Fw: [PD] about filtergraph~

[Jer Welter]

> Anyone does know how calculate the parameters of a biquad filter from the
> center frequencie, bandwith and quality ?

Here are two references that may help:
http://aulos.calarts.edu/pipermail/music-dsp/1997-July/019624.html
http://www-ccrma.stanford.edu/~jos/filters/BiQuad_Section.html

The first is Robert Bristow-Johnson's BiQuad "cookbook recipes" for the
various kinds of filter (such as lowpass, bandpass, highpass, shelving -
is this what you mena by "quality"?)

The second is the section of Julius Smith's Digital Filtering text on
biquads.  The text as a whole is a very informative read.

Jer