Live Dissonance

Extension

Here's an example of how to obtain dissonance curves from live input, either by triggering or through onset detection.

There are a few methods added to DissonanceLib that aid in converting FFT data, such as the one obtained from a buffer with the help of PV_FreqBuffer and PV_MagBuffer (from JoshUgens in sc3-plugins), into n-highest partials in arrays of frequency and amplitude pairs.

These methods are additions to Array: -maxima and Array: -findNlargest.s = Server.internal; // etc all the rest SynthDef(\liveFFT, {|in=8,fftbuf=0,magbuf=1,freqbuf=2| var fft, inp; inp = SoundIn.ar(0); // your input. Also can be In.ar(in); fft = FFT(fftbuf, inp, wintype: 1); // wintype: hanning. Does a better job than the default fft = PV_FreqBuffer(fft, freqbuf); // you need JoshUGens for these two fft = PV_MagBuffer(fft, magbuf); IFFT(fft); // in theory you don't need this line, in practice, don't know why but you do }).add; w = 8192; // the window size (experiment according to your needs); b = Buffer.alloc(s, w); // fft buffer c = Buffer.alloc(s, w div: 2); // mag buffer d = Buffer.alloc(s, w div: 2); // freq buffer a = Synth(\liveFFT, [\in, 8, \fftbuf, b.bufnum, \magbuf, c.bufnum, \freqbuf, d.bufnum]); ~analysis = { // get data from freqbuf d.getn(0, d.numFrames, {|w| ~freqs = w; // get data from magbuf c.getn(0, c.numFrames, {|x| ~mags = x; }); }); }; ~analysis.value // here are the raw frequencies and magnitudes obtained from the fft buffer: [~freqs, ~mags].postln;

A more complete example that calculates a dissonance curve from the fft:~minInt = 0.48; // minimum interval for the dissonance analysis ~maxInt = 4.01; // maximum interval //Bn (k) = 20log10(ζ ∗ |Xn (k)|) where ζ = 184268; from Nick Collins PhD thesis. ~bintodb = {|mag| 20 *( 8 * mag.abs).log10}; // ζ = 8 is enough for this ~analysisDiss = { // get data from freqbuf d.getn(0, d.numFrames, {|w| ~freqs = w; // get data from magbuf c.getn(0, c.numFrames, {|x| ~mags = x; ~max = [~freqs, ~mags].maxima; // this method gets all the maxima ~max = ~max.findNlargest(8); // this one gets the 8 highest partials ~max[1] = ~max[1].collect{|x| ~bintodb.value(x)}; // convert the bin values to dB // convert the amplitudes from dB to sones: ~sones = [~max[0], ~max[1]].flop.asSone(20).round(0.01); // make the dissonance curve k = Dissonance.make(~max[0], ~sones, ~minInt, ~maxInt, 0.01, \parncutt, false); // rationalize, calculate harmonic metrics and make PitchSet: k.harmonicAnalysis(16, \harmonicity, \size, [729, 512], PitchSet.unisons.dim3.et31[1]); }); }); }; ~analysisDiss.value; // 'trigger' the analysis k.postln; //here's your diss curve from the fft