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Spectral Filter Bank using pfft


Sym
October 11, 2013 | 2:34 pm

Hey, I’m currently trying to recreate a spectral Filterbank in Max and want to split the frequency spectrum in 40 parts to control the amplitude of each part independently.

Does anybody have some tipps on how to approach this? Right now my best starting point would be to use several pfft objects with xover.


October 11, 2013 | 4:15 pm

you want equally spaced log frequency, quarter octave over ten octaves? you need a different pfft for each octave with different window sizes; the highest (10k-20k) would have an analysis window of 8 samples; use the index out and some logic operators connected to the index out loop of the pfft to only output indices 4-7; the octave below would be 16 samples, output for indices 4-7 again, etc etc down to the lowest octave (length 4096, sample only 4-7). you also need to have delays on the output of each analysis to compensate for different analysis latencies for each octave.


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