[PD] [sqosc~]-issues

Roman Haefeli reduzierer at yahoo.de
Tue Mar 27 10:14:24 CEST 2007

On Tue, 2007-03-27 at 01:37 +0200, Derek Holzer wrote:
> After having done lots of work with recursive feedback structures in PD 
> using delays and filters, I can positively say that PD (rather then 
> Jack) is making the problem in every one of my cases. YMMV. But for me, 
> it always happens when delay lines or resonant filters become feedback 
> saturated to the point of being pure DC. The offending object must then 
> be cut and pasted (i.e. reset) to get rid of the "nan" signal, so try 
> cut/paste rather than restart and see if it helps you next time.

sometimes it helps to delete the object, that outputs a 'nan'-signal.
but sometimes, as andy said, just cutting this object doesn't help to
get rid of the 'nan'. i even had some cases, where i had to restart
jackd. i don't know the internals behind pd/jackd, but i can say for
sure, that it is _possible_ to turn jackd unusuable with a 'nan'-signal
(i don't say, it happens each time). but i can't tell, whether pd or
jackd is the cause of the problem (maybe both?).


>  I've 
> always considered this something that is inherent in DSP with no sanity 
> checks, as PD often is, rather than a bug specific to PD. The CSound 
> manual mentions this "blowing up" of filters quite frequently, so I know 
> it happens in other applications.
> best,
> d.
> padawan12 wrote:
> > 
> > I get this too. It's never seemed worth filing a bug report
> > because it's not clear whether Pd or an external or Jack
> > itself it where the problem occurs. Sometimes a channel
> > just locks up and all I can get is nans until the application
> > is restarted. It's quite rare, but annoying if it happens 
> > during a talk or performance.

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