KeyTrack key tracker

key = KeyTrack.kr(chain, keydecay=2.0, chromadecay= 1.0)

chain- [fft] Audio input to track. This must have been pre-analysed by a 4096 size FFT. No other FFT sizes are valid except as noted below.

//With standard hop of half FFT size = 2048 samples

b = Buffer.alloc(s,4096,1); //for sampling rates 44100 and 48000

//b = Buffer.alloc(s,8192,1); //for sampling rates 88200 and 96000

keydecay- [sk] Number of seconds for the influence of a window on the final key decision to decay by 40dB (to 0.01 its original value)

chromaleak- [sk] Each frame, the chroma values are set to the previous value multiplied by the chromadecay. 0.0 will start each frame afresh with no memory.

A (12TET major/minor) key tracker based on a pitch class profile of energy across FFT bins and matching this to templates for major and minor scales in all transpositions. It assumes a 440 Hz concert A reference. Output is 0-11 C major to B major, 12-23 C minor to B minor

//The following files are test materials on my machine; you will subsitute your own filenames here

//A major

d=Buffer.read(s,"/Volumes/data/stevebeattrack/samples/100.wav");

//F major; hard to track!

d=Buffer.read(s,"/Volumes/data/stevebeattrack/samples/115.wav");

//straight forward since no transients; training set from MIREX2006

//01= A major

//57 = b minor

//78 e minor

//08 Bb major

d=Buffer.read(s,"/Users/nickcollins/Desktop/ML/training_wav/78.wav")

b = Buffer.alloc(s,4096,1); //for sampling rates 44100 and 48000

(

{

var in, fft, resample;

var key, transientdetection;

in= PlayBuf.ar(1,d,BufRateScale.kr(d),1,0,1);

fft = FFT(b, in);

key=KeyTrack.kr(fft, 2.0, 0.5);

key.poll;

Out.ar(0,Pan2.ar(in));

}.play

)

//alternating major and minor chords as a test

(

{

var in, fft, resample;

var key, transientdetection;

in= Mix(SinOsc.ar((60+[0,MouseX.kr(3,4).round(1),7]).midicps,0,0.1));

//major dom 7 and minor 7; major keys preferred here

//in= Mix(SinOsc.ar((60+(MouseY.kr(0,11).round(1.0))+[0,MouseX.kr(3,4).round(1),7, 10]).midicps,0,0.1));

fft = FFT(b, in);

key=KeyTrack.kr(fft);

key.poll;

Out.ar(0,Pan2.ar(in));

}.play

)

//Nice to hear what KeyTrack thinks:

d=Buffer.read(s,"/Users/nickcollins/Desktop/ML/training_wav/78.wav")

b = Buffer.alloc(s,4096,1); //for sampling rates 44100 and 48000

(

{

var in, fft, resample, chord, rootnote, sympath;

var key, transientdetection;

in= PlayBuf.ar(1,d,BufRateScale.kr(d),1,0,1);

fft = FFT(b, in);

key=KeyTrack.kr(fft, 2.0, 0.5);

key.poll;

key = Median.kr(101, key); // Remove outlier wibbles

chord = if(key<12, #[0,4,7], #[0,3,7]);

rootnote = if(key<12, key, key-12) + 60;

sympath = SinOsc.ar((rootnote + chord).midicps, 0, 0.4).mean;

Out.ar(0,Pan2.ar(in, -0.5) + Pan2.ar(sympath, 0.5));

}.play

)

//Research Notes:

//See the MIREX2006 audio key tracking competition and Emilia Gomez's PhD thesis, Tonal Description of Music Audio Signals

//The following code was used to create the datasets for the UGen, and would be the basis of extensions

//Need one set of bin data for 44100 and one for 48000

//KeyTrack calculations, need to make arrays of FFT bins and weights for each chromatic tone.

//greater resolution, 4096 FFT, avoid lower octaves, too messy there

//60*6*2 output arrays

(

var fftN, fftBins, binsize;

var midinotes;

var sr;

var wtlist, binlist;

sr = 48000; //44100;

fftN=4096;

fftBins=fftN.div(2);

binsize=sr/fftN;

midinotes= (33..92); //60 notes, 55 Hz up to 1661.2187903198 Hz

wtlist=List[];

binlist=List[];

//for each note have six harmonic locations

midinotes.do{|note|

var freq, whichbin, lowerbin, prop;

freq= note.midicps;

6.do{|j|

var partialfreq, partialamp;

partialamp= 1.0/(j+1);

partialfreq= freq*(j+1);

whichbin= partialfreq/binsize;

lowerbin= whichbin.asInteger;

prop= 1.0-(whichbin-lowerbin);

binlist.add(lowerbin).add(lowerbin+1);

wtlist.add(prop*partialamp).add((1.0-prop)*partialamp);

};

};

Post << (binlist) << nl<< nl;

Post << (wtlist) << nl<< nl;

binlist.size.postln;

wtlist.size.postln;

)