2014-01-26 17:49:10 +03:00
|
|
|
@chapter Decoders
|
|
|
|
|
@c man begin DECODERS
|
|
|
|
|
|
|
|
|
|
Decoders are configured elements in Libav which allow the decoding of
|
|
|
|
|
multimedia streams.
|
|
|
|
|
|
|
|
|
|
When you configure your Libav build, all the supported native decoders
|
|
|
|
|
are enabled by default. Decoders requiring an external library must be enabled
|
|
|
|
|
manually via the corresponding @code{--enable-lib} option. You can list all
|
|
|
|
|
available decoders using the configure option @code{--list-decoders}.
|
|
|
|
|
|
|
|
|
|
You can disable all the decoders with the configure option
|
|
|
|
|
@code{--disable-decoders} and selectively enable / disable single decoders
|
|
|
|
|
with the options @code{--enable-decoder=@var{DECODER}} /
|
|
|
|
|
@code{--disable-decoder=@var{DECODER}}.
|
|
|
|
|
|
|
|
|
|
The option @code{-decoders} of the av* tools will display the list of
|
|
|
|
|
enabled decoders.
|
|
|
|
|
|
|
|
|
|
@c man end DECODERS
|
|
|
|
|
|
|
|
|
|
@chapter Audio Decoders
|
|
|
|
|
@c man begin AUDIO DECODERS
|
|
|
|
|
|
|
|
|
|
A description of some of the currently available audio decoders
|
|
|
|
|
follows.
|
|
|
|
|
|
|
|
|
|
@section ac3
|
|
|
|
|
|
|
|
|
|
AC-3 audio decoder.
|
|
|
|
|
|
|
|
|
|
This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as
|
|
|
|
|
the undocumented RealAudio 3 (a.k.a. dnet).
|
|
|
|
|
|
2014-12-07 19:38:56 +02:00
|
|
|
@subsection AC-3 Decoder Options
|
2014-01-26 17:49:10 +03:00
|
|
|
|
|
|
|
|
@table @option
|
|
|
|
|
|
|
|
|
|
@item -drc_scale @var{value}
|
|
|
|
|
Dynamic Range Scale Factor. The factor to apply to dynamic range values
|
|
|
|
|
from the AC-3 stream. This factor is applied exponentially.
|
|
|
|
|
There are 3 notable scale factor ranges:
|
|
|
|
|
@table @option
|
|
|
|
|
@item drc_scale == 0
|
|
|
|
|
DRC disabled. Produces full range audio.
|
|
|
|
|
@item 0 < drc_scale <= 1
|
|
|
|
|
DRC enabled. Applies a fraction of the stream DRC value.
|
|
|
|
|
Audio reproduction is between full range and full compression.
|
|
|
|
|
@item drc_scale > 1
|
|
|
|
|
DRC enabled. Applies drc_scale asymmetrically.
|
|
|
|
|
Loud sounds are fully compressed. Soft sounds are enhanced.
|
|
|
|
|
@end table
|
|
|
|
|
|
|
|
|
|
@end table
|
|
|
|
|
|
|
|
|
|
@c man end AUDIO DECODERS
|
