TI99SoundSmoother.java

/*
  TI99SoundSmoother.java

  (c) 2012-2013 Edward Swartz

  All rights reserved. This program and the accompanying materials
  are made available under the terms of the Eclipse Public License v1.0
  which accompanies this distribution, and is available at
  http://www.eclipse.org/legal/epl-v10.html
 */
package v9t9.common.sound;

import java.util.List;

import ejs.base.sound.IEditableSoundView;
import ejs.base.sound.ISoundMutator;
import ejs.base.sound.ISoundView;
import ejs.base.sound.SoundChunk;

/**
 * @author ejs
 *
 */
public class TI99SoundSmoother implements ISoundMutator {

	private float[] last = new float[2];
	
	/* (non-Javadoc)
	 * @see ejs.base.sound.ISoundMutator#editSoundChunk(ejs.base.sound.ISoundView, java.util.List)
	 */
	@Override
	public void editSoundChunk(ISoundView chunk, List<ISoundView> outViews) {
		ISoundView outView = chunk;
		if (!chunk.isSilent()) {
			int numChans = chunk.getFormat().getChannels();
			int processedChans = Math.min(last.length, numChans);
			
			int length = chunk.getSampleCount();
			
			IEditableSoundView outChunk = null;
			if (chunk instanceof IEditableSoundView) {
				outChunk = (IEditableSoundView) chunk;
			} else {
				outChunk = new SoundChunk(new float[length], chunk.getFormat());
			}
			
			// watch out for errors from bad sounds
			for (int c = 0; c < processedChans; c++) {
				if (Float.isNaN(last[c]))
					last[c] = 0f;
			}
			
			for (int idx = 0; idx < length; idx += numChans) {
				for (int c = 0; c < processedChans; c++) {
					float v = Math.max(-1, Math.min(1, chunk.at(idx + c)));

					v = (1f * v - 0.5f * last[c]);
					last[c] = v;
					
					outChunk.set(idx + c, v);
				}
			}
			
			outView = outChunk;
		}
		outViews.add(outView);
	}
}