lmcache--lmcache
wehub-resource-sync
63 行
2.7 KiB
Plaintext
63 行
2.7 KiB
Plaintext
FFMPEG(1) FFMPEG(1)
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NAME
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ffmpeg - ffmpeg video converter
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SYNOPSIS
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ffmpeg [global_options] {[input_file_options] -i input_url} ...
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{[output_file_options] output_url} ...
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DESCRIPTION
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ffmpeg is a very fast video and audio converter that can also
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grab from a live audio/video source. It can also convert between
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arbitrary sample rates and resize video on the fly with a high
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quality polyphase filter.
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ffmpeg reads from an arbitrary number of input "files" (which
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can be regular files, pipes, network streams, grabbing devices,
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etc.), specified by the "-i" option, and writes to an arbitrary
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number of output "files", which are specified by a plain output
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url. Anything found on the command line which cannot be inter-
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preted as an option is considered to be an output url.
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Each input or output url can, in principle, contain any number of
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streams of different types (video/audio/subtitle/attachment/data).
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The allowed number and/or types of streams may be limited by the
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container format. Selecting which streams from which inputs will
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go into which output is either done automatically or with the
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"-map" option (see the Stream selection chapter).
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To refer to input files in options, you must use their indices
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(0-based). E.g. the first input file is 0, the second is 1, etc.
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Similarly, streams within a file are referred to by their indices.
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E.g. "2:3" refers to the fourth stream in the third input file.
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Also see the Stream specifiers chapter.
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As a general rule, options are applied to the next specified file.
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Therefore, order is important, and you can have the same option on
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the command line multiple times. Each occurrence is then applied
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to the next input or output file. Exceptions from this rule are
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the global options (e.g. verbosity level), which should be specified
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first.
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Do not mix input and output files -- first specify all input files,
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then all output files. Also do not mix options which belong to
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different files. All options apply ONLY to the next input or output
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file and are reset between files.
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• To set the video bitrate of the output file to 64 kbit/s:
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ffmpeg -i input.avi -b:v 64k -bufsize 64k output.avi
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• To force the frame rate of the output file to 24 fps:
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ffmpeg -i input.avi -r 24 output.avi
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• To force the frame rate of the input file (valid for raw formats only) to 1 fps and the frame
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rate of the output file to 24 fps:
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ffmpeg -r 1 -i input.m2v -r 24 output.avi
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The format option may be needed for raw input files.
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