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 mp3 -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-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 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 Set the recording time in seconds.
216 @code{hh:mm:ss[.xxx]} syntax is also supported.
219 Set the file size limit.
222 Seek to given time position in seconds.
223 @code{hh:mm:ss[.xxx]} syntax is also supported.
225 @item -itsoffset offset
226 Set the input time offset in seconds.
227 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
228 This option affects all the input files that follow it.
229 The offset is added to the timestamps of the input files.
230 Specifying a positive offset means that the corresponding
231 streams are delayed by 'offset' seconds.
236 @item -timestamp time
242 @item -copyright string
245 @item -comment string
258 Control amount of logging.
261 Specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "pal-vcd",
262 "ntsc-svcd", ... ). All the format options (bitrate, codecs,
263 buffer sizes) are then set automatically. You can just type:
266 ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
269 Nevertheless you can specify additional options as long as you know
270 they do not conflict with the standard, as in:
273 ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
276 @item -dframes number
277 Set the number of data frames to record.
280 Force subtitle codec ('copy' to copy stream).
283 Add a new subtitle stream to the current output stream.
286 Set the ISO 639 language code (3 letters) of the current subtitle stream.
290 @section Video Options
294 Set the video bitrate in bit/s (default = 200 kb/s).
295 @item -vframes number
296 Set the number of video frames to record.
298 Set frame rate (Hz value, fraction or abbreviation), (default = 25).
300 Set frame size. The format is @samp{wxh} (ffserver default = 160x128, ffmpeg default = same as source).
301 The following abbreviations are recognized:
362 Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
364 Set top crop band size (in pixels).
365 @item -cropbottom size
366 Set bottom crop band size (in pixels).
368 Set left crop band size (in pixels).
369 @item -cropright size
370 Set right crop band size (in pixels).
372 Set top pad band size (in pixels).
373 @item -padbottom size
374 Set bottom pad band size (in pixels).
376 Set left pad band size (in pixels).
378 Set right pad band size (in pixels).
379 @item -padcolor (hex color)
380 Set color of padded bands. The value for padcolor is expressed
381 as a six digit hexadecimal number where the first two digits
382 represent red, the middle two digits green and last two digits
383 blue (default = 000000 (black)).
385 Disable video recording.
387 Set video bitrate tolerance (in bit/s).
388 @item -maxrate bitrate
389 Set max video bitrate tolerance (in bit/s).
390 @item -minrate bitrate
391 Set min video bitrate tolerance (in bit/s).
393 Set rate control buffer size (in bits).
395 Force video codec to @var{codec}. Use the @code{copy} special value to
396 tell that the raw codec data must be copied as is.
398 Use same video quality as source (implies VBR).
401 Select the pass number (1 or 2). It is useful to do two pass
402 encoding. The statistics of the video are recorded in the first
403 pass and the video is generated at the exact requested bitrate
406 @item -passlogfile file
407 Set two pass logfile name to @var{file}.
410 Add a new video stream to the current output stream.
414 @section Advanced Video Options
417 @item -pix_fmt format
419 @item -sws_flags flags
420 Set SwScaler flags (only available when compiled with SwScaler support).
422 Set the group of pictures size.
424 Use only intra frames.
428 Use fixed video quantizer scale (VBR).
430 minimum video quantizer scale (VBR)
432 maximum video quantizer scale (VBR)
434 maximum difference between the quantizer scales (VBR)
436 video quantizer scale blur (VBR)
437 @item -qcomp compression
438 video quantizer scale compression (VBR)
441 minimum video lagrange factor (VBR)
443 max video lagrange factor (VBR)
445 minimum macroblock quantizer scale (VBR)
447 maximum macroblock quantizer scale (VBR)
449 These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
450 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
452 ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
455 @item -rc_init_cplx complexity
456 initial complexity for single pass encoding
457 @item -b_qfactor factor
458 qp factor between P- and B-frames
459 @item -i_qfactor factor
460 qp factor between P- and I-frames
461 @item -b_qoffset offset
462 qp offset between P- and B-frames
463 @item -i_qoffset offset
464 qp offset between P- and I-frames
465 @item -rc_eq equation
466 Set rate control equation (@pxref{FFmpeg formula
467 evaluator}) (default = @code{tex^qComp}).
468 @item -rc_override override
469 rate control override for specific intervals
471 Set motion estimation method to @var{method}.
472 Available methods are (from lowest to best quality):
475 Try just the (0, 0) vector.
482 exhaustive search (slow and marginally better than epzs)
486 Set DCT algorithm to @var{algo}. Available values are:
489 FF_DCT_AUTO (default)
502 @item -idct_algo algo
503 Set IDCT algorithm to @var{algo}. Available values are:
506 FF_IDCT_AUTO (default)
530 Set error resilience to @var{n}.
533 FF_ER_CAREFUL (default)
539 FF_ER_VERY_AGGRESSIVE
543 Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
544 the following values:
547 FF_EC_GUESS_MVS (default = enabled)
549 FF_EC_DEBLOCK (default = enabled)
553 Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
558 FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
560 FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
562 FF_MB_DECISION_RD: rate distortion
566 Use four motion vector by macroblock (MPEG-4 only).
568 Use data partitioning (MPEG-4 only).
570 Work around encoder bugs that are not auto-detected.
571 @item -strict strictness
572 How strictly to follow the standards.
574 Enable Advanced intra coding (h263+).
576 Enable Unlimited Motion Vector (h263+)
579 Deinterlace pictures.
581 Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
582 Use this option if your input file is interlaced and you want
583 to keep the interlaced format for minimum losses.
584 The alternative is to deinterlace the input stream with
585 @option{-deinterlace}, but deinterlacing introduces losses.
587 Calculate PSNR of compressed frames.
589 Dump video coding statistics to @file{vstats_HHMMSS.log}.
590 @item -vstats_file file
591 Dump video coding statistics to @var{file}.
593 Insert video processing @var{module}. @var{module} contains the module
594 name and its parameters separated by spaces.
596 top=1/bottom=0/auto=-1 field first
599 @item -vtag fourcc/tag
600 Force video tag/fourcc.
603 @item -vbsf bitstream filter
604 Bitstream filters available are "dump_extra", "remove_extra", "noise".
607 @section Audio Options
610 @item -aframes number
611 Set the number of audio frames to record.
613 Set the audio sampling frequency (default = 44100 Hz).
615 Set the audio bitrate in bit/s (default = 64k).
617 Set the number of audio channels (default = 1).
619 Disable audio recording.
621 Force audio codec to @var{codec}. Use the @code{copy} special value to
622 specify that the raw codec data must be copied as is.
624 Add a new audio track to the output file. If you want to specify parameters,
625 do so before @code{-newaudio} (@code{-acodec}, @code{-ab}, etc..).
627 Mapping will be done automatically, if the number of output streams is equal to
628 the number of input streams, else it will pick the first one that matches. You
629 can override the mapping using @code{-map} as usual.
633 ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384k test.mpg -acodec mp2 -ab 192k -newaudio
636 Set the ISO 639 language code (3 letters) of the current audio stream.
639 @section Advanced Audio options:
642 @item -atag fourcc/tag
643 Force audio tag/fourcc.
644 @item -absf bitstream filter
645 Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
648 @section Subtitle options:
652 Force subtitle codec ('copy' to copy stream).
654 Add a new subtitle stream to the current output stream.
656 Set the ISO 639 language code (3 letters) of the current subtitle stream.
659 @section Audio/Video grab options
663 Set video grab channel (DV1394 only).
664 @item -tvstd standard
665 Set television standard (NTSC, PAL (SECAM)).
667 Synchronize read on input.
670 @section Advanced options
673 @item -map input stream id[:input stream id]
674 Set stream mapping from input streams to output streams.
675 Just enumerate the input streams in the order you want them in the output.
676 [input stream id] sets the (input) stream to sync against.
677 @item -map_meta_data outfile:infile
678 Set meta data information of outfile from infile.
680 Print specific debug info.
682 Add timings for benchmarking.
684 Dump each input packet.
686 When dumping packets, also dump the payload.
688 Only use bit exact algorithms (for codec testing).
690 Set packet size in bits.
692 Read input at native frame rate. Mainly used to simulate a grab device.
694 Loop over the input stream. Currently it works only for image
695 streams. This option is used for automatic FFserver testing.
696 @item -loop_output number_of_times
697 Repeatedly loop output for formats that support looping such as animated GIF
698 (0 will loop the output infinitely).
701 @item -vsync parameter
702 Video sync method. Video will be stretched/squeezed to match the timestamps,
703 it is done by duplicating and dropping frames. With -map you can select from
704 which stream the timestamps should be taken. You can leave either video or
705 audio unchanged and sync the remaining stream(s) to the unchanged one.
706 @item -async samples_per_second
707 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
708 the parameter is the maximum samples per second by which the audio is changed.
709 -async 1 is a special case where only the start of the audio stream is corrected
710 without any later correction.
713 @node FFmpeg formula evaluator
714 @section FFmpeg formula evaluator
716 When evaluating a rate control string, FFmpeg uses an internal formula
719 The following binary operators are available: @code{+}, @code{-},
720 @code{*}, @code{/}, @code{^}.
722 The following unary operators are available: @code{+}, @code{-},
725 The following functions are available:
747 The following constants are available:
776 @settitle FFmpeg video converter
779 ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
790 The filename can be @file{-} to read from standard input or to write
793 FFmpeg also handles many protocols specified with an URL syntax.
795 Use 'ffmpeg -formats' to see a list of the supported protocols.
797 The protocol @code{http:} is currently used only to communicate with
798 FFserver (see the FFserver documentation). When FFmpeg will be a
799 video player it will also be used for streaming :-)
804 @item For streaming at very low bitrate application, use a low frame rate
805 and a small GOP size. This is especially true for RealVideo where
806 the Linux player does not seem to be very fast, so it can miss
807 frames. An example is:
810 ffmpeg -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
813 @item The parameter 'q' which is displayed while encoding is the current
814 quantizer. The value 1 indicates that a very good quality could
815 be achieved. The value 31 indicates the worst quality. If q=31 appears
816 too often, it means that the encoder cannot compress enough to meet
817 your bitrate. You must either increase the bitrate, decrease the
818 frame rate or decrease the frame size.
820 @item If your computer is not fast enough, you can speed up the
821 compression at the expense of the compression ratio. You can use
822 '-me zero' to speed up motion estimation, and '-intra' to disable
823 motion estimation completely (you have only I-frames, which means it
824 is about as good as JPEG compression).
826 @item To have very low audio bitrates, reduce the sampling frequency
827 (down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
829 @item To have a constant quality (but a variable bitrate), use the option
830 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
833 @item When converting video files, you can use the '-sameq' option which
834 uses the same quality factor in the encoder as in the decoder.
835 It allows almost lossless encoding.
840 @chapter external libraries
842 FFmpeg can be hooked up with a number of external libraries to add support
843 for more formats. None of them are used by default, their use has to be
844 explicitly requested by passing the appropriate flags to @file{./configure}.
848 AMR comes in two different flavors, WB and NB. FFmpeg can make use of the
849 AMR WB (floating-point mode) and the AMR NB (floating-point mode) reference
850 decoders and encoders.
852 Go to @url{http://www.penguin.cz/~utx/amr} and follow the instructions for
853 installing the libraries. Then pass @code{--enable-amr-nb} and/or
854 @code{--enable-amr-wb} to configure to enable the libraries.
857 @chapter Supported File Formats and Codecs
859 You can use the @code{-formats} option to have an exhaustive list.
861 @section File Formats
863 FFmpeg supports the following file formats through the @code{libavformat}
866 @multitable @columnfractions .4 .1 .1 .4
867 @item Supported File Format @tab Encoding @tab Decoding @tab Comments
868 @item MPEG audio @tab X @tab X
869 @item MPEG-1 systems @tab X @tab X
870 @tab muxed audio and video
871 @item MPEG-2 PS @tab X @tab X
872 @tab also known as @code{VOB} file
873 @item MPEG-2 TS @tab @tab X
874 @tab also known as DVB Transport Stream
875 @item ASF@tab X @tab X
876 @item AVI@tab X @tab X
877 @item WAV@tab X @tab X
878 @item Macromedia Flash@tab X @tab X
879 @tab Only embedded audio is decoded.
880 @item FLV @tab X @tab X
881 @tab Macromedia Flash video files
882 @item Real Audio and Video @tab X @tab X
883 @item Raw AC3 @tab X @tab X
884 @item Raw MJPEG @tab X @tab X
885 @item Raw MPEG video @tab X @tab X
886 @item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
887 @item Raw CRI ADX audio @tab X @tab X
888 @item Raw Shorten audio @tab @tab X
889 @item SUN AU format @tab X @tab X
890 @item NUT @tab X @tab X @tab NUT Open Container Format
891 @item QuickTime @tab X @tab X
892 @item MPEG-4 @tab X @tab X
893 @tab MPEG-4 is a variant of QuickTime.
894 @item Raw MPEG4 video @tab X @tab X
895 @item DV @tab X @tab X
896 @item 4xm @tab @tab X
897 @tab 4X Technologies format, used in some games.
898 @item Playstation STR @tab @tab X
899 @item Id RoQ @tab X @tab X
900 @tab Used in Quake III, Jedi Knight 2, other computer games.
901 @item Interplay MVE @tab @tab X
902 @tab Format used in various Interplay computer games.
903 @item WC3 Movie @tab @tab X
904 @tab Multimedia format used in Origin's Wing Commander III computer game.
905 @item Sega FILM/CPK @tab @tab X
906 @tab Used in many Sega Saturn console games.
907 @item Westwood Studios VQA/AUD @tab @tab X
908 @tab Multimedia formats used in Westwood Studios games.
909 @item Id Cinematic (.cin) @tab @tab X
910 @tab Used in Quake II.
911 @item FLIC format @tab @tab X
913 @item Sierra VMD @tab @tab X
914 @tab Used in Sierra CD-ROM games.
915 @item Sierra Online @tab @tab X
916 @tab .sol files used in Sierra Online games.
917 @item Matroska @tab @tab X
918 @item Electronic Arts Multimedia @tab @tab X
919 @tab Used in various EA games; files have extensions like WVE and UV2.
920 @item Nullsoft Video (NSV) format @tab @tab X
921 @item ADTS AAC audio @tab X @tab X
922 @item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
923 @item American Laser Games MM @tab @tab X
924 @tab Multimedia format used in games like Mad Dog McCree
925 @item AVS @tab @tab X
926 @tab Multimedia format used by the Creature Shock game.
927 @item Smacker @tab @tab X
928 @tab Multimedia format used by many games.
929 @item GXF @tab X @tab X
930 @tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
931 @item CIN @tab @tab X
932 @tab Multimedia format used by Delphine Software games.
933 @item MXF @tab @tab X
934 @tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
935 @item SEQ @tab @tab X
936 @tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
937 @item DXA @tab @tab X
938 @tab This format is used in non-Windows version of Feeble Files game and
939 different game cutscenes repacked for use with ScummVM.
940 @item THP @tab @tab X
941 @tab Used on the Nintendo GameCube.
942 @item C93 @tab @tab X
943 @tab Used in the game Cyberia from Interplay.
944 @item Bethsoft VID @tab @tab X
945 @tab Used in some games from Bethesda Softworks.
946 @item CRYO APC @tab @tab X
947 @tab Audio format used in some games by CRYO Interactive Entertainment.
950 @code{X} means that encoding (resp. decoding) is supported.
952 @section Image Formats
954 FFmpeg can read and write images for each frame of a video sequence. The
955 following image formats are supported:
957 @multitable @columnfractions .4 .1 .1 .4
958 @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
959 @item PGM, PPM @tab X @tab X
960 @item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support.
961 @item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
962 @item JPEG @tab X @tab X @tab Progressive JPEG is not supported.
963 @item .Y.U.V @tab X @tab X @tab one raw file per component
964 @item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
965 @item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
966 @item Targa @tab @tab X @tab Targa (.TGA) image format.
967 @item TIFF @tab X @tab X @tab YUV, JPEG and some extension is not supported yet.
968 @item SGI @tab X @tab X @tab SGI RGB image format
969 @item PTX @tab @tab X @tab V.Flash PTX format
972 @code{X} means that encoding (resp. decoding) is supported.
974 @section Video Codecs
976 @multitable @columnfractions .4 .1 .1 .4
977 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
978 @item MPEG-1 video @tab X @tab X
979 @item MPEG-2 video @tab X @tab X
980 @item MPEG-4 @tab X @tab X
981 @item MSMPEG4 V1 @tab X @tab X
982 @item MSMPEG4 V2 @tab X @tab X
983 @item MSMPEG4 V3 @tab X @tab X
984 @item WMV7 @tab X @tab X
985 @item WMV8 @tab X @tab X @tab not completely working
986 @item WMV9 @tab @tab X @tab not completely working
987 @item VC1 @tab @tab X
988 @item H.261 @tab X @tab X
989 @item H.263(+) @tab X @tab X @tab also known as RealVideo 1.0
990 @item H.264 @tab @tab X
991 @item RealVideo 1.0 @tab X @tab X
992 @item RealVideo 2.0 @tab X @tab X
993 @item MJPEG @tab X @tab X
994 @item lossless MJPEG @tab X @tab X
995 @item JPEG-LS @tab X @tab X @tab fourcc: MJLS, lossless and near-lossless is supported
996 @item Apple MJPEG-B @tab @tab X
997 @item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
998 @item DV @tab X @tab X
999 @item HuffYUV @tab X @tab X
1000 @item FFmpeg Video 1 @tab X @tab X @tab experimental lossless codec (fourcc: FFV1)
1001 @item FFmpeg Snow @tab X @tab X @tab experimental wavelet codec (fourcc: SNOW)
1002 @item Asus v1 @tab X @tab X @tab fourcc: ASV1
1003 @item Asus v2 @tab X @tab X @tab fourcc: ASV2
1004 @item Creative YUV @tab @tab X @tab fourcc: CYUV
1005 @item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
1006 @item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
1007 @item On2 VP3 @tab @tab X @tab still experimental
1008 @item On2 VP5 @tab @tab X @tab fourcc: VP50
1009 @item On2 VP6 @tab @tab X @tab fourcc: VP60,VP61,VP62
1010 @item Theora @tab X @tab X @tab still experimental
1011 @item Intel Indeo 3 @tab @tab X
1012 @item FLV @tab X @tab X @tab Sorenson H.263 used in Flash
1013 @item Flash Screen Video @tab X @tab X @tab fourcc: FSV1
1014 @item ATI VCR1 @tab @tab X @tab fourcc: VCR1
1015 @item ATI VCR2 @tab @tab X @tab fourcc: VCR2
1016 @item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
1017 @item 4X Video @tab @tab X @tab Used in certain computer games.
1018 @item Sony Playstation MDEC @tab @tab X
1019 @item Id RoQ @tab @tab X @tab Used in Quake III, Jedi Knight 2, other computer games.
1020 @item Xan/WC3 @tab @tab X @tab Used in Wing Commander III .MVE files.
1021 @item Interplay Video @tab @tab X @tab Used in Interplay .MVE files.
1022 @item Apple Animation @tab @tab X @tab fourcc: 'rle '
1023 @item Apple Graphics @tab @tab X @tab fourcc: 'smc '
1024 @item Apple Video @tab @tab X @tab fourcc: rpza
1025 @item Apple QuickDraw @tab @tab X @tab fourcc: qdrw
1026 @item Cinepak @tab @tab X
1027 @item Microsoft RLE @tab @tab X
1028 @item Microsoft Video-1 @tab @tab X
1029 @item Westwood VQA @tab @tab X
1030 @item Id Cinematic Video @tab @tab X @tab Used in Quake II.
1031 @item Planar RGB @tab @tab X @tab fourcc: 8BPS
1032 @item FLIC video @tab @tab X
1033 @item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
1034 @item Duck TrueMotion v2 @tab @tab X @tab fourcc: TM20
1035 @item VMD Video @tab @tab X @tab Used in Sierra VMD files.
1036 @item MSZH @tab @tab X @tab Part of LCL
1037 @item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
1038 @item TechSmith Camtasia @tab @tab X @tab fourcc: TSCC
1039 @item IBM Ultimotion @tab @tab X @tab fourcc: ULTI
1040 @item Miro VideoXL @tab @tab X @tab fourcc: VIXL
1041 @item QPEG @tab @tab X @tab fourccs: QPEG, Q1.0, Q1.1
1042 @item LOCO @tab @tab X @tab
1043 @item Winnov WNV1 @tab @tab X @tab
1044 @item Autodesk Animator Studio Codec @tab @tab X @tab fourcc: AASC
1045 @item Fraps FPS1 @tab @tab X @tab
1046 @item CamStudio @tab @tab X @tab fourcc: CSCD
1047 @item American Laser Games Video @tab @tab X @tab Used in games like Mad Dog McCree
1048 @item ZMBV @tab X @tab X @tab Encoder works only on PAL8
1049 @item AVS Video @tab @tab X @tab Video encoding used by the Creature Shock game.
1050 @item Smacker Video @tab @tab X @tab Video encoding used in Smacker.
1051 @item RTjpeg @tab @tab X @tab Video encoding used in NuppelVideo files.
1052 @item KMVC @tab @tab X @tab Codec used in Worms games.
1053 @item VMware Video @tab @tab X @tab Codec used in videos captured by VMware.
1054 @item Cin Video @tab @tab X @tab Codec used in Delphine Software games.
1055 @item Tiertex Seq Video @tab @tab X @tab Codec used in DOS CDROM FlashBack game.
1056 @item DXA Video @tab @tab X @tab Codec originally used in Feeble Files game.
1057 @item AVID DNxHD @tab @tab X @tab aka SMPTE VC3
1058 @item C93 Video @tab @tab X @tab Codec used in Cyberia game.
1059 @item THP @tab @tab X @tab Used on the Nintendo GameCube.
1060 @item Bethsoft VID @tab @tab X @tab Used in some games from Bethesda Softworks.
1061 @item Renderware TXD @tab @tab X @tab Texture dictionaries used by the Renderware Engine.
1064 @code{X} means that encoding (resp. decoding) is supported.
1066 @section Audio Codecs
1068 @multitable @columnfractions .4 .1 .1 .1 .7
1069 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
1070 @item MPEG audio layer 2 @tab IX @tab IX
1071 @item MPEG audio layer 1/3 @tab IX @tab IX
1072 @tab MP3 encoding is supported through the external library LAME.
1073 @item AC3 @tab IX @tab IX
1074 @tab liba52 is used internally for decoding.
1075 @item Vorbis @tab X @tab X
1076 @item WMA V1/V2 @tab X @tab X
1077 @item AAC @tab X @tab X
1078 @tab Supported through the external library libfaac/libfaad.
1079 @item Microsoft ADPCM @tab X @tab X
1080 @item MS IMA ADPCM @tab X @tab X
1081 @item QT IMA ADPCM @tab @tab X
1082 @item 4X IMA ADPCM @tab @tab X
1083 @item G.726 ADPCM @tab X @tab X
1084 @item Duck DK3 IMA ADPCM @tab @tab X
1085 @tab Used in some Sega Saturn console games.
1086 @item Duck DK4 IMA ADPCM @tab @tab X
1087 @tab Used in some Sega Saturn console games.
1088 @item Westwood Studios IMA ADPCM @tab @tab X
1089 @tab Used in Westwood Studios games like Command and Conquer.
1090 @item SMJPEG IMA ADPCM @tab @tab X
1091 @tab Used in certain Loki game ports.
1092 @item CD-ROM XA ADPCM @tab @tab X
1093 @item CRI ADX ADPCM @tab X @tab X
1094 @tab Used in Sega Dreamcast games.
1095 @item Electronic Arts ADPCM @tab @tab X
1096 @tab Used in various EA titles.
1097 @item Creative ADPCM @tab @tab X
1098 @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
1099 @item THP ADPCM @tab @tab X
1100 @tab Used on the Nintendo GameCube.
1101 @item RA144 @tab @tab X
1102 @tab Real 14400 bit/s codec
1103 @item RA288 @tab @tab X
1104 @tab Real 28800 bit/s codec
1105 @item RADnet @tab X @tab IX
1106 @tab Real low bitrate AC3 codec, liba52 is used for decoding.
1107 @item AMR-NB @tab X @tab X
1108 @tab Supported through an external library.
1109 @item AMR-WB @tab X @tab X
1110 @tab Supported through an external library.
1111 @item DV audio @tab @tab X
1112 @item Id RoQ DPCM @tab X @tab X
1113 @tab Used in Quake III, Jedi Knight 2, other computer games.
1114 @item Interplay MVE DPCM @tab @tab X
1115 @tab Used in various Interplay computer games.
1116 @item Xan DPCM @tab @tab X
1117 @tab Used in Origin's Wing Commander IV AVI files.
1118 @item Sierra Online DPCM @tab @tab X
1119 @tab Used in Sierra Online game audio files.
1120 @item Apple MACE 3 @tab @tab X
1121 @item Apple MACE 6 @tab @tab X
1122 @item FLAC lossless audio @tab X @tab X
1123 @item Shorten lossless audio @tab @tab X
1124 @item Apple lossless audio @tab @tab X
1125 @tab QuickTime fourcc 'alac'
1126 @item FFmpeg Sonic @tab X @tab X
1127 @tab experimental lossy/lossless codec
1128 @item Qdesign QDM2 @tab @tab X
1129 @tab there are still some distortions
1130 @item Real COOK @tab @tab X
1131 @tab All versions except 5.1 are supported
1132 @item DSP Group TrueSpeech @tab @tab X
1133 @item True Audio (TTA) @tab @tab X
1134 @item Smacker Audio @tab @tab X
1135 @item WavPack Audio @tab @tab X
1136 @item Cin Audio @tab @tab X
1137 @tab Codec used in Delphine Software games.
1138 @item Intel Music Coder @tab @tab X
1139 @item Musepack @tab @tab X
1140 @tab Only SV7 is supported
1141 @item DT$ Coherent Audio @tab @tab X
1142 @item ATRAC 3 @tab @tab X
1145 @code{X} means that encoding (resp. decoding) is supported.
1147 @code{I} means that an integer-only version is available, too (ensures high
1148 performance on systems without hardware floating point support).
1150 @chapter Platform Specific information
1154 BSD make will not build FFmpeg, you need to install and use GNU Make
1159 To get help and instructions for using FFmpeg under Windows, check out
1160 the FFmpeg Windows Help Forum at
1161 @url{http://arrozcru.no-ip.org/ffmpeg/}.
1163 @subsection Native Windows compilation
1166 @item Install the current versions of MSYS and MinGW from
1167 @url{http://www.mingw.org/}. You can find detailed installation
1168 instructions in the download section and the FAQ.
1170 NOTE: Use at least bash 3.1. Older versions are known to be failing on the
1173 @item If you want to test the FFplay, also download
1174 the MinGW development library of SDL 1.2.x
1175 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
1176 @url{http://www.libsdl.org}. Unpack it in a temporary directory, and
1177 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
1178 directory. Edit the @file{sdl-config} script so that it gives the
1179 correct SDL directory when invoked.
1181 @item Extract the current version of FFmpeg.
1183 @item Start the MSYS shell (file @file{msys.bat}).
1185 @item Change to the FFmpeg directory and follow
1186 the instructions of how to compile FFmpeg (file
1187 @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
1188 suffices. If you have problems using SDL, verify that
1189 @file{sdl-config} can be launched from the MSYS command line.
1191 @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
1192 @file{make install}. Do not forget to copy @file{SDL.dll} to the place
1193 you launch @file{ffplay} from.
1200 @item The target @file{make wininstaller} can be used to create a
1201 Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
1202 must be copied to the FFmpeg directory in order to build the
1205 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
1206 you can build @file{avcodec.dll} and @file{avformat.dll}. With
1207 @code{make install} you install the FFmpeg DLLs and the associated
1208 headers in @file{Program Files/FFmpeg}.
1210 @item Visual C++ compatibility: If you used @code{./configure --enable-shared}
1211 when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
1212 C++ @code{lib} tool to build @code{avcodec.lib} and
1213 @code{avformat.lib}. With these libraries you can link your Visual C++
1214 code directly with the FFmpeg DLLs (see below).
1218 @subsection Visual C++ compatibility
1220 FFmpeg will not compile under Visual C++ -- and it has too many
1221 dependencies on the GCC compiler to make a port viable. However,
1222 if you want to use the FFmpeg libraries in your own applications,
1223 you can still compile those applications using Visual C++. An
1224 important restriction to this is that you have to use the
1225 dynamically linked versions of the FFmpeg libraries (i.e. the
1226 DLLs), and you have to make sure that Visual-C++-compatible
1227 import libraries are created during the FFmpeg build process.
1229 This description of how to use the FFmpeg libraries with Visual C++ is
1230 based on Visual C++ 2005 Express Edition Beta 2. If you have a different
1231 version, you might have to modify the procedures slightly.
1233 Here are the step-by-step instructions for building the FFmpeg libraries
1234 so they can be used with Visual C++:
1238 @item Install Visual C++ (if you have not done so already).
1240 @item Install MinGW and MSYS as described above.
1242 @item Add a call to @file{vcvars32.bat} (which sets up the environment
1243 variables for the Visual C++ tools) as the first line of
1244 @file{msys.bat}. The standard location for @file{vcvars32.bat} is
1245 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
1246 and the standard location for @file{msys.bat} is
1247 @file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
1248 following line as the first line of @file{msys.bat}:
1250 @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
1252 @item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
1253 If you get a help message with the command line options of @code{link.exe},
1254 this means your environment variables are set up correctly, the
1255 Microsoft linker is on the path and will be used by FFmpeg to
1256 create Visual-C++-compatible import libraries.
1258 @item Extract the current version of FFmpeg and change to the FFmpeg directory.
1260 @item Type the command
1261 @code{./configure --enable-shared --disable-static --enable-memalign-hack}
1262 to configure and, if that did not produce any errors,
1263 type @code{make} to build FFmpeg.
1265 @item The subdirectories @file{libavformat}, @file{libavcodec}, and
1266 @file{libavutil} should now contain the files @file{avformat.dll},
1267 @file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1268 @file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1269 DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1273 And here is how to use these libraries with Visual C++:
1277 @item Create a new console application ("File / New / Project") and then
1278 select "Win32 Console Application". On the appropriate page of the
1279 Application Wizard, uncheck the "Precompiled headers" option.
1281 @item Write the source code for your application, or, for testing, just
1282 copy the code from an existing sample application into the source file
1283 that Visual C++ has already created for you. (Note that your source
1284 filehas to have a @code{.cpp} extension; otherwise, Visual C++ will not
1285 compile the FFmpeg headers correctly because in C mode, it does not
1286 recognize the @code{inline} keyword.) For example, you can copy
1287 @file{output_example.c} from the FFmpeg distribution (but you will
1288 have to make minor modifications so the code will compile under
1291 @item Open the "Project / Properties" dialog box. In the "Configuration"
1292 combo box, select "All Configurations" so that the changes you make will
1293 affect both debug and release builds. In the tree view on the left hand
1294 side, select "C/C++ / General", then edit the "Additional Include
1295 Directories" setting to contain the complete paths to the
1296 @file{libavformat}, @file{libavcodec}, and @file{libavutil}
1297 subdirectories of your FFmpeg directory. Note that the directories have
1298 to be separated using semicolons. Now select "Linker / General" from the
1299 tree view and edit the "Additional Library Directories" setting to
1300 contain the same three directories.
1302 @item Still in the "Project / Properties" dialog box, select "Linker / Input"
1303 from the tree view, then add the files @file{avformat.lib},
1304 @file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1305 Dependencies". Note that the names of the libraries have to be separated
1308 @item Now, select "C/C++ / Code Generation" from the tree view. Select
1309 "Debug" in the "Configuration" combo box. Make sure that "Runtime
1310 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1311 the "Configuration" combo box and make sure that "Runtime Library" is
1312 set to "Multi-threaded DLL".
1314 @item Click "OK" to close the "Project / Properties" dialog box and build
1315 the application. Hopefully, it should compile and run cleanly. If you
1316 used @file{output_example.c} as your sample application, you will get a
1317 few compiler errors, but they are easy to fix. The first type of error
1318 occurs because Visual C++ does not allow an @code{int} to be converted to
1319 an @code{enum} without a cast. To solve the problem, insert the required
1320 casts (this error occurs once for a @code{CodecID} and once for a
1321 @code{CodecType}). The second type of error occurs because C++ requires
1322 the return value of @code{malloc} to be cast to the exact type of the
1323 pointer it is being assigned to. Visual C++ will complain that, for
1324 example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1325 an explicit cast. So insert an explicit cast in these places to silence
1326 the compiler. The third type of error occurs because the @code{snprintf}
1327 library function is called @code{_snprintf} under Visual C++. So just
1328 add an underscore to fix the problem. With these changes,
1329 @file{output_example.c} should compile under Visual C++, and the
1330 resulting executable should produce valid video files.
1334 @subsection Cross compilation for Windows with Linux
1336 You must use the MinGW cross compilation tools available at
1337 @url{http://www.mingw.org/}.
1339 Then configure FFmpeg with the following options:
1341 ./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
1343 (you can change the cross-prefix according to the prefix chosen for the
1346 Then you can easily test FFmpeg with Wine
1347 (@url{http://www.winehq.com/}).
1349 @subsection Compilation under Cygwin
1351 Cygwin works very much like Unix.
1353 Just install your Cygwin with all the "Base" packages, plus the
1354 following "Devel" ones:
1356 binutils, gcc-core, make, subversion
1359 Do not install binutils-20060709-1 (they are buggy on shared builds);
1360 use binutils-20050610-1 instead.
1365 ./configure --enable-static --disable-shared
1368 to make a static build or
1371 ./configure --enable-shared --disable-static
1374 to build shared libraries.
1376 If you want to build FFmpeg with additional libraries, download Cygwin
1377 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
1378 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
1379 (@url{http://cygwinports.dotsrc.org/}).
1381 @subsection Crosscompilation for Windows under Cygwin
1383 With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
1385 Just install your Cygwin as explained before, plus these additional
1388 gcc-mingw-core, mingw-runtime, mingw-zlib
1391 and add some special flags to your configure invocation.
1393 For a static build run
1395 ./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1398 and for a build with shared libraries
1400 ./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1405 The configure script should guess the configuration itself.
1406 Networking support is currently not finished.
1407 errno issues fixed by Andrew Bachmann.
1411 François Revol - revol at free dot fr - April 2002
1413 The configure script should guess the configuration itself,
1414 however I still did not test building on the net_server version of BeOS.
1416 FFserver is broken (needs poll() implementation).
1418 There are still issues with errno codes, which are negative in BeOS, and
1419 that FFmpeg negates when returning. This ends up turning errors into
1420 valid results, then crashes.
1423 @chapter Developers Guide
1427 @item libavcodec is the library containing the codecs (both encoding and
1428 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1430 @item libavformat is the library containing the file format handling (mux and
1431 demux code for several formats). Look at @file{ffplay.c} to use it in a
1432 player. See @file{output_example.c} to use it to generate audio or video
1437 @section Integrating libavcodec or libavformat in your program
1439 You can integrate all the source code of the libraries to link them
1440 statically to avoid any version problem. All you need is to provide a
1441 'config.mak' and a 'config.h' in the parent directory. See the defines
1442 generated by ./configure to understand what is needed.
1444 You can use libavcodec or libavformat in your commercial program, but
1445 @emph{any patch you make must be published}. The best way to proceed is
1446 to send your patches to the FFmpeg mailing list.
1449 @section Coding Rules
1451 FFmpeg is programmed in the ISO C90 language with a few additional
1452 features from ISO C99, namely:
1455 the @samp{inline} keyword;
1459 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1461 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1464 These features are supported by all compilers we care about, so we will not
1465 accept patches to remove their use unless they absolutely do not impair
1466 clarity and performance.
1468 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1469 compiles with several other compilers, such as the Compaq ccc compiler
1470 or Sun Studio 9, and we would like to keep it that way unless it would
1471 be exceedingly involved. To ensure compatibility, please do not use any
1472 additional C99 features or GCC extensions. Especially watch out for:
1475 mixing statements and declarations;
1477 @samp{long long} (use @samp{int64_t} instead);
1479 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1481 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1485 The presentation is the one specified by 'indent -i4 -kr -nut'.
1486 The TAB character is forbidden outside of Makefiles as is any
1487 form of trailing whitespace. Commits containing either will be
1488 rejected by the Subversion repository.
1490 Main priority in FFmpeg is simplicity and small code size (=less
1493 Comments: Use the JavaDoc/Doxygen
1494 format (see examples below) so that code documentation
1495 can be generated automatically. All nontrivial functions should have a comment
1496 above them explaining what the function does, even if it is just one sentence.
1497 All structures and their member variables should be documented, too.
1510 typedef struct Foobar@{
1511 int var1; /**< var1 description */
1512 int var2; ///< var2 description
1513 /** var3 description */
1521 * @@param my_parameter description of my_parameter
1522 * @@return return value description
1524 int myfunc(int my_parameter)
1528 fprintf and printf are forbidden in libavformat and libavcodec,
1529 please use av_log() instead.
1531 @section Development Policy
1535 You must not commit code which breaks FFmpeg! (Meaning unfinished but
1536 enabled code which breaks compilation or compiles but does not work or
1537 breaks the regression tests)
1538 You can commit unfinished stuff (for testing etc), but it must be disabled
1539 (#ifdef etc) by default so it does not interfere with other developers'
1542 You do not have to over-test things. If it works for you, and you think it
1543 should work for others, then commit. If your code has problems
1544 (portability, triggers compiler bugs, unusual environment etc) they will be
1545 reported and eventually fixed.
1547 Do not commit unrelated changes together, split them into self-contained
1548 pieces. Also do not forget that if part B depends on part A, but A does not
1549 depend on B, then A can and should be committed first and separate from B.
1550 Keeping changes well split into self-contained parts makes reviewing and
1551 understanding them on the commit log mailing list easier. This also helps
1552 in case of debugging later on.
1553 Also if you have doubts about splitting or not splitting, do not hesitate to
1554 ask/discuss it on the developer mailing list.
1556 Do not change behavior of the program (renaming options etc) without
1557 first discussing it on the ffmpeg-devel mailing list. Do not remove
1558 functionality from the code. Just improve!
1560 Note: Redundant code can be removed.
1562 Do not commit changes to the build system (Makefiles, configure script)
1563 which change behavior, defaults etc, without asking first. The same
1564 applies to compiler warning fixes, trivial looking fixes and to code
1565 maintained by other developers. We usually have a reason for doing things
1566 the way we do. Send your changes as patches to the ffmpeg-devel mailing
1567 list, and if the code maintainers say OK, you may commit. This does not
1568 apply to files you wrote and/or maintain.
1570 We refuse source indentation and other cosmetic changes if they are mixed
1571 with functional changes, such commits will be rejected and removed. Every
1572 developer has his own indentation style, you should not change it. Of course
1573 if you (re)write something, you can use your own style, even though we would
1574 prefer if the indentation throughout FFmpeg was consistent (Many projects
1575 force a given indentation style - we do not.). If you really need to make
1576 indentation changes (try to avoid this), separate them strictly from real
1579 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1580 then either do NOT change the indentation of the inner part within (do not
1581 move it to the right)! or do so in a separate commit
1583 Always fill out the commit log message. Describe in a few lines what you
1584 changed and why. You can refer to mailing list postings if you fix a
1585 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1587 If you apply a patch by someone else, include the name and email address in
1588 the log message. Since the ffmpeg-cvslog mailing list is publicly
1589 archived you should add some SPAM protection to the email address. Send an
1590 answer to ffmpeg-devel (or wherever you got the patch from) saying that
1591 you applied the patch.
1593 When applying patches that have been discussed (at length) on the mailing
1594 list, reference the thread in the log message.
1596 Do NOT commit to code actively maintained by others without permission.
1597 Send a patch to ffmpeg-devel instead. If noone answers within a reasonable
1598 timeframe (12h for build failures and security fixes, 3 days small changes,
1599 1 week for big patches) then commit your patch if you think it is OK.
1600 Also note, the maintainer can simply ask for more time to review!
1602 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1603 are sent there and reviewed by all the other developers. Bugs and possible
1604 improvements or general questions regarding commits are discussed there. We
1605 expect you to react if problems with your code are uncovered.
1607 Update the documentation if you change behavior or add features. If you are
1608 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1609 maintainer(s) will review and commit your stuff.
1611 Try to keep important discussions and requests (also) on the public
1612 developer mailing list, so that all developers can benefit from them.
1614 Never write to unallocated memory, never write over the end of arrays,
1615 always check values read from some untrusted source before using them
1616 as array index or other risky things.
1618 Remember to check if you need to bump versions for the specific libav
1619 parts (libavutil, libavcodec, libavformat) you are changing. You need
1620 to change the version integer and the version string.
1621 Incrementing the first component means no backward compatibility to
1622 previous versions (e.g. removal of a function from the public API).
1623 Incrementing the second component means backward compatible change
1624 (e.g. addition of a function to the public API).
1625 Incrementing the third component means a noteworthy binary compatible
1626 change (e.g. encoder bug fix that matters for the decoder).
1628 If you add a new codec, remember to update the changelog, add it to
1629 the supported codecs table in the documentation and bump the second
1630 component of the @file{libavcodec} version number appropriately. If
1631 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1634 Do not change code to hide warnings without ensuring that the underlying
1635 logic is correct and thus the warning was inappropriate.
1637 If you add a new file, give it a proper license header. Do not copy and
1638 paste it from a random place, use an existing file as template.
1641 We think our rules are not too hard. If you have comments, contact us.
1643 Note, these rules are mostly borrowed from the MPlayer project.
1645 @section Submitting patches
1647 First, (@pxref{Coding Rules}) above if you did not yet.
1649 When you submit your patch, try to send a unified diff (diff '-up'
1650 option). I cannot read other diffs :-)
1652 Also please do not submit patches which contain several unrelated changes.
1653 Split them into individual self-contained patches; this makes reviewing
1656 Run the regression tests before submitting a patch so that you can
1657 verify that there are no big problems.
1659 Patches should be posted as base64 encoded attachments (or any other
1660 encoding which ensures that the patch will not be trashed during
1661 transmission) to the ffmpeg-devel mailing list, see
1662 @url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1664 It also helps quite a bit if you tell us what the patch does (for example
1665 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1666 and has no lrint()')
1668 Also please if you send several patches, send each patch as separate mail,
1669 do not attach several unrelated patches to the same mail.
1671 @section patch submission checklist
1675 Do the regression tests pass with the patch applied?
1677 Is the patch a unified diff?
1679 Is the patch against latest FFmpeg SVN?
1681 Are you subscribed to ffmpeg-dev?
1682 (the list is subscribers only due to spam)
1684 Have you checked that the changes are minimal, so that the same cannot be
1685 achieved with a smaller patch and/or simpler final code?
1687 If the change is to speed critical code, did you benchmark it?
1689 If you did any benchmarks, did you provide them in the mail?
1691 Have you checked that the patch does not introduce buffer overflows or
1692 other security issues?
1694 Is the patch created from the root of the source tree, so it can be
1695 applied with @code{patch -p0}?
1697 Does the patch not mix functional and cosmetic changes?
1699 Did you add tabs or trailing whitespace to the code? Both are forbidden.
1701 Is the patch attached to the email you send?
1703 Is the mime type of the patch correct? It should be text/x-diff or
1704 text/x-patch or at least text/plain and not application/octet-stream.
1706 If the patch fixes a bug, did you provide a verbose analysis of the bug?
1708 If the patch fixes a bug, did you provide enough information, including
1709 a sample, so the bug can be reproduced and the fix can be verified?
1711 Did you provide a verbose summary about what the patch does change?
1713 Did you provide a verbose explanation why it changes things like it does?
1715 Did you provide a verbose summary of the user visible advantages and
1716 disadvantages if the patch is applied?
1718 Did you provide an example so we can verify the new feature added by the
1721 If you added a new file, did you insert a license header? It should be
1722 taken from FFmpeg, not randomly copied and pasted from somewhere else.
1724 You should maintain alphabetical order in alphabetically ordered lists as
1725 long as doing so does not break API/ABI compatibility.
1727 Did you provide a suggestion for a clear commit log message?
1730 @section Patch review process
1732 All patches posted to ffmpeg-devel will be reviewed, unless they contain a
1733 clear note that the patch is not for SVN.
1734 Reviews and comments will be posted as replies to the patch on the
1735 mailing list. The patch submitter then has to take care of every comment,
1736 that can be by resubmitting a changed patch or by discussion. Resubmitted
1737 patches will themselves be reviewed like any other patch. If at some point
1738 a patch passes review with no comments then it is approved, that can for
1739 simple and small patches happen immediately while large patches will generally
1740 have to be changed and reviewed many times before they are approved.
1741 After a patch is approved it will be committed to the repository.
1743 We will review all submitted patches, but sometimes we are quite busy so
1744 especially for large patches this can take several weeks.
1746 When resubmitting patches, please do not make any significant changes
1747 not related to the comments received during review. Such patches will
1748 be rejected. Instead, submit significant changes or new features as
1751 @section Regression tests
1753 Before submitting a patch (or committing to the repository), you should at least
1754 test that you did not break anything.
1756 The regression tests build a synthetic video stream and a synthetic
1757 audio stream. These are then encoded and decoded with all codecs or
1758 formats. The CRC (or MD5) of each generated file is recorded in a
1759 result file. A 'diff' is launched to compare the reference results and
1762 The regression tests then go on to test the FFserver code with a
1763 limited set of streams. It is important that this step runs correctly
1766 Run 'make test' to test all the codecs and formats.
1768 Run 'make fulltest' to test all the codecs, formats and FFserver.
1770 [Of course, some patches may change the results of the regression tests. In
1771 this case, the reference results of the regression tests shall be modified