[PD] wierd feedback popping with pd/freebob/jack/rt
reakinator at gmail.com
Wed May 21 23:21:38 CEST 2008
> IIRC, Ubuntu "RT" kernel is not actually Real Time (i.e. with Ingo
> patches), just a "desktop RT" which is not very useful for audio and
> certainly not enough for JACK apps of any heft.
Where are you getting this info from? This is not what I have read, but
maybe I am missing something somewhere. I thought that the Ubuntu kernel
packagers recently switched to using full realtime preemption... I find this
in the package description of linux-image-2.6.22-14-rt :
Ingo Molnar's full real time preemption patch (126.96.36.199-rt9)
Here is the output of uname -a:
Linux pal 2.6.22-14-rt #1 SMP PREEMPT RT Tue Feb 12 09:57:10 UTC 2008 i686
.. and here are the kernel settings from cat /boot/config-2.6.22-14-rt |
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
# CONFIG_PREEMPT_DESKTOP is not set
# CONFIG_DEBUG_PREEMPT is not set
# CONFIG_CRITICAL_PREEMPT_TIMING is not set
Looks realtime to me.. also the latency is really low (5-10ms
conservatively), much lower than I have experienced on other OS's, with or
without realtime. But, if you know something I don't... I have open ears.
Ubuntu runs so nicely on a laptop though... would hate to switch after
finding such an easy-to-operate linux distribution because pd and only pd
doesn't like jack in realtime.
> The "pops/clicks" phenomenon you are noticing that gets resolved by
> starting or killing another JACK app, is something I've experienced before.
> It happens when some app gets an Xrun or otherwise can't process audio in
> time. From that point forward it "clicks" and, in my experience, distorts as
> well with some bitcrushing-style aliasing distortion. When you start or stop
> any JACK app, the entire JACK graph structure gets re-ordered (this isn't
> true with jackdmp, just with single-processor JACK), and that causes the
> misbehaving app to "start from scratch" somewhat and get its audio organized
> I'd suggest 64Studio, Musix, Pure::Dyne, or some other distro that has the
> really serious RT set up with the Ingo patches. With one of those distros,
> everything should run very well on a machine of any decent heft.
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Pd-list