From: Pierre-Louis Bossart Date: Mon, 22 Oct 2012 21:42:15 +0000 (-0500) Subject: ALSA: core: add hooks for audio timestamps X-Git-Tag: omap-for-v3.8/fixes-for-merge-window-v4-signed~39^2~118 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4eeaaeaea1cec60a25979678182720dc91308550;p=pandora-kernel.git ALSA: core: add hooks for audio timestamps ALSA did not provide any direct means to infer the audio time for A/V sync and system/audio time correlations (eg. PulseAudio). Applications had to track the number of samples read/written and add/subtract the number of samples queued in the ring buffer. This accounting led to small errors, typically several samples, due to the two-step process. Computing the audio time in the kernel is more direct, as all the information is available in the same routines. Also add new .audio_wallclock routine to enable fine-grain synchronization between monotonic system time and audio hardware time. Using the wallclock, if supported in hardware, allows for a much better sub-microsecond precision and a common drift tracking for all devices sharing the same wall clock (master clock). Signed-off-by: Pierre-Louis Bossart Signed-off-by: Takashi Iwai --- Reading git-diff-tree failed