R: delwrite/vd question

Alessandro Fogar sfogar at libero.it
Fri Jun 16 23:43:41 CEST 2000

Hi Miller,

Meanwhile as Guenter Geiger suggested, I could simply add a noise~
multiplicated with a small value (0.000000000001) to the input of the
offending patch.

About the patches involved in the problem, the rev4~ is one of them...

I've found the same problem in jMax too :-)

And what about my previous message (Consistency Check failed: signal_free 2)

Many thanks.

Alessandro Fogar

----- Original Message -----
From: Miller Puckette <mpuckett at man104-1.UCSD.Edu>
To: <sfogar at libero.it>
Cc: PD-list <pd-list at iem.mhsg.ac.at>
Sent: Friday, June 16, 2000 9:16 PM
Subject: Re: delwrite/vd question

> Hi all,
> There is a recurring problem in Pd whose symptom is that CPU usage
> sometimes shoots upward unexpectedly.  The cause is usually
> arithmetic underflows in tilde objects.  I've tried to find ways
> to prevent this but it looks like I haven't got it quite right yet.
> For example, in a delay feedback loop, if there's input followed by
> a stream of zeros, eventually the recirculating values drop below 1E-38
> or so.  Each time a calculation does this the processor receives a
> hardware interrupt!
> I believe the I386 offers a way to disable this interrupt but I
> haven't been able to find out how to do it in Linux.  Does anyone
> on the list know about this???
> My workaround has been to fix delwrite~ to bash its input to zero whenever
> it drops below 1E-20.  Apparently this doesn't work in every case.  If
> anyone would like to e-mail me an offending patch I'll be happy to try
> to figure out where the underflows are occurring and fix Pd so they will
> stop.
> cheers
> Miller
> Does anyone on the list know if
> On Tue, Jun 13, 2000 at 04:16:48PM +0200, sfogar at libero.it wrote:
> > Hi everybody,
> >
> > I'm developing my new installation with pd under Linux but I notice a
> > strange behaviour.
> >
> > I'll try to explain it...
> >
> > When, in patchers which use delwrite~+vd~, there is no audio flowing,
> > the cpu utilization increases.
> >
> > For example, you have a patcher which reads a sample, plays it through
> > a chorus or a reverb, the audio goes to a dac~, when the sample is
> > played, the cpu utilization is at a certain level, when the sample is
> > not played, the cpu utilization increases.
> >
> > Is this normal ? Am I wrong ? Is there a possible workaround ?
> >
> > I'm using an RME Hammerfall 9636.
> >
> > Regards
> >
> > Alessandro Fogar
> >
> >
> >

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