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Index › Programming Questions & Help › Sound,  Music Libraries › Sonia: useEnvelope() question
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Sonia: useEnvelope() question (Read 1228 times)
OnionRingOfDoom
Sonia: useEnvelope() question
Nov 19th, 2005, 11:06pm  
What kind of envelope does this function accept anyway? And how does it apply it? I'm trying to apply a low-pass filter to the FFT data, in order to isolate the bass from an input source (in my case, the sound card). How would I go about doing that, exactly?
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toxi
Re: Sonia: useEnvelope() question
Reply #1 - Nov 21st, 2005, 12:47pm  
this function doesn't accept any envelope, but is applying one to the sound buffer before computing the FFT. the envelope is only working in the time domain and is used as windowing (amplification) function to reduce the artifacts caused by a rectangular time window (i.e. an unmodified buffer of x samples). the shape of the envolope is a bell curve, emphasizing the centre of the time window. the 2nd parameter of the function defines the shape of the bell curve.

you can see all this in action in my tutorial applet @ http://toxi.co.uk/p5/fftDebug/

the source code also contains a generic FIR filter class (supports low passs, band pass and high pass).

hth!
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OnionRingOfDoom
Re: Sonia: useEnvelope() question
Reply #2 - Nov 24th, 2005, 1:10am  
Ah, I see. Thank you very much, this is very helpful!
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