wm4
6c8362ef54
The main change is that we wait with opening the muxer ("writing
headers") until we have data from all streams. This fixes race
conditions at init due to broken assumptions in the old code.
This also changes a lot of other stuff. I found and fixed a few API
violations (often things for which better mechanisms were invented, and
the old ones are not valid anymore). I try to get away from the public
mutex and shared fields in encode_lavc_context. For now it's still
needed for some timestamp-related fields, but most are gone. It also
removes some bad code duplication between audio and video paths.
174 lines
6.3 KiB
ReStructuredText
174 lines
6.3 KiB
ReStructuredText
ENCODING
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========
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You can encode files from one format/codec to another using this facility.
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``--o=<filename>``
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Enables encoding mode and specifies the output file name.
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``--of=<format>``
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Specifies the output format (overrides autodetection by the file name
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extension of the file specified by ``-o``). See ``--of=help`` for a full
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list of supported formats.
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``--ofopts=<options>``
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Specifies the output format options for libavformat.
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See ``--ofopts=help`` for a full list of supported options.
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Options are managed in lists. There are a few commands to manage the
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options list.
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``--ofopts-add=<options1[,options2,...]>``
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Appends the options given as arguments to the options list.
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``--ofopts-pre=<options1[,options2,...]>``
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Prepends the options given as arguments to the options list.
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``--ofopts-del=<index1[,index2,...]>``
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Deletes the options at the given indexes. Index numbers start at 0,
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negative numbers address the end of the list (-1 is the last).
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``--ofopts-clr``
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Completely empties the options list.
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``--ofps=<float value>``
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Specifies the output format time base (default: 24000). Low values like 25
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limit video fps by dropping frames.
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``--oautofps``
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Sets the output format time base to the guessed frame rate of the input
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video (simulates MEncoder behavior, useful for AVI; may cause frame drops).
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Note that not all codecs and not all formats support VFR encoding, and some
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which do have bugs when a target bitrate is specified - use ``--ofps`` or
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``--oautofps`` to force CFR encoding in these cases.
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``--omaxfps=<float value>``
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Specifies the minimum distance of adjacent frames (default: 0, which means
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unset). Content of lower frame rate is not readjusted to this frame rate;
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content of higher frame rate is decimated to this frame rate.
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``--oharddup``
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If set, the frame rate given by ``--ofps`` is attained not by skipping time
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codes, but by duplicating frames (constant frame rate mode).
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``--oneverdrop``
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If set, frames are never dropped. Instead, time codes of video are
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readjusted to always increase. This may cause AV desync, though; to work
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around this, use a high-fps time base using ``--ofps`` and absolutely
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avoid ``--oautofps``.
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``--oac=<codec>``
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Specifies the output audio codec. See ``--oac=help`` for a full list of
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supported codecs.
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``--oaoffset=<value>``
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Shifts audio data by the given time (in seconds) by adding/removing
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samples at the start. Deprecated.
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``--oacopts=<options>``
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Specifies the output audio codec options for libavcodec.
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See ``--oacopts=help`` for a full list of supported options.
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.. admonition:: Example
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"``--oac=libmp3lame --oacopts=b=128000``"
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selects 128 kbps MP3 encoding.
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Options are managed in lists. There are a few commands to manage the
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options list.
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``--oacopts-add=<options1[,options2,...]>``
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Appends the options given as arguments to the options list.
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``--oacopts-pre=<options1[,options2,...]>``
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Prepends the options given as arguments to the options list.
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``--oacopts-del=<index1[,index2,...]>``
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Deletes the options at the given indexes. Index numbers start at 0,
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negative numbers address the end of the list (-1 is the last).
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``--oacopts-clr``
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Completely empties the options list.
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``--oafirst``
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Force the audio stream to become the first stream in the output.
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By default, the order is unspecified. Deprecated.
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``--ovc=<codec>``
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Specifies the output video codec. See ``--ovc=help`` for a full list of
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supported codecs.
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``--ovoffset=<value>``
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Shifts video data by the given time (in seconds) by shifting the pts
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values. Deprecated.
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``--ovcopts <options>``
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Specifies the output video codec options for libavcodec.
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See --ovcopts=help for a full list of supported options.
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.. admonition:: Examples
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``"--ovc=mpeg4 --ovcopts=qscale=5"``
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selects constant quantizer scale 5 for MPEG-4 encoding.
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``"--ovc=libx264 --ovcopts=crf=23"``
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selects VBR quality factor 23 for H.264 encoding.
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Options are managed in lists. There are a few commands to manage the
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options list.
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``--ovcopts-add=<options1[,options2,...]>``
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Appends the options given as arguments to the options list.
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``--ovcopts-pre=<options1[,options2,...]>``
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Prepends the options given as arguments to the options list.
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``--ovcopts-del=<index1[,index2,...]>``
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Deletes the options at the given indexes. Index numbers start at 0,
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negative numbers address the end of the list (-1 is the last).
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``--ovcopts-clr``
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Completely empties the options list.
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``--ovfirst``
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Force the video stream to become the first stream in the output.
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By default, the order is unspecified. Deprecated.
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``--ocopyts``
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Copies input pts to the output video (not supported by some output
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container formats, e.g. AVI). Discontinuities are still fixed.
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By default, audio pts are set to playback time and video pts are
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synchronized to match audio pts, as some output formats do not support
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anything else.
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``--orawts``
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Copies input pts to the output video (not supported by some output
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container formats, e.g. AVI). In this mode, discontinuities are not fixed
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and all pts are passed through as-is. Never seek backwards or use multiple
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input files in this mode!
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``--no-ocopy-metadata``
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Turns off copying of metadata from input files to output files when
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encoding (which is enabled by default).
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``--oset-metadata=<metadata-tag[,metadata-tag,...]>``
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Specifies metadata to include in the output file.
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Supported keys vary between output formats. For example, Matroska (MKV) and
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FLAC allow almost arbitrary keys, while support in MP4 and MP3 is more
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limited.
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.. admonition:: Example
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"``--oset-metadata=title="Output title",comment="Another tag"``"
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adds a title and a comment to the output file.
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``--oremove-metadata=<metadata-tag[,metadata-tag,...]>``
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Specifies metadata to exclude from the output file when copying from the
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input file.
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.. admonition:: Example
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"``--oremove-metadata=comment,genre``"
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excludes copying of the the comment and genre tags to the output
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file.
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