Hi,
On Sat, Sep 11, 2010 at 04:03:00PM -0400, brandon zeeb wrote:
So I'm reading Miller's book hoping for a real world explanation of the elementary filter objects in Pd (z~, rpole~, czero~, etc). Unfortunately, this only occupies 3-4 pages.
Does anyone have a set of tutorials, abstractions, or are their any documents available which go into further detail into these objects? For starters, I'd like to build a few simple classic filter types (ie: lpf, hpf w/ recirculation). lop~, hip~, and bp~ are nice, and one can build recirculating filters with these, but they don't offer audio-rate control of filter cutoff.
A few of these are included in the rj library that you can get at http://github.com/rjdj/
Basically it includes two kinds of filters: Some are direct implementations using the c/r_pole or c/r_zero objects directly. An example would be e_resonzq, the classical two-pole resonator. (We use "e_..." to designate effects.)
The approach taken with several other filters is to split up the process into a biquad filter and a set of utility abstractions like "u_lowpass.pd" to generate filter coefficients for that. In addition to the biquad~ internal the rj library also includes an interpolating clone built with elementary filters called "e_beequad.pd".
The coefficient-calculation is made using the filter recipes from the Audio-EQ-Cookbook: http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt
These objects are all Pd vanilla abstractions, so they should run on every flavour of Pd and you can change and play around with them easily.
A good read also is the "The Scientist and Engineer's Guide to Digital Signal Processing": http://www.dspguide.com/
Frank Barknecht Do You RjDj.me? _ ______footils.org__