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path: root/firmware/export/pcm_sw_volume.h
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2013-04-27Provide high resolution volume and prescaler to hosted targets.Michael Sevakis1-0/+6
HAVE_SW_VOLUME_CONTROL is required and at this time only affects the SDL targets using pcm-sdl.c. Enables balance control in SDL targets, unless mono volume is in use. Compiles software volume control as unbuffered when PCM_SW_VOLUME_UNBUFFERED is defined. This avoids the overhead and extra latency introduced by the double buffer when it is not needed. Use this config when the target's PCM driver is buffered and sufficient latency exists to perform safely the volume scaling. Simulated targets that are double-buffered when made as native targets remain so in the sim in order to run the same code. Change-Id: Ifa77d2d3ae7376c65afecdfc785a084478cb5ffb Reviewed-on: http://gerrit.rockbox.org/457 Reviewed-by: Michael Sevakis <jethead71@rockbox.org> Tested-by: Michael Sevakis <jethead71@rockbox.org>
2013-04-11Fix f5a5b94 errors. Employ SW volume for select targets on SIM.Michael Sevakis1-0/+1
Onda VX747 sim was missing a limits #define; #include limits.h in pcm_sw_volume.h. Simply use the software volume control for the SIM volume control rather than the SDL volume control when the target would have it natively. Change-Id: I8e924a2ff1b410f602452d2ea9b691efb82c931e
2013-04-11Implement universal in-PCM-driver software volume control.Michael Sevakis1-0/+40
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>