[pulseaudio-discuss] alsa sink latency - how to account for startup delay

Tanu Kaskinen tanuk at iki.fi
Wed Mar 30 14:46:23 UTC 2016

On Sun, 2016-03-27 at 17:50 +0200, Georg Chini wrote:
> On 27.03.2016 10:47, Tanu Kaskinen wrote:
> > 
> > On Sat, 2016-03-26 at 13:16 +0100, Georg Chini wrote:
> > > 
> > > On 24.03.2016 13:38, Tanu Kaskinen wrote:
> > > 
> > > For me it still looks like pulseaudio should be able to detect and handle
> > > that situation.
> > Why can't the alsa driver report the delay correctly from the very
> > beginning? I don't see why the startup delay case would be any
> > different from the normal playback delay, and if there's no difference,
> > why can't the driver report the latency accurately in the beginning if
> > it can report it accurately later? And what can pulseaudio do that the
> > alsa driver can't?
> > 
> > 
> To put it simple, the current pulseaudio code answers the question:
> How long does it take for the audio to reach the alsa driver?
> And I think it should answer the question:
> How long does it take for the audio to reach the DAC?

Which code are you talking about? pa_sink_get_latency() reports the
full latency. However, the "configured latency" value only deals with
the size of the alsa ring buffer, which is smaller than the full
latency. module-loopback would benefit if it could set and query the
"configured full latency" (which is a thing that doesn't currently
exist in the code).


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