[PD] [sqosc~]-issues

Derek Holzer derek at umatic.nl
Tue Mar 27 01:37:32 CEST 2007

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. 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.


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.

derek holzer ::: http://www.umatic.nl
---Oblique Strategy # 203:
"When is it for?
Who is it for?"

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