[PD] biquad and karplus-strong

[Peter P.]

Salut Cyrille,

* cyrille henry <ch at chnry.net> [2016-06-14 22:41]:
> hello,
> 
> i've just read the original article from 1983 describing KS algo, including decay stretching.
> as far as i understand, averaging the last 2 sample is a very optimized low pass iir filter at fixed frequency. the decay stretching allow to change the filter cutoff.
> now that processing power allow to easily compute filter at different frequency, I would suggest to replace the averaging algo with a simple lop~ filter and experiment with the cutoff frequency.
I am looking into this because the paper seems to give a relation of
that filter to the period length (pitch) that allows for constant decay
amongst low and hight pitches. 
I understand that they switch randomly between a 2-sample-average
filter, and the unmodified version of the delay on a sample-per sample
basis. Perhaps this is a crude 1983 way of moving the filter cutoff
frequency upwards and should indeed be done in a different way today.

cheers, P