Audio Tracer

MotionWhistleTracerViterbi.java

package processing.signals;

import java.util.ArrayList;

import processing.utils.ProbabilityUtils;

/**
 * Viterbi Style Whistle Tracing
 *
 * @author Daniel Kohlsdorf
 */
public class MotionWhistleTracer {

    /**
     * Probability defined by magnitude of each sin / cosine component.
     */
    public double[] mag_pdf(double[] dft) {
        double pdf[] = new double[dft.length];
        double sum = 0.0;
        for (int i = 0; i < pdf.length; i++) {
            sum += dft[i];
            pdf[i] = dft[i];
        }

        for (int i = 0; i < pdf.length; i++) {
            pdf[i] = ProbabilityUtils.lg(pdf[i] / sum);
        }

        return pdf;
    }

    public double[] trace(ArrayList<double[]> spec, double variance) {
        int N = spec.size();
        int D = spec.get(0).length;
        double v[][] = new double[N][D];
        double var[][] = new double[N][D];
        double velocity[][] = new double[N][D];
        int bt_ptr[][] = new int[N][D];

        v[0] = mag_pdf(spec.get(0));
        for (int i = 0; i < D; i++) {
            velocity[0][i] = 1;
            var[0][i] = variance;
        }

        for (int t = 1; t < N; t++) {
            double obs[] = mag_pdf(spec.get(t));
            for (int f = 0; f < D; f++) {
                double max_ll = ProbabilityUtils.ZERO;
                int max_f = 0;
                for (int _f = 0; _f < D; _f++) {
                    double ll = ProbabilityUtils.lgnormpdf(new double[]{f}, new double[]{velocity[t - 1][_f] + _f}, new double[]{variance});
                    ll +=   + v[t - 1][_f];
                    if (ll > max_ll && _f != f) {
                        max_ll = ll;
                        max_f = _f;
                    }
                }
                velocity[t][f] = (f - max_f);
                v[t][f] = max_ll + obs[f];
                bt_ptr[t][f] = max_f;
            }
            
        }

        double path[] = new double[N];

        double max = ProbabilityUtils.ZERO;
        int max_ptr = 0;
        for (int i = 0; i < D; i++) {
            if (v[N - 1][i] > max) {
                max = v[N - 1][i];
                max_ptr = i;
            }
        }
        path[N - 1] = max_ptr;

        for (int i = N - 2; i > 0; i--) {
            path[i] = bt_ptr[i][max_ptr];
            max_ptr = bt_ptr[i][max_ptr];
        }

        return path;
    }

}