[PD] DSP loops

Roman Haefeli reduzierer at yahoo.de
Tue Jan 30 16:43:59 CET 2007

On Tue, 2007-01-30 at 12:55 +0000, Kim Taylor wrote:
> Roman,
> > either you set the block-size to 1 or you could use
> > [fexpr~ ] or any other object that allows recursion ([rpole~], [rzero~],
> > [biquad~] and the like), which might not do exactly, what you want. so
> > [block~ 1] might still be the best choice.
> When you say they allow recursion, I don't understand how they can be
> used to overcome the DSP loop problem.

actually, they don't overcome the dsp loop problem. they get one block
of audio samples for computation, compute something (it doesn't matter,
if the object internally uses '1' as a block-size) and spit the result
to the outlet, again in a block of samples. of course, this recursion
happens only internally, within the object.

>  As I understand it these
> functions work recursively- in the case of the filters rpole~ and
> rzero~ by using the values associated with previous sampling
> intervals- but on a higher level their addition to the signal chain
> doesn't allow for recursive behaviour...

yes, true.

>  or am I missing the point?

no. it possibly was a bit confusing from my side to bring [rzero~] and
such in. it depends on what you want to achieve. if it's something
filterlike, they might would have helped. also, if you can pack your
whole program into one [fexpr~ ], that would possibly be an alternative,
too (though [expr]/[expr~]/[fepxr~] are known to be slow).  if nothing
of this is better, then using [block~ 1] is the best, though not nice.


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