h264_metadata: Add option to delete filler data
[libav.git] / doc / decoders.texi
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1@chapter Decoders
2@c man begin DECODERS
3
4Decoders are configured elements in Libav which allow the decoding of
5multimedia streams.
6
7When you configure your Libav build, all the supported native decoders
8are enabled by default. Decoders requiring an external library must be enabled
9manually via the corresponding @code{--enable-lib} option. You can list all
10available decoders using the configure option @code{--list-decoders}.
11
12You can disable all the decoders with the configure option
13@code{--disable-decoders} and selectively enable / disable single decoders
14with the options @code{--enable-decoder=@var{DECODER}} /
15@code{--disable-decoder=@var{DECODER}}.
16
17The option @code{-decoders} of the av* tools will display the list of
18enabled decoders.
19
20@c man end DECODERS
21
22@chapter Audio Decoders
23@c man begin AUDIO DECODERS
24
25A description of some of the currently available audio decoders
26follows.
27
28@section ac3
29
30AC-3 audio decoder.
31
32This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as
33the undocumented RealAudio 3 (a.k.a. dnet).
34
6a880090 35@subsection AC-3 Decoder Options
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36
37@table @option
38
39@item -drc_scale @var{value}
40Dynamic Range Scale Factor. The factor to apply to dynamic range values
41from the AC-3 stream. This factor is applied exponentially.
42There are 3 notable scale factor ranges:
43@table @option
44@item drc_scale == 0
45DRC disabled. Produces full range audio.
46@item 0 < drc_scale <= 1
47DRC enabled. Applies a fraction of the stream DRC value.
48Audio reproduction is between full range and full compression.
49@item drc_scale > 1
50DRC enabled. Applies drc_scale asymmetrically.
51Loud sounds are fully compressed. Soft sounds are enhanced.
52@end table
53
54@end table
55
56@c man end AUDIO DECODERS