[PD] glitches when streaming UDP

Roman Haefeli reduzent at gmail.com
Tue Jan 30 21:25:26 CET 2018


On Die, 2018-01-30 at 16:38 +0100, Dan Wilcox wrote:
> Is it running with the *same* OS and settings?

As far as I can tell: yes. Same OS (Ubuntu 16.04), same Kernel (4.13.0-
32-lowlatency), both tuned so that "realtimeconfigquickscan" doesn't
complain anymore. This includes configuring /etc/security/limits.conf,
adding user to audio group, making high-precision timer /dev/hpet und
realtime clock /dev/rtc readable by members of audio group, etc. I get
stable performance with Ardour with the same qjackctl settings, with
built-in soundcard, but also with external USB sound interface on BOTH
machines.

>  It might be a scheduling issue with the kernel, realtime settings,
> crappy networking driver, etc. 

I thought about that, too. But why does it affect only Pd? On the
"troubled" machine - where everything else runs supersmooth - this
setup suffers a couple of glitches per second (jack routing):

mpv -> Pd running [adc~]-[dac~] -> system output

The probable causes you mentioned would affect other audio softwares,
too, wouldn't they? 

The Pd version doesn't seem to make a difference...

Anyway, thanks for your thoughts.

Roman



> > On Jan 30, 2018, at 12:00 PM, pd-list-request at lists.iem.at wrote:
> > 
> > From: Roman Haefeli <reduzent at gmail.com>
> > To: "pd-list at lists.iem.at" <pd-list at lists.iem.at>
> > Subject: Re: [PD] glitches when streaming UDP
> > Message-ID: <1517306864.2068.8.camel at gmail.com>
> > Content-Type: text/plain; charset="utf-8"
> > 
> > On Mon, 2018-01-29 at 10:25 +0100, Roman Haefeli wrote:
> > 
> > > I'm working on a patch that transmits audio through UDP. The
> > > patch
> > > runs
> > > totally smooth on macOS (10.10 and 10.11) with Pd 0.48-1 and JACK
> > > as
> > > back-end. On the Linux machines I tested (all Ubuntu 16.04) with
> > > the
> > > same version of Pd I get a lot of glitches, although I'm using
> > > very
> > > similar Jack settings (128 frames/period, 3 periods).
> > Update:
> > My personal, somewhat outdated laptop from 2007 has absolutely
> > stable
> > performance with same patch, same Pd version, same OS, same kernel.
> > To
> > be clear: It's only Pd that performs well on one computer and not
> > so
> > well on others. I get glitch-free audio with Ardour on all tested
> > computers. So I wonder what circumstances affect specifically Pd.
> > It's
> > a pity the most powerful computer I have access to is in its
> > current
> > state not suitable for Pd projects :-(
> > 
> > Roman 
> --------
> Dan Wilcox
> @danomatika
> danomatika.com
> robotcowboy.com
> 
> 
> 
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