Re: [music-dsp] music-dsp Digest, Vol 9, Issue 1

If you are sweeping a filter, then no need to zero the states. We do this in all our filters and you can sweep our parametric filters or crossover filters (LP and HP) very quickly and there are no artifact noises at all. If you do zero the states for any coefficient changes, then in the

Re: [music-dsp] Changing Biquad filter coefficients on-the-fly, how to handle filter state?

I use biquads in JSyn. The coefficients are calculated using RBJ's excellent biquad cookbook from the music-dsp archives. I have found that I can recalculate and update the filter coefficients on the fly without unpleasant artifacts. I do NOT zero out or modify the internal state variables. I

Re: [music-dsp] Changing Biquad filter coefficients on-the-fly, how to handle filter state?

Paul Stoffregen wrote: Does anyone have any suggestions or publications or references to best practices for what to do with the state variables of a biquad filter when changing the coefficients? Use an implementation designed to handle nicely coefficient changes. For example the trapezoidal

Re: [music-dsp] Changing Biquad filter coefficients on-the-fly, how to handle filter state?

This is a common and well-researched problem. The two solutions are usually: 1. cross-fade between two filter settings (this actually works reasonably well) 2. use a filter architecture that is guaranteed to be stable for intermediate states. (e.g., I believe lattice filters have this property,

Re: [music-dsp] Changing Biquad filter coefficients on-the-fly, how to handle filter state?

Have a look also for the book "the art of virtual analog filter design" by Vadim Zavalishin. It provides a new structure for simulating state variable filters especially suited for time varying cases. Ivan MusicalEntropy.com Blog

Re: [music-dsp] Changing Biquad filter coefficients on-the-fly, how to handle filter state?

yes - don’t use biquads :-) On 1 Mar 2016, at 14:56, Paul Stoffregen wrote: > Does anyone have any suggestions or publications or references to best > practices for what to do with the state variables of a biquad filter when > changing the coefficients? > > For a bit of

Re: [music-dsp] Changing Biquad filter coefficients on-the-fly, how to handle filter state?

Have a look at these G. Stoyanov and M. Kawamata, “Variable digital filters,” J.Signal Processing, vol. 1, no. 4, pp. 275–289, 1997. J. Laroche, “On the stability of time-varying recursive filters,”Journal of the Audio Engineering Society, vol. 55, no.6, pp. 460–471, 2007.  V. Välimäki and T.I.

[music-dsp] Changing Biquad filter coefficients on-the-fly, how to handle filter state?

Does anyone have any suggestions or publications or references to best practices for what to do with the state variables of a biquad filter when changing the coefficients? For a bit of background, I implement a Biquad Direct Form 1 filter in this audio library. It works well.