@jameslo said:
- It looks like you are simply passing the bins that are below the threshold frequency to the left inverse transform, and the rest to the right (with the omitted bins on each side muted), is that correct?
yes, that's correct.
- If so, then why does the transition band sound continuous? i.e. when I output lowpass to the left and highpass to the right, as I sweep up it moves continuously from left to right around the threshold frequency.
that is the result of spectral smearing i guess https://en.wikipedia.org/wiki/Spectral_leakage
the slopes of the lowpass/highpass are not perfectly steep
- I struggled to make a test to see what phase distortions occur near the threshold frequency, and there don't appear to be any. Could that be true? (I'm not confident I tested properly)
there shouldn't be any phase distortion. essentially it's a linear phase FIR filter.
@tungee thanks for the links!
I made this pp.ladder~ filter to get an idea about the concept of "zero delay filters". So I kind of mapped it out as a pd patch to get an overview (not that i fully understand it now...)
However, it makes much more sense to create externals (instead of vanilla abstractions) of this filters. Pure data is really not efficient in processing patches with one sample dsp blocks.