[pulseaudio-discuss] Stream move + latency problems

[Tanu Kaskinen]

On Tue, 2011-06-14 at 16:43 -0700, Arun Raghavan wrote:
> Hey folks,
> As Amanda and Alejandro reported and debugged (thanks to both of you for
> the analysis!), there seem to be problems with latency calculations on
> stream moves. I've spotted 2 issues so far.
> 
> 1. Latency calculations are made assuming that current latency values
> are what was requested. As Amanda points out, the result is that the
> sink latency halves on each move, eventually causing a rewind flood. I'm
> attaching a patch for this. Just want some eye-balls on this before I
> push this out.

Looks good to me.

> 2. While moving, we can't update the destination sink latency.
> Currently, the pa_sink_input->moving() function is called before the
> sink input's 'sink' member is updated (it is NULL during this time). As
> a result, we can't actually set the sink latency, and the overall
> latency is calculated assuming that the sink will be able to provide
> ~1/2 the requested latency. I'm not sure how we should be fixing this.
> I'm tempted to call sink_input->moving() after setting the sink on it,
> but this might (probably will?) break stuff. Anybody got a cleaner
> alternative?

I didn't look at the code too closely, but what about adding some field
in pa_sink_input.thread_info that gives enough information for the sink
to do the right thing in the PA_SINK_MESSAGE_FINISH_MOVE handler?

-- 
Tanu