Takashi Iwai kirjoitti:
At Mon, 26 Nov 2007 09:59:29 +0200, Heikki Lindholm wrote:
Jaroslav Kysela kirjoitti:
On Mon, 26 Nov 2007, Heikki Lindholm wrote:
Hello,
Some years ago there was some talk about UST support in Linux, but the support never happened. With the hrtimers patch (and I'm not quite sure if even earlier?) CLOCK_MONOTONIC would seem like a fairly good UST time source. What I'd like to see, is a selectable clock for ALSA timestamping, e.g. something like snd_sw_params_clock(..., clockid_t clk). Would this seem plausible? I don't know that much about ALSA internals, so, no idea whether different clocks on different pcms/whatever would quickly turn into an unmanageable mess.
We are aware about this extension and I already proposed an implementation. I hope to implement it soon. Timestamps are not used in driver internally.
I can't seem to google up the proposal. I'd like to read it; was it on the alsa ml?
Yes, it was on alsa-devel ML. At that time I didn't like the proposal much because currently there was no real user of timestamps.
What do you mean by this? Aren't all applications that try to do playback/capture A/V sync or sync between two audio cards or latency measurement potential users? And those kind of apps have definitely been there before 2007-02 (Jaroslav's RFC's date.) If you mean _monotonic_ timestamps, not all users would probably care, though.
-- Heikki Lindholm