[PD] Convolve in pd

[Mathieu Bouchard]

On Thu, 8 Jul 2010, William Brent wrote:

> I just looked at the source, and it doesn't do any multiplying in the
> frequency domain.  It seems to route the input signal alternately to
> either the left or right outlet.

It's worse than that : [convolve~] does strictly nothing at all. It 
doesn't do what it says in its comments.

convolve_tilde_perform doesn't even write to its left outlet and right 
outlet buffers, and it doesn't read from its inlet buffer.

To make an audio convolution, you can use several [z~] with several [*~], 
or whatever is equivalent. There exist some shortcuts : for example, [z~ 
1] multiplied by anything and added to the original signal, is something 
you can do with [rzero~].

In longer-term cases (big delays), it may be better to use [delwrite~], 
especially because you can share a single queue for several different 
delays at once, and because you have the option of using [vd~] for more 
precision, smoothing, and clickless change of delay.

Certain useful patterns of infinite convolution can be made by using delay 
lines with feedback (and a small enough [*~]).

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| Mathieu Bouchard, Montréal, Québec. téléphone: +1.514.383.3801