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Implement universal in-PCM-driver software volume control.

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Implements double-buffered volume, balance and prescaling control in
the main PCM driver when HAVE_SW_VOLUME_CONTROL is defined ensuring
that all PCM is volume controlled and level changes are low in latency.

Supports -73 to +6 dB using a 15-bit factor so that no large-integer
math is needed.

Low-level hardware drivers do not have to implement it themselves but
parameters can be changed (currently defined in pcm-internal.h) to work
best with a particular SoC or to provide different volume ranges.

Volume and prescale calls should be made in the codec driver. It should
appear as a normal hardware interface. PCM volume calls expect .1 dB
units.

Change-Id: Idf6316a64ef4fb8abcede10707e1e6c6d01d57db
Reviewed-on: http://gerrit.rockbox.org/423
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested-by: Michael Sevakis <jethead71@rockbox.org>
This commit is contained in:
Michael Sevakis 2013-04-05 04:36:05 -04:00
parent a9049a79d7
commit f5a5b94686
13 changed files with 478 additions and 156 deletions
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3
lib/rbcodec/dsp/pga.h
View file

@ -28,9 +28,6 @@ enum pga_gain_ids
{
PGA_EQ_PRECUT = 0,
PGA_REPLAYGAIN,
#ifdef HAVE_SW_VOLUME_CONTROL
PGA_VOLUME,
#endif
PGA_NUM_GAINS,
};