From f5a5b946867677de76c405ee72e2ea47e36e4c83 Mon Sep 17 00:00:00 2001 From: Michael Sevakis Date: Fri, 5 Apr 2013 04:36:05 -0400 Subject: Implement universal in-PCM-driver software volume control. 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 Tested-by: Michael Sevakis --- firmware/export/pcm_sw_volume.h | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 firmware/export/pcm_sw_volume.h (limited to 'firmware/export/pcm_sw_volume.h') diff --git a/firmware/export/pcm_sw_volume.h b/firmware/export/pcm_sw_volume.h new file mode 100644 index 0000000000..b86e78f500 --- /dev/null +++ b/firmware/export/pcm_sw_volume.h @@ -0,0 +1,40 @@ +/*************************************************************************** + * __________ __ ___. + * Open \______ \ ____ ____ | | _\_ |__ _______ ___ + * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / + * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < + * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ + * \/ \/ \/ \/ \/ + * $Id$ + * + * Copyright (C) 2013 by Michael Sevakis + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY + * KIND, either express or implied. + * + ****************************************************************************/ +#ifndef PCM_SW_VOLUME_H +#define PCM_SW_VOLUME_H + +#ifdef HAVE_SW_VOLUME_CONTROL + +#include + +#define PCM_MUTE_LEVEL INT_MIN + +#ifdef AUDIOHW_HAVE_PRESCALER +/* Set the prescaler value for all PCM playback */ +void pcm_set_prescaler(int prescale); +#endif /* AUDIOHW_HAVE_PRESCALER */ + +/* Set the per-channel volume cut/gain for all PCM playback */ +void pcm_set_master_volume(int vol_l, int vol_r); + +#endif /* HAVE_SW_VOLUME_CONTROL */ + +#endif /* PCM_SW_VOLUME_H */ -- cgit v1.2.3