[PlanetCCRMA] Audiophile 2496 input, Nvidia nforce4 output, and xruns?

[Fernando Lopez-Lezcano]

On Thu, 2008-02-07 at 19:56 -0600, Wade Nelson wrote:
> I'm using an m-audio audiophile 2496 for input from a mixer (using the
> RCAs on the back) and the onboard nforce4 audio on my box for output to
> my 5.1 speaker system.  I'm getting a lot of xruns, especially with a
> couple apps running like ardour and hydrogen, but I can get xruns with
> nothing but the jack server running as well.
> 
> I'm using qjackctl to set up the server, I've set the audiophile for
> input, the nvidia for output... rate at 96khz, and the samples per
> period (or whatever that setting is) down low enough that I get about
> 5.3 msec latency.  However even at a very conservative setting where I
> get 21.7 msec latency I'm still getting xruns.
> 
> Is the problem using two separate cards for input/output, or is there
> something I need to do to get the xruns down?  When I was just using the
> nvidia for input & output I was able to run at about 5.3 msec latency
> 48khz and never saw a single xrun.  Seems awfully strange that I can't
> seem to find any settings using the audiophile that don't result in a
> bunch of xruns.

Jack can't use two soundcards at the same time unless they are
synchronized. Otherwise the two clocks are going to be slightly
different and the cards will drift apart until one of them will have to
miss a period and you will get an xrun... Jack can't sync them, it has
to be done at the hardware level. 

-- Fernando