44 lines
1.2 KiB
Text
44 lines
1.2 KiB
Text
|
class:: SpecCentroid
|
||
|
|
summary:: Spectral centroid
|
||
|
|
categories:: UGens>FFT
|
||
|
|
related:: Classes/SpecFlatness, Classes/SpecPcile
|
||
|
|
|
||
|
|
description::
|
||
|
|
Given an link::Classes/FFT:: strong::chain::, this measures the emphasis::spectral:: centroid, which is the weighted mean frequency, or the "centre of mass" of the spectrum. (DC is ignored.)
|
||
|
|
|
||
|
|
This can be a useful indicator of the perceptual emphasis::brightness:: of a signal.
|
||
|
|
|
||
|
|
classmethods::
|
||
|
|
method:: kr
|
||
|
|
|
||
|
|
argument:: buffer
|
||
|
|
an link::Classes/FFT:: chain.
|
||
|
|
|
||
|
|
examples::
|
||
|
|
|
||
|
|
A link::Classes/Blip:: oscillator is ideal for demonstrating this because the number of harmonics is directly manipulated: as the number of harmonics increases, the centroid is pushed higher. In the example, left-to-right changes the number of harmonics, but up-to-down changes the fundamental pitch; note the different effects of these two on the centroid.
|
||
|
|
|
||
|
|
code::
|
||
|
|
s.boot;
|
||
|
|
b = Buffer.alloc(s,2048,1);
|
||
|
|
(
|
||
|
|
x = {
|
||
|
|
var in, chain, freq, rq, centroid;
|
||
|
|
|
||
|
|
//freq = LFPar.kr(0.3).exprange(100, 1000);
|
||
|
|
freq = MouseY.kr(1000, 100, 1);
|
||
|
|
|
||
|
|
in = Blip.ar(freq, MouseX.kr(1, 100, 1));
|
||
|
|
|
||
|
|
chain = FFT(b, in);
|
||
|
|
|
||
|
|
centroid = SpecCentroid.kr(chain);
|
||
|
|
|
||
|
|
Out.ar(0, in.dup * 0.1);
|
||
|
|
centroid.poll(10);
|
||
|
|
}.play(s);
|
||
|
|
)
|
||
|
|
|
||
|
|
x.free;
|
||
|
|
::
|