14 Oct
2016
14 Oct
'16
11:51 p.m.
In pd 0.47.1 [hip~] is still not perfect. Attenuation at cutoff is not constant over the frequency range: -6 dB with cutoff=SR/8, -3 dB with cutoff=SR/4, 0 DB with cutoff=SR/2. In contrast, iemlib's [hp1~] has -3 dB at cutoff consistently.
Could vanilla pd implement iemlib's hipass filter recipe? I don't know if the license also covers the math. Documentation in https://git.iem.at/pd/iemlib/tree/master points to external literature for part of the math (bilinear transform). I've implemented the recipe with vanilla objects for comparison, see attached.
Katja