @item Supported File Format @tab Encoding @tab Decoding @tab Comments
842 @item MPEG audio @tab X @tab X
843 @item MPEG-1 systems @tab X @tab X
844 @tab muxed audio and video
845 @item MPEG-2 PS @tab X @tab X
846 @tab also known as @code{VOB} file
847 @item MPEG-2 TS @tab @tab X
848 @tab also known as DVB Transport Stream
849 @item ASF@tab X @tab X
850 @item AVI@tab X @tab X
851 @item WAV@tab X @tab X
852 @item Macromedia Flash@tab X @tab X
853 @tab Only embedded audio is decoded.
854 @item FLV @tab X @tab X
855 @tab Macromedia Flash video files
856 @item Real Audio and Video @tab X @tab X
857 @item Raw AC3 @tab X @tab X
858 @item Raw MJPEG @tab X @tab X
859 @item Raw MPEG video @tab X @tab X
860 @item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
861 @item Raw CRI ADX audio @tab X @tab X
862 @item Raw Shorten audio @tab @tab X
863 @item SUN AU format @tab X @tab X
864 @item NUT @tab X @tab X @tab NUT Open Container Format
865 @item QuickTime @tab X @tab X
866 @item MPEG-4 @tab X @tab X
867 @tab MPEG-4 is a variant of QuickTime.
868 @item Raw MPEG4 video @tab X @tab X
869 @item DV @tab X @tab X
870 @item 4xm @tab @tab X
871 @tab 4X Technologies format, used in some games.
872 @item Playstation STR @tab @tab X
873 @item Id RoQ @tab @tab X
874 @tab Used in Quake III, Jedi Knight 2, other computer games.
875 @item Interplay MVE @tab @tab X
876 @tab Format used in various Interplay computer games.
877 @item WC3 Movie @tab @tab X
878 @tab Multimedia format used in Origin's Wing Commander III computer game.
879 @item Sega FILM/CPK @tab @tab X
880 @tab Used in many Sega Saturn console games.
881 @item Westwood Studios VQA/AUD @tab @tab X
882 @tab Multimedia formats used in Westwood Studios games.
883 @item Id Cinematic (.cin) @tab @tab X
884 @tab Used in Quake II.
885 @item FLIC format @tab @tab X
887 @item Sierra VMD @tab @tab X
888 @tab Used in Sierra CD-ROM games.
889 @item Sierra Online @tab @tab X
890 @tab .sol files used in Sierra Online games.
891 @item Matroska @tab @tab X
892 @item Electronic Arts Multimedia @tab @tab X
893 @tab Used in various EA games; files have extensions like WVE and UV2.
894 @item Nullsoft Video (NSV) format @tab @tab X
895 @item ADTS AAC audio @tab X @tab X
896 @item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
897 @item American Laser Games MM @tab @tab X
898 @tab Multimedia format used in games like Mad Dog McCree
899 @item AVS @tab @tab X
900 @tab Multimedia format used by the Creature Shock game.
901 @item Smacker @tab @tab X
902 @tab Multimedia format used by many games.
903 @item GXF @tab X @tab X
904 @tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
905 @item CIN @tab @tab X
906 @tab Multimedia format used by Delphine Software games.
907 @item MXF @tab @tab X
908 @tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
909 @item SEQ @tab @tab X
910 @tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
913 @code{X} means that encoding (resp. decoding) is supported.
915 @section Image Formats
917 FFmpeg can read and write images for each frame of a video sequence. The
918 following image formats are supported:
920 @multitable @columnfractions .4 .1 .1 .4
921 @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
922 @item PGM, PPM @tab X @tab X
923 @item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support.
924 @item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
925 @item JPEG @tab X @tab X @tab Progressive JPEG is not supported.
926 @item .Y.U.V @tab X @tab X @tab one raw file per component
927 @item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
928 @item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
929 @item Targa @tab @tab X @tab Targa (.TGA) image format.
930 @item TIFF @tab @tab X @tab Only 24 bit/pixel images are supported.
931 @item SGI @tab X @tab X @tab SGI RGB image format
934 @code{X} means that encoding (resp. decoding) is supported.
936 @section Video Codecs
938 @multitable @columnfractions .4 .1 .1 .4
939 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
940 @item MPEG-1 video @tab X @tab X
941 @item MPEG-2 video @tab X @tab X
942 @item MPEG-4 @tab X @tab X
943 @item MSMPEG4 V1 @tab X @tab X
944 @item MSMPEG4 V2 @tab X @tab X
945 @item MSMPEG4 V3 @tab X @tab X
946 @item WMV7 @tab X @tab X
947 @item WMV8 @tab X @tab X @tab not completely working
948 @item WMV9 @tab @tab X @tab not completely working
949 @item VC1 @tab @tab X
950 @item H.261 @tab X @tab X
951 @item H.263(+) @tab X @tab X @tab also known as RealVideo 1.0
952 @item H.264 @tab @tab X
953 @item RealVideo 1.0 @tab X @tab X
954 @item RealVideo 2.0 @tab X @tab X
955 @item MJPEG @tab X @tab X
956 @item lossless MJPEG @tab X @tab X
957 @item JPEG-LS @tab X @tab X @tab fourcc: MJLS, lossless and near-lossless is supported
958 @item Apple MJPEG-B @tab @tab X
959 @item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
960 @item DV @tab X @tab X
961 @item HuffYUV @tab X @tab X
962 @item FFmpeg Video 1 @tab X @tab X @tab experimental lossless codec (fourcc: FFV1)
963 @item FFmpeg Snow @tab X @tab X @tab experimental wavelet codec (fourcc: SNOW)
964 @item Asus v1 @tab X @tab X @tab fourcc: ASV1
965 @item Asus v2 @tab X @tab X @tab fourcc: ASV2
966 @item Creative YUV @tab @tab X @tab fourcc: CYUV
967 @item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
968 @item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
969 @item On2 VP3 @tab @tab X @tab still experimental
970 @item On2 VP5 @tab @tab X @tab fourcc: VP50
971 @item On2 VP6 @tab @tab X @tab fourcc: VP60,VP61,VP62
972 @item Theora @tab X @tab X @tab still experimental
973 @item Intel Indeo 3 @tab @tab X
974 @item FLV @tab X @tab X @tab Sorenson H.263 used in Flash
975 @item Flash Screen Video @tab X @tab X @tab fourcc: FSV1
976 @item ATI VCR1 @tab @tab X @tab fourcc: VCR1
977 @item ATI VCR2 @tab @tab X @tab fourcc: VCR2
978 @item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
979 @item 4X Video @tab @tab X @tab Used in certain computer games.
980 @item Sony Playstation MDEC @tab @tab X
981 @item Id RoQ @tab @tab X @tab Used in Quake III, Jedi Knight 2, other computer games.
982 @item Xan/WC3 @tab @tab X @tab Used in Wing Commander III .MVE files.
983 @item Interplay Video @tab @tab X @tab Used in Interplay .MVE files.
984 @item Apple Animation @tab @tab X @tab fourcc: 'rle '
985 @item Apple Graphics @tab @tab X @tab fourcc: 'smc '
986 @item Apple Video @tab @tab X @tab fourcc: rpza
987 @item Apple QuickDraw @tab @tab X @tab fourcc: qdrw
988 @item Cinepak @tab @tab X
989 @item Microsoft RLE @tab @tab X
990 @item Microsoft Video-1 @tab @tab X
991 @item Westwood VQA @tab @tab X
992 @item Id Cinematic Video @tab @tab X @tab Used in Quake II.
993 @item Planar RGB @tab @tab X @tab fourcc: 8BPS
994 @item FLIC video @tab @tab X
995 @item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
996 @item Duck TrueMotion v2 @tab @tab X @tab fourcc: TM20
997 @item VMD Video @tab @tab X @tab Used in Sierra VMD files.
998 @item MSZH @tab @tab X @tab Part of LCL
999 @item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
1000 @item TechSmith Camtasia @tab @tab X @tab fourcc: TSCC
1001 @item IBM Ultimotion @tab @tab X @tab fourcc: ULTI
1002 @item Miro VideoXL @tab @tab X @tab fourcc: VIXL
1003 @item QPEG @tab @tab X @tab fourccs: QPEG, Q1.0, Q1.1
1004 @item LOCO @tab @tab X @tab
1005 @item Winnov WNV1 @tab @tab X @tab
1006 @item Autodesk Animator Studio Codec @tab @tab X @tab fourcc: AASC
1007 @item Fraps FPS1 @tab @tab X @tab
1008 @item CamStudio @tab @tab X @tab fourcc: CSCD
1009 @item American Laser Games Video @tab @tab X @tab Used in games like Mad Dog McCree
1010 @item ZMBV @tab X @tab X @tab Encoder works only on PAL8
1011 @item AVS Video @tab @tab X @tab Video encoding used by the Creature Shock game.
1012 @item Smacker Video @tab @tab X @tab Video encoding used in Smacker.
1013 @item RTjpeg @tab @tab X @tab Video encoding used in NuppelVideo files.
1014 @item KMVC @tab @tab X @tab Codec used in Worms games.
1015 @item VMware Video @tab @tab X @tab Codec used in videos captured by VMware.
1016 @item Cin Video @tab @tab X @tab Codec used in Delphine Software games.
1017 @item Tiertex Seq Video @tab @tab X @tab Codec used in DOS CDROM FlashBack game.
1020 @code{X} means that encoding (resp. decoding) is supported.
1022 @section Audio Codecs
1024 @multitable @columnfractions .4 .1 .1 .1 .7
1025 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
1026 @item MPEG audio layer 2 @tab IX @tab IX
1027 @item MPEG audio layer 1/3 @tab IX @tab IX
1028 @tab MP3 encoding is supported through the external library LAME.
1029 @item AC3 @tab IX @tab IX
1030 @tab liba52 is used internally for decoding.
1031 @item Vorbis @tab X @tab X
1032 @item WMA V1/V2 @tab X @tab X
1033 @item AAC @tab X @tab X
1034 @tab Supported through the external library libfaac/libfaad.
1035 @item Microsoft ADPCM @tab X @tab X
1036 @item MS IMA ADPCM @tab X @tab X
1037 @item QT IMA ADPCM @tab @tab X
1038 @item 4X IMA ADPCM @tab @tab X
1039 @item G.726 ADPCM @tab X @tab X
1040 @item Duck DK3 IMA ADPCM @tab @tab X
1041 @tab Used in some Sega Saturn console games.
1042 @item Duck DK4 IMA ADPCM @tab @tab X
1043 @tab Used in some Sega Saturn console games.
1044 @item Westwood Studios IMA ADPCM @tab @tab X
1045 @tab Used in Westwood Studios games like Command and Conquer.
1046 @item SMJPEG IMA ADPCM @tab @tab X
1047 @tab Used in certain Loki game ports.
1048 @item CD-ROM XA ADPCM @tab @tab X
1049 @item CRI ADX ADPCM @tab X @tab X
1050 @tab Used in Sega Dreamcast games.
1051 @item Electronic Arts ADPCM @tab @tab X
1052 @tab Used in various EA titles.
1053 @item Creative ADPCM @tab @tab X
1054 @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
1055 @item RA144 @tab @tab X
1056 @tab Real 14400 bit/s codec
1057 @item RA288 @tab @tab X
1058 @tab Real 28800 bit/s codec
1059 @item RADnet @tab X @tab IX
1060 @tab Real low bitrate AC3 codec, liba52 is used for decoding.
1061 @item AMR-NB @tab X @tab X
1062 @tab Supported through an external library.
1063 @item AMR-WB @tab X @tab X
1064 @tab Supported through an external library.
1065 @item DV audio @tab @tab X
1066 @item Id RoQ DPCM @tab @tab X
1067 @tab Used in Quake III, Jedi Knight 2, other computer games.
1068 @item Interplay MVE DPCM @tab @tab X
1069 @tab Used in various Interplay computer games.
1070 @item Xan DPCM @tab @tab X
1071 @tab Used in Origin's Wing Commander IV AVI files.
1072 @item Sierra Online DPCM @tab @tab X
1073 @tab Used in Sierra Online game audio files.
1074 @item Apple MACE 3 @tab @tab X
1075 @item Apple MACE 6 @tab @tab X
1076 @item FLAC lossless audio @tab @tab X
1077 @item Shorten lossless audio @tab @tab X
1078 @item Apple lossless audio @tab @tab X
1079 @tab QuickTime fourcc 'alac'
1080 @item FFmpeg Sonic @tab X @tab X
1081 @tab experimental lossy/lossless codec
1082 @item Qdesign QDM2 @tab @tab X
1083 @tab there are still some distortions
1084 @item Real COOK @tab @tab X
1085 @tab All versions except 5.1 are supported
1086 @item DSP Group TrueSpeech @tab @tab X
1087 @item True Audio (TTA) @tab @tab X
1088 @item Smacker Audio @tab @tab X
1089 @item WavPack Audio @tab @tab X
1090 @item Cin Audio @tab @tab X
1091 @tab Codec used in Delphine Software games.
1092 @item Intel Music Coder @tab @tab X
1093 @item Musepack @tab @tab X
1094 @tab Only SV7 is supported
1097 @code{X} means that encoding (resp. decoding) is supported.
1099 @code{I} means that an integer-only version is available, too (ensures high
1100 performance on systems without hardware floating point support).
1102 @chapter Platform Specific information
1106 BSD make will not build FFmpeg, you need to install and use GNU Make
1111 To get help and instructions for using FFmpeg under Windows, check out
1112 the FFmpeg Windows Help Forum at
1113 @url{http://arrozcru.no-ip.org/ffmpeg/}.
1115 @subsection Native Windows compilation
1118 @item Install the current versions of MSYS and MinGW from
1119 @url{http://www.mingw.org/}. You can find detailed installation
1120 instructions in the download section and the FAQ.
1122 @item If you want to test the FFplay, also download
1123 the MinGW development library of SDL 1.2.x
1124 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
1125 @url{http://www.libsdl.org}. Unpack it in a temporary directory, and
1126 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
1127 directory. Edit the @file{sdl-config} script so that it gives the
1128 correct SDL directory when invoked.
1130 @item Extract the current version of FFmpeg.
1132 @item Start the MSYS shell (file @file{msys.bat}).
1134 @item Change to the FFmpeg directory and follow
1135 the instructions of how to compile FFmpeg (file
1136 @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
1137 suffices. If you have problems using SDL, verify that
1138 @file{sdl-config} can be launched from the MSYS command line.
1140 @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
1141 @file{make install}. Don't forget to copy @file{SDL.dll} to the place
1142 you launch @file{ffplay} from.
1149 @item The target @file{make wininstaller} can be used to create a
1150 Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
1151 must be copied to the FFmpeg directory in order to build the
1154 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
1155 you can build @file{avcodec.dll} and @file{avformat.dll}. With
1156 @code{make install} you install the FFmpeg DLLs and the associated
1157 headers in @file{Program Files/FFmpeg}.
1159 @item Visual C++ compatibility: If you used @code{./configure --enable-shared}
1160 when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
1161 C++ @code{lib} tool to build @code{avcodec.lib} and
1162 @code{avformat.lib}. With these libraries you can link your Visual C++
1163 code directly with the FFmpeg DLLs (see below).
1167 @subsection Visual C++ compatibility
1169 FFmpeg will not compile under Visual C++ -- and it has too many
1170 dependencies on the GCC compiler to make a port viable. However,
1171 if you want to use the FFmpeg libraries in your own applications,
1172 you can still compile those applications using Visual C++. An
1173 important restriction to this is that you have to use the
1174 dynamically linked versions of the FFmpeg libraries (i.e. the
1175 DLLs), and you have to make sure that Visual-C++-compatible
1176 import libraries are created during the FFmpeg build process.
1178 This description of how to use the FFmpeg libraries with Visual C++ is
1179 based on Visual C++ 2005 Express Edition Beta 2. If you have a different
1180 version, you might have to modify the procedures slightly.
1182 Here are the step-by-step instructions for building the FFmpeg libraries
1183 so they can be used with Visual C++:
1187 @item Install Visual C++ (if you haven't done so already).
1189 @item Install MinGW and MSYS as described above.
1191 @item Add a call to @file{vcvars32.bat} (which sets up the environment
1192 variables for the Visual C++ tools) as the first line of
1193 @file{msys.bat}. The standard location for @file{vcvars32.bat} is
1194 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
1195 and the standard location for @file{msys.bat} is
1196 @file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
1197 following line as the first line of @file{msys.bat}:
1199 @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
1201 @item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
1202 If you get a help message with the command line options of @code{link.exe},
1203 this means your environment variables are set up correctly, the
1204 Microsoft linker is on the path and will be used by FFmpeg to
1205 create Visual-C++-compatible import libraries.
1207 @item Extract the current version of FFmpeg and change to the FFmpeg directory.
1209 @item Type the command
1210 @code{./configure --enable-shared --disable-static --enable-memalign-hack}
1211 to configure and, if that didn't produce any errors,
1212 type @code{make} to build FFmpeg.
1214 @item The subdirectories @file{libavformat}, @file{libavcodec}, and
1215 @file{libavutil} should now contain the files @file{avformat.dll},
1216 @file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1217 @file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1218 DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1222 And here is how to use these libraries with Visual C++:
1226 @item Create a new console application ("File / New / Project") and then
1227 select "Win32 Console Application". On the appropriate page of the
1228 Application Wizard, uncheck the "Precompiled headers" option.
1230 @item Write the source code for your application, or, for testing, just
1231 copy the code from an existing sample application into the source file
1232 that Visual C++ has already created for you. (Note that your source
1233 filehas to have a @code{.cpp} extension; otherwise, Visual C++ won't
1234 compile the FFmpeg headers correctly because in C mode, it doesn't
1235 recognize the @code{inline} keyword.) For example, you can copy
1236 @file{output_example.c} from the FFmpeg distribution (but you will
1237 have to make minor modifications so the code will compile under
1240 @item Open the "Project / Properties" dialog box. In the "Configuration"
1241 combo box, select "All Configurations" so that the changes you make will
1242 affect both debug and release builds. In the tree view on the left hand
1243 side, select "C/C++ / General", then edit the "Additional Include
1244 Directories" setting to contain the complete paths to the
1245 @file{libavformat}, @file{libavcodec}, and @file{libavutil}
1246 subdirectories of your FFmpeg directory. Note that the directories have
1247 to be separated using semicolons. Now select "Linker / General" from the
1248 tree view and edit the "Additional Library Directories" setting to
1249 contain the same three directories.
1251 @item Still in the "Project / Properties" dialog box, select "Linker / Input"
1252 from the tree view, then add the files @file{avformat.lib},
1253 @file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1254 Dependencies". Note that the names of the libraries have to be separated
1257 @item Now, select "C/C++ / Code Generation" from the tree view. Select
1258 "Debug" in the "Configuration" combo box. Make sure that "Runtime
1259 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1260 the "Configuration" combo box and make sure that "Runtime Library" is
1261 set to "Multi-threaded DLL".
1263 @item Click "OK" to close the "Project / Properties" dialog box and build
1264 the application. Hopefully, it should compile and run cleanly. If you
1265 used @file{output_example.c} as your sample application, you will get a
1266 few compiler errors, but they are easy to fix. The first type of error
1267 occurs because Visual C++ doesn't allow an @code{int} to be converted to
1268 an @code{enum} without a cast. To solve the problem, insert the required
1269 casts (this error occurs once for a @code{CodecID} and once for a
1270 @code{CodecType}). The second type of error occurs because C++ requires
1271 the return value of @code{malloc} to be cast to the exact type of the
1272 pointer it is being assigned to. Visual C++ will complain that, for
1273 example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1274 an explicit cast. So insert an explicit cast in these places to silence
1275 the compiler. The third type of error occurs because the @code{snprintf}
1276 library function is called @code{_snprintf} under Visual C++. So just
1277 add an underscore to fix the problem. With these changes,
1278 @file{output_example.c} should compile under Visual C++, and the
1279 resulting executable should produce valid video files.
1283 @subsection Cross compilation for Windows with Linux
1285 You must use the MinGW cross compilation tools available at
1286 @url{http://www.mingw.org/}.
1288 Then configure FFmpeg with the following options:
1290 ./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
1292 (you can change the cross-prefix according to the prefix chosen for the
1295 Then you can easily test FFmpeg with Wine
1296 (@url{http://www.winehq.com/}).
1298 @subsection Compilation under Cygwin
1300 Cygwin works very much like Unix.
1302 Just install your Cygwin with all the "Base" packages, plus the
1303 following "Devel" ones:
1305 binutils, gcc-core, make, subversion
1308 Do not install binutils-20060709-1 (they are buggy on shared builds);
1309 use binutils-20050610-1 instead.
1314 ./configure --enable-static --disable-shared
1317 to make a static build or
1320 ./configure --enable-shared --disable-static
1323 to build shared libraries.
1325 If you want to build FFmpeg with additional libraries, download Cygwin
1326 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
1327 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
1328 (@url{http://cygwinports.dotsrc.org/}).
1330 @subsection Crosscompilation for Windows under Cygwin
1332 With Cygwin you can create Windows binaries that don't need the cygwin1.dll.
1334 Just install your Cygwin as explained before, plus these additional
1337 gcc-mingw-core, mingw-runtime, mingw-zlib
1340 and add some special flags to your configure invocation.
1342 For a static build run
1344 ./configure --enable-mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1347 and for a build with shared libraries
1349 ./configure --enable-mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1354 The configure script should guess the configuration itself.
1355 Networking support is currently not finished.
1356 errno issues fixed by Andrew Bachmann.
1360 François Revol - revol at free dot fr - April 2002
1362 The configure script should guess the configuration itself,
1363 however I still didn't test building on the net_server version of BeOS.
1365 FFserver is broken (needs poll() implementation).
1367 There are still issues with errno codes, which are negative in BeOS, and
1368 that FFmpeg negates when returning. This ends up turning errors into
1369 valid results, then crashes.
1372 @chapter Developers Guide
1376 @item libavcodec is the library containing the codecs (both encoding and
1377 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1379 @item libavformat is the library containing the file format handling (mux and
1380 demux code for several formats). Look at @file{ffplay.c} to use it in a
1381 player. See @file{output_example.c} to use it to generate audio or video
1386 @section Integrating libavcodec or libavformat in your program
1388 You can integrate all the source code of the libraries to link them
1389 statically to avoid any version problem. All you need is to provide a
1390 'config.mak' and a 'config.h' in the parent directory. See the defines
1391 generated by ./configure to understand what is needed.
1393 You can use libavcodec or libavformat in your commercial program, but
1394 @emph{any patch you make must be published}. The best way to proceed is
1395 to send your patches to the FFmpeg mailing list.
1398 @section Coding Rules
1400 FFmpeg is programmed in the ISO C90 language with a few additional
1401 features from ISO C99, namely:
1404 the @samp{inline} keyword;
1408 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1410 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1413 These features are supported by all compilers we care about, so we won't
1414 accept patches to remove their use unless they absolutely don't impair
1415 clarity and performance.
1417 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1418 compiles with several other compilers, such as the Compaq ccc compiler
1419 or Sun Studio 9, and we would like to keep it that way unless it would
1420 be exceedingly involved. To ensure compatibility, please don't use any
1421 additional C99 features or GCC extensions. Especially watch out for:
1424 mixing statements and declarations;
1426 @samp{long long} (use @samp{int64_t} instead);
1428 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1430 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1434 The presentation is the one specified by 'indent -i4 -kr -nut'.
1435 The TAB character is forbidden outside of Makefiles as is any
1436 form of trailing whitespace. Commits containing either will be
1437 rejected by the Subversion repository.
1439 Main priority in FFmpeg is simplicity and small code size (=less
1442 Comments: Use the JavaDoc/Doxygen
1443 format (see examples below) so that code documentation
1444 can be generated automatically. All nontrivial functions should have a comment
1445 above them explaining what the function does, even if it's just one sentence.
1446 All structures and their member variables should be documented, too.
1459 typedef struct Foobar@{
1460 int var1; /**< var1 description */
1461 int var2; ///< var2 description
1462 /** var3 description */
1470 * @@param my_parameter description of my_parameter
1471 * @@return return value description
1473 int myfunc(int my_parameter)
1477 fprintf and printf are forbidden in libavformat and libavcodec,
1478 please use av_log() instead.
1480 @section Development Policy
1484 You must not commit code which breaks FFmpeg! (Meaning unfinished but
1485 enabled code which breaks compilation or compiles but does not work or
1486 breaks the regression tests)
1487 You can commit unfinished stuff (for testing etc), but it must be disabled
1488 (#ifdef etc) by default so it does not interfere with other developers'
1491 You don't have to over-test things. If it works for you, and you think it
1492 should work for others, then commit. If your code has problems
1493 (portability, triggers compiler bugs, unusual environment etc) they will be
1494 reported and eventually fixed.
1496 Do not commit unrelated changes together, split them into self-contained
1499 Do not change behavior of the program (renaming options etc) without
1500 first discussing it on the ffmpeg-devel mailing list. Do not remove
1501 functionality from the code. Just improve!
1503 Note: Redundant code can be removed.
1505 Do not commit changes to the build system (Makefiles, configure script)
1506 which change behavior, defaults etc, without asking first. The same
1507 applies to compiler warning fixes, trivial looking fixes and to code
1508 maintained by other developers. We usually have a reason for doing things
1509 the way we do. Send your changes as patches to the ffmpeg-devel mailing
1510 list, and if the code maintainers say OK, you may commit. This does not
1511 apply to files you wrote and/or maintain.
1513 We refuse source indentation and other cosmetic changes if they are mixed
1514 with functional changes, such commits will be rejected and removed. Every
1515 developer has his own indentation style, you should not change it. Of course
1516 if you (re)write something, you can use your own style, even though we would
1517 prefer if the indentation throughout FFmpeg was consistent (Many projects
1518 force a given indentation style - we don't.). If you really need to make
1519 indentation changes (try to avoid this), separate them strictly from real
1522 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1523 then either do NOT change the indentation of the inner part within (don't
1524 move it to the right)! or do so in a separate commit
1526 Always fill out the commit log message. Describe in a few lines what you
1527 changed and why. You can refer to mailing list postings if you fix a
1528 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1530 If you apply a patch by someone else, include the name and email address in
1531 the log message. Since the ffmpeg-cvslog mailing list is publicly
1532 archived you should add some SPAM protection to the email address. Send an
1533 answer to ffmpeg-devel (or wherever you got the patch from) saying that
1534 you applied the patch.
1536 Do NOT commit to code actively maintained by others without permission.
1537 Send a patch to ffmpeg-devel instead. If noone answers within a reasonable
1538 timeframe (12h for build failures and security fixes, 3 days small changes,
1539 1 week for big patches) then commit your patch if you think it's OK.
1540 Also note, the maintainer can simply ask for more time to review!
1542 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1543 are sent there and reviewed by all the other developers. Bugs and possible
1544 improvements or general questions regarding commits are discussed there. We
1545 expect you to react if problems with your code are uncovered.
1547 Update the documentation if you change behavior or add features. If you are
1548 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1549 maintainer(s) will review and commit your stuff.
1551 Never write to unallocated memory, never write over the end of arrays,
1552 always check values read from some untrusted source before using them
1553 as array index or other risky things.
1555 Remember to check if you need to bump versions for the specific libav
1556 parts (libavutil, libavcodec, libavformat) you are changing. You need
1557 to change the version integer and the version string.
1558 Incrementing the first component means no backward compatibility to
1559 previous versions (e.g. removal of a function from the public API).
1560 Incrementing the second component means backward compatible change
1561 (e.g. addition of a function to the public API).
1562 Incrementing the third component means a noteworthy binary compatible
1563 change (e.g. encoder bug fix that matters for the decoder).
1565 If you add a new codec, remember to update the changelog, add it to
1566 the supported codecs table in the documentation and bump the second
1567 component of the @file{libavcodec} version number appropriately. If
1568 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1572 We think our rules are not too hard. If you have comments, contact us.
1574 Note, these rules are mostly borrowed from the MPlayer project.
1576 @section Submitting patches
1578 First, (@pxref{Coding Rules}) above if you didn't yet.
1580 When you submit your patch, try to send a unified diff (diff '-up'
1581 option). I cannot read other diffs :-)
1583 Also please do not submit patches which contain several unrelated changes.
1584 Split them into individual self-contained patches; this makes reviewing
1587 Run the regression tests before submitting a patch so that you can
1588 verify that there are no big problems.
1590 Patches should be posted as base64 encoded attachments (or any other
1591 encoding which ensures that the patch won't be trashed during
1592 transmission) to the ffmpeg-devel mailing list, see
1593 @url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1595 It also helps quite a bit if you tell us what the patch does (for example
1596 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1597 and has no lrint()')
1599 We reply to all submitted patches and either apply or reject with some
1600 explanation why, but sometimes we are quite busy so it can take a week or two.
1602 @section Regression tests
1604 Before submitting a patch (or committing to the repository), you should at least
1605 test that you did not break anything.
1607 The regression tests build a synthetic video stream and a synthetic
1608 audio stream. These are then encoded and decoded with all codecs or
1609 formats. The CRC (or MD5) of each generated file is recorded in a
1610 result file. A 'diff' is launched to compare the reference results and
1613 The regression tests then go on to test the FFserver code with a
1614 limited set of streams. It is important that this step runs correctly
1617 Run 'make test' to test all the codecs and formats.
1619 Run 'make fulltest' to test all the codecs, formats and FFserver.
1621 [Of course, some patches may change the results of the regression tests. In
1622 this case, the reference results of the regression tests shall be modified