141 lines
3.9 KiB
Plaintext
141 lines
3.9 KiB
Plaintext
@chapter Decoders
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@c man begin DECODERS
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Decoders are configured elements in FFmpeg which allow the decoding of
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multimedia streams.
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When you configure your FFmpeg build, all the supported native decoders
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are enabled by default. Decoders requiring an external library must be enabled
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manually via the corresponding @code{--enable-lib} option. You can list all
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available decoders using the configure option @code{--list-decoders}.
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You can disable all the decoders with the configure option
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@code{--disable-decoders} and selectively enable / disable single decoders
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with the options @code{--enable-decoder=@var{DECODER}} /
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@code{--disable-decoder=@var{DECODER}}.
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The option @code{-codecs} of the ff* tools will display the list of
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enabled decoders.
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@c man end DECODERS
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@chapter Video Decoders
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@c man begin VIDEO DECODERS
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A description of some of the currently available video decoders
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follows.
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@section rawvideo
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Raw video decoder.
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This decoder decodes rawvideo streams.
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@subsection Options
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@table @option
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@item top @var{top_field_first}
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Specify the assumed field type of the input video.
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@table @option
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@item -1
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the video is assumed to be progressive (default)
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@item 0
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bottom-field-first is assumed
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@item 1
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top-field-first is assumed
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@end table
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@end table
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@c man end VIDEO DECODERS
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@chapter Audio Decoders
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@c man begin AUDIO DECODERS
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@section ffwavesynth
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Internal wave synthetizer.
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This decoder generates wave patterns according to predefined sequences. Its
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use is purely internal and the format of the data it accepts is not publicly
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documented.
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@section libcelt
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libcelt decoder wrapper
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libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
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Requires the presence of the libcelt headers and library during configuration.
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You need to explicitly configure the build with @code{--enable-libcelt}.
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@section libgsm
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libgsm decoder wrapper
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libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
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the presence of the libgsm headers and library during configuration. You need
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to explicitly configure the build with @code{--enable-libgsm}.
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This decoder supports both the ordinary GSM and the Microsoft variant.
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@section libilbc
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libilbc decoder wrapper
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libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
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audio codec. Requires the presence of the libilbc headers and library during
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configuration. You need to explicitly configure the build with
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@code{--enable-libilbc}.
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@subsection Options
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The following option is supported by the libilbc wrapper.
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@table @option
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@item enhance
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Enable the enhancement of the decoded audio when set to 1. The default
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value is 0 (disabled).
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@end table
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@section libopencore-amrnb
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libopencore-amrnb decoder wrapper
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libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
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Narrowband audio codec. Using it requires the presence of the
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libopencore-amrnb headers and library during configuration. You need to
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explicitly configure the build with @code{--enable-libopencore-amrnb}.
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An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
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without this library.
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@c man end AUDIO DECODERS
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@chapter Subtitles Decoders
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@c man begin SUBTILES DECODERS
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@section dvdsub
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This codec decodes the bitmap subtitles used in DVDs; the same subtitles can
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also be found in VobSub file pairs and in some Matroska files.
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@subsection Options
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@table @option
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@item palette
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Specify the global palette used by the bitmaps. When stored in VobSub, the
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palette is normally specified in the index file; in Matroska, the palette is
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stored in the codec extra-data in the same format as in VobSub. In DVDs, the
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palette is stored in the IFO file, and therefore not available when reading
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from dumped VOB files.
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The format for this option is a string containing 16 24-bits hexadecimal
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numbers (without 0x prefix) separated by comas, for example @code{0d00ee,
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ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
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7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}.
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@end table
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@c man end SUBTILES DECODERS
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