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1156c6b05f
-f oss and -f audio_beos should be used instead. Originally committed as revision 10429 to svn://svn.ffmpeg.org/ffmpeg/trunk
854 lines
21 KiB
Plaintext
854 lines
21 KiB
Plaintext
\input texinfo @c -*- texinfo -*-
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@settitle FFmpeg Documentation
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@titlepage
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@sp 7
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@center @titlefont{FFmpeg Documentation}
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@sp 3
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@end titlepage
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@chapter Introduction
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FFmpeg is a very fast video and audio converter. It can also grab from
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a live audio/video source.
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The command line interface is designed to be intuitive, in the sense
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that FFmpeg tries to figure out all parameters that can possibly be
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derived automatically. You usually only have to specify the target
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bitrate you want.
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FFmpeg can also convert from any sample rate to any other, and resize
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video on the fly with a high quality polyphase filter.
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@chapter Quick Start
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@c man begin EXAMPLES
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@section Video and Audio grabbing
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FFmpeg can grab video and audio from devices given that you specify the input
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format and device.
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@example
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ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
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@end example
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Note that you must activate the right video source and channel before
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launching FFmpeg with any TV viewer such as xawtv
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(@url{http://bytesex.org/xawtv/}) by Gerd Knorr. You also
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have to set the audio recording levels correctly with a
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standard mixer.
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@section X11 grabbing
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FFmpeg can grab the X11 display.
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@example
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ffmpeg -f x11grab -s cif -i :0.0 /tmp/out.mpg
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@end example
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0.0 is display.screen number of your X11 server, same as
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the DISPLAY environment variable.
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@example
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ffmpeg -f x11grab -s cif -i :0.0+10,20 /tmp/out.mpg
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@end example
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0.0 is display.screen number of your X11 server, same as the DISPLAY environment
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variable. 10 is the x-offset and 20 the y-offset for the grabbing.
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@section Video and Audio file format conversion
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* FFmpeg can use any supported file format and protocol as input:
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Examples:
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* You can use YUV files as input:
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@example
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ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
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@end example
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It will use the files:
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@example
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/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
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/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
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@end example
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The Y files use twice the resolution of the U and V files. They are
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raw files, without header. They can be generated by all decent video
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decoders. You must specify the size of the image with the @option{-s} option
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if FFmpeg cannot guess it.
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* You can input from a raw YUV420P file:
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@example
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ffmpeg -i /tmp/test.yuv /tmp/out.avi
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@end example
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test.yuv is a file containing raw YUV planar data. Each frame is composed
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of the Y plane followed by the U and V planes at half vertical and
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horizontal resolution.
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* You can output to a raw YUV420P file:
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@example
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ffmpeg -i mydivx.avi hugefile.yuv
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@end example
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* You can set several input files and output files:
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@example
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ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
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@end example
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Converts the audio file a.wav and the raw YUV video file a.yuv
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to MPEG file a.mpg.
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* You can also do audio and video conversions at the same time:
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@example
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ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
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@end example
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Converts a.wav to MPEG audio at 22050Hz sample rate.
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* You can encode to several formats at the same time and define a
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mapping from input stream to output streams:
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@example
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ffmpeg -i /tmp/a.wav -ab 64k /tmp/a.mp2 -ab 128k /tmp/b.mp2 -map 0:0 -map 0:0
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@end example
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Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
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file:index' specifies which input stream is used for each output
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stream, in the order of the definition of output streams.
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* You can transcode decrypted VOBs
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@example
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ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800k -g 300 -bf 2 -acodec libmp3lame -ab 128k snatch.avi
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@end example
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This is a typical DVD ripping example; the input is a VOB file, the
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output an AVI file with MPEG-4 video and MP3 audio. Note that in this
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command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
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GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
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input video. Furthermore, the audio stream is MP3-encoded so you need
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to enable LAME support by passing @code{--enable-libmp3lame} to configure.
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The mapping is particularly useful for DVD transcoding
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to get the desired audio language.
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NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
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@c man end
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@chapter Invocation
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@section Syntax
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The generic syntax is:
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@example
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@c man begin SYNOPSIS
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ffmpeg [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
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@c man end
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@end example
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@c man begin DESCRIPTION
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As a general rule, options are applied to the next specified
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file. Therefore, order is important, and you can have the same
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option on the command line multiple times. Each occurrence is
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then applied to the next input or output file.
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* To set the video bitrate of the output file to 64kbit/s:
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@example
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ffmpeg -i input.avi -b 64k output.avi
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@end example
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* To force the frame rate of the input and output file to 24 fps:
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@example
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ffmpeg -r 24 -i input.avi output.avi
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@end example
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* To force the frame rate of the output file to 24 fps:
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@example
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ffmpeg -i input.avi -r 24 output.avi
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@end example
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* To force the frame rate of input file to 1 fps and the output file to 24 fps:
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@example
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ffmpeg -r 1 -i input.avi -r 24 output.avi
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@end example
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The format option may be needed for raw input files.
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By default, FFmpeg tries to convert as losslessly as possible: It
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uses the same audio and video parameters for the outputs as the one
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specified for the inputs.
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@c man end
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@c man begin OPTIONS
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@section Main options
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@table @option
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@item -L
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Show license.
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@item -h
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Show help.
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@item -version
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Show version.
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@item -formats
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Show available formats, codecs, protocols, ...
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@item -f fmt
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Force format.
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@item -i filename
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input filename
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@item -y
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Overwrite output files.
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@item -t duration
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Restrict the transcoded/captured video sequence
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to the duration specified in seconds.
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@code{hh:mm:ss[.xxx]} syntax is also supported.
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@item -fs limit_size
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Set the file size limit.
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@item -ss position
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Seek to given time position in seconds.
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@code{hh:mm:ss[.xxx]} syntax is also supported.
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@item -itsoffset offset
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Set the input time offset in seconds.
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@code{[-]hh:mm:ss[.xxx]} syntax is also supported.
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This option affects all the input files that follow it.
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The offset is added to the timestamps of the input files.
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Specifying a positive offset means that the corresponding
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streams are delayed by 'offset' seconds.
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@item -title string
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Set the title.
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@item -timestamp time
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Set the timestamp.
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@item -author string
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Set the author.
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@item -copyright string
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Set the copyright.
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@item -comment string
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Set the comment.
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@item -album string
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Set the album.
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@item -track number
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Set the track.
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@item -year number
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Set the year.
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@item -v verbose
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Control amount of logging.
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@item -target type
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Specify target file type ("vcd", "svcd", "dvd", "dv", "dv50", "pal-vcd",
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"ntsc-svcd", ... ). All the format options (bitrate, codecs,
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buffer sizes) are then set automatically. You can just type:
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@example
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ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
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@end example
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Nevertheless you can specify additional options as long as you know
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they do not conflict with the standard, as in:
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@example
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ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
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@end example
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@item -dframes number
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Set the number of data frames to record.
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@item -scodec codec
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Force subtitle codec ('copy' to copy stream).
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@item -newsubtitle
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Add a new subtitle stream to the current output stream.
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@item -slang code
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Set the ISO 639 language code (3 letters) of the current subtitle stream.
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@end table
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@section Video Options
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@table @option
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@item -b bitrate
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Set the video bitrate in bit/s (default = 200 kb/s).
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@item -vframes number
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Set the number of video frames to record.
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@item -r fps
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Set frame rate (Hz value, fraction or abbreviation), (default = 25).
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@item -s size
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Set frame size. The format is @samp{wxh} (ffserver default = 160x128, ffmpeg default = same as source).
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The following abbreviations are recognized:
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@table @samp
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@item sqcif
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128x96
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@item qcif
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176x144
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@item cif
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352x288
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@item 4cif
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704x576
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@item qqvga
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160x120
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@item qvga
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320x240
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@item vga
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640x480
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@item svga
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800x600
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@item xga
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1024x768
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@item uxga
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1600x1200
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@item qxga
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2048x1536
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@item sxga
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1280x1024
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@item qsxga
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2560x2048
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@item hsxga
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5120x4096
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@item wvga
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852x480
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@item wxga
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1366x768
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@item wsxga
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1600x1024
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@item wuxga
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1920x1200
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@item woxga
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2560x1600
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@item wqsxga
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3200x2048
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@item wquxga
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3840x2400
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@item whsxga
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6400x4096
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@item whuxga
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7680x4800
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@item cga
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320x200
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@item ega
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640x350
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@item hd480
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852x480
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@item hd720
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1280x720
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@item hd1080
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1920x1080
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@end table
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@item -aspect aspect
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Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
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@item -croptop size
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Set top crop band size (in pixels).
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@item -cropbottom size
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Set bottom crop band size (in pixels).
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@item -cropleft size
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Set left crop band size (in pixels).
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@item -cropright size
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Set right crop band size (in pixels).
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@item -padtop size
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Set top pad band size (in pixels).
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@item -padbottom size
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Set bottom pad band size (in pixels).
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@item -padleft size
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Set left pad band size (in pixels).
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@item -padright size
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Set right pad band size (in pixels).
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@item -padcolor (hex color)
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Set color of padded bands. The value for padcolor is expressed
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as a six digit hexadecimal number where the first two digits
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represent red, the middle two digits green and last two digits
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blue (default = 000000 (black)).
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@item -vn
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Disable video recording.
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@item -bt tolerance
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Set video bitrate tolerance (in bit/s).
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@item -maxrate bitrate
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Set max video bitrate (in bit/s).
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@item -minrate bitrate
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Set min video bitrate (in bit/s).
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@item -bufsize size
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Set video buffer verifier buffer size (in bits).
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@item -vcodec codec
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Force video codec to @var{codec}. Use the @code{copy} special value to
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tell that the raw codec data must be copied as is.
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@item -sameq
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Use same video quality as source (implies VBR).
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@item -pass n
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Select the pass number (1 or 2). It is useful to do two pass
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encoding. The statistics of the video are recorded in the first
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pass and the video is generated at the exact requested bitrate
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in the second pass.
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@item -passlogfile file
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Set two pass logfile name to @var{file}.
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@item -newvideo
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Add a new video stream to the current output stream.
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@end table
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@section Advanced Video Options
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@table @option
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@item -pix_fmt format
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Set pixel format. Use 'list' as parameter to show all the supported
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pixel formats.
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@item -sws_flags flags
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Set SwScaler flags (only available when compiled with SwScaler support).
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@item -g gop_size
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Set the group of pictures size.
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@item -intra
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Use only intra frames.
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@item -vdt n
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Discard threshold.
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@item -qscale q
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Use fixed video quantizer scale (VBR).
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@item -qmin q
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minimum video quantizer scale (VBR)
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@item -qmax q
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maximum video quantizer scale (VBR)
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@item -qdiff q
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maximum difference between the quantizer scales (VBR)
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@item -qblur blur
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video quantizer scale blur (VBR)
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@item -qcomp compression
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video quantizer scale compression (VBR)
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@item -lmin lambda
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minimum video lagrange factor (VBR)
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@item -lmax lambda
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max video lagrange factor (VBR)
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@item -mblmin lambda
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minimum macroblock quantizer scale (VBR)
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@item -mblmax lambda
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maximum macroblock quantizer scale (VBR)
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These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
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but you may use the QP2LAMBDA constant to easily convert from 'q' units:
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@example
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ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
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@end example
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@item -rc_init_cplx complexity
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initial complexity for single pass encoding
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@item -b_qfactor factor
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qp factor between P- and B-frames
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@item -i_qfactor factor
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qp factor between P- and I-frames
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@item -b_qoffset offset
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qp offset between P- and B-frames
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@item -i_qoffset offset
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qp offset between P- and I-frames
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@item -rc_eq equation
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Set rate control equation (@pxref{FFmpeg formula
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evaluator}) (default = @code{tex^qComp}).
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@item -rc_override override
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rate control override for specific intervals
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@item -me_method method
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Set motion estimation method to @var{method}.
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Available methods are (from lowest to best quality):
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@table @samp
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@item zero
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Try just the (0, 0) vector.
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@item phods
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@item log
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@item x1
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@item hex
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@item umh
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@item epzs
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(default method)
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@item full
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exhaustive search (slow and marginally better than epzs)
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@end table
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@item -dct_algo algo
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Set DCT algorithm to @var{algo}. Available values are:
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@table @samp
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@item 0
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FF_DCT_AUTO (default)
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@item 1
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FF_DCT_FASTINT
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@item 2
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FF_DCT_INT
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@item 3
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FF_DCT_MMX
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@item 4
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FF_DCT_MLIB
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@item 5
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FF_DCT_ALTIVEC
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@end table
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@item -idct_algo algo
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Set IDCT algorithm to @var{algo}. Available values are:
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@table @samp
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@item 0
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FF_IDCT_AUTO (default)
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@item 1
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FF_IDCT_INT
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@item 2
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FF_IDCT_SIMPLE
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@item 3
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FF_IDCT_SIMPLEMMX
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@item 4
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FF_IDCT_LIBMPEG2MMX
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@item 5
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FF_IDCT_PS2
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@item 6
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FF_IDCT_MLIB
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@item 7
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FF_IDCT_ARM
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@item 8
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FF_IDCT_ALTIVEC
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@item 9
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FF_IDCT_SH4
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@item 10
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FF_IDCT_SIMPLEARM
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@end table
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@item -er n
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Set error resilience to @var{n}.
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@table @samp
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@item 1
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FF_ER_CAREFUL (default)
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@item 2
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FF_ER_COMPLIANT
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@item 3
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FF_ER_AGGRESSIVE
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@item 4
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FF_ER_VERY_AGGRESSIVE
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@end table
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@item -ec bit_mask
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Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
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the following values:
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@table @samp
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@item 1
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FF_EC_GUESS_MVS (default = enabled)
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@item 2
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FF_EC_DEBLOCK (default = enabled)
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@end table
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@item -bf frames
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Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
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@item -mbd mode
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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: Choose the one which needs the fewest bits.
|
|
@item 2
|
|
FF_MB_DECISION_RD: rate distortion
|
|
@end table
|
|
|
|
@item -4mv
|
|
Use four motion vector by macroblock (MPEG-4 only).
|
|
@item -part
|
|
Use data partitioning (MPEG-4 only).
|
|
@item -bug param
|
|
Work around encoder bugs that are not auto-detected.
|
|
@item -strict strictness
|
|
How strictly to follow the standards.
|
|
@item -aic
|
|
Enable Advanced intra coding (h263+).
|
|
@item -umv
|
|
Enable Unlimited Motion Vector (h263+)
|
|
|
|
@item -deinterlace
|
|
Deinterlace pictures.
|
|
@item -ilme
|
|
Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
|
|
Use this option if your input file is interlaced and you want
|
|
to keep the interlaced format for minimum losses.
|
|
The alternative is to deinterlace the input stream with
|
|
@option{-deinterlace}, but deinterlacing introduces losses.
|
|
@item -psnr
|
|
Calculate PSNR of compressed frames.
|
|
@item -vstats
|
|
Dump video coding statistics to @file{vstats_HHMMSS.log}.
|
|
@item -vstats_file file
|
|
Dump video coding statistics to @var{file}.
|
|
@item -vhook module
|
|
Insert video processing @var{module}. @var{module} contains the module
|
|
name and its parameters separated by spaces.
|
|
@item -top n
|
|
top=1/bottom=0/auto=-1 field first
|
|
@item -dc precision
|
|
Intra_dc_precision.
|
|
@item -vtag fourcc/tag
|
|
Force video tag/fourcc.
|
|
@item -qphist
|
|
Show QP histogram.
|
|
@item -vbsf bitstream filter
|
|
Bitstream filters available are "dump_extra", "remove_extra", "noise".
|
|
@end table
|
|
|
|
@section Audio Options
|
|
|
|
@table @option
|
|
@item -aframes number
|
|
Set the number of audio frames to record.
|
|
@item -ar freq
|
|
Set the audio sampling frequency (default = 44100 Hz).
|
|
@item -ab bitrate
|
|
Set the audio bitrate in bit/s (default = 64k).
|
|
@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
|
|
specify that the raw codec data must be copied as is.
|
|
@item -newaudio
|
|
Add a new audio track to the output file. If you want to specify parameters,
|
|
do so before @code{-newaudio} (@code{-acodec}, @code{-ab}, etc..).
|
|
|
|
Mapping will be done automatically, if the number of output streams is equal to
|
|
the number of input streams, else it will pick the first one that matches. You
|
|
can override the mapping using @code{-map} as usual.
|
|
|
|
Example:
|
|
@example
|
|
ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384k test.mpg -acodec mp2 -ab 192k -newaudio
|
|
@end example
|
|
@item -alang code
|
|
Set the ISO 639 language code (3 letters) of the current audio stream.
|
|
@end table
|
|
|
|
@section Advanced Audio options:
|
|
|
|
@table @option
|
|
@item -atag fourcc/tag
|
|
Force audio tag/fourcc.
|
|
@item -absf bitstream filter
|
|
Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
|
|
@end table
|
|
|
|
@section Subtitle options:
|
|
|
|
@table @option
|
|
@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 Audio/Video grab options
|
|
|
|
@table @option
|
|
@item -vc channel
|
|
Set video grab channel (DV1394 only).
|
|
@item -tvstd standard
|
|
Set television standard (NTSC, PAL (SECAM)).
|
|
@item -isync
|
|
Synchronize read on input.
|
|
@end table
|
|
|
|
@section Advanced options
|
|
|
|
@table @option
|
|
@item -map input stream id[:input stream id]
|
|
Set stream mapping from input streams to output streams.
|
|
Just enumerate the input streams in the order you want them in the output.
|
|
[input stream id] sets the (input) stream to sync against.
|
|
@item -map_meta_data outfile:infile
|
|
Set meta data information of outfile from infile.
|
|
@item -debug
|
|
Print specific debug info.
|
|
@item -benchmark
|
|
Add timings for benchmarking.
|
|
@item -dump
|
|
Dump each input packet.
|
|
@item -hex
|
|
When dumping packets, also dump the payload.
|
|
@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_input
|
|
Loop over the input stream. Currently it works only for image
|
|
streams. This option is used for automatic FFserver testing.
|
|
@item -loop_output number_of_times
|
|
Repeatedly loop output for formats that support looping such as animated GIF
|
|
(0 will loop the output infinitely).
|
|
@item -threads count
|
|
Thread count.
|
|
@item -vsync parameter
|
|
Video sync method. Video will be stretched/squeezed to match the timestamps,
|
|
it is done by duplicating and dropping frames. With -map you can select from
|
|
which stream the timestamps should be taken. You can leave either video or
|
|
audio unchanged and sync the remaining stream(s) to the unchanged one.
|
|
@item -async samples_per_second
|
|
Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
|
|
the parameter is the maximum samples per second by which the audio is changed.
|
|
-async 1 is a special case where only the start of the audio stream is corrected
|
|
without any later correction.
|
|
@item -copyts
|
|
Copy timestamps from input to output.
|
|
@item -shortest
|
|
Finish encoding when the shortest input stream ends.
|
|
@item -dts_delta_threshold
|
|
Timestamp discontinuity delta threshold.
|
|
@item -muxdelay seconds
|
|
Set the maximum demux-decode delay.
|
|
@item -muxpreload seconds
|
|
Set the initial demux-decode delay.
|
|
@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 standard input or to write
|
|
to standard output.
|
|
|
|
FFmpeg also handles many protocols specified with an URL syntax.
|
|
|
|
Use 'ffmpeg -formats' to see 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 bitrate application, use a low frame rate
|
|
and a small GOP size. This is especially true for RealVideo 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 50k -s qcif -f rv10 /tmp/b.rm
|
|
@end example
|
|
|
|
@item The parameter 'q' which is displayed while encoding is the current
|
|
quantizer. The value 1 indicates that a very good quality could
|
|
be achieved. The value 31 indicates the worst quality. If q=31 appears
|
|
too often, it means that the encoder cannot compress enough to meet
|
|
your bitrate. You must either increase the bitrate, 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
|
|
motion estimation completely (you have only I-frames, which means it
|
|
is about as good as JPEG compression).
|
|
|
|
@item To have very low audio bitrates, 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 the same quality factor in the encoder as in the decoder.
|
|
It allows almost lossless encoding.
|
|
|
|
@end itemize
|
|
|
|
@bye
|