On Wed, 5 May 2004, Takashi Iwai wrote:
> > I set SND_TSTAMP_MMAP like you told me. What function may i use? I've tried
> > snd_pcm_status_get_trigger_tstamp and snd_pcm_status_get_tstamp, and the first
> > always return the same timestamp or it changes every 4 or 6 seconds. And the
> > second returns the "now" timestamp. What am i doing wrong?
>
> no, you're not wrong, i overlooked that the SND_PCM_STATUS ioctl calls
> the update of timestamp. so, apparently there is no this timestamp
> mode for the period-updates.
>
> but, anyway, you can get the sound frame position and the timestamp at
> the same time. it should suffice to calculate the sync, i believe.
That's right. The semantics is - mark timestamp when the stream pointer
is updated - not at period boundary (which can be shifted with interrupt
latency issues).
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
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