[PD] jack clicks but alsa or oss runs smoothly

patrick patrick at 11h11.com
Sun May 1 10:16:34 CEST 2005

if you are running devel, try this flag: -cb_scheduler.
sleepgrain should be 0.1 or something like that.

please tell us if it's working.

----- Original Message -----
From: "Iain Mott" <mott at reverberant.com>
To: <pd-list at iem.at>
Sent: Sunday, May 01, 2005 2:37 AM
Subject: [PD] jack clicks but alsa or oss runs smoothly


I'm running an a Pd patch that reads and writes to disk simultaneously
with a number readsf~ and writesf~ objects. It runs very well using alsa
or with oss emulation but produces occasional clicks when running with
jack. I'm wondering if there's anything I can do to fix this?

Latency is not an issue with this application and i'm running the
following to set up jack:

/usr/bin/jackd -R -dalsa -dhw:0 -r44100 -p2048 -n2 &

Pd includes the following start options: -rt -jack

Have compiled pd-0.38-4 with the following configuration: ./configure
--enable-newhash --enable-jack --enable-fftw --enable-simd
--enable-optimize=pentium4 --enable-threadedsf --enable-atomic –

I'm using a Gentoo 2.6.10 kernel. Also using realtime-lsm to get
non-root realtime priority (althought this feature doesn't seem to
create any audible benefits or problems in this particular patch). The
computer is a Compaq Presario R3000 laptop using atiixp alsa drivers.

alsa is being loaded as a module and not compiled into the kernel
(haven't tried compiling into the kernel)

When clicks occur, Pd reports errors such as:
     8.41       A/D/A sync
    18.41       A/D/A sync
    18.41       A/D/A sync
    18.78       unknown
    18.78       unknown
    18.78       unknown

Can anyone please suggest what might be causing the glitches? (Ardour
by-the-way seems to run well heavily loaded, without any glitches)

Best, Iain

Iain Mott

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