SampleDependencyBox.java

/*
 *  Copyright (C) 2011 in-somnia
 * 
 *  This file is part of JAAD.
 * 
 *  JAAD is free software; you can redistribute it and/or modify it 
 *  under the terms of the GNU Lesser General Public License as 
 *  published by the Free Software Foundation; either version 3 of the 
 *  License, or (at your option) any later version.
 *
 *  JAAD 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 Lesser General 
 *  Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library.
 *  If not, see <http://www.gnu.org/licenses/>.
 */
package net.sourceforge.jaad.mp4.boxes.impl;

import java.io.IOException;
import net.sourceforge.jaad.mp4.MP4InputStream;
import net.sourceforge.jaad.mp4.boxes.BoxTypes;
import net.sourceforge.jaad.mp4.boxes.FullBox;

/**
 * This box contains the sample dependencies for each switching sample. The
 * dependencies are stored in the table, one record for each sample. The size of
 * the table is taken from the the Sample Size Box ('stsz') or Compact Sample
 * Size Box ('stz2').
 *
 * @author in-somnia
 */
public class SampleDependencyBox extends FullBox {

	private int[] dependencyCount;
	private int[][] relativeSampleNumber;

	public SampleDependencyBox() {
		super("Sample Dependency Box");
	}

	@Override
	public void decode(MP4InputStream in) throws IOException {
		super.decode(in);

		final int sampleCount = ((SampleSizeBox) parent.getChild(BoxTypes.SAMPLE_SIZE_BOX)).getSampleCount();

		int j;
		for(int i = 0; i<sampleCount; i++) {
			dependencyCount[i] = (int) in.readBytes(2);
			for(j = 0; j<dependencyCount[i]; j++) {
				relativeSampleNumber[i][j] = (int) in.readBytes(2);
			}
		}
	}

	/**
	 * The dependency count is an integer that counts the number of samples
	 * in the source track on which this switching sample directly depends.
	 *
	 * @return all dependency counts
	 */
	public int[] getDependencyCount() {
		return dependencyCount;
	}

	/**
	 * The relative sample number is an integer that identifies a sample in
	 * the source track. The relative sample numbers are encoded as follows.
	 * If there is a sample in the source track with the same decoding time,
	 * it has a relative sample number of 0. Whether or not this sample
	 * exists, the sample in the source track which immediately precedes the
	 * decoding time of the switching sample has relative sample number –1,
	 * the sample before that –2, and so on. Similarly, the sample in the
	 * source track which immediately follows the decoding time of the
	 * switching sample has relative sample number +1, the sample after that
	 * +2, and so on.
	 *
	 * @return all relative sample numbers
	 */
	public int[][] getRelativeSampleNumber() {
		return relativeSampleNumber;
	}
}