[PD] pause writing to delay line / hybrid of array and delay

[Dario Sanfilippo]

Hi, Max.

You could have a looper feeding into a variable delay line whose delay is
modulated appropriately.

A looper would be an N-sample feedback loop with some input feeding into
it, where the input gain and the feedback gain are mutually exclusive. That
would prevent new elements from being added and you'd have the same
recirculating material when you freeze it:

y[n] = Rx[n] + (1-R)y[n-N]

with R being 1 to write into it, or 0 to freeze it.

The output of the looper could then feed an N-sample delay line whose delay
is offset consistently to always point to the same buffer position:

delay[n] = (lineN[n] + element[n]) % N

where

lineN[n] = (1[n-1] + lineN[n-1]) % N

and element[n] is an int between 0 and N - 1 determining the array element
that is being output.

I don't have this in PD but here's the Faust implementation:

https://faustide.grame.fr/?autorun=1&voices=0&name=lotkavolterra_A&inline=aW1wb3J0KCJzdGRmYXVzdC5saWIiKTsKc2l6ZSA9IG1hLlNSOyAvLyBhc3N1bWluZyBhIDk2IGtIeiBzYW1wbGUtcmF0ZQpyZWMgPSBjaGVja2JveCgiRnJlZXplIik7IC8vIGNoZWNrIHRvIGZyZWV6ZSwgdW5jaGVjayB0byBhZGQgbmV3IGVsZW1lbnRzCnBvc2l0aW9uID0gKGJhLnBlcmlvZChzaXplKSArIGhzbGlkZXIoImFycmF5IGVsZW1lbnQiLCAwLCAwLCA5NjAwMCwgMSkpICUgKHNpemUpOwpsb29wZXIoeCkgPSArKHggKiAoMSAtIHJlYykpCiAgICAgICAgICAgIH4gZGUuZGVsYXkoc2l6ZSAtIDEsIHNpemUgLSAxKSAqIHJlYzsgLy8gbGVuZ3RoIGlzIHNpemUgLSAxIGJlY2F1c2Ugb2YgdGhlIGltcGxpY2l0IG9uZS1zYW1wbGUgZGVsYXkgaW4gZmVlZGJhY2sgbG9vcHMKYXJyYXkocG9zKSA9IGRlLmRlbGF5KHNpemUsIHBvc2l0aW9uKTsKcHJvY2Vzcyh4KSA9IGFycmF5KHBvc2l0aW9uLCBsb29wZXIoeCkpOwo%3D

Ciao,
Dario


On Fri, 26 Feb 2021 at 14:03, Max <abonnements at revolwear.com> wrote:

> Hi list,
>
> I'm looking for concepts like a queue or arrayDeque in Pd.
> Like a delay line which I can pause adding new elements into and it will
> act like an array until I decide to add more. At audio rate.
> Is there something simple that I have overlooked? What's the best
> strategy to implement this?
>
> M.
>
>
>
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