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jpcima / ensemble-chorus

Digital model of electronic string ensemble chorus
Boost Software License 1.0
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Make the anti-aliasing filter controllable #8

Closed jpcima closed 6 years ago

jpcima commented 6 years ago

Allow the user to control the cutoff for the AA filter which precedes the sampling process by BBD. The filter requirement is depending on number of stages and frequency range, but I've read about typical 15kHz filter use.

In many configurations the AA filter is useless currently but I can allow it to be user controllable. When I implemented BBD for variable sample rates, I've picked the Butterworth filter as approximation (now Legendre) of the original filter used.

I could allow the filter to be dynamically designed for the wanted cutoff. Then, Butterworth will be a finer choice for simplicity; or I may switch to another kind of simple filter. (it needs to look back into the filter design and reevaluate)

jpcima commented 6 years ago

Implemented with Butterworth filter of DSPfilters. Checked the performance and the RT behavior