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 the parameters, when
18 possible. You have usually to give only the target bitrate you want.
20 FFmpeg can also convert from any sample rate to any other, and resize
21 video on the fly with a high quality polyphase filter.
26 @section Video and Audio grabbing
28 FFmpeg can use a video4linux compatible video source and any Open Sound
35 Note that you must activate the right video source and channel before
36 launching ffmpeg. You can use any TV viewer such as xawtv
37 (@url{http://bytesex.org/xawtv/}) by Gerd Knorr which I find very
38 good. You must also set correctly the audio recording levels with a
41 @section Video and Audio file format conversion
43 * ffmpeg can use any supported file format and protocol as input:
47 * You can input from YUV files:
50 ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
53 It will use the files:
55 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
56 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
59 The Y files use twice the resolution of the U and V files. They are
60 raw files, without header. They can be generated by all decent video
61 decoders. You must specify the size of the image with the @option{-s} option
62 if ffmpeg cannot guess it.
64 * You can input from a RAW YUV420P file:
67 ffmpeg -i /tmp/test.yuv /tmp/out.avi
70 The RAW YUV420P is a file containing RAW YUV planar, for each frame first
71 come the Y plane followed by U and V planes, which are half vertical and
72 horizontal resolution.
74 * You can output to a RAW YUV420P file:
77 ffmpeg -i mydivx.avi -o hugefile.yuv
80 * You can set several input files and output files:
83 ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
86 Convert the audio file a.wav and the raw yuv video file a.yuv
89 * You can also do audio and video conversions at the same time:
92 ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
95 Convert the sample rate of a.wav to 22050 Hz and encode it to MPEG audio.
97 * You can encode to several formats at the same time and define a
98 mapping from input stream to output streams:
101 ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0
104 Convert a.wav to a.mp2 at 64 kbits and b.mp2 at 128 kbits. '-map
105 file:index' specify which input stream is used for each output
106 stream, in the order of the definition of output streams.
108 * You can transcode decrypted VOBs
111 ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800 -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi
114 This is a typical DVD ripper example, input from a VOB file, output
115 to an AVI file with MPEG-4 video and MP3 audio, note that in this
116 command we use B frames so the MPEG-4 stream is DivX5 compatible, GOP
117 size is 300 that means an INTRA frame every 10 seconds for 29.97 fps
118 input video. Also the audio stream is MP3 encoded so you need LAME
119 support which is enabled using @code{--enable-mp3lame} when
120 configuring. The mapping is particularly useful for DVD transcoding
121 to get the desired audio language.
123 NOTE: to see the supported input formats, use @code{ffmpeg -formats}.
130 The generic syntax is:
133 @c man begin SYNOPSIS
134 ffmpeg [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
137 @c man begin DESCRIPTION
138 If no input file is given, audio/video grabbing is done.
140 As a general rule, options are applied to the next specified
141 file. For example, if you give the @option{-b 64} option, it sets the video
142 bitrate of the next file. Format option may be needed for raw input
145 By default, ffmpeg tries to convert as losslessly as possible: it
146 uses the same audio and video parameter for the outputs as the one
147 specified for the inputs.
151 @section Main options
161 show available formats, codecs, protocols, ...
170 overwrite output files
173 set the recording time in seconds. @code{hh:mm:ss[.xxx]} syntax is also
177 seek to given time position. @code{hh:mm:ss[.xxx]} syntax is also
186 @item -copyright string
189 @item -comment string
193 specify target file type ("vcd", "svcd" or "dvd"). All the format
194 options (bitrate, codecs, buffer sizes) are automatically set by this
195 option. You can just type:
198 ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
202 activate high quality settings
204 @item -itsoffset offset
205 set the input time offset in seconds. @code{[-]hh:mm:ss[.xxx]} syntax
206 is also supported. This option affects all the input files that
207 follow it. The offset is added to the input files' timestamps;
208 specifying a positive offset means that the corresponding streams are
209 delayed by 'offset' seconds.
213 @section Video Options
217 set the video bitrate in kbit/s (default = 200 kb/s)
219 set frame rate (default = 25)
221 set frame size. The format is @samp{WxH} (default 160x128). The
222 following abbreviations are recognized:
235 set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)
237 set top crop band size (in pixels)
238 @item -cropbottom size
239 set bottom crop band size (in pixels)
241 set left crop band size (in pixels)
242 @item -cropright size
243 set right crop band size (in pixels)
245 set top pad band size (in pixels)
246 @item -padbottom size
247 set bottom pad band size (in pixels)
249 set left pad band size (in pixels)
251 set right pad band size (in pixels)
252 @item -padcolor (hex color)
253 set color of padded bands. The value for pad color is expressed
254 as a six digit hexidecimal number where the first two digits represent red,
255 middle two digits green and last two digits blue. Defaults to 000000 (black)
257 disable video recording
259 set video bitrate tolerance (in kbit/s)
260 @item -maxrate bitrate
261 set max video bitrate tolerance (in kbit/s)
262 @item -minrate bitrate
263 set min video bitrate tolerance (in kbit/s)
265 set ratecontrol buffere size (in kbit)
267 force video codec to @var{codec}. Use the @code{copy} special value to
268 tell that the raw codec data must be copied as is.
270 use same video quality as source (implies VBR)
273 select the pass number (1 or 2). It is useful to do two pass
274 encoding. The statistics of the video are recorded in the first pass and
275 the video at the exact requested bit rate is generated in the second
278 @item -passlogfile file
279 select two pass log file name to @var{file}.
283 @section Advanced Video Options
287 set the group of picture size
289 use only intra frames
291 use fixed video quantiser scale (VBR)
293 min video quantiser scale (VBR)
295 max video quantiser scale (VBR)
297 max difference between the quantiser scale (VBR)
299 video quantiser scale blur (VBR)
300 @item -qcomp compression
301 video quantiser scale compression (VBR)
303 @item -rc_init_cplx complexity
304 initial complexity for 1-pass encoding
305 @item -b_qfactor factor
306 qp factor between p and b frames
307 @item -i_qfactor factor
308 qp factor between p and i frames
309 @item -b_qoffset offset
310 qp offset between p and b frames
311 @item -i_qoffset offset
312 qp offset between p and i frames
313 @item -rc_eq equation
314 set rate control equation (@pxref{FFmpeg formula
315 evaluator}). Default is @code{tex^qComp}.
316 @item -rc_override override
317 rate control override for specific intervals
319 set motion estimation method to @var{method}. Available methods are
320 (from lower to best quality):
323 Try just the (0, 0) vector.
330 exhaustive search (slow and marginally better than epzs)
334 set dct algorithm to @var{algo}. Available values are:
337 FF_DCT_AUTO (default)
350 @item -idct_algo algo
351 set idct algorithm to @var{algo}. Available values are:
354 FF_IDCT_AUTO (default)
378 set error resilience to @var{n}.
381 FF_ER_CAREFULL (default)
387 FF_ER_VERY_AGGRESSIVE
391 set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
392 the following values:
395 FF_EC_GUESS_MVS (default=enabled)
397 FF_EC_DEBLOCK (default=enabled)
401 use 'frames' B frames (supported for MPEG-1, MPEG-2 and MPEG-4)
406 FF_MB_DECISION_SIMPLE: use mb_cmp (cannot change it yet in ffmpeg)
408 FF_MB_DECISION_BITS: chooses the one which needs the fewest bits
410 FF_MB_DECISION_RD: rate distoration
414 use four motion vector by macroblock (only MPEG-4)
416 use data partitioning (only MPEG-4)
418 workaround not auto detected encoder bugs
419 @item -strict strictness
420 how strictly to follow the standarts
422 enable Advanced intra coding (h263+)
424 enable Unlimited Motion Vector (h263+)
429 force interlacing support in encoder (only MPEG-2 and MPEG-4). Use this option
430 if your input file is interlaced and if you want to keep the interlaced
431 format for minimum losses. The alternative is to deinterlace the input
432 stream with @option{-deinterlace}, but deinterlacing introduces more
435 calculate PSNR of compressed frames
437 dump video coding statistics to @file{vstats_HHMMSS.log}.
439 insert video processing @var{module}. @var{module} contains the module
440 name and its parameters separated by spaces.
443 @section Audio Options
447 set the audio sampling freq (default = 44100 Hz)
449 set the audio bitrate in kbit/s (default = 64)
451 set the number of audio channels (default = 1)
453 disable audio recording
455 force audio codec to @var{codec}. Use the @code{copy} special value to
456 tell that the raw codec data must be copied as is.
459 @section Audio/Video grab options
463 set video grab device (e.g. @file{/dev/video0})
465 set video grab channel (DV1394 only)
466 @item -tvstd standard
467 set television standard (NTSC, PAL (SECAM))
471 set audio device (e.g. @file{/dev/dsp})
474 @section Advanced options
477 @item -map file:stream
478 set input stream mapping
480 print specific debug info
482 add timings for benchmarking
484 dump each input packet
486 only use bit exact algorithms (for codec testing)
488 set packet size in bits
490 read input at native frame rate. Mainly used to simulate a grab device.
492 loop over the input stream. Currently it works only for image
493 streams. This option is used for ffserver automatic testing.
496 @node FFmpeg formula evaluator
497 @section FFmpeg formula evaluator
499 When evaluating a rate control string, FFmpeg uses an internal formula
502 The following binary operators are available: @code{+}, @code{-},
503 @code{*}, @code{/}, @code{^}.
505 The following unary operators are available: @code{+}, @code{-},
508 The following functions are available:
530 The following constants are available:
559 @settitle FFmpeg video converter
562 ffserver(1), ffplay(1) and the html documentation of @file{ffmpeg}.
573 The filename can be @file{-} to read from the standard input or to write
574 to the standard output.
576 ffmpeg handles also many protocols specified with the URL syntax.
578 Use 'ffmpeg -formats' to have a list of the supported protocols.
580 The protocol @code{http:} is currently used only to communicate with
581 ffserver (see the ffserver documentation). When ffmpeg will be a
582 video player it will also be used for streaming :-)
587 @item For streaming at very low bit rate application, use a low frame rate
588 and a small gop size. This is especially true for real video where
589 the Linux player does not seem to be very fast, so it can miss
590 frames. An example is:
593 ffmpeg -g 3 -r 3 -t 10 -b 50 -s qcif -f rv10 /tmp/b.rm
596 @item The parameter 'q' which is displayed while encoding is the current
597 quantizer. The value of 1 indicates that a very good quality could
598 be achieved. The value of 31 indicates the worst quality. If q=31
599 too often, it means that the encoder cannot compress enough to meet
600 your bit rate. You must either increase the bit rate, decrease the
601 frame rate or decrease the frame size.
603 @item If your computer is not fast enough, you can speed up the
604 compression at the expense of the compression ratio. You can use
605 '-me zero' to speed up motion estimation, and '-intra' to disable
606 completely motion estimation (you have only I frames, which means it
607 is about as good as JPEG compression).
609 @item To have very low bitrates in audio, reduce the sampling frequency
610 (down to 22050 kHz for mpeg audio, 22050 or 11025 for ac3).
612 @item To have a constant quality (but a variable bitrate), use the option
613 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
616 @item When converting video files, you can use the '-sameq' option which
617 uses in the encoder the same quality factor than in the decoder. It
618 allows to be almost lossless in encoding.
622 @chapter Supported File Formats and Codecs
624 You can use the @code{-formats} option to have an exhaustive list.
626 @section File Formats
628 FFmpeg supports the following file formats through the @code{libavformat}
631 @multitable @columnfractions .4 .1 .1
632 @item Supported File Format @tab Encoding @tab Decoding @tab Comments
633 @item MPEG audio @tab X @tab X
634 @item MPEG1 systems @tab X @tab X
635 @tab muxed audio and video
636 @item MPEG2 PS @tab X @tab X
637 @tab also known as @code{VOB} file
638 @item MPEG2 TS @tab @tab X
639 @tab also known as DVB Transport Stream
640 @item ASF@tab X @tab X
641 @item AVI@tab X @tab X
642 @item WAV@tab X @tab X
643 @item Macromedia Flash@tab X @tab X
644 @tab Only embedded audio is decoded
645 @item FLV @tab X @tab X
646 @tab Macromedia Flash video files
647 @item Real Audio and Video @tab X @tab X
648 @item Raw AC3 @tab X @tab X
649 @item Raw MJPEG @tab X @tab X
650 @item Raw MPEG video @tab X @tab X
651 @item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
652 @item Raw CRI ADX audio @tab X @tab X
653 @item SUN AU format @tab X @tab X
654 @item NUT @tab X @tab X @tab NUT Open Container Format
655 @item Quicktime @tab X @tab X
656 @item MPEG4 @tab X @tab X
657 @tab MPEG4 is a variant of Quicktime
658 @item Raw MPEG4 video @tab X @tab X
659 @item DV @tab X @tab X
660 @item 4xm @tab @tab X
661 @tab 4X Technologies format, used in some games
662 @item Playstation STR @tab @tab X
663 @item Id RoQ @tab @tab X
664 @tab used in Quake III, Jedi Knight 2, other computer games
665 @item Interplay MVE @tab @tab X
666 @tab format used in various Interplay computer games
667 @item WC3 Movie @tab @tab X
668 @tab multimedia format used in Origin's Wing Commander III computer game
669 @item Sega FILM/CPK @tab @tab X
670 @tab used in many Sega Saturn console games
671 @item Westwood Studios VQA/AUD @tab @tab X
672 @tab Multimedia formats used in Westwood Studios games
673 @item Id Cinematic (.cin) @tab @tab X
674 @tab Used in Quake II
675 @item FLIC format @tab @tab X
677 @item Sierra VMD @tab @tab X
678 @tab used in Sierra CD-ROM games
679 @item Matroska @tab @tab X
682 @code{X} means that the encoding (resp. decoding) is supported.
684 @section Image Formats
686 FFmpeg can read and write images for each frame of a video sequence. The
687 following image formats are supported:
689 @multitable @columnfractions .4 .1 .1
690 @item Supported Image Format @tab Encoding @tab Decoding @tab Comments
691 @item PGM, PPM @tab X @tab X
692 @item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support
693 @item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
694 @item JPEG @tab X @tab X @tab Progressive JPEG is not supported
695 @item .Y.U.V @tab X @tab X @tab One raw file per component
696 @item Animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated
697 @item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet
698 @item SGI @tab X @tab X @tab SGI RGB image format
701 @code{X} means that the encoding (resp. decoding) is supported.
703 @section Video Codecs
705 @multitable @columnfractions .4 .1 .1 .7
706 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
707 @item MPEG1 video @tab X @tab X
708 @item MPEG2 video @tab X @tab X
709 @item MPEG4 @tab X @tab X @tab Also known as DIVX4/5
710 @item MSMPEG4 V1 @tab X @tab X
711 @item MSMPEG4 V2 @tab X @tab X
712 @item MSMPEG4 V3 @tab X @tab X @tab Also known as DIVX3
713 @item WMV7 @tab X @tab X
714 @item WMV8 @tab X @tab X @tab Not completely working
715 @item H263(+) @tab X @tab X @tab Also known as Real Video 1.0
716 @item MJPEG @tab X @tab X
717 @item Lossless MJPEG @tab X @tab X
718 @item Apple MJPEG-B @tab @tab X
719 @item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
720 @item DV @tab X @tab X
721 @item Huff YUV @tab X @tab X
722 @item FFmpeg Video 1 @tab X @tab X @tab Lossless codec (fourcc: FFV1)
723 @item Asus v1 @tab X @tab X @tab fourcc: ASV1
724 @item Asus v2 @tab X @tab X @tab fourcc: ASV2
725 @item Creative YUV @tab @tab X @tab fourcc: CYUV
726 @item H.264 @tab @tab X
727 @item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
728 @item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
729 @item On2 VP3 @tab @tab X @tab still experimental
730 @item Theora @tab @tab X @tab still experimental
731 @item Intel Indeo 3 @tab @tab X @tab only works on i386 right now
732 @item FLV @tab X @tab X @tab Flash H263 variant
733 @item ATI VCR1 @tab @tab X @tab fourcc: VCR1
734 @item ATI VCR2 @tab @tab X @tab fourcc: VCR2
735 @item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
736 @item 4X Video @tab @tab X @tab used in certain computer games
737 @item Sony Playstation MDEC @tab @tab X
738 @item Id RoQ @tab @tab X @tab used in Quake III, Jedi Knight 2, other computer games
739 @item Xan/WC3 @tab @tab X @tab used in Wing Commander III .MVE files
740 @item Interplay Video @tab @tab X @tab used in Interplay .MVE files
741 @item Apple Animation @tab @tab X @tab fourcc: 'rle '
742 @item Apple Graphics @tab @tab X @tab fourcc: 'smc '
743 @item Apple Video @tab @tab X @tab fourcc: rpza
744 @item Cinepak @tab @tab X
745 @item Microsoft RLE @tab @tab X
746 @item Microsoft Video-1 @tab @tab X
747 @item Westwood VQA @tab @tab X
748 @item Id Cinematic Video @tab @tab X @tab used in Quake II
749 @item Planar RGB @tab @tab X @tab fourcc: 8BPS
750 @item FLIC video @tab @tab X
751 @item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
752 @item VMD Video @tab @tab X @tab used in Sierra VMD files
753 @item MSZH @tab @tab X @tab Part of LCL
754 @item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
757 @code{X} means that the encoding (resp. decoding) is supported.
759 Check at @url{http://www.mplayerhq.hu/~michael/codec-features.html} to
760 get a precise comparison of FFmpeg MPEG4 codec compared to the other
763 @section Audio Codecs
765 @multitable @columnfractions .4 .1 .1 .1 .7
766 @item Supported Codec @tab Encoding @tab Decoding @tab Comments
767 @item MPEG audio layer 2 @tab IX @tab IX
768 @item MPEG audio layer 1/3 @tab IX @tab IX
769 @tab MP3 encoding is supported through the external library LAME
770 @item AC3 @tab IX @tab IX
771 @tab liba52 is used internally for decoding
772 @item Vorbis @tab X @tab X
773 @tab supported through the external library libvorbis
774 @item WMA V1/V2 @tab @tab X
775 @item AAC @tab X @tab X
776 @tab supported through the external library libfaac/libfaad
777 @item Microsoft ADPCM @tab X @tab X
778 @item MS IMA ADPCM @tab X @tab X
779 @item QT IMA ADPCM @tab @tab X
780 @item 4X IMA ADPCM @tab @tab X
781 @item G.726 ADPCM @tab X @tab X
782 @item Duck DK3 IMA ADPCM @tab @tab X
783 @tab used in some Sega Saturn console games
784 @item Duck DK4 IMA ADPCM @tab @tab X
785 @tab used in some Sega Saturn console games
786 @item Westwood Studios IMA ADPCM @tab @tab X
787 @tab used in Westwood Studios games like Command and Conquer
788 @item SMJPEG IMA ADPCM @tab @tab X
789 @tab used in certain Loki game ports
790 @item CD-ROM XA ADPCM @tab @tab X
791 @item CRI ADX ADPCM @tab X @tab X
792 @tab used in Sega Dreamcast games
793 @item Electronic Arts ADPCM @tab @tab X
794 @tab used in various EA titles
795 @item RA144 @tab @tab X
796 @tab Real 14400 bit/s codec
797 @item RA288 @tab @tab X
798 @tab Real 28800 bit/s codec
799 @item RADnet @tab X @tab IX
800 @tab Real lowbitrate AC3 codec, liba52 is used for decoding
801 @item AMR-NB @tab X @tab X
802 @tab supported through an external library
803 @item AMR-WB @tab X @tab X
804 @tab supported through an external library
805 @item DV audio @tab @tab X
806 @item Id RoQ DPCM @tab @tab X
807 @tab used in Quake III, Jedi Knight 2, other computer games
808 @item Interplay MVE DPCM @tab @tab X
809 @tab used in various Interplay computer games
810 @item Xan DPCM @tab @tab X
811 @tab used in Origin's Wing Commander IV AVI files
812 @item Apple MACE 3 @tab @tab X
813 @item Apple MACE 6 @tab @tab X
814 @item FLAC @tab @tab X
817 @code{X} means that the encoding (resp. decoding) is supported.
819 @code{I} means that an integer only version is available too (ensures highest
820 performances on systems without hardware floating point support).
822 @chapter Platform Specific information
826 ffmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
827 preferred compiler now for ffmpeg. All future optimizations will depend on
828 features only found in GCC 3.2.
834 @subsection Native Windows compilation
837 @item Install the current versions of MSYS and MinGW from
838 @url{http://www.mingw.org/}. You can find detailed installation
839 instructions in the download section and the FAQ.
841 @item If you want to test the FFmpeg Simple Media Player, also download
842 the MinGW development library of SDL 1.2.x
843 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
844 @url{http://www.libsdl.org}. Unpack it in a temporary place, and
845 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
846 directory. Edit the @file{sdl-config} script so that it gives the
847 correct SDL directory when invoked.
849 @item Extract the current version of FFmpeg (the latest release version or the current CVS snapshot whichever is recommended).
851 @item Start the MSYS shell (file @file{msys.bat}).
853 @item Change to the FFMPEG directory and follow
854 the instructions of how to compile ffmpeg (file
855 @file{INSTALL}). Usually, launching @file{./configure} and @file{make}
856 suffices. If you have problems using SDL, verify that
857 @file{sdl-config} can be launched from the MSYS command line.
859 @item You can install FFmpeg in @file{Program Files/FFmpeg} by typing @file{make install}. Don't forget to copy @file{SDL.dll} at the place you launch
867 @item The target @file{make wininstaller} can be used to create a
868 Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
869 must be copied in the ffmpeg directory in order to build the
872 @item By using @code{./configure --enable-shared} when configuring ffmpeg,
873 you can build @file{avcodec.dll} and @file{avformat.dll}. With
874 @code{make install} you install the FFmpeg DLLs and the associated
875 headers in @file{Program Files/FFmpeg}.
877 @item Visual C++ compatibility: if you used @code{./configure --enable-shared}
878 when configuring FFmpeg, then FFmpeg tries to use the Microsoft Visual
879 C++ @code{lib} tool to build @code{avcodec.lib} and
880 @code{avformat.lib}. With these libraries, you can link your Visual C++
881 code directly with the FFmpeg DLLs.
885 @subsection Cross compilation for Windows with Linux
887 You must use the MinGW cross compilation tools available at
888 @url{http://www.mingw.org/}.
890 Then configure ffmpeg with the following options:
892 ./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
894 (you can change the cross-prefix according to the prefix choosen for the
897 Then you can easily test ffmpeg with wine
898 (@url{http://www.winehq.com/}).
904 The configure script should guess the configuration itself.
905 Networking support is currently not finished.
906 errno issues fixed by Andrew Bachmann.
910 François Revol - revol at free dot fr - April 2002
912 The configure script should guess the configuration itself,
913 however I still didn't tested building on net_server version of BeOS.
915 ffserver is broken (needs poll() implementation).
917 There is still issues with errno codes, which are negative in BeOs, and
918 that ffmpeg negates when returning. This ends up turning errors into
919 valid results, then crashes.
922 @chapter Developers Guide
926 @item libavcodec is the library containing the codecs (both encoding and
927 decoding). See @file{libavcodec/apiexample.c} to see how to use it.
929 @item libavformat is the library containing the file formats handling (mux and
930 demux code for several formats). See @file{ffplay.c} to use it in a
931 player. See @file{output_example.c} to use it to generate audio or video
936 @section Integrating libavcodec or libavformat in your program
938 You can integrate all the source code of the libraries to link them
939 statically to avoid any version problem. All you need is to provide a
940 'config.mak' and a 'config.h' in the parent directory. See the defines
941 generated by ./configure to understand what is needed.
943 You can use libavcodec or libavformat in your commercial program, but
944 @emph{any patch you make must be published}. The best way to proceed is
945 to send your patches to the ffmpeg mailing list.
948 @section Coding Rules
950 ffmpeg is programmed in the ISO C90 language with a few additional
951 features from ISO C99, namely:
954 the @samp{inline} keyword;
958 designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
960 compound literals (@samp{x = (struct s) { 17, 23 @};})
963 These features are supported by all compilers we care about, so we won't
964 accept patches to remove their use unless they absolutely don't impair
965 clarity and performance.
967 All code must compile with gcc 2.95 and gcc 3.3. Currently, ffmpeg also
968 compiles with several other compilers, such as the Compaq ccc compiler
969 or Sun Studio 9, and we would like to keep it that way unless it would
970 be exceedingly involved. To ensure compatibility, please don't use any
971 additional C99 features or gcc extensions. Watch out especially for:
974 mixing statements and declarations;
976 @samp{long long} (use @samp{int64_t} instead);
978 @samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
980 gcc statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
983 Indent size is 4. The TAB character should not be used.
984 The presentation is the one specified by 'indent -i4 -kr'.
986 Main priority in ffmpeg is simplicity and small code size (=less
989 Comments: use the JavaDoc/Doxygen
990 format (see examples in @file{libavformat/utils.c}) so that a documentation
991 can be generated automatically. All non trivial functions should have a comment
992 above it explaining what the function does, even if its just one sentance.
993 All Structures and their member variables should be documented too.
996 fprintf and printf are forbidden in libavformat and libavcodec,
997 please use av_log() instead.
999 @section Submitting patches
1001 First, (@pxref{Coding Rules}) above if you didn't yet.
1003 When you submit your patch, try to send a unified diff (diff '-up'
1004 option). I cannot read other diffs :-)
1006 Run the regression tests before submitting a patch so that you can
1007 verify that there are no big problems.
1009 Patches should be posted as base64 encoded attachments (or any other
1010 encoding which ensures that the patch wont be trashed during
1011 transmission) to the ffmpeg-devel mailinglist, see
1012 @url{http://lists.sourceforge.net/lists/listinfo/ffmpeg-devel}
1014 It also helps quite a bit if you tell us what the patch does (for example
1015 'replaces lrint by lrintf') , and why (for example '*bsd isnt c99 compliant
1016 and has no lrint()')
1018 @section Regression tests
1020 Before submitting a patch (or committing with CVS), you should at least
1021 test that you did not break anything.
1023 The regression test build a synthetic video stream and a synthetic
1024 audio stream. Then these are encoded then decoded with all codecs or
1025 formats. The CRC (or MD5) of each generated file is recorded in a
1026 result file. Then a 'diff' is launched with the reference results and
1029 The regression test then goes on to test the ffserver code with a
1030 limited set of streams. It is important that this step runs correctly
1033 Run 'make test' to test all the codecs and formats.
1035 Run 'make fulltest' to test all the codecs, formats and ffserver.
1037 [Of course, some patches may change the regression tests results. In
1038 this case, the regression tests reference results shall be modified