From 61d0583384b81de28498544ea3ec2e5c8eba42be Mon Sep 17 00:00:00 2001 From: Michael Sevakis Date: Fri, 23 Aug 2013 14:18:08 -0400 Subject: Greatly reduce volume-change zipper artifacts with SW volume. Uses a cosine factor to smoothly shift the PCM level from the old level to the new one over the length of a frame. Implements indirect calls to PCM scaling function instead of testing conditions on every callback, cleanly assigning a different call to do the volume transition. The volume change call then assigns the final scaling function. Change-Id: If1004b92a91c5ca766dd0e4014ec274636e8ed26 Reviewed-on: http://gerrit.rockbox.org/763 Reviewed-by: Michael Sevakis Tested: Michael Sevakis --- firmware/pcm.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'firmware/pcm.c') diff --git a/firmware/pcm.c b/firmware/pcm.c index 60ccdbd2fc..640bb7830f 100644 --- a/firmware/pcm.c +++ b/firmware/pcm.c @@ -111,6 +111,10 @@ void pcm_play_stop_int(void); ** pcm_sw_volume.c **/ static inline void pcm_play_dma_start_int(const void *addr, size_t size) { +#ifdef HAVE_SW_VOLUME_CONTROL + /* Smoothed transition might not have happened so sync now */ + pcm_sync_pcm_factors(); +#endif pcm_play_dma_start(addr, size); } -- cgit v1.2.3