SuperCollider CLASSES (extension)

FFTSubbandFlatness
ExtensionExtension

Spectral flatness, divided into subbands

Description

Calculates the spectral flatness measure, in the same manner as FFTFlatness, but divides the spectrum into (adjacent, non-overlapping) subbands, so returns separate measures for the different subbands.

The parameter cutfreqs can only be specified on initialisation - they can't be modulated.

Class Methods

*kr (chain, cutfreqs)

Arguments:

chain
cutfreqs

must be an array of frequencies. For example, to divide a 44100Hz signal into three subbands we might specify [ 5512, 11025 ] as the cutfreqs, giving subbands of 0-5512Hz, 5512-11025Hz, and 11025-22050Hz. (Frequencies above the Nyquist frequency are not included.)

Returns:

#[flatness1, flatness2, ... flatnessN+1]

Inherited class methods

Instance Methods

Inherited instance methods

Undocumented instance methods

-numbands

Examples

In this example we take a "flat" sound (white noise) and an "unflat" sound (a sawtooth wave) and mix them together bandwise using [PV_BinWipe]. With the spectrum divided into three bands you should be able to see the results.

s.boot;
b = Buffer.alloc(s,2048,1);
c = Buffer.alloc(s,2048,1);
(
x = {
var inA, inB, chainA, chainB, chain, vals, cutfreqs;
//in = LPF.ar(WhiteNoise.ar, MouseX.kr(10,10000, 1));

inA = WhiteNoise.ar;
inB = Saw.ar;

chainA = FFT(b.bufnum, inA);
chainB = FFT(c.bufnum, inB);

chain = PV_BinWipe(chainA, chainB, MouseX.kr(-1, 1));

vals = FFTSubbandPower.kr(chain, [300, 500, 1500]);

vals[3].poll(10, "hi ");
vals[2].poll(10, "med");
vals[1].poll(10, "low");

Out.ar(0, IFFT(chain).dup * 0.2);
}.play(s);
)
x.free;