yes - don’t use biquads :-)
On 1 Mar 2016, at 14:56, Paul Stoffregen <p...@pjrc.com> 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 background, I implement a Biquad Direct Form 1 filter in this > audio library. It works well. > > https://github.com/PaulStoffregen/Audio/blob/master/filter_biquad.cpp#L94 > > There's a function which allows the user to change the 5 coefficients. Lines > 94 & 95 set the 4 filter state variables (which are 16 bits, packed into two > 32 bit integers) to zero. I did this clear-to-zero out of an abundance of > caution, for concern (maybe paranoia) that a stable filter might do something > unexpected or unstable if the 4 state variables are initialized with non-zero > values. > > The problem is people wish to change the coefficients in real time with as > little audible artifact as possible between the old and new filter response. > Clearing the state to zero usually results in a very noticeable click or pop > sound. > > https://github.com/PaulStoffregen/Audio/issues/171 > > Am I just being overly paranoid by setting all 4 state variables to zero? If > "bad things" could happen, are there any guidelines about how to manage the > filter state safely, but with with as graceful a transition as possible? > > > > _______________________________________________ > dupswapdrop: music-dsp mailing list > music-dsp@music.columbia.edu > https://lists.columbia.edu/mailman/listinfo/music-dsp > _______________________________________________ dupswapdrop: music-dsp mailing list music-dsp@music.columbia.edu https://lists.columbia.edu/mailman/listinfo/music-dsp
