On 17/12/14 23:37, Raymond Yau wrote:
System tstamp types rely on high-res timers. Audio tstamp types delegate to the pcm driver. Current start_at timer is cancelled on attempt to change stream state.
http://git.alsa-project.org/?p=alsa-lib.git;a=blob_plain;f=test/timer.c;hb=H...
Are there any difference between sound card's timer with high res timer/wall clock time stamp ?
It seem those sound cards timer have resolution and max tick
https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/commit/sound/pc...
snd_timer_status_get_resolution
The clock tick counters are 32 bits and wrap around
This may mean that snd_pcm_start_at can only start within certian time interval
[and this time I'll post to the list :)]
I had presumed it would be pretty simple to use the timer-wrap interrupt to maintain a monotonic sense of time. Hardware that can't support this might not be able to support start_at.
T