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/*
* Copyright 2012 Phil Burk, Mobileer Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.jsyn.unitgen;
import com.jsyn.ports.UnitInputPort;
import com.jsyn.ports.UnitOutputPort;
import com.jsyn.util.AutoCorrelator;
import com.jsyn.util.SignalCorrelator;
/**
* Estimate the fundamental frequency of a monophonic signal. Analyzes an input signal and outputs
* an estimated period in frames and a frequency in Hertz. The frequency is frameRate/period. The
* confidence tells you how accurate the estimate is. When the confidence is low, you should ignore
* the period. You can use a CompareUnit and a LatchUnit to hold values that you are confident of.
* <P>
* Note that a stable monophonic signal is required for accurate pitch tracking.
*
* @author (C) 2012 Phil Burk, Mobileer Inc
*/
public class PitchDetector extends UnitGenerator {
public UnitInputPort input;
public UnitOutputPort period;
public UnitOutputPort confidence;
public UnitOutputPort frequency;
public UnitOutputPort updated;
protected SignalCorrelator signalCorrelator;
private double lastFrequency = 440.0;
private double lastPeriod = 44100.0 / lastFrequency; // result of analysis
private double lastConfidence = 0.0; // Measure of confidence in the result.
private static final int LOWEST_FREQUENCY = 40;
private static final int HIGHEST_RATE = 48000;
private static final int CYCLES_NEEDED = 2;
public PitchDetector() {
super();
addPort(input = new UnitInputPort("Input"));
addPort(period = new UnitOutputPort("Period"));
addPort(confidence = new UnitOutputPort("Confidence"));
addPort(frequency = new UnitOutputPort("Frequency"));
addPort(updated = new UnitOutputPort("Updated"));
signalCorrelator = createSignalCorrelator();
}
public SignalCorrelator createSignalCorrelator() {
int framesNeeded = HIGHEST_RATE * CYCLES_NEEDED / LOWEST_FREQUENCY;
return new AutoCorrelator(framesNeeded);
}
@Override
public void generate(int start, int limit) {
double[] inputs = input.getValues();
double[] periods = period.getValues();
double[] confidences = confidence.getValues();
double[] frequencies = frequency.getValues();
double[] updateds = updated.getValues();
for (int i = start; i < limit; i++) {
double current = inputs[i];
if (signalCorrelator.addSample(current)) {
lastPeriod = signalCorrelator.getPeriod();
if (lastPeriod < 0.1) {
System.out.println("ILLEGAL PERIOD");
}
double currentFrequency = getFrameRate() / (lastPeriod + 0);
double confidence = signalCorrelator.getConfidence();
if (confidence > 0.1) {
if (true) {
double coefficient = confidence * 0.2;
// Take weighted average with previous frequency.
lastFrequency = ((lastFrequency * (1.0 - coefficient)) + (currentFrequency * coefficient));
} else {
lastFrequency = ((lastFrequency * lastConfidence) + (currentFrequency * confidence))
/ (lastConfidence + confidence);
}
}
lastConfidence = confidence;
updateds[i] = 1.0;
} else {
updateds[i] = 0.0;
}
periods[i] = lastPeriod;
confidences[i] = lastConfidence;
frequencies[i] = lastFrequency;
}
}
/**
* For debugging only.
*
* @return internal array of correlation results.
*/
public float[] getDiffs() {
return signalCorrelator.getDiffs();
}
}
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