FFTTest.java :  » Game » libgdx » com » badlogic » gdx » tests » Android Open Source

/*
 * Copyright 2010 Mario Zechner (contact@badlogicgames.com), Nathan Sweet (admin@esotericsoftware.com)
 * 
 * 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.badlogic.gdx.tests;

import java.nio.FloatBuffer;
import java.nio.ShortBuffer;
import java.util.Arrays;

import com.badlogic.gdx.audio.analysis.AudioTools;
import com.badlogic.gdx.audio.analysis.FFT;
import com.badlogic.gdx.audio.analysis.KissFFT;

public class FFTTest {
  static int SAMPLES = 256;

  public static void main (String[] argv) {
    float[] samples = new float[SAMPLES];
    ShortBuffer shortSamples = AudioTools.allocateShortBuffer(SAMPLES, 1);

// createFlat( samples, shortSamples );
    createSine(samples, shortSamples);
    analyse(samples, shortSamples);
  }

  private static void analyse (float samples[], ShortBuffer shortSamples) {
    FFT fft = new FFT(SAMPLES, 44100);
    KissFFT kfft = new KissFFT(SAMPLES);
    fft.forward(samples);
    float[] spectrum = fft.getSpectrum();
    FloatBuffer floatSpectrum = AudioTools.allocateFloatBuffer(SAMPLES / 2 + 1, 1);

    System.out.println(Arrays.toString(spectrum));

    System.out.print("[");
    kfft.spectrum(shortSamples, floatSpectrum);
    for (int i = 0; i < SAMPLES / 2 + 1; i++)
      System.out.print(floatSpectrum.get(i) + ", ");
    System.out.println("]");

    System.out.println(sum(samples) / SAMPLES);
// System.out.println( sum( spectrum ) );
// System.out.println( sum( floatSpectrum ));
    kfft.dispose();
  }

  private static float sum (float samples[]) {
    float sum = 0;
    for (int i = 1; i < samples.length; i++)
      sum += samples[i];
    return sum;
  }

  private static float sum (FloatBuffer buffer) {
    float sum = 0;
    for (int i = 1; i < SAMPLES / 2 + 1; i++)
      sum += buffer.get(i) * 2 / SAMPLES;
    return sum;
  }

  private static void createFlat (float samples[], ShortBuffer shortSamples) {
    for (int i = 0; i < samples.length; i++) {
      samples[i] = 1;
      shortSamples.put(Short.MAX_VALUE);
    }
  }

  private static void createSine (float samples[], ShortBuffer shortSamples) {
    final float frequency = 44100 / (SAMPLES / 2);
    float increment = (float)(2 * Math.PI) * frequency / 44100; // angular increment for each sample
    float angle = 0;
    final float frequency2 = 44100 / (SAMPLES / 2) * 4;
    float increment2 = (float)(2 * Math.PI) * frequency2 / 44100;
    float angle2 = 0;

    for (int i = 0; i < samples.length; i++) {
      samples[i] = Math.max(0, Math.min((float)Math.sin(angle) + (float)Math.sin(angle2), 1));
      shortSamples.put((short)(Short.MAX_VALUE * samples[i]));
      angle += increment;
      angle2 += increment2;
    }
  }
}