musicg.extension.Spectrogram Maven / Gradle / Ivy

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/*
 *
 *  *
 *  *  * Copyright 2015 Skymind,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 musicg.extension;


import musicg.Wave;
import musicg.dsp.FastFourierTransform;
import musicg.dsp.WindowFunction;

/**
 * Handles the wave data in frequency-time domain.
 *
 * @author Jacquet Wong
 */
public class Spectrogram{

	public static final int SPECTROGRAM_DEFAULT_FFT_SAMPLE_SIZE = 1024;
	public static final int SPECTROGRAM_DEFAULT_OVERLAP_FACTOR = 0;	// 0 for no overlapping

	private Wave wave;
	private double[][] spectrogram;	// relative spectrogram
	private double[][] absoluteSpectrogram;	// absolute spectrogram
	private int fftSampleSize;	// number of sample in fft, the value needed to be a number to power of 2
	private int overlapFactor;	// 1/overlapFactor overlapping, e.g. 1/4=25% overlapping
	private int numFrames;	// number of frames of the spectrogram
	private int framesPerSecond;	// frame per second of the spectrogram
	private int numFrequencyUnit;	// number of y-axis unit
	private double unitFrequency;	// frequency per y-axis unit

	/**
	 * Constructor
	 *
	 * @param wave
	 */
	public Spectrogram(Wave wave) {
		this.wave=wave;
		// default
		this.fftSampleSize=SPECTROGRAM_DEFAULT_FFT_SAMPLE_SIZE;
		this.overlapFactor=SPECTROGRAM_DEFAULT_OVERLAP_FACTOR;
		buildSpectrogram();
	}

	/**
	 * Constructor
	 *
	 * @param wave
	 * @param fftSampleSize	number of sample in fft, the value needed to be a number to power of 2
	 * @param overlapFactor	1/overlapFactor overlapping, e.g. 1/4=25% overlapping, 0 for no overlapping
	 */
	public Spectrogram(Wave wave, int fftSampleSize, int overlapFactor) {
		this.wave=wave;

		if (Integer.bitCount(fftSampleSize)==1){
			this.fftSampleSize=fftSampleSize;
		}
		else{
			System.err.print("The input number must be a power of 2");
			this.fftSampleSize=SPECTROGRAM_DEFAULT_FFT_SAMPLE_SIZE;
		}

		this.overlapFactor=overlapFactor;

		buildSpectrogram();
	}

	/**
	 * Build spectrogram
	 */
	private void buildSpectrogram(){

		short[] amplitudes=wave.getSampleAmplitudes();
		int numSamples = amplitudes.length;

		int pointer=0;
		// overlapping
		if (overlapFactor>1){
			int numOverlappedSamples=numSamples*overlapFactor;
			int backSamples=fftSampleSize*(overlapFactor-1)/overlapFactor;
			int fftSampleSize_1=fftSampleSize-1;
			short[] overlapAmp= new short[numOverlappedSamples];
			pointer=0;
			for (int i=0; i0){

			numFrequencyUnit=absoluteSpectrogram[0].length;
			unitFrequency=(double)wave.getWaveHeader().getSampleRate()/2/numFrequencyUnit;	// frequency could be caught within the half of nSamples according to Nyquist theory

			// normalization of absoultSpectrogram
			spectrogram=new double[numFrames][numFrequencyUnit];

			// set max and min amplitudes
			double maxAmp=Double.MIN_VALUE;
			double minAmp=Double.MAX_VALUE;
			for (int i=0; imaxAmp){
						maxAmp=absoluteSpectrogram[i][j];
					}
					else if(absoluteSpectrogram[i][j]