[LAU] Dual Delta Setup

Ben Bell bjb-linux-audio-user at deus.net
Sun Dec 30 14:22:51 UTC 2012

Actually, I've just spotted that this topic has been raised again on the
jack mailing list so perhaps this would be better followed up over there.


That said:

On Sat, Dec 29, 2012 at 01:28:47PM -0500, drew Roberts wrote:
>> Having recently acquired a second Delta 1010 for my setup I've been trying
>> to run the two in tandem using the alsa Multi hack. I'm getting the xruns
> Have you tried using one via jack and the other one via an alsa<->jack bridge 
> and then sync the two via the wordclock?

OK, well I've tried this morning and the news on this is mixed. Sitting idle,
and clocked from S/PDIF everything works fine with alsa_in.

Running with my large ardour session which is, frankly, on the limits of
what this machine will cope with results in loads of clicks during playback.
I suppose the graph is just too big at that point.

Running with a more modest session hovering at 30% normally, pulling the
alsa_in channels (just into jack -- no connections) raises the CPU to ~55%
but there are no xruns.

So it seems that the problem is most likely in the alsa multi plugin. As an
aside I'm surprised at the extent of resource usage caused by simply having
alsa_in running. Normal, or suspicious? jack_netsource doesn't cause this
sort of load, and tweaking sample rate and the like doesn't seem to affect
things. A side-effect of it expecting to need to resample everything?


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