Forums > MaxMSP

antialiasing filter?

May 14, 2006 | 2:53 pm

Hello,

Just wondering if there is a way to do antialias filtering? Perhaps an object that I could use to filter the output of the phasor~ object for example.

Thanks for your help.


May 14, 2006 | 4:30 pm

You need to filter aliasing before it occurs in the signal, because you
can’t filter the aliased frequencies out of an already aliased signal. Put
your phasor in an up-sampled poly~, followed by a lowpass/brickwall filter.
There are different filters you could use like butterworth or FIR. I’m not
sure what’s best.
If you just want anti-aliased oscilators use saw~/tri~/rect~

hth, -thijs


May 14, 2006 | 8:04 pm

Anything in the lowpass familiy should work
Svf~
Onepole~
Biquad~ (with low pass coeffs)

-lcc


May 15, 2006 | 5:32 am

I have made a butterworth low-pass filter, tl.butterlp~. Butterworth
filters have a flat frequency response in the passband. I also have a
more expensive filter CPU-wise: tl.crossover4~. That is a fourth order
Linkiwitz-Riley filter.

Best,
Trond


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