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 grab video and audio from devices given that you specify the input
33 ffmpeg -f audio_device -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
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 -s cif -i :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 -s cif -i :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 64k /tmp/a.mp2 -ab 128k /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 libmp3lame -ab 128k 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-libmp3lame} 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 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.
162 * To set the video bitrate of the output file to 64kbit/s:
164 ffmpeg -i input.avi -b 64k output.avi
167 * To force the frame rate of the input and output file to 24 fps:
169 ffmpeg -r 24 -i input.avi output.avi
172 * To force the frame rate of the output file to 24 fps:
174 ffmpeg -i input.avi -r 24 output.avi
177 * To force the frame rate of input file to 1 fps and the output file to 24 fps:
179 ffmpeg -r 1 -i input.avi -r 24 output.avi
182 The format option may be needed for raw input files.
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.
190 @section Main options
203 Show available formats, codecs, protocols, ...
212 Overwrite output files.
215 Restrict the transcoded/captured video sequence
216 to the duration specified in seconds.
217 @code{hh:mm:ss[.xxx]} syntax is also supported.
220 Set the file size limit.
223 Seek to given time position in seconds.
224 @code{hh:mm:ss[.xxx]} syntax is also supported.
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.
237 @item -timestamp time
243 @item -copyright string
246 @item -comment string
259 Control amount of logging.
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:
267 ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
270 Nevertheless you can specify additional options as long as you know
271 they do not conflict with the standard, as in:
274 ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
277 @item -dframes number
278 Set the number of data frames to record.
281 Force subtitle codec ('copy' to copy stream).
284 Add a new subtitle stream to the current output stream.
287 Set the ISO 639 language code (3 letters) of the current subtitle stream.
291 @section Video Options
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.
299 Set frame rate (Hz value, fraction or abbreviation), (default = 25).
301 Set frame size. The format is @samp{wxh} (ffserver default = 160x128, ffmpeg default = same as source).
302 The following abbreviations are recognized:
363 Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
365 Set top crop band size (in pixels).
366 @item -cropbottom size
367 Set bottom crop band size (in pixels).
369 Set left crop band size (in pixels).
370 @item -cropright size
371 Set right crop band size (in pixels).
373 Set top pad band size (in pixels).
374 @item -padbottom size
375 Set bottom pad band size (in pixels).
377 Set left pad band size (in pixels).
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)).
386 Disable video recording.
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).
394 Set video buffer verifier buffer size (in bits).
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.
399 Use same video quality as source (implies VBR).
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
407 @item -passlogfile file
408 Set two pass logfile name to @var{file}.
411 Add a new video stream to the current output stream.
415 @section Advanced Video Options
418 @item -pix_fmt format
419 Set pixel format. Use 'list' as parameter to show all the supported
421 @item -sws_flags flags
422 Set SwScaler flags (only available when compiled with SwScaler support).
424 Set the group of pictures size.
426 Use only intra frames.
430 Use fixed video quantizer scale (VBR).
432 minimum video quantizer scale (VBR)
434 maximum video quantizer scale (VBR)
436 maximum difference between the quantizer scales (VBR)
438 video quantizer scale blur (VBR)
439 @item -qcomp compression
440 video quantizer scale compression (VBR)
443 minimum video lagrange factor (VBR)
445 max video lagrange factor (VBR)
447 minimum macroblock quantizer scale (VBR)
449 maximum macroblock quantizer scale (VBR)
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:
454 ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
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):
477 Try just the (0, 0) vector.
486 exhaustive search (slow and marginally better than epzs)
490 Set DCT algorithm to @var{algo}. Available values are:
493 FF_DCT_AUTO (default)
506 @item -idct_algo algo
507 Set IDCT algorithm to @var{algo}. Available values are:
510 FF_IDCT_AUTO (default)
534 Set error resilience to @var{n}.
537 FF_ER_CAREFUL (default)
543 FF_ER_VERY_AGGRESSIVE
547 Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
548 the following values:
551 FF_EC_GUESS_MVS (default = enabled)
553 FF_EC_DEBLOCK (default = enabled)
557 Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
562 FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
564 FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
566 FF_MB_DECISION_RD: rate distortion
570 Use four motion vector by macroblock (MPEG-4 only).
572 Use data partitioning (MPEG-4 only).
574 Work around encoder bugs that are not auto-detected.
575 @item -strict strictness
576 How strictly to follow the standards.
578 Enable Advanced intra coding (h263+).
580 Enable Unlimited Motion Vector (h263+)
583 Deinterlace pictures.
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.
591 Calculate PSNR of compressed frames.
593 Dump video coding statistics to @file{vstats_HHMMSS.log}.
594 @item -vstats_file file
595 Dump video coding statistics to @var{file}.
597 Insert video processing @var{module}. @var{module} contains the module
598 name and its parameters separated by spaces.
600 top=1/bottom=0/auto=-1 field first
603 @item -vtag fourcc/tag
604 Force video tag/fourcc.
607 @item -vbsf bitstream filter
608 Bitstream filters available are "dump_extra", "remove_extra", "noise".
611 @section Audio Options
614 @item -aframes number
615 Set the number of audio frames to record.
617 Set the audio sampling frequency (default = 44100 Hz).
619 Set the audio bitrate in bit/s (default = 64k).
621 Set the number of audio channels (default = 1).
623 Disable audio recording.
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.
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..).
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.
637 ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384k test.mpg -acodec mp2 -ab 192k -newaudio
640 Set the ISO 639 language code (3 letters) of the current audio stream.
643 @section Advanced Audio options:
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".
652 @section Subtitle options:
656 Force subtitle codec ('copy' to copy stream).
658 Add a new subtitle stream to the current output stream.
660 Set the ISO 639 language code (3 letters) of the current subtitle stream.
663 @section Audio/Video grab options
667 Set video grab channel (DV1394 only).
668 @item -tvstd standard
669 Set television standard (NTSC, PAL (SECAM)).
671 Synchronize read on input.
674 @section Advanced options
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.
684 Print specific debug info.
686 Add timings for benchmarking.
688 Dump each input packet.
690 When dumping packets, also dump the payload.
692 Only use bit exact algorithms (for codec testing).
694 Set packet size in bits.
696 Read input at native frame rate. Mainly used to simulate a grab device.
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).
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.
716 Copy timestamps from input to output.
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.
727 @node FFmpeg formula evaluator
728 @section FFmpeg formula evaluator
730 When evaluating a rate control string, FFmpeg uses an internal formula
733 The following binary operators are available: @code{+}, @code{-},
734 @code{*}, @code{/}, @code{^}.
736 The following unary operators are available: @code{+}, @code{-},
739 The following functions are available:
761 The following constants are available:
790 @settitle FFmpeg video converter
793 ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
804 The filename can be @file{-} to read from standard input or to write
807 FFmpeg also handles many protocols specified with an URL syntax.
809 Use 'ffmpeg -formats' to see a list of the supported protocols.
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 :-)
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:
824 ffmpeg -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
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.
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).
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).
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
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.
854 @chapter external libraries
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}.
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.
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.
871 @chapter Supported File Formats and Codecs
873 You can use the @code{-formats} option to have an exhaustive list.
875 @section File Formats
877 FFmpeg supports the following file formats through the @code{libavformat}
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
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.
964 @code{X} means that encoding (resp. decoding) is supported.
966 @section Image Formats
968 FFmpeg can read and write images for each frame of a video sequence. The
969 following image formats are supported:
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
986 @code{X} means that encoding (resp. decoding) is supported.
988 @section Video Codecs
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.
1078 @code{X} means that encoding (resp. decoding) is supported.
1080 @section Audio Codecs
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
1159 @code{X} means that encoding (resp. decoding) is supported.
1161 @code{I} means that an integer-only version is available, too (ensures high
1162 performance on systems without hardware floating point support).
1164 @chapter Platform Specific information
1168 BSD make will not build FFmpeg, you need to install and use GNU Make
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/}.
1177 @subsection Native Windows compilation
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.
1184 NOTE: Use at least bash 3.1. Older versions are known to be failing on the
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.
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}.
1198 @item Extract the current version of FFmpeg.
1200 @item Start the MSYS shell (file @file{msys.bat}).
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.
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.
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
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}.
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).
1235 @subsection Visual C++ compatibility
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.
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.
1250 Here are the step-by-step instructions for building the FFmpeg libraries
1251 so they can be used with Visual C++:
1255 @item Install Visual C++ (if you have not done so already).
1257 @item Install MinGW and MSYS as described above.
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}:
1267 @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
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.
1275 @item Extract the current version of FFmpeg and change to the FFmpeg directory.
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.
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}).
1290 And here is how to use these libraries with Visual C++:
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.
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
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.
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
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".
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.
1351 @subsection Cross compilation for Windows with Linux
1353 You must use the MinGW cross compilation tools available at
1354 @url{http://www.mingw.org/}.
1356 Then configure FFmpeg with the following options:
1358 ./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
1360 (you can change the cross-prefix according to the prefix chosen for the
1363 Then you can easily test FFmpeg with Wine
1364 (@url{http://www.winehq.com/}).
1366 @subsection Compilation under Cygwin
1368 Cygwin works very much like Unix.
1370 Just install your Cygwin with all the "Base" packages, plus the
1371 following "Devel" ones:
1373 binutils, gcc-core, make, subversion
1376 Do not install binutils-20060709-1 (they are buggy on shared builds);
1377 use binutils-20050610-1 instead.
1382 ./configure --enable-static --disable-shared
1385 to make a static build or
1388 ./configure --enable-shared --disable-static
1391 to build shared libraries.
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/}).
1398 @subsection Crosscompilation for Windows under Cygwin
1400 With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
1402 Just install your Cygwin as explained before, plus these additional
1405 gcc-mingw-core, mingw-runtime, mingw-zlib
1408 and add some special flags to your configure invocation.
1410 For a static build run
1412 ./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1415 and for a build with shared libraries
1417 ./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1422 The configure script should guess the configuration itself.
1423 Networking support is currently not finished.
1424 errno issues fixed by Andrew Bachmann.
1428 François Revol - revol at free dot fr - April 2002
1430 The configure script should guess the configuration itself,
1431 however I still did not test building on the net_server version of BeOS.
1433 FFserver is broken (needs poll() implementation).
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.
1440 @chapter Developers Guide
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.
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
1454 @section Integrating libavcodec or libavformat in your program
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.
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.
1466 @section Coding Rules
1468 FFmpeg is programmed in the ISO C90 language with a few additional
1469 features from ISO C99, namely:
1472 the @samp{inline} keyword;
1476 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1478 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
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.
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:
1492 mixing statements and declarations;
1494 @samp{long long} (use @samp{int64_t} instead);
1496 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1498 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
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.
1507 The main priority in FFmpeg is simplicity and small code size in order to
1508 minimize the bug count.
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.
1527 typedef struct Foobar@{
1528 int var1; /**< var1 description */
1529 int var2; ///< var2 description
1530 /** var3 description */
1538 * @@param my_parameter description of my_parameter
1539 * @@return return value description
1541 int myfunc(int my_parameter)
1545 fprintf and printf are forbidden in libavformat and libavcodec,
1546 please use av_log() instead.
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.
1551 @section Development Policy
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
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'
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.
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.
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!
1585 Note: Redundant code can be removed.
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.
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
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
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.
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.
1618 When applying patches that have been discussed (at length) on the mailing
1619 list, reference the thread in the log message.
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!
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.
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.
1636 Try to keep important discussions and requests (also) on the public
1637 developer mailing list, so that all developers can benefit from them.
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.
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).
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
1659 Do not change code to hide warnings without ensuring that the underlying
1660 logic is correct and thus the warning was inappropriate.
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.
1666 We think our rules are not too hard. If you have comments, contact us.
1668 Note, these rules are mostly borrowed from the MPlayer project.
1670 @section Submitting patches
1672 First, (@pxref{Coding Rules}) above if you did not yet.
1674 When you submit your patch, try to send a unified diff (diff '-up'
1675 option). We cannot read other diffs :-)
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.
1684 Run the regression tests before submitting a patch so that you can
1685 verify that there are no big problems.
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}
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()')
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.
1699 @section patch submission checklist
1703 Do the regression tests pass with the patch applied?
1705 Is the patch a unified diff?
1707 Is the patch against latest FFmpeg SVN?
1709 Are you subscribed to ffmpeg-dev?
1710 (the list is subscribers only due to spam)
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?
1715 If the change is to speed critical code, did you benchmark it?
1717 If you did any benchmarks, did you provide them in the mail?
1719 Have you checked that the patch does not introduce buffer overflows or
1720 other security issues?
1722 Is the patch created from the root of the source tree, so it can be
1723 applied with @code{patch -p0}?
1725 Does the patch not mix functional and cosmetic changes?
1727 Did you add tabs or trailing whitespace to the code? Both are forbidden.
1729 Is the patch attached to the email you send?
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.
1734 If the patch fixes a bug, did you provide a verbose analysis of the bug?
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
1741 Did you provide a verbose summary about what the patch does change?
1743 Did you provide a verbose explanation why it changes things like it does?
1745 Did you provide a verbose summary of the user visible advantages and
1746 disadvantages if the patch is applied?
1748 Did you provide an example so we can verify the new feature added by the
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.
1754 You should maintain alphabetical order in alphabetically ordered lists as
1755 long as doing so does not break API/ABI compatibility.
1757 Lines with similar content should be aligned vertically when doing so
1758 improves readability.
1760 Did you provide a suggestion for a clear commit log message?
1763 @section Patch review process
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.
1776 We will review all submitted patches, but sometimes we are quite busy so
1777 especially for large patches this can take several weeks.
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
1784 @section Regression tests
1786 Before submitting a patch (or committing to the repository), you should at least
1787 test that you did not break anything.
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
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
1799 Run 'make test' to test all the codecs and formats.
1801 Run 'make fulltest' to test all the codecs, formats and FFserver.
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