diagnostic tools to trace the reason xruns are happening?

[Ralf Mardorf]

On Sun, 2011-06-05 at 19:39 +0200, Hartmut Noack wrote:
> Am 05.06.2011 11:00, schrieb Robert Klaar:
> > What happens if you set the frames/period settings higher? I have similar
> > setup and can't get it to run on any lower than 1024 frames(if I want to
> > avoid xruns), but then I've set the sample rate to 48000. I've never noticed
> > any problems with the latency, it's at 46 or something now but I can't hear
> > any difference between this and something lower, can you? .)
> 
> Yes I can.
> 
> I work with musicians and my experience is:
> 
> lower than 5ms: nobody noticed that in comparison with 10ms
> 
> 5-10ms: everything fine, no complaints
> 
> around 16ms: all but some singers realise that something is going on, 
> faces grow longer, some demand changes.

Ok, so we do agree that the Haas-Effect has nothing to do with audible
delay for a groove, but I don't agree that lower than 5 seconds isn't
audible. It is, regarding to a groove, e.g. played by a MIDI keyboard,
controlling a soft-synth. It's annoying, but a constant delay is
something a musician is able to handle, anyway, I do agree that up to 11
ms are 'quasi' inaudible. Pipe organs might have a delay up to 30 or 50
ms, I dunno, but musicians are able to play such an instrument. Just
jitter is a no go, especially for this case ...

> 
> For very big projects on lesser machines I run Jack with 30 or more ms 
> latency. It is OK for mixing/editing etc but I do not record any 
> overdubs with such settings.

...

What's the problem with overdubs? You listen to the delayed sound, but
for you it isn't delayed, you play in real-time without monitoring the
delayed recording and the latency compensation moves it to the correct
time. Hence latency has no impact, but jitter would have, because jitter
can't be auto-compensated.

> I remember I did some years ago but it 
> really was not fun and the results where not as good as they could have 
> been.

I don't understand? What happened? Latency only will become an issue, if
it isn't a fix delay, or if you need to monitor the delayed output, e.g.
for soft synth, apart from that latency has no influence.

> Any recent Linux sould allow settings for 16ms or lower for normal load.

It's related to the hardware and work flow. ElCheapo cards might be able
to keep such latency when Periods/Buffer are set ex 3, jitter than might
be another issue ;).
 
> If it does not, I try the standard-procedures to fix it, if this does 
> not help I switch the distro.

And first of all, don't care that much about latency, because latency
very seldom is an issue, just jitter could become an issue.

Cheers!

Ralf