987 lines
28 KiB
Plaintext
987 lines
28 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 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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* 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 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 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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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} (deprecated - use -vf crop=x:y:width:height instead)
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Set top crop band size (in pixels).
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@item -cropbottom @var{size} (deprecated - use -vf crop=x:y:width:height instead)
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Set bottom crop band size (in pixels).
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@item -cropleft @var{size} (deprecated - use -vf crop=x:y:width:height instead)
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Set left crop band size (in pixels).
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@item -cropright @var{size} (deprecated - use -vf crop=x:y:width:height instead)
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Set right crop band size (in pixels).
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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 (@pxref{FFmpeg formula
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evaluator}) (default = @code{tex^qComp}).
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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".
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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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@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 (default = 44100 Hz).
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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 (default = 1).
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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.
|
|
@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 @var{code}
|
|
Set the ISO 639 language code (3 letters) of the current audio stream.
|
|
@end table
|
|
|
|
@section Advanced Audio options:
|
|
|
|
@table @option
|
|
@item -atag @var{fourcc/tag}
|
|
Force audio tag/fourcc.
|
|
@item -absf @var{bitstream_filter}
|
|
Bitstream filters available are "dump_extra", "remove_extra", "noise", "mp3comp", "mp3decomp".
|
|
@end table
|
|
|
|
@section Subtitle options:
|
|
|
|
@table @option
|
|
@item -scodec @var{codec}
|
|
Force subtitle codec ('copy' to copy stream).
|
|
@item -newsubtitle
|
|
Add a new subtitle stream to the current output stream.
|
|
@item -slang @var{code}
|
|
Set the ISO 639 language code (3 letters) of the current subtitle stream.
|
|
@item -sn
|
|
Disable subtitle recording.
|
|
@item -sbsf @var{bitstream_filter}
|
|
Bitstream filters available are "mov2textsub", "text2movsub".
|
|
@example
|
|
ffmpeg -i file.mov -an -vn -sbsf mov2textsub -scodec copy -f rawvideo sub.txt
|
|
@end example
|
|
@end table
|
|
|
|
@section Audio/Video grab options
|
|
|
|
@table @option
|
|
@item -vc @var{channel}
|
|
Set video grab channel (DV1394 only).
|
|
@item -tvstd @var{standard}
|
|
Set television standard (NTSC, PAL (SECAM)).
|
|
@item -isync
|
|
Synchronize read on input.
|
|
@end table
|
|
|
|
@section Advanced options
|
|
|
|
@table @option
|
|
@item -map @var{input_stream_id}[:@var{sync_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.
|
|
@var{sync_stream_id} if specified sets the input stream to sync
|
|
against.
|
|
@item -map_meta_data @var{outfile}:@var{infile}
|
|
Set meta data information of @var{outfile} from @var{infile}.
|
|
@item -debug
|
|
Print specific debug info.
|
|
@item -benchmark
|
|
Show benchmarking information at the end of an encode.
|
|
Shows CPU time used and maximum memory consumption.
|
|
Maximum memory consumption is not supported on all systems,
|
|
it will usually display as 0 if not supported.
|
|
@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 @var{size}
|
|
Set RTP payload size in bytes.
|
|
@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 @var{number_of_times}
|
|
Repeatedly loop output for formats that support looping such as animated GIF
|
|
(0 will loop the output infinitely).
|
|
@item -threads @var{count}
|
|
Thread count.
|
|
@item -vsync @var{parameter}
|
|
Video sync method.
|
|
0 Each frame is passed with its timestamp from the demuxer to the muxer
|
|
1 Frames will be duplicated and dropped to achieve exactly the requested
|
|
constant framerate.
|
|
2 Frames are passed through with their timestamp or dropped so as to prevent
|
|
2 frames from having the same timestamp
|
|
-1 Chooses between 1 and 2 depending on muxer capabilities. This is the default method.
|
|
|
|
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 @var{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 @var{seconds}
|
|
Set the maximum demux-decode delay.
|
|
@item -muxpreload @var{seconds}
|
|
Set the initial demux-decode delay.
|
|
@item -streamid @var{output-stream-index}:@var{new-value}
|
|
Assign a new value to a stream's stream-id field in the next output file.
|
|
All stream-id fields are reset to default for each output file.
|
|
|
|
For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
|
|
an output mpegts file:
|
|
@example
|
|
ffmpeg -i infile -streamid 0:33 -streamid 1:36 out.ts
|
|
@end example
|
|
@end table
|
|
|
|
@section Preset files
|
|
|
|
A preset file contains a sequence of @var{option}=@var{value} pairs,
|
|
one for each line, specifying a sequence of options which would be
|
|
awkward to specify on the command line. Lines starting with the hash
|
|
('#') character are ignored and are used to provide comments. Check
|
|
the @file{ffpresets} directory in the FFmpeg source tree for examples.
|
|
|
|
Preset files are specified with the @code{vpre}, @code{apre},
|
|
@code{spre}, and @code{fpre} options. The @code{fpre} option takes the
|
|
filename of the preset instead of a preset name as input and can be
|
|
used for any kind of codec. For the @code{vpre}, @code{apre}, and
|
|
@code{spre} options, the options specified in a preset file are
|
|
applied to the currently selected codec of the same type as the preset
|
|
option.
|
|
|
|
The argument passed to the @code{vpre}, @code{apre}, and @code{spre}
|
|
preset options identifies the preset file to use according to the
|
|
following rules:
|
|
|
|
First ffmpeg searches for a file named @var{arg}.ffpreset in the
|
|
directories @file{$FFMPEG_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
|
|
the datadir defined at configuration time (usually @file{PREFIX/share/ffmpeg})
|
|
in that order. For example, if the argument is @code{libx264-max}, it will
|
|
search for the file @file{libx264-max.ffpreset}.
|
|
|
|
If no such file is found, then ffmpeg will search for a file named
|
|
@var{codec_name}-@var{arg}.ffpreset in the above-mentioned
|
|
directories, where @var{codec_name} is the name of the codec to which
|
|
the preset file options will be applied. For example, if you select
|
|
the video codec with @code{-vcodec libx264} and use @code{-vpre max},
|
|
then it will search for the file @file{libx264-max.ffpreset}.
|
|
|
|
@anchor{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 statements are available: @code{ld}, @code{st},
|
|
@code{while}.
|
|
|
|
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 atan(x)
|
|
@item asin(x)
|
|
@item acos(x)
|
|
@item exp(x)
|
|
@item log(x)
|
|
@item abs(x)
|
|
@item squish(x)
|
|
@item gauss(x)
|
|
@item mod(x, y)
|
|
@item max(x, y)
|
|
@item min(x, y)
|
|
@item eq(x, y)
|
|
@item gte(x, y)
|
|
@item gt(x, y)
|
|
@item lte(x, y)
|
|
@item lt(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
|
|
|
|
@section Protocols
|
|
|
|
The file name 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 -protocols' 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
|
|
@c man begin 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 Hz for MPEG audio, 22050 or 11025 for AC-3).
|
|
|
|
@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
|
|
@c man end TIPS
|
|
|
|
@chapter Examples
|
|
@c man begin EXAMPLES
|
|
|
|
@section Video and Audio grabbing
|
|
|
|
FFmpeg can grab video and audio from devices given that you specify the input
|
|
format and device.
|
|
|
|
@example
|
|
ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
|
|
@end example
|
|
|
|
Note that you must activate the right video source and channel before
|
|
launching FFmpeg with any TV viewer such as xawtv
|
|
(@url{http://linux.bytesex.org/xawtv/}) by Gerd Knorr. You also
|
|
have to set the audio recording levels correctly with a
|
|
standard mixer.
|
|
|
|
@section X11 grabbing
|
|
|
|
FFmpeg can grab the X11 display.
|
|
|
|
@example
|
|
ffmpeg -f x11grab -s cif -i :0.0 /tmp/out.mpg
|
|
@end example
|
|
|
|
0.0 is display.screen number of your X11 server, same as
|
|
the DISPLAY environment variable.
|
|
|
|
@example
|
|
ffmpeg -f x11grab -s cif -i :0.0+10,20 /tmp/out.mpg
|
|
@end example
|
|
|
|
0.0 is display.screen number of your X11 server, same as the DISPLAY environment
|
|
variable. 10 is the x-offset and 20 the y-offset for the grabbing.
|
|
|
|
@section Video and Audio file format conversion
|
|
|
|
* FFmpeg can use any supported file format and protocol as input:
|
|
|
|
Examples:
|
|
|
|
* You can use YUV files as input:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
|
|
@end example
|
|
|
|
It will use the files:
|
|
@example
|
|
/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
|
|
/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
|
|
@end example
|
|
|
|
The Y files use twice the resolution of the U and V files. They are
|
|
raw files, without header. They can be generated by all decent video
|
|
decoders. You must specify the size of the image with the @option{-s} option
|
|
if FFmpeg cannot guess it.
|
|
|
|
* You can input from a raw YUV420P file:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/test.yuv /tmp/out.avi
|
|
@end example
|
|
|
|
test.yuv is a file containing raw YUV planar data. Each frame is composed
|
|
of the Y plane followed by the U and V planes at half vertical and
|
|
horizontal resolution.
|
|
|
|
* You can output to a raw YUV420P file:
|
|
|
|
@example
|
|
ffmpeg -i mydivx.avi hugefile.yuv
|
|
@end example
|
|
|
|
* You can set several input files and output files:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
|
|
@end example
|
|
|
|
Converts the audio file a.wav and the raw YUV video file a.yuv
|
|
to MPEG file a.mpg.
|
|
|
|
* You can also do audio and video conversions at the same time:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
|
|
@end example
|
|
|
|
Converts a.wav to MPEG audio at 22050 Hz sample rate.
|
|
|
|
* You can encode to several formats at the same time and define a
|
|
mapping from input stream to output streams:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/a.wav -ab 64k /tmp/a.mp2 -ab 128k /tmp/b.mp2 -map 0:0 -map 0:0
|
|
@end example
|
|
|
|
Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
|
|
file:index' specifies which input stream is used for each output
|
|
stream, in the order of the definition of output streams.
|
|
|
|
* You can transcode decrypted VOBs:
|
|
|
|
@example
|
|
ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800k -g 300 -bf 2 -acodec libmp3lame -ab 128k snatch.avi
|
|
@end example
|
|
|
|
This is a typical DVD ripping example; the input is a VOB file, the
|
|
output an AVI file with MPEG-4 video and MP3 audio. Note that in this
|
|
command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
|
|
GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
|
|
input video. Furthermore, the audio stream is MP3-encoded so you need
|
|
to enable LAME support by passing @code{--enable-libmp3lame} to configure.
|
|
The mapping is particularly useful for DVD transcoding
|
|
to get the desired audio language.
|
|
|
|
NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
|
|
|
|
* You can extract images from a video, or create a video from many images:
|
|
|
|
For extracting images from a video:
|
|
@example
|
|
ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
|
|
@end example
|
|
|
|
This will extract one video frame per second from the video and will
|
|
output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
|
|
etc. Images will be rescaled to fit the new WxH values.
|
|
|
|
If you want to extract just a limited number of frames, you can use the
|
|
above command in combination with the -vframes or -t option, or in
|
|
combination with -ss to start extracting from a certain point in time.
|
|
|
|
For creating a video from many images:
|
|
@example
|
|
ffmpeg -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
|
|
@end example
|
|
|
|
The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
|
|
composed of three digits padded with zeroes to express the sequence
|
|
number. It is the same syntax supported by the C printf function, but
|
|
only formats accepting a normal integer are suitable.
|
|
|
|
* You can put many streams of the same type in the output:
|
|
|
|
@example
|
|
ffmpeg -i test1.avi -i test2.avi -vcodec copy -acodec copy -vcodec copy -acodec copy test12.avi -newvideo -newaudio
|
|
@end example
|
|
|
|
In addition to the first video and audio streams, the resulting
|
|
output file @file{test12.avi} will contain the second video
|
|
and the second audio stream found in the input streams list.
|
|
|
|
The @code{-newvideo}, @code{-newaudio} and @code{-newsubtitle}
|
|
options have to be specified immediately after the name of the output
|
|
file to which you want to add them.
|
|
@c man end EXAMPLES
|
|
|
|
@include indevs.texi
|
|
@include outdevs.texi
|
|
@include filters.texi
|
|
|
|
@ignore
|
|
|
|
@setfilename ffmpeg
|
|
@settitle FFmpeg video converter
|
|
|
|
@c man begin SEEALSO
|
|
ffplay(1), ffprobe(1), ffserver(1) and the FFmpeg HTML documentation
|
|
@c man end
|
|
|
|
@c man begin AUTHORS
|
|
The FFmpeg developers
|
|
@c man end
|
|
|
|
@end ignore
|
|
|
|
@bye
|