gen delay / spline6 interpolation mode

Alexis Baskind's icon

Dear all,

I just noticed that the "spline6" interpolation mode from delay in gen seems not to work: whatever I put as a delay as input I get a quasi DC-component.

Best,

Alexis

Graham Wakefield's icon

Hi Alexis,

Thank you, you have found a bug in the delay operator for @interp spline6! I've dug into this and found the culprit (a typo), and there's a fix checked in for code review and inclusion in the next update hopefully (ticket #13572)

In the meantime, if you need @interp spline6, it *is* working fine for the sampler operators (sample, peek etc.) and for the interp operator (interp @mode spline6) -- and there's a codebox equivalent in the gen~.interpolation example patcher; you could perhaps use one of these to implement the equivalent of delay @interp spline6 until the update fix is released.

Graham

Alexis Baskind's icon

Hi Graham,

Thanks for your answer and for the info. I don't need spline6 right now, I was actually experimenting with different interpolation modes and I found this bug by chance.

Alexis

Alexis Baskind's icon

Hi again Graham,

While I'm a it: the reason why I was experimenting with interpolations is that I'd like to reproduce exactly the behavior of tapin/tapout in gen~. But as far as I know, tapout~ is performing a 4-point Lagrange interpolation, is it correct? If yes, would it be possible to implement also 4-point Lagrange in the delay operator?

Alexis

Pi4 B's icon

Hi, i was struggling trying to implement the Lagrange interpolation to the gen~ delay operator too.

I ended up translating a Julius Smith solution written in Faust code which is about using Lagrange to make a tuning filter for Karplus Strong.

You can see it at page 14 of his document:

This post is old but maybe this can be usefull to someone. Let me know if you find something wrong in the code, i'm not an expert so it happens i make naive errors but it seems working for now: i was working with KS and this implementation keeps the string almost perfectly tuned up to a fundamental of 2000Hz.

Cheers

P.

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