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\input texinfo @c -*- texinfo -*-
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@settitle FFmpeg Documentation
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@titlepage
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@center @titlefont{FFmpeg Documentation}
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@end titlepage
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@top
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@contents
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@chapter Synopsis
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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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@chapter Description
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@c man begin DESCRIPTION
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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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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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@itemize
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@item
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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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@item
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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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@item
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To force the frame rate of the input file (valid for raw formats only)
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to 1 fps and the frame rate of the output file to 24 fps:
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@example
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ffmpeg -r 1 -i input.m2v -r 24 output.avi
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@end example
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@end itemize
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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 DESCRIPTION
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@chapter Options
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@c man begin OPTIONS
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@include fftools-common-opts.texi
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@section Main options
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@table @option
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@item -f @var{fmt}
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Force format.
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@item -i @var{filename}
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input file name
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@item -y
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Overwrite output files.
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@item -t @var{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 @var{limit_size}
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Set the file size limit.
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@item -ss @var{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 @var{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 -timestamp @var{time}
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Set the recording timestamp in the container.
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The syntax for @var{time} is:
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@example
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now|([(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH[:MM[:SS[.m...]]])|(HH[MM[SS[.m...]]]))[Z|z])
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@end example
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If the value is "now" it takes the current time.
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Time is local time unless 'Z' or 'z' is appended, in which case it is
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interpreted as UTC.
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If the year-month-day part is not specified it takes the current
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year-month-day.
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@item -metadata @var{key}=@var{value}
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Set a metadata key/value pair.
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For example, for setting the title in the output file:
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@example
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ffmpeg -i in.avi -metadata title="my title" out.flv
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@end example
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@item -v @var{number}
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Set the logging verbosity level.
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@item -target @var{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 @var{number}
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Set the number of data frames to record.
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@item -scodec @var{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 @var{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 @var{bitrate}
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Set the video bitrate in bit/s (default = 200 kb/s).
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@item -vframes @var{number}
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Set the number of video frames to record.
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@item -r @var{fps}
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Set frame rate (Hz value, fraction or abbreviation), (default = 25).
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@item -s @var{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 16cif
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1408x1152
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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 @var{aspect}
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Set aspect ratio (4:3, 16:9 or 1.3333, 1.7777).
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@item -croptop @var{size}
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@item -cropbottom @var{size}
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@item -cropleft @var{size}
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@item -cropright @var{size}
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All the crop options have been removed. Use -vf
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crop=width:height:x:y instead.
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@item -padtop @var{size}
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@item -padbottom @var{size}
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@item -padleft @var{size}
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@item -padright @var{size}
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@item -padcolor @var{hex_color}
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All the pad options have been removed. Use -vf
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pad=width:height:x:y:color instead.
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@item -vn
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Disable video recording.
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@item -bt @var{tolerance}
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Set video bitrate tolerance (in bits, default 4000k).
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Has a minimum value of: (target_bitrate/target_framerate).
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In 1-pass mode, bitrate tolerance specifies how far ratecontrol is
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willing to deviate from the target average bitrate value. This is
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not related to min/max bitrate. Lowering tolerance too much has
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an adverse effect on quality.
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@item -maxrate @var{bitrate}
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Set max video bitrate (in bit/s).
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Requires -bufsize to be set.
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@item -minrate @var{bitrate}
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Set min video bitrate (in bit/s).
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Most useful in setting up a CBR encode:
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@example
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ffmpeg -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
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@end example
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It is of little use elsewise.
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@item -bufsize @var{size}
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Set video buffer verifier buffer size (in bits).
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@item -vcodec @var{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 @var{n}
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Select the pass number (1 or 2). It is used to do two-pass
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video encoding. The statistics of the video are recorded in the first
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pass into a log file (see also the option -passlogfile),
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and in the second pass that log file is used to generate the video
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at the exact requested bitrate.
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On pass 1, you may just deactivate audio and set output to null,
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examples for Windows and Unix:
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@example
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ffmpeg -i foo.mov -vcodec libxvid -pass 1 -an -f rawvideo -y NUL
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ffmpeg -i foo.mov -vcodec libxvid -pass 1 -an -f rawvideo -y /dev/null
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@end example
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@item -passlogfile @var{prefix}
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Set two-pass log file name prefix to @var{prefix}, the default file name
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prefix is ``ffmpeg2pass''. The complete file name will be
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@file{PREFIX-N.log}, where N is a number specific to the output
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stream.
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@item -newvideo
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Add a new video stream to the current output stream.
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@item -vlang @var{code}
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Set the ISO 639 language code (3 letters) of the current video stream.
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@item -vf @var{filter_graph}
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@var{filter_graph} is a description of the filter graph to apply to
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the input video.
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Use the option "-filters" to show all the available filters (including
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also sources and sinks).
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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 @var{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 @var{flags}
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Set SwScaler flags.
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@item -g @var{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 @var{n}
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Discard threshold.
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@item -qscale @var{q}
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Use fixed video quantizer scale (VBR).
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@item -qmin @var{q}
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minimum video quantizer scale (VBR)
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@item -qmax @var{q}
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maximum video quantizer scale (VBR)
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@item -qdiff @var{q}
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maximum difference between the quantizer scales (VBR)
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@item -qblur @var{blur}
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video quantizer scale blur (VBR) (range 0.0 - 1.0)
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@item -qcomp @var{compression}
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video quantizer scale compression (VBR) (default 0.5).
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Constant of ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0
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@item -lmin @var{lambda}
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minimum video lagrange factor (VBR)
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@item -lmax @var{lambda}
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max video lagrange factor (VBR)
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@item -mblmin @var{lambda}
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minimum macroblock quantizer scale (VBR)
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@item -mblmax @var{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 @var{complexity}
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initial complexity for single pass encoding
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@item -b_qfactor @var{factor}
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qp factor between P- and B-frames
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@item -i_qfactor @var{factor}
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qp factor between P- and I-frames
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@item -b_qoffset @var{offset}
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qp offset between P- and B-frames
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@item -i_qoffset @var{offset}
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qp offset between P- and I-frames
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@item -rc_eq @var{equation}
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Set rate control equation (see section "Expression Evaluation")
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(default = @code{tex^qComp}).
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When computing the rate control equation expression, besides the
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standard functions defined in the section "Expression Evaluation", the
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following functions are available:
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@table @var
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@item bits2qp(bits)
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@item qp2bits(qp)
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@end table
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and the following constants are available:
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@table @var
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@item iTex
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@item pTex
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@item tex
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@item mv
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@item fCode
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@item iCount
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@item mcVar
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@item var
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@item isI
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@item isP
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@item isB
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@item avgQP
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@item qComp
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@item avgIITex
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@item avgPITex
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@item avgPPTex
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@item avgBPTex
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@item avgTex
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@end table
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@item -rc_override @var{override}
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rate control override for specific intervals
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@item -me_method @var{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 @var{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 @var{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 @var{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 @var{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 @var{frames}
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Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
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@item -mbd @var{mode}
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macroblock decision
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@table @samp
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@item 0
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FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in FFmpeg).
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@item 1
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FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
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@item 2
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FF_MB_DECISION_RD: rate distortion
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@end table
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@item -4mv
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Use four motion vector by macroblock (MPEG-4 only).
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@item -part
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Use data partitioning (MPEG-4 only).
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@item -bug @var{param}
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Work around encoder bugs that are not auto-detected.
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@item -strict @var{strictness}
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How strictly to follow the standards.
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@item -aic
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Enable Advanced intra coding (h263+).
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@item -umv
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Enable Unlimited Motion Vector (h263+)
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@item -deinterlace
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Deinterlace pictures.
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@item -ilme
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Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
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Use this option if your input file is interlaced and you want
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to keep the interlaced format for minimum losses.
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The alternative is to deinterlace the input stream with
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@option{-deinterlace}, but deinterlacing introduces losses.
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@item -psnr
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Calculate PSNR of compressed frames.
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@item -vstats
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Dump video coding statistics to @file{vstats_HHMMSS.log}.
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@item -vstats_file @var{file}
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Dump video coding statistics to @var{file}.
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@item -top @var{n}
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top=1/bottom=0/auto=-1 field first
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@item -dc @var{precision}
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Intra_dc_precision.
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@item -vtag @var{fourcc/tag}
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Force video tag/fourcc.
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@item -qphist
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Show QP histogram.
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@item -vbsf @var{bitstream_filter}
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Bitstream filters available are "dump_extra", "remove_extra", "noise", "h264_mp4toannexb", "imxdump", "mjpegadump", "mjpeg2jpeg".
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@example
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ffmpeg -i h264.mp4 -vcodec copy -vbsf h264_mp4toannexb -an out.h264
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@end example
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@item -force_key_frames @var{time}[,@var{time}...]
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Force key frames at the specified timestamps, more precisely at the first
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frames after each specified time.
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This option can be useful to ensure that a seek point is present at a
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chapter mark or any other designated place in the output file.
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The timestamps must be specified in ascending order.
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@end table
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@section Audio Options
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@table @option
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@item -aframes @var{number}
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Set the number of audio frames to record.
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@item -ar @var{freq}
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Set the audio sampling frequency. For input streams it is set by
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default to 44100 Hz, for output streams it is set by default to the
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frequency of the input stream. If the input file has audio streams
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with different frequencies, the behaviour is undefined.
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@item -ab @var{bitrate}
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Set the audio bitrate in bit/s (default = 64k).
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@item -aq @var{q}
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Set the audio quality (codec-specific, VBR).
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@item -ac @var{channels}
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Set the number of audio channels. For input streams it is set by
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default to 1, for output streams it is set by default to the same
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number of audio channels in input. If the input file has audio streams
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with different channel count, the behaviour is undefined.
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@item -an
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Disable audio recording.
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@item -acodec @var{codec}
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Force audio codec to @var{codec}. Use the @code{copy} special value to
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specify that the raw codec data must be copied as is.
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@item -newaudio
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Add a new audio track to the output file. If you want to specify parameters,
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do so before @code{-newaudio} (@code{-acodec}, @code{-ab}, etc..).
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Mapping will be done automatically, if the number of output streams is equal to
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the number of input streams, else it will pick the first one that matches. You
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can override the mapping using @code{-map} as usual.
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Example:
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@example
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ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384k test.mpg -acodec mp2 -ab 192k -newaudio
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@end example
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@item -alang @var{code}
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Set the ISO 639 language code (3 letters) of the current audio stream.
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@end table
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@section Advanced Audio options:
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@table @option
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@item -atag @var{fourcc/tag}
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Force audio tag/fourcc.
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@item -absf @var{bitstream_filter}
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Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
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@end table
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@section Subtitle options:
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@table @option
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@item -scodec @var{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 @var{code}
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Set the ISO 639 language code (3 letters) of the current subtitle stream.
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@item -sn
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Disable subtitle recording.
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@item -sbsf @var{bitstream_filter}
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Bitstream filters available are "mov2textsub", "text2movsub".
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@example
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ffmpeg -i file.mov -an -vn -sbsf mov2textsub -scodec copy -f rawvideo sub.txt
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@end example
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@end table
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@section Audio/Video grab options
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@table @option
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@item -vc @var{channel}
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Set video grab channel (DV1394 only).
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@item -tvstd @var{standard}
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Set television standard (NTSC, PAL (SECAM)).
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@item -isync
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Synchronize read on input.
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@end table
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@section Advanced options
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@table @option
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@item -map @var{input_file_id}.@var{input_stream_id}[:@var{sync_file_id}.@var{sync_stream_id}]
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Designate an input stream as a source for the output file. Each input
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stream is identified by the input file index @var{input_file_id} and
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the input stream index @var{input_stream_id} within the input
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file. Both indexes start at 0. If specified,
631
@var{sync_file_id}.@var{sync_stream_id} sets which input stream
632
is used as a presentation sync reference.
633

    
634
The @code{-map} options must be specified just after the output file.
635
If any @code{-map} options are used, the number of @code{-map} options
636
on the command line must match the number of streams in the output
637
file. The first @code{-map} option on the command line specifies the
638
source for output stream 0, the second @code{-map} option specifies
639
the source for output stream 1, etc.
640

    
641
For example, if you have two audio streams in the first input file,
642
these streams are identified by "0.0" and "0.1". You can use
643
@code{-map} to select which stream to place in an output file. For
644
example:
645
@example
646
ffmpeg -i INPUT out.wav -map 0.1
647
@end example
648
will map the input stream in @file{INPUT} identified by "0.1" to
649
the (single) output stream in @file{out.wav}.
650

    
651
For example, to select the stream with index 2 from input file
652
@file{a.mov} (specified by the identifier "0.2"), and stream with
653
index 6 from input @file{b.mov} (specified by the identifier "1.6"),
654
and copy them to the output file @file{out.mov}:
655
@example
656
ffmpeg -i a.mov -i b.mov -vcodec copy -acodec copy out.mov -map 0.2 -map 1.6
657
@end example
658

    
659
To add more streams to the output file, you can use the
660
@code{-newaudio}, @code{-newvideo}, @code{-newsubtitle} options.
661

    
662
@item -map_meta_data @var{outfile}[,@var{metadata}]:@var{infile}[,@var{metadata}]
663
Deprecated, use @var{-map_metadata} instead.
664

    
665
@item -map_metadata @var{outfile}[,@var{metadata}]:@var{infile}[,@var{metadata}]
666
Set metadata information of @var{outfile} from @var{infile}. Note that those
667
are file indices (zero-based), not filenames.
668
Optional @var{metadata} parameters specify, which metadata to copy - (g)lobal
669
(i.e. metadata that applies to the whole file), per-(s)tream, per-(c)hapter or
670
per-(p)rogram. All metadata specifiers other than global must be followed by the
671
stream/chapter/program number. If metadata specifier is omitted, it defaults to
672
global.
673

    
674
By default, global metadata is copied from the first input file to all output files,
675
per-stream and per-chapter metadata is copied along with streams/chapters. These
676
default mappings are disabled by creating any mapping of the relevant type. A negative
677
file index can be used to create a dummy mapping that just disables automatic copying.
678

    
679
For example to copy metadata from the first stream of the input file to global metadata
680
of the output file:
681
@example
682
ffmpeg -i in.ogg -map_metadata 0:0,s0 out.mp3
683
@end example
684
@item -map_chapters @var{outfile}:@var{infile}
685
Copy chapters from @var{infile} to @var{outfile}. If no chapter mapping is specified,
686
then chapters are copied from the first input file with at least one chapter to all
687
output files. Use a negative file index to disable any chapter copying.
688
@item -debug
689
Print specific debug info.
690
@item -benchmark
691
Show benchmarking information at the end of an encode.
692
Shows CPU time used and maximum memory consumption.
693
Maximum memory consumption is not supported on all systems,
694
it will usually display as 0 if not supported.
695
@item -dump
696
Dump each input packet.
697
@item -hex
698
When dumping packets, also dump the payload.
699
@item -bitexact
700
Only use bit exact algorithms (for codec testing).
701
@item -ps @var{size}
702
Set RTP payload size in bytes.
703
@item -re
704
Read input at native frame rate. Mainly used to simulate a grab device.
705
@item -loop_input
706
Loop over the input stream. Currently it works only for image
707
streams. This option is used for automatic FFserver testing.
708
@item -loop_output @var{number_of_times}
709
Repeatedly loop output for formats that support looping such as animated GIF
710
(0 will loop the output infinitely).
711
@item -threads @var{count}
712
Thread count.
713
@item -vsync @var{parameter}
714
Video sync method.
715

    
716
@table @option
717
@item 0
718
Each frame is passed with its timestamp from the demuxer to the muxer.
719
@item 1
720
Frames will be duplicated and dropped to achieve exactly the requested
721
constant framerate.
722
@item 2
723
Frames are passed through with their timestamp or dropped so as to
724
prevent 2 frames from having the same timestamp.
725
@item -1
726
Chooses between 1 and 2 depending on muxer capabilities. This is the
727
default method.
728
@end table
729

    
730
With -map you can select from which stream the timestamps should be
731
taken. You can leave either video or audio unchanged and sync the
732
remaining stream(s) to the unchanged one.
733

    
734
@item -async @var{samples_per_second}
735
Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
736
the parameter is the maximum samples per second by which the audio is changed.
737
-async 1 is a special case where only the start of the audio stream is corrected
738
without any later correction.
739
@item -copyts
740
Copy timestamps from input to output.
741
@item -copytb
742
Copy input stream time base from input to output when stream copying.
743
@item -shortest
744
Finish encoding when the shortest input stream ends.
745
@item -dts_delta_threshold
746
Timestamp discontinuity delta threshold.
747
@item -muxdelay @var{seconds}
748
Set the maximum demux-decode delay.
749
@item -muxpreload @var{seconds}
750
Set the initial demux-decode delay.
751
@item -streamid @var{output-stream-index}:@var{new-value}
752
Assign a new stream-id value to an output stream. This option should be
753
specified prior to the output filename to which it applies.
754
For the situation where multiple output files exist, a streamid
755
may be reassigned to a different value.
756

    
757
For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
758
an output mpegts file:
759
@example
760
ffmpeg -i infile -streamid 0:33 -streamid 1:36 out.ts
761
@end example
762
@end table
763

    
764
@section Preset files
765

    
766
A preset file contains a sequence of @var{option}=@var{value} pairs,
767
one for each line, specifying a sequence of options which would be
768
awkward to specify on the command line. Lines starting with the hash
769
('#') character are ignored and are used to provide comments. Check
770
the @file{ffpresets} directory in the Libav source tree for examples.
771

    
772
Preset files are specified with the @code{vpre}, @code{apre},
773
@code{spre}, and @code{fpre} options. The @code{fpre} option takes the
774
filename of the preset instead of a preset name as input and can be
775
used for any kind of codec. For the @code{vpre}, @code{apre}, and
776
@code{spre} options, the options specified in a preset file are
777
applied to the currently selected codec of the same type as the preset
778
option.
779

    
780
The argument passed to the @code{vpre}, @code{apre}, and @code{spre}
781
preset options identifies the preset file to use according to the
782
following rules:
783

    
784
First ffmpeg searches for a file named @var{arg}.ffpreset in the
785
directories @file{$FFMPEG_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
786
the datadir defined at configuration time (usually @file{PREFIX/share/ffmpeg})
787
in that order. For example, if the argument is @code{libx264-max}, it will
788
search for the file @file{libx264-max.ffpreset}.
789

    
790
If no such file is found, then ffmpeg will search for a file named
791
@var{codec_name}-@var{arg}.ffpreset in the above-mentioned
792
directories, where @var{codec_name} is the name of the codec to which
793
the preset file options will be applied. For example, if you select
794
the video codec with @code{-vcodec libx264} and use @code{-vpre max},
795
then it will search for the file @file{libx264-max.ffpreset}.
796
@c man end
797

    
798
@chapter Tips
799
@c man begin TIPS
800

    
801
@itemize
802
@item
803
For streaming at very low bitrate application, use a low frame rate
804
and a small GOP size. This is especially true for RealVideo where
805
the Linux player does not seem to be very fast, so it can miss
806
frames. An example is:
807

    
808
@example
809
ffmpeg -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
810
@end example
811

    
812
@item
813
The parameter 'q' which is displayed while encoding is the current
814
quantizer. The value 1 indicates that a very good quality could
815
be achieved. The value 31 indicates the worst quality. If q=31 appears
816
too often, it means that the encoder cannot compress enough to meet
817
your bitrate. You must either increase the bitrate, decrease the
818
frame rate or decrease the frame size.
819

    
820
@item
821
If your computer is not fast enough, you can speed up the
822
compression at the expense of the compression ratio. You can use
823
'-me zero' to speed up motion estimation, and '-intra' to disable
824
motion estimation completely (you have only I-frames, which means it
825
is about as good as JPEG compression).
826

    
827
@item
828
To have very low audio bitrates, reduce the sampling frequency
829
(down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
830

    
831
@item
832
To have a constant quality (but a variable bitrate), use the option
833
'-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
834
quality).
835

    
836
@item
837
When converting video files, you can use the '-sameq' option which
838
uses the same quality factor in the encoder as in the decoder.
839
It allows almost lossless encoding.
840

    
841
@end itemize
842
@c man end TIPS
843

    
844
@chapter Examples
845
@c man begin EXAMPLES
846

    
847
@section Video and Audio grabbing
848

    
849
FFmpeg can grab video and audio from devices given that you specify the input
850
format and device.
851

    
852
@example
853
ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
854
@end example
855

    
856
Note that you must activate the right video source and channel before
857
launching FFmpeg with any TV viewer such as xawtv
858
(@url{http://linux.bytesex.org/xawtv/}) by Gerd Knorr. You also
859
have to set the audio recording levels correctly with a
860
standard mixer.
861

    
862
@section X11 grabbing
863

    
864
FFmpeg can grab the X11 display.
865

    
866
@example
867
ffmpeg -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
868
@end example
869

    
870
0.0 is display.screen number of your X11 server, same as
871
the DISPLAY environment variable.
872

    
873
@example
874
ffmpeg -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
875
@end example
876

    
877
0.0 is display.screen number of your X11 server, same as the DISPLAY environment
878
variable. 10 is the x-offset and 20 the y-offset for the grabbing.
879

    
880
@section Video and Audio file format conversion
881

    
882
FFmpeg can use any supported file format and protocol as input:
883

    
884
Examples:
885
@itemize
886
@item
887
You can use YUV files as input:
888

    
889
@example
890
ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
891
@end example
892

    
893
It will use the files:
894
@example
895
/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
896
/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
897
@end example
898

    
899
The Y files use twice the resolution of the U and V files. They are
900
raw files, without header. They can be generated by all decent video
901
decoders. You must specify the size of the image with the @option{-s} option
902
if FFmpeg cannot guess it.
903

    
904
@item
905
You can input from a raw YUV420P file:
906

    
907
@example
908
ffmpeg -i /tmp/test.yuv /tmp/out.avi
909
@end example
910

    
911
test.yuv is a file containing raw YUV planar data. Each frame is composed
912
of the Y plane followed by the U and V planes at half vertical and
913
horizontal resolution.
914

    
915
@item
916
You can output to a raw YUV420P file:
917

    
918
@example
919
ffmpeg -i mydivx.avi hugefile.yuv
920
@end example
921

    
922
@item
923
You can set several input files and output files:
924

    
925
@example
926
ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
927
@end example
928

    
929
Converts the audio file a.wav and the raw YUV video file a.yuv
930
to MPEG file a.mpg.
931

    
932
@item
933
You can also do audio and video conversions at the same time:
934

    
935
@example
936
ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
937
@end example
938

    
939
Converts a.wav to MPEG audio at 22050 Hz sample rate.
940

    
941
@item
942
You can encode to several formats at the same time and define a
943
mapping from input stream to output streams:
944

    
945
@example
946
ffmpeg -i /tmp/a.wav -ab 64k /tmp/a.mp2 -ab 128k /tmp/b.mp2 -map 0:0 -map 0:0
947
@end example
948

    
949
Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
950
file:index' specifies which input stream is used for each output
951
stream, in the order of the definition of output streams.
952

    
953
@item
954
You can transcode decrypted VOBs:
955

    
956
@example
957
ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800k -g 300 -bf 2 -acodec libmp3lame -ab 128k snatch.avi
958
@end example
959

    
960
This is a typical DVD ripping example; the input is a VOB file, the
961
output an AVI file with MPEG-4 video and MP3 audio. Note that in this
962
command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
963
GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
964
input video. Furthermore, the audio stream is MP3-encoded so you need
965
to enable LAME support by passing @code{--enable-libmp3lame} to configure.
966
The mapping is particularly useful for DVD transcoding
967
to get the desired audio language.
968

    
969
NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
970

    
971
@item
972
You can extract images from a video, or create a video from many images:
973

    
974
For extracting images from a video:
975
@example
976
ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
977
@end example
978

    
979
This will extract one video frame per second from the video and will
980
output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
981
etc. Images will be rescaled to fit the new WxH values.
982

    
983
If you want to extract just a limited number of frames, you can use the
984
above command in combination with the -vframes or -t option, or in
985
combination with -ss to start extracting from a certain point in time.
986

    
987
For creating a video from many images:
988
@example
989
ffmpeg -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
990
@end example
991

    
992
The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
993
composed of three digits padded with zeroes to express the sequence
994
number. It is the same syntax supported by the C printf function, but
995
only formats accepting a normal integer are suitable.
996

    
997
@item
998
You can put many streams of the same type in the output:
999

    
1000
@example
1001
ffmpeg -i test1.avi -i test2.avi -vcodec copy -acodec copy -vcodec copy -acodec copy test12.avi -newvideo -newaudio
1002
@end example
1003

    
1004
In addition to the first video and audio streams, the resulting
1005
output file @file{test12.avi} will contain the second video
1006
and the second audio stream found in the input streams list.
1007

    
1008
The @code{-newvideo}, @code{-newaudio} and @code{-newsubtitle}
1009
options have to be specified immediately after the name of the output
1010
file to which you want to add them.
1011

    
1012
@end itemize
1013
@c man end EXAMPLES
1014

    
1015
@include eval.texi
1016
@include encoders.texi
1017
@include demuxers.texi
1018
@include muxers.texi
1019
@include indevs.texi
1020
@include outdevs.texi
1021
@include protocols.texi
1022
@include bitstream_filters.texi
1023
@include filters.texi
1024
@include metadata.texi
1025

    
1026
@ignore
1027

    
1028
@setfilename ffmpeg
1029
@settitle FFmpeg video converter
1030

    
1031
@c man begin SEEALSO
1032
ffplay(1), ffprobe(1), ffserver(1) and the Libav HTML documentation
1033
@c man end
1034

    
1035
@c man begin AUTHORS
1036
The Libav developers
1037
@c man end
1038

    
1039
@end ignore
1040

    
1041
@bye