Unpack1FFT | SuperCollider 3.13.1 Help

Unpack1FFT(chain, bufsize, binindex, whichmeasure=0)

Description

Takes an FFT chain and extracts a single scalar value as a demand-rate stream. To call it, a "demander" is needed, which fires whenever the FFT chain fires - this is normally achieved using PackFFT but can also be done using Demand.

NOTE: This UGen is commonly not used directly. Its main purpose is as a component in PV_ChainUGen: -pvcollect, PV_ChainUGen: -pvcalc, and PV_ChainUGen: -pvcalc2 processes. You're welcome to use it on its own - the example below shows how.

Class Methods

Unpack1FFT.new(chain, bufsize, binindex, whichmeasure: 0)

Arguments:

chain	an FFT chain
bufsize	the size of the expected input FFT frames
binindex	the integer index of the bin you want to query
whichmeasure	0 for magnitude and 1 for phase. None of these arguments can be modulated.

Discussion:

​x
 
// Let's extract the DC component - i.e. the magnitude at binindex zero.({    var sig, chain, stream, windowStarts, demand;    var fftsize = 1024;​    sig = SinOsc.ar(LFDNoise3.kr(LFNoise0.kr(1) * 40 + 60) * 700 + 800);​    chain = FFT(LocalBuf(fftsize), sig);    stream = Unpack1FFT(chain, bufsize: fftsize, binindex: 0, whichmeasure: 0);​    // each time an FFT window starts, the unpacker returns a new value    windowStarts = chain > -1;    demand = Demand.kr(windowStarts, 0, stream);    demand.poll(windowStarts);​    sig * 0.05}.play)