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af_volume: implement replaygain pre-amplification

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This adds a new "replaygain_preamp" option to the filter, and simply adds its
value to the replaygain gain value.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
This commit is contained in:
Alessandro Ghedini 2014-04-04 18:42:09 +02:00 committed by Anton Khirnov
parent c74b86699c
commit a49aa440c9
3 changed files with 10 additions and 1 deletions
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6
doc/filters.texi
View File

@ -633,6 +633,12 @@ Prefer track gain, if present.
@item album
Prefer album gain, if present.
@end table
@item replaygain_preamp
Pre-amplification gain in dB to apply to the selected replaygain gain.
Default value for @var{replaygain_preamp} is 0.0.
@end table
@subsection Examples

4
libavfilter/af_volume.c
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@ -59,6 +59,8 @@ static const AVOption options[] = {
{ "ignore", "replaygain side data is ignored", 0, AV_OPT_TYPE_CONST, { .i64 = REPLAYGAIN_IGNORE }, 0, 0, A, "replaygain" },
{ "track", "track gain is preferred", 0, AV_OPT_TYPE_CONST, { .i64 = REPLAYGAIN_TRACK }, 0, 0, A, "replaygain" },
{ "album", "album gain is preferred", 0, AV_OPT_TYPE_CONST, { .i64 = REPLAYGAIN_ALBUM }, 0, 0, A, "replaygain" },
{ "replaygain_preamp", "Apply replaygain pre-amplification",
OFFSET(replaygain_preamp), AV_OPT_TYPE_DOUBLE, { .dbl = 0.0 }, -15.0, 15.0, A },
{ NULL },
};
@ -262,7 +264,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
av_log(inlink->dst, AV_LOG_VERBOSE,
"Using gain %f dB from replaygain side data.\n", g);
vol->volume = pow(10, g / 20);
vol->volume = pow(10, (g + vol->replaygain_preamp) / 20);
vol->volume_i = (int)(vol->volume * 256 + 0.5);
volume_init(vol);

1
libavfilter/af_volume.h
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@ -47,6 +47,7 @@ typedef struct VolumeContext {
AVFloatDSPContext fdsp;
enum PrecisionType precision;
enum ReplayGainType replaygain;
double replaygain_preamp;
double volume;
int volume_i;
int channels;