A chromagram, measuring the energy at particular chroma within an nTET tuning system.
Possible extension: TODO: Could have arbitrary tuning systems if precalculated the exact fft bin + interpolation data.
| fft |
input fft chain, that is, from an FFT UGen |
| fftsize |
FFT size, required for initialisation |
| n |
Equal divisions of an octave, e.g. n=12 is 12TET, 12 steps in an octave |
| tuningbase |
Base frequency or tuning; will correspong to index 0 in results (conventionally, this would be a 'C' in 12TET, but its an arbitrary reference) |
| octaves |
Number of octaves considered from tuning base up |
| integrationflag |
Whether to integrate from frame to frame, off by default |
| coeff |
Coefficient of integration |
| octaveratio |
Default of 2 is a 'normal' octave; other ratios are possible, e.g. Bohlen-Pierce scale uses 13 equal divisions over the ratio of 3 for a 'tritave' |
| perframenormalize |
Defaults to off, but if set to 1 will normalize each frame with respect to itself (as long as there is non-negligible power), potentially providing a more robust measure for comparison between frames (each frame will have then a normalized distribution over chroma, independent of volume) |
(
{
var in, fft, chroma;
//in = SinOsc.ar(440,0,0.1);
in= SoundIn.ar;
fft = FFT(LocalBuf(2048), in);
chroma=Chromagram.kr(fft);
chroma.poll;
Out.ar(0,Pan2.ar(in));
}.play
)
//n TET display
n= 12; //19, 24
(
x = {
var in, fft, chroma;
//in = SinOsc.ar(440,0,0.1);
in= SoundIn.ar;
fft = FFT(LocalBuf(2048), in);
chroma=Chromagram.kr(fft, 2048, n);
//chroma=Chromagram.kr(fft, 2048, n, 36.midicps, 7, 1, 0.9);
Out.kr(0,chroma);
}.play;
c= Bus.new('control', 0, n);
)
//poll coefficients snapshot
c.getn(n,{arg val; {val.plot;}.defer});
//Continuous graphical display of Chromagram values; free routine before closing window
(
var ms;
w=Window.new((n.asString)++" chroma coefficients", Rect(200,400,n*20+50,300));
ms= MultiSliderView.new(w, Rect(10,10,n*20,280));
ms.value_(Array.fill(n,0.0));
ms.valueThumbSize_(20.0);
ms.indexThumbSize_(20.0);
ms.gap_(0);
w.front;
r= {
inf.do{
c.getn(n,{arg val; {ms.value_(val)}.defer});
0.04.wait; //25 frames per second
};
}.fork;
w.onClose = {
r.stop;
c.free;
x.free;
};
)
b.free;
//Bohlen-Pierce over 3 tritaves, normalized results per frame
(
{
var in, fft, chroma;
//in = SinOsc.ar(440,0,0.1);
in= SoundIn.ar;
fft = FFT(LocalBuf(2048), in);
chroma=Chromagram.kr(fft,2048,13,octaves:3,octaveratio:3,perframenormalize:1);
chroma.poll;
Out.ar(0,Pan2.ar(in));
}.play
)