[LAU] Jack frequently crashes when running LinuxSampler + Qsynth

Hello everyone,
  This is my first post on this list. My compliments & gratitude to
everyone working towards Linux Audio! I'm a semi-pro musician
(keyboardist + singer), and for the past few months have been working on
a linux-based setup for live performances. Here's what I use:
1. LinuxSampler, which loads my main piano sample. I depend on this
sample throughout the performance (it happens to be a 888 MB sample). I
also have additional pianos and drums loaded on. The other pianos are
more of a backup, but I almost never use them. Drums are triggered by a
Korg NanoPad.
2. Qsynth, on which I have a few string soundfonts on different
channels, totalling less than 20 MB. Typically these are layered on top
of tmy main piano sample.
3. I use a python script based on Mididings to for midi processing, to
achieve splits and layers, and map hardware controllers.
4. JackMixDesk as a software mixer, to adjust the levels of the various
layers, and vocals.
5. Jack-Rack, loading Calf reverb plugins + amplifier, for vocals.
6. Everything started through QJackCtl.

I use a Casio keyboard as a Midi controller (thru USB) and a Korg
NanoKontrol. I recently migrated from a Celeron laptop to a core2 duo
Macbook, both running Ubuntu 9.04. On both, I've been using the builtin
soundcards. After migrations, there's been a persistant issue with
Jack's stability:
-After a few minutes of playing on the keyboard, the sound from the
samples become horribly distorted, crackly, buzzy and tinny (sorry,
thats the best description I can give!).
-At the instant of this 'crash', this appears in the Messages window of
qjackctl: "subgraph starting at LinuxSampler1 timed out
(subgraph_wait_fd=31, status = 0, state = Finsihed, pollret = 0 revents
= 0x0)
-When I restart Qsynth, it says "Qsynth1: Failed to create te audio
driver (jack). Cannot continue without it".

Upon restarting Jack, everything's happily back to normal, until the
crash happens again. I checked with the system monitor, and the resource
usage is well within limits - max of ~80% CPU/core, and less than 50% of
RAM being used at any point of time.
Needless to say, this effectively rules out using my linux system as a
live performance tool. Like all stage musicians, I place a VERY high
premium on stability. But I would love to have a completely open-source
setup - so any pointers/help would be greatly appreciated!
Cheers,

Guru

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Received on Mon Oct 19 12:15:01 2009