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\input texinfo @c -*- texinfo -*-
@settitle FFmpeg Documentation
@titlepage
@sp 7
@center @titlefont{FFmpeg Documentation}
@sp 3
@end titlepage
@chapter Introduction
FFmpeg is a very fast video and audio converter. It can also grab from
a live audio/video source.
The command line interface is designed to be intuitive, in the sense
that ffmpeg tries to figure out all the parameters, when
possible. You have usually to give only the target bitrate you want.
FFmpeg can also convert from any sample rate to any other, and resize
video on the fly with a high quality polyphase filter.
@chapter Quick Start
@c man begin EXAMPLES
@section Video and Audio grabbing
FFmpeg can use a video4linux compatible video source and any Open Sound
System audio source:
@example
ffmpeg /tmp/out.mpg
@end example
Note that you must activate the right video source and channel before
launching ffmpeg. You can use any TV viewer such as xawtv
(@url{http://bytesex.org/xawtv/}) by Gerd Knorr which I find very
good. You must also set correctly the audio recording levels with a
standard mixer.
@section Video and Audio file format conversion
* ffmpeg can use any supported file format and protocol as input:
Examples:
* You can input from YUV files:
@example
ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
@end example
It will use the files:
@example
/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
@end example
The Y files use twice the resolution of the U and V files. They are
raw files, without header. They can be generated by all decent video
decoders. You must specify the size of the image with the @option{-s} option
if ffmpeg cannot guess it.
* You can input from a RAW YUV420P file:
@example
ffmpeg -i /tmp/test.yuv /tmp/out.avi
@end example
The RAW YUV420P is a file containing RAW YUV planar, for each frame first
come the Y plane followed by U and V planes, which are half vertical and
horizontal resolution.
* You can output to a RAW YUV420P file:
@example
ffmpeg -i mydivx.avi -o hugefile.yuv
@end example
* You can set several input files and output files:
@example
ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
@end example
Convert the audio file a.wav and the raw yuv video file a.yuv
to mpeg file a.mpg
* You can also do audio and video conversions at the same time:
@example
ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
@end example
Convert the sample rate of a.wav to 22050 Hz and encode it to MPEG audio.
* You can encode to several formats at the same time and define a
mapping from input stream to output streams:
@example
ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0
@end example
Convert a.wav to a.mp2 at 64 kbits and b.mp2 at 128 kbits. '-map
file:index' specify which input stream is used for each output
stream, in the order of the definition of output streams.
* You can transcode decrypted VOBs
@example
ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800 -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi
@end example
This is a typical DVD ripper example, input from a VOB file, output
to an AVI file with MPEG-4 video and MP3 audio, note that in this
command we use B frames so the MPEG-4 stream is DivX5 compatible, GOP
size is 300 that means an INTRA frame every 10 seconds for 29.97 fps
input video. Also the audio stream is MP3 encoded so you need LAME
support which is enabled using @code{--enable-mp3lame} when
configuring. The mapping is particularly useful for DVD transcoding
to get the desired audio language.
NOTE: to see the supported input formats, use @code{ffmpeg -formats}.
@c man end
@chapter Invocation
@section Syntax
The generic syntax is:
@example
@c man begin SYNOPSIS
ffmpeg [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
@c man end
@end example
@c man begin DESCRIPTION
If no input file is given, audio/video grabbing is done.
As a general rule, options are applied to the next specified
file. For example, if you give the @option{-b 64} option, it sets the video
bitrate of the next file. Format option may be needed for raw input
files.
By default, ffmpeg tries to convert as losslessly as possible: it
uses the same audio and video parameter for the outputs as the one
specified for the inputs.
@c man end
@c man begin OPTIONS
@section Main options
@table @option
@item -L
show license
@item -h
show help
@item -formats
show available formats, codecs, protocols, ...
@item -f fmt
force format
@item -i filename
input file name
@item -y
overwrite output files
@item -t duration
set the recording time in seconds. @code{hh:mm:ss[.xxx]} syntax is also
supported.
@item -ss position
seek to given time position. @code{hh:mm:ss[.xxx]} syntax is also
supported.
@item -title string
set the title
@item -author string
set the author
@item -copyright string
set the copyright
@item -comment string
set the comment
@item -target type
specify target file type ("vcd", "svcd" or "dvd"). All the format
options (bitrate, codecs, buffer sizes) are automatically set by this
option. You can just type:
@example
ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
@end example
@item -hq
activate high quality settings
@item -itsoffset offset
set the input time offset in seconds. @code{[-]hh:mm:ss[.xxx]} syntax
is also supported. This option affects all the input files that
follow it. The offset is added to the input files' timestamps;
specifying a positive offset means that the corresponding streams are
delayed by 'offset' seconds.
@end table
@section Video Options
@table @option
@item -b bitrate
set the video bitrate in kbit/s (default = 200 kb/s)
@item -r fps
set frame rate (default = 25)
@item -s size
set frame size. The format is @samp{WxH} (default 160x128). The
following abbreviations are recognized:
@table @samp
@item sqcif
128x96
@item qcif
176x144
@item cif
352x288
@item 4cif
704x576
@end table
@item -aspect aspect
set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)
@item -croptop size
set top crop band size (in pixels)
@item -cropbottom size
set bottom crop band size (in pixels)
@item -cropleft size
set left crop band size (in pixels)
@item -cropright size
set right crop band size (in pixels)
@item -padtop size
set top pad band size (in pixels)
@item -padbottom size
set bottom pad band size (in pixels)
@item -padleft size
set left pad band size (in pixels)
@item -padright size
set right pad band size (in pixels)
@item -padcolor (hex color)
set color of padded bands. The value for pad color is expressed
as a six digit hexidecimal number where the first two digits represent red,
middle two digits green and last two digits blue. Defaults to 000000 (black)
@item -vn
disable video recording
@item -bt tolerance
set video bitrate tolerance (in kbit/s)
@item -maxrate bitrate
set max video bitrate tolerance (in kbit/s)
@item -minrate bitrate
set min video bitrate tolerance (in kbit/s)
@item -bufsize size
set ratecontrol buffere size (in kbit)
@item -vcodec codec
force video codec to @var{codec}. Use the @code{copy} special value to
tell that the raw codec data must be copied as is.
@item -sameq
use same video quality as source (implies VBR)
@item -pass n
select the pass number (1 or 2). It is useful to do two pass
encoding. The statistics of the video are recorded in the first pass and
the video at the exact requested bit rate is generated in the second
pass.
@item -passlogfile file
select two pass log file name to @var{file}.
@end table
@section Advanced Video Options
@table @option
@item -g gop_size
set the group of picture size
@item -intra
use only intra frames
@item -qscale q
use fixed video quantiser scale (VBR)
@item -qmin q
min video quantiser scale (VBR)
@item -qmax q
max video quantiser scale (VBR)
@item -qdiff q
max difference between the quantiser scale (VBR)
@item -qblur blur
video quantiser scale blur (VBR)
@item -qcomp compression
video quantiser scale compression (VBR)
@item -rc_init_cplx complexity
initial complexity for 1-pass encoding
@item -b_qfactor factor
qp factor between p and b frames
@item -i_qfactor factor
qp factor between p and i frames
@item -b_qoffset offset
qp offset between p and b frames
@item -i_qoffset offset
qp offset between p and i frames
@item -rc_eq equation
set rate control equation (@pxref{FFmpeg formula
evaluator}). Default is @code{tex^qComp}.
@item -rc_override override
rate control override for specific intervals
@item -me method
set motion estimation method to @var{method}. Available methods are
(from lower to best quality):
@table @samp
@item zero
Try just the (0, 0) vector.
@item phods
@item log
@item x1
@item epzs
(default method)
@item full
exhaustive search (slow and marginally better than epzs)
@end table
@item -dct_algo algo
set dct algorithm to @var{algo}. Available values are:
@table @samp
@item 0
FF_DCT_AUTO (default)
@item 1
FF_DCT_FASTINT
@item 2
FF_DCT_INT
@item 3
FF_DCT_MMX
@item 4
FF_DCT_MLIB
@item 5
FF_DCT_ALTIVEC
@end table
@item -idct_algo algo
set idct algorithm to @var{algo}. Available values are:
@table @samp
@item 0
FF_IDCT_AUTO (default)
@item 1
FF_IDCT_INT
@item 2
FF_IDCT_SIMPLE
@item 3
FF_IDCT_SIMPLEMMX
@item 4
FF_IDCT_LIBMPEG2MMX
@item 5
FF_IDCT_PS2
@item 6
FF_IDCT_MLIB
@item 7
FF_IDCT_ARM
@item 8
FF_IDCT_ALTIVEC
@item 9
FF_IDCT_SH4
@item 10
FF_IDCT_SIMPLEARM
@end table
@item -er n
set error resilience to @var{n}.
@table @samp
@item 1
FF_ER_CAREFULL (default)
@item 2
FF_ER_COMPLIANT
@item 3
FF_ER_AGGRESSIVE
@item 4
FF_ER_VERY_AGGRESSIVE
@end table
@item -ec bit_mask
set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
the following values:
@table @samp
@item 1
FF_EC_GUESS_MVS (default=enabled)
@item 2
FF_EC_DEBLOCK (default=enabled)
@end table
@item -bf frames
use 'frames' B frames (supported for MPEG-1, MPEG-2 and MPEG-4)
@item -mbd mode
macroblock decision
@table @samp
@item 0
FF_MB_DECISION_SIMPLE: use mb_cmp (cannot change it yet in ffmpeg)
@item 1
FF_MB_DECISION_BITS: chooses the one which needs the fewest bits
@item 2
FF_MB_DECISION_RD: rate distoration
@end table
@item -4mv
use four motion vector by macroblock (only MPEG-4)
@item -part
use data partitioning (only MPEG-4)
@item -bug param
workaround not auto detected encoder bugs
@item -strict strictness
how strictly to follow the standarts
@item -aic
enable Advanced intra coding (h263+)
@item -umv
enable Unlimited Motion Vector (h263+)
@item -deinterlace
deinterlace pictures
@item -interlace
force interlacing support in encoder (only MPEG-2 and MPEG-4). Use this option
if your input file is interlaced and if you want to keep the interlaced
format for minimum losses. The alternative is to deinterlace the input
stream with @option{-deinterlace}, but deinterlacing introduces more
losses.
@item -psnr
calculate PSNR of compressed frames
@item -vstats
dump video coding statistics to @file{vstats_HHMMSS.log}.
@item -vhook module
insert video processing @var{module}. @var{module} contains the module
name and its parameters separated by spaces.
@end table
@section Audio Options
@table @option
@item -ar freq
set the audio sampling freq (default = 44100 Hz)
@item -ab bitrate
set the audio bitrate in kbit/s (default = 64)
@item -ac channels
set the number of audio channels (default = 1)
@item -an
disable audio recording
@item -acodec codec
force audio codec to @var{codec}. Use the @code{copy} special value to
tell that the raw codec data must be copied as is.
@end table
@section Audio/Video grab options
@table @option
@item -vd device
set video grab device (e.g. @file{/dev/video0})
@item -vc channel
set video grab channel (DV1394 only)
@item -tvstd standard
set television standard (NTSC, PAL (SECAM))
@item -dv1394
set DV1394 grab
@item -ad device
set audio device (e.g. @file{/dev/dsp})
@end table
@section Advanced options
@table @option
@item -map file:stream
set input stream mapping
@item -debug
print specific debug info
@item -benchmark
add timings for benchmarking
@item -hex
dump each input packet
@item -bitexact
only use bit exact algorithms (for codec testing)
@item -ps size
set packet size in bits
@item -re
read input at native frame rate. Mainly used to simulate a grab device.
@item -loop
loop over the input stream. Currently it works only for image
streams. This option is used for ffserver automatic testing.
@end table
@node FFmpeg formula evaluator
@section FFmpeg formula evaluator
When evaluating a rate control string, FFmpeg uses an internal formula
evaluator.
The following binary operators are available: @code{+}, @code{-},
@code{*}, @code{/}, @code{^}.
The following unary operators are available: @code{+}, @code{-},
@code{(...)}.
The following functions are available:
@table @var
@item sinh(x)
@item cosh(x)
@item tanh(x)
@item sin(x)
@item cos(x)
@item tan(x)
@item exp(x)
@item log(x)
@item squish(x)
@item gauss(x)
@item abs(x)
@item max(x, y)
@item min(x, y)
@item gt(x, y)
@item lt(x, y)
@item eq(x, y)
@item bits2qp(bits)
@item qp2bits(qp)
@end table
The following constants are available:
@table @var
@item PI
@item E
@item iTex
@item pTex
@item tex
@item mv
@item fCode
@item iCount
@item mcVar
@item var
@item isI
@item isP
@item isB
@item avgQP
@item qComp
@item avgIITex
@item avgPITex
@item avgPPTex
@item avgBPTex
@item avgTex
@end table
@c man end
@ignore
@setfilename ffmpeg
@settitle FFmpeg video converter
@c man begin SEEALSO
ffserver(1), ffplay(1) and the html documentation of @file{ffmpeg}.
@c man end
@c man begin AUTHOR
Fabrice Bellard
@c man end
@end ignore
@section Protocols
The filename can be @file{-} to read from the standard input or to write
to the standard output.
ffmpeg handles also many protocols specified with the URL syntax.
Use 'ffmpeg -formats' to have a list of the supported protocols.
The protocol @code{http:} is currently used only to communicate with
ffserver (see the ffserver documentation). When ffmpeg will be a
video player it will also be used for streaming :-)
@chapter Tips
@itemize
@item For streaming at very low bit rate application, use a low frame rate
and a small gop size. This is especially true for real video where
the Linux player does not seem to be very fast, so it can miss
frames. An example is:
@example
ffmpeg -g 3 -r 3 -t 10 -b 50 -s qcif -f rv10 /tmp/b.rm
@end example
@item The parameter 'q' which is displayed while encoding is the current
quantizer. The value of 1 indicates that a very good quality could
be achieved. The value of 31 indicates the worst quality. If q=31
too often, it means that the encoder cannot compress enough to meet
your bit rate. You must either increase the bit rate, decrease the
frame rate or decrease the frame size.
@item If your computer is not fast enough, you can speed up the
compression at the expense of the compression ratio. You can use
'-me zero' to speed up motion estimation, and '-intra' to disable
completely motion estimation (you have only I frames, which means it
is about as good as JPEG compression).
@item To have very low bitrates in audio, reduce the sampling frequency
(down to 22050 kHz for mpeg audio, 22050 or 11025 for ac3).
@item To have a constant quality (but a variable bitrate), use the option
'-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
quality).
@item When converting video files, you can use the '-sameq' option which
uses in the encoder the same quality factor than in the decoder. It
allows to be almost lossless in encoding.
@end itemize
@chapter Supported File Formats and Codecs
You can use the @code{-formats} option to have an exhaustive list.
@section File Formats
FFmpeg supports the following file formats through the @code{libavformat}
library:
@multitable @columnfractions .4 .1 .1
@item Supported File Format @tab Encoding @tab Decoding @tab Comments
@item MPEG audio @tab X @tab X
@item MPEG1 systems @tab X @tab X
@tab muxed audio and video
@item MPEG2 PS @tab X @tab X
@tab also known as @code{VOB} file
@item MPEG2 TS @tab @tab X
@tab also known as DVB Transport Stream
@item ASF@tab X @tab X
@item AVI@tab X @tab X
@item WAV@tab X @tab X
@item Macromedia Flash@tab X @tab X
@tab Only embedded audio is decoded
@item FLV @tab X @tab X
@tab Macromedia Flash video files
@item Real Audio and Video @tab X @tab X
@item Raw AC3 @tab X @tab X
@item Raw MJPEG @tab X @tab X
@item Raw MPEG video @tab X @tab X
@item Raw PCM8/16 bits, mulaw/Alaw@tab X @tab X
@item Raw CRI ADX audio @tab X @tab X
@item SUN AU format @tab X @tab X
@item NUT @tab X @tab X @tab NUT Open Container Format
@item Quicktime @tab X @tab X
@item MPEG4 @tab X @tab X
@tab MPEG4 is a variant of Quicktime
@item Raw MPEG4 video @tab X @tab X
@item DV @tab X @tab X
@item 4xm @tab @tab X
@tab 4X Technologies format, used in some games
@item Playstation STR @tab @tab X
@item Id RoQ @tab @tab X
@tab used in Quake III, Jedi Knight 2, other computer games
@item Interplay MVE @tab @tab X
@tab format used in various Interplay computer games
@item WC3 Movie @tab @tab X
@tab multimedia format used in Origin's Wing Commander III computer game
@item Sega FILM/CPK @tab @tab X
@tab used in many Sega Saturn console games
@item Westwood Studios VQA/AUD @tab @tab X
@tab Multimedia formats used in Westwood Studios games
@item Id Cinematic (.cin) @tab @tab X
@tab Used in Quake II
@item FLIC format @tab @tab X
@tab .fli/.flc files
@item Sierra VMD @tab @tab X
@tab used in Sierra CD-ROM games
@item Matroska @tab @tab X
@end multitable
@code{X} means that the encoding (resp. decoding) is supported.
@section Image Formats
FFmpeg can read and write images for each frame of a video sequence. The
following image formats are supported:
@multitable @columnfractions .4 .1 .1
@item Supported Image Format @tab Encoding @tab Decoding @tab Comments
@item PGM, PPM @tab X @tab X
@item PAM @tab X @tab X @tab PAM is a PNM extension with alpha support
@item PGMYUV @tab X @tab X @tab PGM with U and V components in YUV 4:2:0
@item JPEG @tab X @tab X @tab Progressive JPEG is not supported
@item .Y.U.V @tab X @tab X @tab One raw file per component
@item Animated GIF @tab X @tab X @tab Only uncompressed GIFs are generated
@item PNG @tab X @tab X @tab 2 bit and 4 bit/pixel not supported yet
@item SGI @tab X @tab X @tab SGI RGB image format
@end multitable
@code{X} means that the encoding (resp. decoding) is supported.
@section Video Codecs
@multitable @columnfractions .4 .1 .1 .7
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
@item MPEG1 video @tab X @tab X
@item MPEG2 video @tab X @tab X
@item MPEG4 @tab X @tab X @tab Also known as DIVX4/5
@item MSMPEG4 V1 @tab X @tab X
@item MSMPEG4 V2 @tab X @tab X
@item MSMPEG4 V3 @tab X @tab X @tab Also known as DIVX3
@item WMV7 @tab X @tab X
@item WMV8 @tab X @tab X @tab Not completely working
@item H263(+) @tab X @tab X @tab Also known as Real Video 1.0
@item MJPEG @tab X @tab X
@item Lossless MJPEG @tab X @tab X
@item Apple MJPEG-B @tab @tab X
@item Sunplus MJPEG @tab @tab X @tab fourcc: SP5X
@item DV @tab X @tab X
@item Huff YUV @tab X @tab X
@item FFmpeg Video 1 @tab X @tab X @tab Lossless codec (fourcc: FFV1)
@item Asus v1 @tab X @tab X @tab fourcc: ASV1
@item Asus v2 @tab X @tab X @tab fourcc: ASV2
@item Creative YUV @tab @tab X @tab fourcc: CYUV
@item H.264 @tab @tab X
@item Sorenson Video 1 @tab X @tab X @tab fourcc: SVQ1
@item Sorenson Video 3 @tab @tab X @tab fourcc: SVQ3
@item On2 VP3 @tab @tab X @tab still experimental
@item Theora @tab @tab X @tab still experimental
@item Intel Indeo 3 @tab @tab X @tab only works on i386 right now
@item FLV @tab X @tab X @tab Flash H263 variant
@item ATI VCR1 @tab @tab X @tab fourcc: VCR1
@item ATI VCR2 @tab @tab X @tab fourcc: VCR2
@item Cirrus Logic AccuPak @tab @tab X @tab fourcc: CLJR
@item 4X Video @tab @tab X @tab used in certain computer games
@item Sony Playstation MDEC @tab @tab X
@item Id RoQ @tab @tab X @tab used in Quake III, Jedi Knight 2, other computer games
@item Xan/WC3 @tab @tab X @tab used in Wing Commander III .MVE files
@item Interplay Video @tab @tab X @tab used in Interplay .MVE files
@item Apple Animation @tab @tab X @tab fourcc: 'rle '
@item Apple Graphics @tab @tab X @tab fourcc: 'smc '
@item Apple Video @tab @tab X @tab fourcc: rpza
@item Cinepak @tab @tab X
@item Microsoft RLE @tab @tab X
@item Microsoft Video-1 @tab @tab X
@item Westwood VQA @tab @tab X
@item Id Cinematic Video @tab @tab X @tab used in Quake II
@item Planar RGB @tab @tab X @tab fourcc: 8BPS
@item FLIC video @tab @tab X
@item Duck TrueMotion v1 @tab @tab X @tab fourcc: DUCK
@item VMD Video @tab @tab X @tab used in Sierra VMD files
@item MSZH @tab @tab X @tab Part of LCL
@item ZLIB @tab X @tab X @tab Part of LCL, encoder experimental
@end multitable
@code{X} means that the encoding (resp. decoding) is supported.
Check at @url{http://www.mplayerhq.hu/~michael/codec-features.html} to
get a precise comparison of FFmpeg MPEG4 codec compared to the other
solutions.
@section Audio Codecs
@multitable @columnfractions .4 .1 .1 .1 .7
@item Supported Codec @tab Encoding @tab Decoding @tab Comments
@item MPEG audio layer 2 @tab IX @tab IX
@item MPEG audio layer 1/3 @tab IX @tab IX
@tab MP3 encoding is supported through the external library LAME
@item AC3 @tab IX @tab IX
@tab liba52 is used internally for decoding
@item Vorbis @tab X @tab X
@tab supported through the external library libvorbis
@item WMA V1/V2 @tab @tab X
@item AAC @tab X @tab X
@tab supported through the external library libfaac/libfaad
@item Microsoft ADPCM @tab X @tab X
@item MS IMA ADPCM @tab X @tab X
@item QT IMA ADPCM @tab @tab X
@item 4X IMA ADPCM @tab @tab X
@item G.726 ADPCM @tab X @tab X
@item Duck DK3 IMA ADPCM @tab @tab X
@tab used in some Sega Saturn console games
@item Duck DK4 IMA ADPCM @tab @tab X
@tab used in some Sega Saturn console games
@item Westwood Studios IMA ADPCM @tab @tab X
@tab used in Westwood Studios games like Command and Conquer
@item SMJPEG IMA ADPCM @tab @tab X
@tab used in certain Loki game ports
@item CD-ROM XA ADPCM @tab @tab X
@item CRI ADX ADPCM @tab X @tab X
@tab used in Sega Dreamcast games
@item Electronic Arts ADPCM @tab @tab X
@tab used in various EA titles
@item RA144 @tab @tab X
@tab Real 14400 bit/s codec
@item RA288 @tab @tab X
@tab Real 28800 bit/s codec
@item RADnet @tab X @tab IX
@tab Real lowbitrate AC3 codec, liba52 is used for decoding
@item AMR-NB @tab X @tab X
@tab supported through an external library
@item AMR-WB @tab X @tab X
@tab supported through an external library
@item DV audio @tab @tab X
@item Id RoQ DPCM @tab @tab X
@tab used in Quake III, Jedi Knight 2, other computer games
@item Interplay MVE DPCM @tab @tab X
@tab used in various Interplay computer games
@item Xan DPCM @tab @tab X
@tab used in Origin's Wing Commander IV AVI files
@item Apple MACE 3 @tab @tab X
@item Apple MACE 6 @tab @tab X
@item FLAC @tab @tab X
@end multitable
@code{X} means that the encoding (resp. decoding) is supported.
@code{I} means that an integer only version is available too (ensures highest
performances on systems without hardware floating point support).
@chapter Platform Specific information
@section Linux
ffmpeg should be compiled with at least GCC 2.95.3. GCC 3.2 is the
preferred compiler now for ffmpeg. All future optimizations will depend on
features only found in GCC 3.2.
@section BSD
@section Windows
@subsection Native Windows compilation
@itemize
@item Install the current versions of MSYS and MinGW from
@url{http://www.mingw.org/}. You can find detailed installation
instructions in the download section and the FAQ.
@item If you want to test the FFmpeg Simple Media Player, also download
the MinGW development library of SDL 1.2.x
(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
@url{http://www.libsdl.org}. Unpack it in a temporary place, and
unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
directory. Edit the @file{sdl-config} script so that it gives the
correct SDL directory when invoked.
@item Extract the current version of FFmpeg (the latest release version or the current CVS snapshot whichever is recommended).
@item Start the MSYS shell (file @file{msys.bat}).
@item Change to the FFMPEG directory and follow
the instructions of how to compile ffmpeg (file
@file{INSTALL}). Usually, launching @file{./configure} and @file{make}
suffices. If you have problems using SDL, verify that
@file{sdl-config} can be launched from the MSYS command line.
@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
@file{ffplay}.
@end itemize
Notes:
@itemize
@item The target @file{make wininstaller} can be used to create a
Nullsoft based Windows installer for FFmpeg and FFplay. @file{SDL.dll}
must be copied in the ffmpeg directory in order to build the
installer.
@item By using @code{./configure --enable-shared} when configuring ffmpeg,
you can build @file{avcodec.dll} and @file{avformat.dll}. With
@code{make install} you install the FFmpeg DLLs and the associated
headers in @file{Program Files/FFmpeg}.
@item Visual C++ compatibility: if you used @code{./configure --enable-shared}
when configuring FFmpeg, then FFmpeg tries to use the Microsoft Visual
C++ @code{lib} tool to build @code{avcodec.lib} and
@code{avformat.lib}. With these libraries, you can link your Visual C++
code directly with the FFmpeg DLLs.
@end itemize
@subsection Cross compilation for Windows with Linux
You must use the MinGW cross compilation tools available at
@url{http://www.mingw.org/}.
Then configure ffmpeg with the following options:
@example
./configure --enable-mingw32 --cross-prefix=i386-mingw32msvc-
@end example
(you can change the cross-prefix according to the prefix choosen for the
MinGW tools).
Then you can easily test ffmpeg with wine
(@url{http://www.winehq.com/}).
@section MacOS X
@section BeOS
The configure script should guess the configuration itself.
Networking support is currently not finished.
errno issues fixed by Andrew Bachmann.
Old stuff:
Fran<EFBFBD>ois Revol - revol at free dot fr - April 2002
The configure script should guess the configuration itself,
however I still didn't tested building on net_server version of BeOS.
ffserver is broken (needs poll() implementation).
There is still issues with errno codes, which are negative in BeOs, and
that ffmpeg negates when returning. This ends up turning errors into
valid results, then crashes.
(To be fixed)
@chapter Developers Guide
@section API
@itemize
@item libavcodec is the library containing the codecs (both encoding and
decoding). See @file{libavcodec/apiexample.c} to see how to use it.
@item libavformat is the library containing the file formats handling (mux and
demux code for several formats). See @file{ffplay.c} to use it in a
player. See @file{output_example.c} to use it to generate audio or video
streams.
@end itemize
@section Integrating libavcodec or libavformat in your program
You can integrate all the source code of the libraries to link them
statically to avoid any version problem. All you need is to provide a
'config.mak' and a 'config.h' in the parent directory. See the defines
generated by ./configure to understand what is needed.
You can use libavcodec or libavformat in your commercial program, but
@emph{any patch you make must be published}. The best way to proceed is
to send your patches to the ffmpeg mailing list.
@node Coding Rules
@section Coding Rules
ffmpeg is programmed in the ISO C90 language with a few additional
features from ISO C99, namely:
@itemize @bullet
@item
the @samp{inline} keyword;
@item
@samp{//} comments;
@item
designated struct initializers (@samp{struct s x = @{ .i = 17 @};})
@item
compound literals (@samp{x = (struct s) { 17, 23 @};})
@end itemize
These features are supported by all compilers we care about, so we won't
accept patches to remove their use unless they absolutely don't impair
clarity and performance.
All code must compile with gcc 2.95 and gcc 3.3. Currently, ffmpeg also
compiles with several other compilers, such as the Compaq ccc compiler
or Sun Studio 9, and we would like to keep it that way unless it would
be exceedingly involved. To ensure compatibility, please don't use any
additional C99 features or gcc extensions. Watch out especially for:
@itemize @bullet
@item
mixing statements and declarations;
@item
@samp{long long} (use @samp{int64_t} instead);
@item
@samp{__attribute__} not protected by @samp{#ifdef __GNUC__} or similar;
@item
gcc statement expressions (@samp{(x = (@{ int y = 4; y; @})}).
@end itemize
Indent size is 4. The TAB character should not be used.
The presentation is the one specified by 'indent -i4 -kr'.
Main priority in ffmpeg is simplicity and small code size (=less
bugs).
Comments: use the JavaDoc/Doxygen
format (see examples below) so that a documentation
can be generated automatically. All non trivial functions should have a comment
above it explaining what the function does, even if its just one sentance.
All Structures and their member variables should be documented too.
@example
/**
<EFBFBD>* @file mpeg.c
<EFBFBD>* mpeg codec.
<EFBFBD>* @author ...
<EFBFBD>*/
/**
<EFBFBD>* Summary sentance.
<EFBFBD>* more text ...
<EFBFBD>* ...
<EFBFBD>*/
typedef struct Foobar{
<EFBFBD> <20> int var1; /**< var1 description */
<EFBFBD> <20> int var2; ///< var2 description
<EFBFBD> <20> /** var3 description */
<EFBFBD> <20> int var3;
} Foobar;
/**
<EFBFBD>* Summary sentance.
<EFBFBD>* more text ...
<EFBFBD>* ...
<EFBFBD>* @param my_parameter description of my_parameter
<EFBFBD>* @return return value description
<EFBFBD>*/
int myfunc(int my_parameter)
...
@end example
fprintf and printf are forbidden in libavformat and libavcodec,
please use av_log() instead.
@section Submitting patches
First, (@pxref{Coding Rules}) above if you didn't yet.
When you submit your patch, try to send a unified diff (diff '-up'
option). I cannot read other diffs :-)
Run the regression tests before submitting a patch so that you can
verify that there are no big problems.
Patches should be posted as base64 encoded attachments (or any other
encoding which ensures that the patch wont be trashed during
transmission) to the ffmpeg-devel mailinglist, see
@url{http://lists.sourceforge.net/lists/listinfo/ffmpeg-devel}
It also helps quite a bit if you tell us what the patch does (for example
'replaces lrint by lrintf') , and why (for example '*bsd isnt c99 compliant
and has no lrint()')
@section Regression tests
Before submitting a patch (or committing with CVS), you should at least
test that you did not break anything.
The regression test build a synthetic video stream and a synthetic
audio stream. Then these are encoded then decoded with all codecs or
formats. The CRC (or MD5) of each generated file is recorded in a
result file. Then a 'diff' is launched with the reference results and
the result file.
The regression test then goes on to test the ffserver code with a
limited set of streams. It is important that this step runs correctly
as well.
Run 'make test' to test all the codecs and formats.
Run 'make fulltest' to test all the codecs, formats and ffserver.
[Of course, some patches may change the regression tests results. In
this case, the regression tests reference results shall be modified
accordingly].
@bye
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