[LAU] Something odd

Len Ovens len at ovenwerks.net
Sat Aug 15 22:25:26 UTC 2015

On Sat, 15 Aug 2015, Will Godfrey wrote:

> Clock mismatch was the clue :o
> I had been a bit lazy. While switching the output device I'd neglected to also
> switch the input device, so jack was seeing two slightly different 48kHz
> clocks. Switch both at the same time and the problem disappears.

> As a matter of curiosity I wonder if we can work out what the actual difference
> is. Would the Xrun occur when there was a one frame difference, one period, or
> 1 buffer? It's running at 256 frames per period and 2 periods per buffer. The
> xruns occur every 11 minutes (and a few seconds).

While the xrun would happen at a buffer read boundary, the offending IF 
would only have to be 1 frame out to be late. (if my thinking is correct) 
So the timing of the xrun would be the difference in clock plus the size 
of a buffer (or portion there of). That is, I think it would be unlikely 
the time between xruns would be exactly the same. The minimum time between 
xruns is the value I would use.

Now which one is faster?

Len Ovens

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