ffmpeg-doc.texi.svn-base

mediastreamer2是开源的网络传输媒体流的库

\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 parameters that can possibly be
derived automatically. You usually only have to specify 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 grab video and audio from devices given that you specify the input
format and device.

@example
ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
@end example

Note that you must activate the right video source and channel before
launching FFmpeg with any TV viewer such as xawtv
(@url{http://bytesex.org/xawtv/}) by Gerd Knorr. You also
have to set the audio recording levels correctly with a
standard mixer.

@section X11 grabbing

FFmpeg can grab the X11 display.

@example
ffmpeg -f x11grab -s cif -i :0.0 /tmp/out.mpg
@end example

0.0 is display.screen number of your X11 server, same as
the DISPLAY environment variable.

@example
ffmpeg -f x11grab -s cif -i :0.0+10,20 /tmp/out.mpg
@end example

0.0 is display.screen number of your X11 server, same as the DISPLAY environment
variable. 10 is the x-offset and 20 the y-offset for the grabbing.

@section Video and Audio file format conversion

* FFmpeg can use any supported file format and protocol as input:

Examples:

* You can use YUV files as input:

@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

test.yuv is a file containing raw YUV planar data. Each frame is composed
of the Y plane followed by the U and V planes at half vertical and
horizontal resolution.

* You can output to a raw YUV420P file:

@example
ffmpeg -i mydivx.avi 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

Converts 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

Converts a.wav to MPEG audio at 22050Hz sample rate.

* 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 64k /tmp/a.mp2 -ab 128k /tmp/b.mp2 -map 0:0 -map 0:0
@end example

Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
file:index' specifies 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 800k -g 300 -bf 2 -acodec libmp3lame -ab 128k snatch.avi
@end example

This is a typical DVD ripping example; the input is a VOB file, the
output 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, and
GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
input video. Furthermore, the audio stream is MP3-encoded so you need
to enable LAME support by passing @code{--enable-libmp3lame} to configure.
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
As a general rule, options are applied to the next specified
file. Therefore, order is important, and you can have the same
option on the command line multiple times. Each occurrence is
then applied to the next input or output file.

* To set the video bitrate of the output file to 64kbit/s:
@example
ffmpeg -i input.avi -b 64k output.avi
@end example

* To force the frame rate of the input and output file to 24 fps:
@example
ffmpeg -r 24 -i input.avi output.avi
@end example

* To force the frame rate of the output file to 24 fps:
@example
ffmpeg -i input.avi -r 24 output.avi
@end example

* To force the frame rate of input file to 1 fps and the output file to 24 fps:
@example
ffmpeg -r 1 -i input.avi -r 24 output.avi
@end example

The 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 parameters 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 -version
Show version.

@item -formats
Show available formats, codecs, protocols, ...

@item -f fmt
Force format.

@item -i filename
input filename

@item -y
Overwrite output files.

@item -t duration
Restrict the transcoded/captured video sequence
to the duration specified in seconds.
@code{hh:mm:ss[.xxx]} syntax is also supported.

@item -fs limit_size
Set the file size limit.

@item -ss position
Seek to given time position in seconds.
@code{hh:mm:ss[.xxx]} syntax is also supported.

@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 timestamps of the input files.
Specifying a positive offset means that the corresponding
streams are delayed by 'offset' seconds.

@item -title string
Set the title.

@item -timestamp time
Set the timestamp.

@item -author string
Set the author.

@item -copyright string
Set the copyright.

@item -comment string
Set the comment.

@item -album string
Set the album.

@item -track number
Set the track.

@item -year number
Set the year.

@item -v verbose
Control amount of logging.

@item -target type
Specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "pal-vcd",
"ntsc-svcd", ... ). All the format options (bitrate, codecs,
buffer sizes) are then set automatically. You can just type:

@example
ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
@end example

Nevertheless you can specify additional options as long as you know
they do not conflict with the standard, as in:

@example
ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
@end example

@item -dframes number
Set the number of data frames to record.

@item -scodec codec
Force subtitle codec ('copy' to copy stream).

@item -newsubtitle
Add a new subtitle stream to the current output stream.

@item -slang code
Set the ISO 639 language code (3 letters) of the current subtitle stream.

@end table

@section Video Options

@table @option
@item -b bitrate
Set the video bitrate in bit/s (default = 200 kb/s).
@item -vframes number
Set the number of video frames to record.
@item -r fps
Set frame rate (Hz value, fraction or abbreviation), (default = 25).
@item -s size
Set frame size. The format is @samp{wxh} (ffserver default = 160x128, ffmpeg default = same as source).
The following abbreviations are recognized:
@table @samp
@item sqcif
128x96
@item qcif
176x144
@item cif
352x288
@item 4cif
704x576
@item qqvga
160x120
@item qvga
320x240
@item vga
640x480
@item svga
800x600
@item xga
1024x768
@item uxga
1600x1200
@item qxga
2048x1536
@item sxga
1280x1024
@item qsxga
2560x2048
@item hsxga
5120x4096
@item wvga
852x480
@item wxga
1366x768
@item wsxga
1600x1024
@item wuxga
1920x1200
@item woxga
2560x1600
@item wqsxga
3200x2048
@item wquxga
3840x2400
@item whsxga
6400x4096
@item whuxga
7680x4800
@item cga
320x200
@item ega
640x350
@item hd480
852x480
@item hd720
1280x720
@item hd1080
1920x1080
@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 padcolor is expressed
as a six digit hexadecimal number where the first two digits
represent red, the middle two digits green and last two digits
blue (default = 000000 (black)).
@item -vn
Disable video recording.
@item -bt tolerance
Set video bitrate tolerance (in bit/s).
@item -maxrate bitrate
Set max video bitrate (in bit/s).
@item -minrate bitrate
Set min video bitrate (in bit/s).
@item -bufsize size
Set video buffer verifier buffer size (in bits).
@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 is generated at the exact requested bitrate
in the second pass.

@item -passlogfile file
Set two pass logfile name to @var{file}.

@item -newvideo
Add a new video stream to the current output stream.

@end table

@section Advanced Video Options

@table @option
@item -pix_fmt format
Set pixel format. Use 'list' as parameter to show all the supported
pixel formats.
@item -sws_flags flags
Set SwScaler flags (only available when compiled with SwScaler support).
@item -g gop_size
Set the group of pictures size.
@item -intra
Use only intra frames.
@item -vdt n