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 -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 -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:
314 Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
316 Set top crop band size (in pixels).
317 @item -cropbottom size
318 Set bottom crop band size (in pixels).
320 Set left crop band size (in pixels).
321 @item -cropright size
322 Set right crop band size (in pixels).
324 Set top pad band size (in pixels).
325 @item -padbottom size
326 Set bottom pad band size (in pixels).
328 Set left pad band size (in pixels).
330 Set right pad band size (in pixels).
331 @item -padcolor (hex color)
332 Set color of padded bands. The value for padcolor is expressed
333 as a six digit hexadecimal number where the first two digits
334 represent red, the middle two digits green and last two digits
335 blue (default = 000000 (black)).
337 Disable video recording.
339 Set video bitrate tolerance (in bit/s).
340 @item -maxrate bitrate
341 Set max video bitrate tolerance (in bit/s).
342 @item -minrate bitrate
343 Set min video bitrate tolerance (in bit/s).
345 Set rate control buffer size (in bits).
347 Force video codec to @var{codec}. Use the @code{copy} special value to
348 tell that the raw codec data must be copied as is.
350 Use same video quality as source (implies VBR).
353 Select the pass number (1 or 2). It is useful to do two pass
354 encoding. The statistics of the video are recorded in the first
355 pass and the video is generated at the exact requested bitrate
358 @item -passlogfile file
359 Set two pass logfile name to @var{file}.
362 Add a new video stream to the current output stream.
366 @section Advanced Video Options
369 @item -pix_fmt format
372 Set the group of pictures size.
374 Use only intra frames.
378 Use fixed video quantizer scale (VBR).
380 minimum video quantizer scale (VBR)
382 maximum video quantizer scale (VBR)
384 maximum difference between the quantizer scales (VBR)
386 video quantizer scale blur (VBR)
387 @item -qcomp compression
388 video quantizer scale compression (VBR)
391 minimum video lagrange factor (VBR)
393 max video lagrange factor (VBR)
395 minimum macroblock quantizer scale (VBR)
397 maximum macroblock quantizer scale (VBR)
399 These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
400 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
402 ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
405 @item -rc_init_cplx complexity
406 initial complexity for single pass encoding
407 @item -b_qfactor factor
408 qp factor between P- and B-frames
409 @item -i_qfactor factor
410 qp factor between P- and I-frames
411 @item -b_qoffset offset
412 qp offset between P- and B-frames
413 @item -i_qoffset offset
414 qp offset between P- and I-frames
415 @item -rc_eq equation
416 Set rate control equation (@pxref{FFmpeg formula
417 evaluator}) (default = @code{tex^qComp}).
418 @item -rc_override override
419 rate control override for specific intervals
421 Set motion estimation method to @var{method}.
422 Available methods are (from lowest to best quality):
425 Try just the (0, 0) vector.
432 exhaustive search (slow and marginally better than epzs)
436 Set DCT algorithm to @var{algo}. Available values are:
439 FF_DCT_AUTO (default)
452 @item -idct_algo algo
453 Set IDCT algorithm to @var{algo}. Available values are:
456 FF_IDCT_AUTO (default)
480 Set error resilience to @var{n}.
483 FF_ER_CAREFUL (default)
489 FF_ER_VERY_AGGRESSIVE
493 Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
494 the following values:
497 FF_EC_GUESS_MVS (default = enabled)
499 FF_EC_DEBLOCK (default = enabled)
503 Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
508 FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
510 FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
512 FF_MB_DECISION_RD: rate distortion
516 Use four motion vector by macroblock (MPEG-4 only).
518 Use data partitioning (MPEG-4 only).
520 Work around encoder bugs that are not auto-detected.
521 @item -strict strictness
522 How strictly to follow the standards.
524 Enable Advanced intra coding (h263+).
526 Enable Unlimited Motion Vector (h263+)
529 Deinterlace pictures.
531 Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
532 Use this option if your input file is interlaced and you want
533 to keep the interlaced format for minimum losses.
534 The alternative is to deinterlace the input stream with
535 @option{-deinterlace}, but deinterlacing introduces losses.
537 Calculate PSNR of compressed frames.
539 Dump video coding statistics to @file{vstats_HHMMSS.log}.
541 Insert video processing @var{module}. @var{module} contains the module
542 name and its parameters separated by spaces.
544 top=1/bottom=0/auto=-1 field first
547 @item -vtag fourcc/tag
548 Force video tag/fourcc.
551 @item -vbsf bitstream filter
552 Bitstream filters available are "dump_extra", "remove_extra", "noise".
555 @section Audio Options
558 @item -aframes number
559 Set the number of audio frames to record.
561 Set the audio sampling frequency (default = 44100 Hz).
563 Set the audio bitrate in bit/s (default = 64k).
565 Set the number of audio channels (default = 1).
567 Disable audio recording.
569 Force audio codec to @var{codec}. Use the @code{copy} special value to
570 specify that the raw codec data must be copied as is.
572 Add a new audio track to the output file. If you want to specify parameters,
573 do so before @code{-newaudio} (@code{-acodec}, @code{-ab}, etc..).
575 Mapping will be done automatically, if the number of output streams is equal to
576 the number of input streams, else it will pick the first one that matches. You
577 can override the mapping using @code{-map} as usual.
581 ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384k test.mpg -acodec mp2 -ab 192k -newaudio
584 Set the ISO 639 language code (3 letters) of the current audio stream.
587 @section Advanced Audio options:
590 @item -atag fourcc/tag
591 Force audio tag/fourcc.
592 @item -absf bitstream filter
593 Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
596 @section Subtitle options:
600 Force subtitle codec ('copy' to copy stream).
602 Add a new subtitle stream to the current output stream.
604 Set the ISO 639 language code (3 letters) of the current subtitle stream.
607 @section Audio/Video grab options
611 Set video grab channel (DV1394 only).
612 @item -tvstd standard
613 Set television standard (NTSC, PAL (SECAM)).
615 Synchronize read on input.
618 @section Advanced options
621 @item -map input stream id[:input stream id]
622 Set stream mapping from input streams to output streams.
623 Just enumerate the input streams in the order you want them in the output.
624 [input stream id] sets the (input) stream to sync against.
625 @item -map_meta_data outfile:infile
626 Set meta data information of outfile from infile.
628 Print specific debug info.
630 Add timings for benchmarking.
632 Dump each input packet.
634 When dumping packets, also dump the payload.
636 Only use bit exact algorithms (for codec testing).
638 Set packet size in bits.
640 Read input at native frame rate. Mainly used to simulate a grab device.
642 Loop over the input stream. Currently it works only for image
643 streams. This option is used for automatic FFserver testing.
644 @item -loop_output number_of_times
645 Repeatedly loop output for formats that support looping such as animated GIF
646 (0 will loop the output infinitely).
649 @item -vsync parameter
650 Video sync method. Video will be stretched/squeezed to match the timestamps,
651 it is done by duplicating and dropping frames. With -map you can select from
652 which stream the timestamps should be taken. You can leave either video or
653 audio unchanged and sync the remaining stream(s) to the unchanged one.
654 @item -async samples_per_second
655 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
656 the parameter is the maximum samples per second by which the audio is changed.
657 -async 1 is a special case where only the start of the audio stream is corrected
658 without any later correction.
661 @node FFmpeg formula evaluator
662 @section FFmpeg formula evaluator
664 When evaluating a rate control string, FFmpeg uses an internal formula
667 The following binary operators are available: @code{+}, @code{-},
668 @code{*}, @code{/}, @code{^}.
670 The following unary operators are available: @code{+}, @code{-},
673 The following functions are available:
695 The following constants are available:
724 @settitle FFmpeg video converter
727 ffserver(1), ffplay(1) and the HTML documentation of @file{ffmpeg}.
738 The filename can be @file{-} to read from standard input or to write
741 FFmpeg also handles many protocols specified with an URL syntax.
743 Use 'ffmpeg -formats' to see a list of the supported protocols.
745 The protocol @code{http:} is currently used only to communicate with
746 FFserver (see the FFserver documentation). When FFmpeg will be a
747 video player it will also be used for streaming :-)
752 @item For streaming at very low bitrate application, use a low frame rate
753 and a small GOP size. This is especially true for RealVideo where
754 the Linux player does not seem to be very fast, so it can miss
755 frames. An example is:
758 ffmpeg -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
761 @item The parameter 'q' which is displayed while encoding is the current
762 quantizer. The value 1 indicates that a very good quality could
763 be achieved. The value 31 indicates the worst quality. If q=31 appears
764 too often, it means that the encoder cannot compress enough to meet
765 your bitrate. You must either increase the bitrate, decrease the
766 frame rate or decrease the frame size.
768 @item If your computer is not fast enough, you can speed up the
769 compression at the expense of the compression ratio. You can use
770 '-me zero' to speed up motion estimation, and '-intra' to disable
771 motion estimation completely (you have only I-frames, which means it
772 is about as good as JPEG compression).
774 @item To have very low audio bitrates, reduce the sampling frequency
775 (down to 22050 kHz for MPEG audio, 22050 or 11025 for AC3).
777 @item To have a constant quality (but a variable bitrate), use the option
778 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
781 @item When converting video files, you can use the '-sameq' option which
782 uses the same quality factor in the encoder as in the decoder.
783 It allows almost lossless encoding.
788 @chapter external libraries
790 FFmpeg can be hooked up with a number of external libraries to add support
795 AMR comes in two different flavors, WB and NB. FFmpeg can make use of the
796 AMR WB (floating-point mode) and the AMR NB (both floating-point and
797 fixed-point mode) reference decoders and encoders.
801 @item For AMR WB floating-point download TS26.204 V5.1.0 from
802 @url{http://www.3gpp.org/ftp/Specs/archive/26_series/26.204/26204-510.zip}
803 and extract the source to @file{libavcodec/amrwb_float/}.
805 @item For AMR NB floating-point download TS26.104 REL-5 V5.1.0 from
806 @url{http://www.3gpp.org/ftp/Specs/archive/26_series/26.104/26104-510.zip}
807 and extract the source to @file{libavcodec/amr_float/}.
808 If you try this on Alpha, you may need to change @code{Word32} to
809 @code{int} in @file{amr/typedef.h}.
811 @item For AMR NB fixed-point download TS26.073 REL-5 V5.1.0 from
812 @url{http://www.3gpp.org/ftp/Specs/archive/26_series/26.073/26073-510.zip}
813 and extract the source to @file{libavcodec/amr}.
814 You must also add @code{-DMMS_IO} and remove @code{-pedantic-errors}
815 to/from @code{CFLAGS} in @file{libavcodec/amr/makefile}, i.e.
816 ``@code{CFLAGS = -Wall -I. \$(CFLAGS_\$(MODE)) -D\$(VAD) -DMMS_IO}''.
821 @chapter Supported File Formats and Codecs
823 You can use the @code{-formats} option to have an exhaustive list.
825 @section File Formats
827 FFmpeg supports the following file formats through the @code{libavformat}
830 @multitable @columnfractions .4 .1 .1 .4
831 @item Supported File Format @tab Encoding @tab Decoding @tab Comments
832 @item MPEG audio @tab X @tab X
833 @item MPEG-1 systems @tab X @tab X
834 @tab muxed audio and video
835 @item MPEG-2 PS @tab X @tab X
836 @tab also known as @code{VOB} file
837 @item MPEG-2 TS @tab @tab X
838 @tab also known as DVB Transport Stream
839 @item ASF@tab X @tab X
840 @item AVI@tab X @tab X
841 @item WAV@tab X @tab X
842 @item Macromedia Flash@tab X @tab X
843 @tab Only embedded audio is decoded.
844 @item FLV @tab X @tab X
845 @tab Macromedia Flash video files
846 @item Real Audio and Video @tab X @tab X
847 @item Raw AC3 @tab X @tab X
848 @item Raw MJPEG @tab X @tab X
849 @item Raw MPEG video @tab X @tab X
850 @item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
851 @item Raw CRI ADX audio @tab X @tab X
852 @item Raw Shorten audio @tab @tab X
853 @item SUN AU format @tab X @tab X
854 @item NUT @tab X @tab X @tab NUT Open Container Format
855 @item QuickTime @tab X @tab X
856 @item MPEG-4 @tab X @tab X
857 @tab MPEG-4 is a variant of QuickTime.
858 @item Raw MPEG4 video @tab X @tab X
859 @item DV @tab X @tab X
860 @item 4xm @tab @tab X
861 @tab 4X Technologies format, used in some games.
862 @item Playstation STR @tab @tab X
863 @item Id RoQ @tab @tab X
864 @tab Used in Quake III, Jedi Knight 2, other computer games.
865 @item Interplay MVE @tab @tab X
866 @tab Format used in various Interplay computer games.
867 @item WC3 Movie @tab @tab X
868 @tab Multimedia format used in Origin's Wing Commander III computer game.
869 @item Sega FILM/CPK @tab @tab X
870 @tab Used in many Sega Saturn console games.
871 @item Westwood Studios VQA/AUD @tab @tab X
872 @tab Multimedia formats used in Westwood Studios games.
873 @item Id Cinematic (.cin) @tab @tab X
874 @tab Used in Quake II.
875 @item FLIC format @tab @tab X
877 @item Sierra VMD @tab @tab X
878 @tab Used in Sierra CD-ROM games.
879 @item Sierra Online @tab @tab X
880 @tab .sol files used in Sierra Online games.
881 @item Matroska @tab @tab X
882 @item Electronic Arts Multimedia @tab @tab X
883 @tab Used in various EA games; files have extensions like WVE and UV2.
884 @item Nullsoft Video (NSV) format @tab @tab X
885 @item ADTS AAC audio @tab X @tab X
886 @item Creative VOC @tab X @tab X @tab Created for the Sound Blaster Pro.
887 @item American Laser Games MM @tab @tab X
888 @tab Multimedia format used in games like Mad Dog McCree
889 @item AVS @tab @tab X
890 @tab Multimedia format used by the Creature Shock game.
891 @item Smacker @tab @tab X
892 @tab Multimedia format used by many games.
893 @item GXF @tab X @tab X
894 @tab General eXchange Format SMPTE 360M, used by Thomson Grass Valley playout servers.
895 @item CIN @tab @tab X
896 @tab Multimedia format used by Delphine Software games.
897 @item MXF @tab @tab X
898 @tab Material eXchange Format SMPTE 377M, used by D-Cinema, broadcast industry.
899 @item SEQ @tab @tab X
900 @tab Tiertex .seq files used in the DOS CDROM version of the game Flashback.
901 @item DXA @tab @tab X
902 @tab This format is used in non-Windows version of Feeble Files game and
903 different game cutscenes repacked for use with ScummVM.
904 @item THP @tab @tab X
905 @tab Used on the Nintendo GameCube.
906 @item C93 @tab @tab X
907 @tab Used in the game Cyberia from Interplay.
910 @code{X} means that encoding (resp. decoding) is supported.
912 @section Image Formats
914 FFmpeg can read and write images for each frame of a video sequence. The
915 following image formats are supported:
917 @multitable @columnfractions .4 .1 .1 .4
918 @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
919 @item PGM, PPM @tab X @tab X
920 @item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support.
921 @item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
922 @item JPEG @tab X @tab X @tab Progressive JPEG is not supported.
923 @item .Y.U.V @tab X @tab X @tab one raw file per component
924 @item animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated.
925 @item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet.
926 @item Targa @tab @tab X @tab Targa (.TGA) image format.
927 @item TIFF @tab X @tab X @tab YUV, JPEG and some extension is not supported yet.
928 @item SGI @tab X @tab X @tab SGI RGB image format
931 @code{X} means that encoding (resp. decoding) is supported.
933 @section Video Codecs
935 @multitable @columnfractions .4 .1 .1 .4
936 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
937 @item MPEG-1 video @tab X @tab X
938 @item MPEG-2 video @tab X @tab X
939 @item MPEG-4 @tab X @tab X
940 @item MSMPEG4 V1 @tab X @tab X
941 @item MSMPEG4 V2 @tab X @tab X
942 @item MSMPEG4 V3 @tab X @tab X
943 @item WMV7 @tab X @tab X
944 @item WMV8 @tab X @tab X @tab not completely working
945 @item WMV9 @tab @tab X @tab not completely working
946 @item VC1 @tab @tab X
947 @item H.261 @tab X @tab X
948 @item H.263(+) @tab X @tab X @tab also known as RealVideo 1.0
949 @item H.264 @tab @tab X
950 @item RealVideo 1.0 @tab X @tab X
951 @item RealVideo 2.0 @tab X @tab X
952 @item MJPEG @tab X @tab X
953 @item lossless MJPEG @tab X @tab X
954 @item JPEG-LS @tab X @tab X @tab fourcc: MJLS, lossless and near-lossless is supported
955 @item Apple MJPEG-B @tab @tab X
956 @item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
957 @item DV @tab X @tab X
958 @item HuffYUV @tab X @tab X
959 @item FFmpeg Video 1 @tab X @tab X @tab experimental lossless codec (fourcc: FFV1)
960 @item FFmpeg Snow @tab X @tab X @tab experimental wavelet codec (fourcc: SNOW)
961 @item Asus v1 @tab X @tab X @tab fourcc: ASV1
962 @item Asus v2 @tab X @tab X @tab fourcc: ASV2
963 @item Creative YUV @tab @tab X @tab fourcc: CYUV
964 @item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
965 @item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
966 @item On2 VP3 @tab @tab X @tab still experimental
967 @item On2 VP5 @tab @tab X @tab fourcc: VP50
968 @item On2 VP6 @tab @tab X @tab fourcc: VP60,VP61,VP62
969 @item Theora @tab X @tab X @tab still experimental
970 @item Intel Indeo 3 @tab @tab X
971 @item FLV @tab X @tab X @tab Sorenson H.263 used in Flash
972 @item Flash Screen Video @tab X @tab X @tab fourcc: FSV1
973 @item ATI VCR1 @tab @tab X @tab fourcc: VCR1
974 @item ATI VCR2 @tab @tab X @tab fourcc: VCR2
975 @item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
976 @item 4X Video @tab @tab X @tab Used in certain computer games.
977 @item Sony Playstation MDEC @tab @tab X
978 @item Id RoQ @tab @tab X @tab Used in Quake III, Jedi Knight 2, other computer games.
979 @item Xan/WC3 @tab @tab X @tab Used in Wing Commander III .MVE files.
980 @item Interplay Video @tab @tab X @tab Used in Interplay .MVE files.
981 @item Apple Animation @tab @tab X @tab fourcc: 'rle '
982 @item Apple Graphics @tab @tab X @tab fourcc: 'smc '
983 @item Apple Video @tab @tab X @tab fourcc: rpza
984 @item Apple QuickDraw @tab @tab X @tab fourcc: qdrw
985 @item Cinepak @tab @tab X
986 @item Microsoft RLE @tab @tab X
987 @item Microsoft Video-1 @tab @tab X
988 @item Westwood VQA @tab @tab X
989 @item Id Cinematic Video @tab @tab X @tab Used in Quake II.
990 @item Planar RGB @tab @tab X @tab fourcc: 8BPS
991 @item FLIC video @tab @tab X
992 @item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
993 @item Duck TrueMotion v2 @tab @tab X @tab fourcc: TM20
994 @item VMD Video @tab @tab X @tab Used in Sierra VMD files.
995 @item MSZH @tab @tab X @tab Part of LCL
996 @item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
997 @item TechSmith Camtasia @tab @tab X @tab fourcc: TSCC
998 @item IBM Ultimotion @tab @tab X @tab fourcc: ULTI
999 @item Miro VideoXL @tab @tab X @tab fourcc: VIXL
1000 @item QPEG @tab @tab X @tab fourccs: QPEG, Q1.0, Q1.1
1001 @item LOCO @tab @tab X @tab
1002 @item Winnov WNV1 @tab @tab X @tab
1003 @item Autodesk Animator Studio Codec @tab @tab X @tab fourcc: AASC
1004 @item Fraps FPS1 @tab @tab X @tab
1005 @item CamStudio @tab @tab X @tab fourcc: CSCD
1006 @item American Laser Games Video @tab @tab X @tab Used in games like Mad Dog McCree
1007 @item ZMBV @tab X @tab X @tab Encoder works only on PAL8
1008 @item AVS Video @tab @tab X @tab Video encoding used by the Creature Shock game.
1009 @item Smacker Video @tab @tab X @tab Video encoding used in Smacker.
1010 @item RTjpeg @tab @tab X @tab Video encoding used in NuppelVideo files.
1011 @item KMVC @tab @tab X @tab Codec used in Worms games.
1012 @item VMware Video @tab @tab X @tab Codec used in videos captured by VMware.
1013 @item Cin Video @tab @tab X @tab Codec used in Delphine Software games.
1014 @item Tiertex Seq Video @tab @tab X @tab Codec used in DOS CDROM FlashBack game.
1015 @item DXA Video @tab @tab X @tab Codec originally used in Feeble Files game.
1016 @item AVID DNxHD @tab @tab X @tab aka SMPTE VC3
1017 @item C93 Video @tab @tab X @tab Codec used in Cyberia game.
1020 @code{X} means that encoding (resp. decoding) is supported.
1022 @section Audio Codecs
1024 @multitable @columnfractions .4 .1 .1 .1 .7
1025 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
1026 @item MPEG audio layer 2 @tab IX @tab IX
1027 @item MPEG audio layer 1/3 @tab IX @tab IX
1028 @tab MP3 encoding is supported through the external library LAME.
1029 @item AC3 @tab IX @tab IX
1030 @tab liba52 is used internally for decoding.
1031 @item Vorbis @tab X @tab X
1032 @item WMA V1/V2 @tab X @tab X
1033 @item AAC @tab X @tab X
1034 @tab Supported through the external library libfaac/libfaad.
1035 @item Microsoft ADPCM @tab X @tab X
1036 @item MS IMA ADPCM @tab X @tab X
1037 @item QT IMA ADPCM @tab @tab X
1038 @item 4X IMA ADPCM @tab @tab X
1039 @item G.726 ADPCM @tab X @tab X
1040 @item Duck DK3 IMA ADPCM @tab @tab X
1041 @tab Used in some Sega Saturn console games.
1042 @item Duck DK4 IMA ADPCM @tab @tab X
1043 @tab Used in some Sega Saturn console games.
1044 @item Westwood Studios IMA ADPCM @tab @tab X
1045 @tab Used in Westwood Studios games like Command and Conquer.
1046 @item SMJPEG IMA ADPCM @tab @tab X
1047 @tab Used in certain Loki game ports.
1048 @item CD-ROM XA ADPCM @tab @tab X
1049 @item CRI ADX ADPCM @tab X @tab X
1050 @tab Used in Sega Dreamcast games.
1051 @item Electronic Arts ADPCM @tab @tab X
1052 @tab Used in various EA titles.
1053 @item Creative ADPCM @tab @tab X
1054 @tab 16 -> 4, 8 -> 4, 8 -> 3, 8 -> 2
1055 @item RA144 @tab @tab X
1056 @tab Real 14400 bit/s codec
1057 @item RA288 @tab @tab X
1058 @tab Real 28800 bit/s codec
1059 @item RADnet @tab X @tab IX
1060 @tab Real low bitrate AC3 codec, liba52 is used for decoding.
1061 @item AMR-NB @tab X @tab X
1062 @tab Supported through an external library.
1063 @item AMR-WB @tab X @tab X
1064 @tab Supported through an external library.
1065 @item DV audio @tab @tab X
1066 @item Id RoQ DPCM @tab @tab X
1067 @tab Used in Quake III, Jedi Knight 2, other computer games.
1068 @item Interplay MVE DPCM @tab @tab X
1069 @tab Used in various Interplay computer games.
1070 @item Xan DPCM @tab @tab X
1071 @tab Used in Origin's Wing Commander IV AVI files.
1072 @item Sierra Online DPCM @tab @tab X
1073 @tab Used in Sierra Online game audio files.
1074 @item Apple MACE 3 @tab @tab X
1075 @item Apple MACE 6 @tab @tab X
1076 @item FLAC lossless audio @tab X @tab X
1077 @item Shorten lossless audio @tab @tab X
1078 @item Apple lossless audio @tab @tab X
1079 @tab QuickTime fourcc 'alac'
1080 @item FFmpeg Sonic @tab X @tab X
1081 @tab experimental lossy/lossless codec
1082 @item Qdesign QDM2 @tab @tab X
1083 @tab there are still some distortions
1084 @item Real COOK @tab @tab X
1085 @tab All versions except 5.1 are supported
1086 @item DSP Group TrueSpeech @tab @tab X
1087 @item True Audio (TTA) @tab @tab X
1088 @item Smacker Audio @tab @tab X
1089 @item WavPack Audio @tab @tab X
1090 @item Cin Audio @tab @tab X
1091 @tab Codec used in Delphine Software games.
1092 @item Intel Music Coder @tab @tab X
1093 @item Musepack @tab @tab X
1094 @tab Only SV7 is supported
1095 @item DT$ Coherent Audio @tab @tab X
1098 @code{X} means that encoding (resp. decoding) is supported.
1100 @code{I} means that an integer-only version is available, too (ensures high
1101 performance on systems without hardware floating point support).
1103 @chapter Platform Specific information
1107 BSD make will not build FFmpeg, you need to install and use GNU Make
1112 To get help and instructions for using FFmpeg under Windows, check out
1113 the FFmpeg Windows Help Forum at
1114 @url{http://arrozcru.no-ip.org/ffmpeg/}.
1116 @subsection Native Windows compilation
1119 @item Install the current versions of MSYS and MinGW from
1120 @url{http://www.mingw.org/}. You can find detailed installation
1121 instructions in the download section and the FAQ.
1123 NOTE: Use at least bash 3.1. Older versions are known to be failing on the
1126 @item If you want to test the FFplay, also download
1127 the MinGW development library of SDL 1.2.x
1128 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
1129 @url{http://www.libsdl.org}. Unpack it in a temporary directory, and
1130 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
1131 directory. Edit the @file{sdl-config} script so that it gives the
1132 correct SDL directory when invoked.
1134 @item Extract the current version of FFmpeg.
1136 @item Start the MSYS shell (file @file{msys.bat}).
1138 @item Change to the FFmpeg directory and follow
1139 the instructions of how to compile FFmpeg (file
1140 @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
1141 suffices. If you have problems using SDL, verify that
1142 @file{sdl-config} can be launched from the MSYS command line.
1144 @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing
1145 @file{make install}. Do not forget to copy @file{SDL.dll} to the place
1146 you launch @file{ffplay} from.
1153 @item The target @file{make wininstaller} can be used to create a
1154 Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
1155 must be copied to the FFmpeg directory in order to build the
1158 @item By using @code{./configure --enable-shared} when configuring FFmpeg,
1159 you can build @file{avcodec.dll} and @file{avformat.dll}. With
1160 @code{make install} you install the FFmpeg DLLs and the associated
1161 headers in @file{Program Files/FFmpeg}.
1163 @item Visual C++ compatibility: If you used @code{./configure --enable-shared}
1164 when configuring FFmpeg, FFmpeg tries to use the Microsoft Visual
1165 C++ @code{lib} tool to build @code{avcodec.lib} and
1166 @code{avformat.lib}. With these libraries you can link your Visual C++
1167 code directly with the FFmpeg DLLs (see below).
1171 @subsection Visual C++ compatibility
1173 FFmpeg will not compile under Visual C++ -- and it has too many
1174 dependencies on the GCC compiler to make a port viable. However,
1175 if you want to use the FFmpeg libraries in your own applications,
1176 you can still compile those applications using Visual C++. An
1177 important restriction to this is that you have to use the
1178 dynamically linked versions of the FFmpeg libraries (i.e. the
1179 DLLs), and you have to make sure that Visual-C++-compatible
1180 import libraries are created during the FFmpeg build process.
1182 This description of how to use the FFmpeg libraries with Visual C++ is
1183 based on Visual C++ 2005 Express Edition Beta 2. If you have a different
1184 version, you might have to modify the procedures slightly.
1186 Here are the step-by-step instructions for building the FFmpeg libraries
1187 so they can be used with Visual C++:
1191 @item Install Visual C++ (if you have not done so already).
1193 @item Install MinGW and MSYS as described above.
1195 @item Add a call to @file{vcvars32.bat} (which sets up the environment
1196 variables for the Visual C++ tools) as the first line of
1197 @file{msys.bat}. The standard location for @file{vcvars32.bat} is
1198 @file{C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat},
1199 and the standard location for @file{msys.bat} is
1200 @file{C:\msys\1.0\msys.bat}. If this corresponds to your setup, add the
1201 following line as the first line of @file{msys.bat}:
1203 @code{call "C:\Program Files\Microsoft Visual Studio 8\VC\bin\vcvars32.bat"}
1205 @item Start the MSYS shell (file @file{msys.bat}) and type @code{link.exe}.
1206 If you get a help message with the command line options of @code{link.exe},
1207 this means your environment variables are set up correctly, the
1208 Microsoft linker is on the path and will be used by FFmpeg to
1209 create Visual-C++-compatible import libraries.
1211 @item Extract the current version of FFmpeg and change to the FFmpeg directory.
1213 @item Type the command
1214 @code{./configure --enable-shared --disable-static --enable-memalign-hack}
1215 to configure and, if that did not produce any errors,
1216 type @code{make} to build FFmpeg.
1218 @item The subdirectories @file{libavformat}, @file{libavcodec}, and
1219 @file{libavutil} should now contain the files @file{avformat.dll},
1220 @file{avformat.lib}, @file{avcodec.dll}, @file{avcodec.lib},
1221 @file{avutil.dll}, and @file{avutil.lib}, respectively. Copy the three
1222 DLLs to your System32 directory (typically @file{C:\Windows\System32}).
1226 And here is how to use these libraries with Visual C++:
1230 @item Create a new console application ("File / New / Project") and then
1231 select "Win32 Console Application". On the appropriate page of the
1232 Application Wizard, uncheck the "Precompiled headers" option.
1234 @item Write the source code for your application, or, for testing, just
1235 copy the code from an existing sample application into the source file
1236 that Visual C++ has already created for you. (Note that your source
1237 filehas to have a @code{.cpp} extension; otherwise, Visual C++ will not
1238 compile the FFmpeg headers correctly because in C mode, it does not
1239 recognize the @code{inline} keyword.) For example, you can copy
1240 @file{output_example.c} from the FFmpeg distribution (but you will
1241 have to make minor modifications so the code will compile under
1244 @item Open the "Project / Properties" dialog box. In the "Configuration"
1245 combo box, select "All Configurations" so that the changes you make will
1246 affect both debug and release builds. In the tree view on the left hand
1247 side, select "C/C++ / General", then edit the "Additional Include
1248 Directories" setting to contain the complete paths to the
1249 @file{libavformat}, @file{libavcodec}, and @file{libavutil}
1250 subdirectories of your FFmpeg directory. Note that the directories have
1251 to be separated using semicolons. Now select "Linker / General" from the
1252 tree view and edit the "Additional Library Directories" setting to
1253 contain the same three directories.
1255 @item Still in the "Project / Properties" dialog box, select "Linker / Input"
1256 from the tree view, then add the files @file{avformat.lib},
1257 @file{avcodec.lib}, and @file{avutil.lib} to the end of the "Additional
1258 Dependencies". Note that the names of the libraries have to be separated
1261 @item Now, select "C/C++ / Code Generation" from the tree view. Select
1262 "Debug" in the "Configuration" combo box. Make sure that "Runtime
1263 Library" is set to "Multi-threaded Debug DLL". Then, select "Release" in
1264 the "Configuration" combo box and make sure that "Runtime Library" is
1265 set to "Multi-threaded DLL".
1267 @item Click "OK" to close the "Project / Properties" dialog box and build
1268 the application. Hopefully, it should compile and run cleanly. If you
1269 used @file{output_example.c} as your sample application, you will get a
1270 few compiler errors, but they are easy to fix. The first type of error
1271 occurs because Visual C++ does not allow an @code{int} to be converted to
1272 an @code{enum} without a cast. To solve the problem, insert the required
1273 casts (this error occurs once for a @code{CodecID} and once for a
1274 @code{CodecType}). The second type of error occurs because C++ requires
1275 the return value of @code{malloc} to be cast to the exact type of the
1276 pointer it is being assigned to. Visual C++ will complain that, for
1277 example, @code{(void *)} is being assigned to @code{(uint8_t *)} without
1278 an explicit cast. So insert an explicit cast in these places to silence
1279 the compiler. The third type of error occurs because the @code{snprintf}
1280 library function is called @code{_snprintf} under Visual C++. So just
1281 add an underscore to fix the problem. With these changes,
1282 @file{output_example.c} should compile under Visual C++, and the
1283 resulting executable should produce valid video files.
1287 @subsection Cross compilation for Windows with Linux
1289 You must use the MinGW cross compilation tools available at
1290 @url{http://www.mingw.org/}.
1292 Then configure FFmpeg with the following options:
1294 ./configure --target-os=mingw32 --cross-prefix=i386-mingw32msvc-
1296 (you can change the cross-prefix according to the prefix chosen for the
1299 Then you can easily test FFmpeg with Wine
1300 (@url{http://www.winehq.com/}).
1302 @subsection Compilation under Cygwin
1304 Cygwin works very much like Unix.
1306 Just install your Cygwin with all the "Base" packages, plus the
1307 following "Devel" ones:
1309 binutils, gcc-core, make, subversion
1312 Do not install binutils-20060709-1 (they are buggy on shared builds);
1313 use binutils-20050610-1 instead.
1318 ./configure --enable-static --disable-shared
1321 to make a static build or
1324 ./configure --enable-shared --disable-static
1327 to build shared libraries.
1329 If you want to build FFmpeg with additional libraries, download Cygwin
1330 "Devel" packages for Ogg and Vorbis from any Cygwin packages repository
1331 and/or SDL, xvid, faac, faad2 packages from Cygwin Ports,
1332 (@url{http://cygwinports.dotsrc.org/}).
1334 @subsection Crosscompilation for Windows under Cygwin
1336 With Cygwin you can create Windows binaries that do not need the cygwin1.dll.
1338 Just install your Cygwin as explained before, plus these additional
1341 gcc-mingw-core, mingw-runtime, mingw-zlib
1344 and add some special flags to your configure invocation.
1346 For a static build run
1348 ./configure --target-os=mingw32 --enable-memalign-hack --enable-static --disable-shared --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1351 and for a build with shared libraries
1353 ./configure --target-os=mingw32 --enable-memalign-hack --enable-shared --disable-static --extra-cflags=-mno-cygwin --extra-libs=-mno-cygwin
1358 The configure script should guess the configuration itself.
1359 Networking support is currently not finished.
1360 errno issues fixed by Andrew Bachmann.
1364 François Revol - revol at free dot fr - April 2002
1366 The configure script should guess the configuration itself,
1367 however I still did not test building on the net_server version of BeOS.
1369 FFserver is broken (needs poll() implementation).
1371 There are still issues with errno codes, which are negative in BeOS, and
1372 that FFmpeg negates when returning. This ends up turning errors into
1373 valid results, then crashes.
1376 @chapter Developers Guide
1380 @item libavcodec is the library containing the codecs (both encoding and
1381 decoding). Look at @file{libavcodec/apiexample.c} to see how to use it.
1383 @item libavformat is the library containing the file format handling (mux and
1384 demux code for several formats). Look at @file{ffplay.c} to use it in a
1385 player. See @file{output_example.c} to use it to generate audio or video
1390 @section Integrating libavcodec or libavformat in your program
1392 You can integrate all the source code of the libraries to link them
1393 statically to avoid any version problem. All you need is to provide a
1394 'config.mak' and a 'config.h' in the parent directory. See the defines
1395 generated by ./configure to understand what is needed.
1397 You can use libavcodec or libavformat in your commercial program, but
1398 @emph{any patch you make must be published}. The best way to proceed is
1399 to send your patches to the FFmpeg mailing list.
1402 @section Coding Rules
1404 FFmpeg is programmed in the ISO C90 language with a few additional
1405 features from ISO C99, namely:
1408 the @samp{inline} keyword;
1412 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
1414 compound literals (@samp{x = (struct s) @{ 17, 23 @};})
1417 These features are supported by all compilers we care about, so we will not
1418 accept patches to remove their use unless they absolutely do not impair
1419 clarity and performance.
1421 All code must compile with GCC 2.95 and GCC 3.3. Currently, FFmpeg also
1422 compiles with several other compilers, such as the Compaq ccc compiler
1423 or Sun Studio 9, and we would like to keep it that way unless it would
1424 be exceedingly involved. To ensure compatibility, please do not use any
1425 additional C99 features or GCC extensions. Especially watch out for:
1428 mixing statements and declarations;
1430 @samp{long long} (use @samp{int64_t} instead);
1432 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
1434 GCC statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
1438 The presentation is the one specified by 'indent -i4 -kr -nut'.
1439 The TAB character is forbidden outside of Makefiles as is any
1440 form of trailing whitespace. Commits containing either will be
1441 rejected by the Subversion repository.
1443 Main priority in FFmpeg is simplicity and small code size (=less
1446 Comments: Use the JavaDoc/Doxygen
1447 format (see examples below) so that code documentation
1448 can be generated automatically. All nontrivial functions should have a comment
1449 above them explaining what the function does, even if it is just one sentence.
1450 All structures and their member variables should be documented, too.
1463 typedef struct Foobar@{
1464 int var1; /**< var1 description */
1465 int var2; ///< var2 description
1466 /** var3 description */
1474 * @@param my_parameter description of my_parameter
1475 * @@return return value description
1477 int myfunc(int my_parameter)
1481 fprintf and printf are forbidden in libavformat and libavcodec,
1482 please use av_log() instead.
1484 @section Development Policy
1488 You must not commit code which breaks FFmpeg! (Meaning unfinished but
1489 enabled code which breaks compilation or compiles but does not work or
1490 breaks the regression tests)
1491 You can commit unfinished stuff (for testing etc), but it must be disabled
1492 (#ifdef etc) by default so it does not interfere with other developers'
1495 You do not have to over-test things. If it works for you, and you think it
1496 should work for others, then commit. If your code has problems
1497 (portability, triggers compiler bugs, unusual environment etc) they will be
1498 reported and eventually fixed.
1500 Do not commit unrelated changes together, split them into self-contained
1501 pieces. Also do not forget that if part B depends on part A, but A does not
1502 depend on B, then A can and should be committed first and separate from B.
1503 Keeping changes well split into self-contained parts makes reviewing and
1504 understanding them on the commit log mailing list easier. This also helps
1505 in case of debugging later on.
1506 Also if you have doubts about splitting or not splitting, do not hesitate to
1507 ask/disscuss it on the developer mailing list.
1509 Do not change behavior of the program (renaming options etc) without
1510 first discussing it on the ffmpeg-devel mailing list. Do not remove
1511 functionality from the code. Just improve!
1513 Note: Redundant code can be removed.
1515 Do not commit changes to the build system (Makefiles, configure script)
1516 which change behavior, defaults etc, without asking first. The same
1517 applies to compiler warning fixes, trivial looking fixes and to code
1518 maintained by other developers. We usually have a reason for doing things
1519 the way we do. Send your changes as patches to the ffmpeg-devel mailing
1520 list, and if the code maintainers say OK, you may commit. This does not
1521 apply to files you wrote and/or maintain.
1523 We refuse source indentation and other cosmetic changes if they are mixed
1524 with functional changes, such commits will be rejected and removed. Every
1525 developer has his own indentation style, you should not change it. Of course
1526 if you (re)write something, you can use your own style, even though we would
1527 prefer if the indentation throughout FFmpeg was consistent (Many projects
1528 force a given indentation style - we do not.). If you really need to make
1529 indentation changes (try to avoid this), separate them strictly from real
1532 NOTE: If you had to put if()@{ .. @} over a large (> 5 lines) chunk of code,
1533 then either do NOT change the indentation of the inner part within (do not
1534 move it to the right)! or do so in a separate commit
1536 Always fill out the commit log message. Describe in a few lines what you
1537 changed and why. You can refer to mailing list postings if you fix a
1538 particular bug. Comments such as "fixed!" or "Changed it." are unacceptable.
1540 If you apply a patch by someone else, include the name and email address in
1541 the log message. Since the ffmpeg-cvslog mailing list is publicly
1542 archived you should add some SPAM protection to the email address. Send an
1543 answer to ffmpeg-devel (or wherever you got the patch from) saying that
1544 you applied the patch.
1546 Do NOT commit to code actively maintained by others without permission.
1547 Send a patch to ffmpeg-devel instead. If noone answers within a reasonable
1548 timeframe (12h for build failures and security fixes, 3 days small changes,
1549 1 week for big patches) then commit your patch if you think it is OK.
1550 Also note, the maintainer can simply ask for more time to review!
1552 Subscribe to the ffmpeg-cvslog mailing list. The diffs of all commits
1553 are sent there and reviewed by all the other developers. Bugs and possible
1554 improvements or general questions regarding commits are discussed there. We
1555 expect you to react if problems with your code are uncovered.
1557 Update the documentation if you change behavior or add features. If you are
1558 unsure how best to do this, send a patch to ffmpeg-devel, the documentation
1559 maintainer(s) will review and commit your stuff.
1561 Try to keep important discussions and requests (also) on the public
1562 developer mailing list, so that all developers can benefit from them.
1564 Never write to unallocated memory, never write over the end of arrays,
1565 always check values read from some untrusted source before using them
1566 as array index or other risky things.
1568 Remember to check if you need to bump versions for the specific libav
1569 parts (libavutil, libavcodec, libavformat) you are changing. You need
1570 to change the version integer and the version string.
1571 Incrementing the first component means no backward compatibility to
1572 previous versions (e.g. removal of a function from the public API).
1573 Incrementing the second component means backward compatible change
1574 (e.g. addition of a function to the public API).
1575 Incrementing the third component means a noteworthy binary compatible
1576 change (e.g. encoder bug fix that matters for the decoder).
1578 If you add a new codec, remember to update the changelog, add it to
1579 the supported codecs table in the documentation and bump the second
1580 component of the @file{libavcodec} version number appropriately. If
1581 it has a fourcc, add it to @file{libavformat/avienc.c}, even if it
1584 Do not change code to hide warnings without ensuring that the underlying
1585 logic is correct and thus the warning was inappropriate.
1588 We think our rules are not too hard. If you have comments, contact us.
1590 Note, these rules are mostly borrowed from the MPlayer project.
1592 @section Submitting patches
1594 First, (@pxref{Coding Rules}) above if you did not yet.
1596 When you submit your patch, try to send a unified diff (diff '-up'
1597 option). I cannot read other diffs :-)
1599 Also please do not submit patches which contain several unrelated changes.
1600 Split them into individual self-contained patches; this makes reviewing
1603 Run the regression tests before submitting a patch so that you can
1604 verify that there are no big problems.
1606 Patches should be posted as base64 encoded attachments (or any other
1607 encoding which ensures that the patch will not be trashed during
1608 transmission) to the ffmpeg-devel mailing list, see
1609 @url{http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel}
1611 It also helps quite a bit if you tell us what the patch does (for example
1612 'replaces lrint by lrintf'), and why (for example '*BSD isn't C99 compliant
1613 and has no lrint()')
1615 @section Patch review process
1617 All patches posted to ffmpeg-devel will be reviewed, unless they contain a
1618 clear note that the patch is not for SVN.
1619 Reviews and comments will be posted as replies to the patch on the
1620 mailing list. The patch submitter then has to take care of every comment,
1621 that can be by resubmitting a changed patch or by disscussion. Resubmitted
1622 patches will themselves be reviewed like any other patch. If at some point
1623 a patch passes review with no comments then it is approved, that can for
1624 simple and small patches happen immediately while large patches will generally
1625 have to be changed and reviewed many times before they are approved.
1626 After a patch is approved it will be committed to the repository.
1628 We will review all submitted patches, but sometimes we are quite busy so
1629 especially for large patches this can take several weeks.
1631 When resubmitting patches, please do not make any significant changes
1632 not related to the comments received during review. Such patches will
1633 be rejected. Instead, submit significant changes or new features as
1636 @section Regression tests
1638 Before submitting a patch (or committing to the repository), you should at least
1639 test that you did not break anything.
1641 The regression tests build a synthetic video stream and a synthetic
1642 audio stream. These are then encoded and decoded with all codecs or
1643 formats. The CRC (or MD5) of each generated file is recorded in a
1644 result file. A 'diff' is launched to compare the reference results and
1647 The regression tests then go on to test the FFserver code with a
1648 limited set of streams. It is important that this step runs correctly
1651 Run 'make test' to test all the codecs and formats.
1653 Run 'make fulltest' to test all the codecs, formats and FFserver.
1655 [Of course, some patches may change the results of the regression tests. In
1656 this case, the reference results of the regression tests shall be modified