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@chapter Decoders |
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@c man begin DECODERS |
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Decoders are configured elements in Libav which allow the decoding of |
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multimedia streams. |
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When you configure your Libav 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{-decoders} of the av* 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 Audio Decoders |
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@c man begin AUDIO DECODERS |
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A description of some of the currently available audio decoders |
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follows. |
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@section ac3 |
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AC-3 audio decoder. |
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This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as |
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the undocumented RealAudio 3 (a.k.a. dnet). |
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@subsubsection AC-3 Decoder Options |
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@table @option |
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@item -drc_scale @var{value} |
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Dynamic Range Scale Factor. The factor to apply to dynamic range values |
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from the AC-3 stream. This factor is applied exponentially. |
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There are 3 notable scale factor ranges: |
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@table @option |
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@item drc_scale == 0 |
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DRC disabled. Produces full range audio. |
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@item 0 < drc_scale <= 1 |
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DRC enabled. Applies a fraction of the stream DRC value. |
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Audio reproduction is between full range and full compression. |
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@item drc_scale > 1 |
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DRC enabled. Applies drc_scale asymmetrically. |
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Loud sounds are fully compressed. Soft sounds are enhanced. |
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@end table |
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@end table |
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@c man end AUDIO DECODERS |
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