Android Open Source - voicesmith Window

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License

The source code is released under:

GNU General Public License

Java Source Code

/*
 * Voicesmith <http://voicesmith.jurihock.de/>
 */*from   w  w w.  j  av a  2 s.co  m*/
 * Copyright (c) 2011-2014 Juergen Hock
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package de.jurihock.voicesmith.dsp;

import static de.jurihock.voicesmith.dsp.Math.PI;
import static de.jurihock.voicesmith.dsp.Math.cos;
import static de.jurihock.voicesmith.dsp.Math.sqrt;

public final class Window
{
  private final int    frameSize;
  private final int    hopSize;
  private final boolean  isPeriodic;
  private final boolean  isWeighted;

  /**
   * @param isPeriodic
   *            Compute first N coefficients for the N+1 window.
   * */
  public Window(int frameSize, boolean isPeriodic)
  {
    this(frameSize, frameSize, isPeriodic, false);
  }

  /**
   * @param isPeriodic
   *            Compute first N coefficients for the N+1 window.
   * @param isWeighted
   *            Weight window according to the Weighted Overlap Add (WOLA)
   *            routine.
   * */
  public Window(int frameSize, int hopSize, boolean isPeriodic, boolean isWeighted)
  {
    this.frameSize = frameSize;
    this.hopSize = hopSize;
    this.isPeriodic = isPeriodic;
    this.isWeighted = isWeighted;
  }

  private void weight(float[] window)
  {
    float weighting = 0;

    for (int n = 0; n < frameSize; n++)
      weighting += window[n] * window[n];

    weighting = 1F / sqrt(weighting / hopSize);

    for (int n = 0; n < frameSize; n++)
      window[n] *= weighting;
  }

  public float[] hann()
  {
    final float[] window = new float[frameSize];
    final int N = (isPeriodic) ? frameSize + 1 : frameSize;

    for (int n = 0; n < frameSize; n++)
    {
      window[n] = 0.5F * (1F - cos(2F * PI * n / (N - 1F)));
    }

    if (isWeighted) weight(window);

    return window;
  }
}

Java Source Code List

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