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

/**
 * This box contains a compact version of a table that allows indexing from
 * decoding time to sample number. Other tables give sample sizes and pointers,
 * from the sample number. Each entry in the table gives the number of
 * consecutive samples with the same time delta, and the delta of those samples.
 * By adding the deltas a complete time-to-sample map may be built.
 * The Decoding Time to Sample Box contains decode time delta's:
 * DT(n+1) = DT(n) + STTS(n)
 * where STTS(n) is the (uncompressed) table entry for sample n.
 * The sample entries are ordered by decoding time stamps; therefore the deltas
 * are all non-negative.
 * The DT axis has a zero origin; DT(i) = SUM(for j=0 to i-1 of delta(j)), and
 * the sum of all deltas gives the length of the media in the track (not mapped
 * to the overall timescale, and not considering any edit list).
 * The Edit List Box provides the initial CT value if it is non-empty
 * (non-zero).
 * 
 * @author in-somnia
 */
public class DecodingTimeToSampleBox extends FullBox {

	private long[] sampleCounts, sampleDeltas;

	public DecodingTimeToSampleBox() {
		super("Time To Sample Box");
	}

	@Override
	public void decode(MP4InputStream in) throws IOException {
		super.decode(in);
		
		final int entryCount = (int) in.readBytes(4);
		sampleCounts = new long[entryCount];
		sampleDeltas = new long[entryCount];

		for(int i = 0; i<entryCount; i++) {
			sampleCounts[i] = in.readBytes(4);
			sampleDeltas[i] = in.readBytes(4);
		}
	}

	public long[] getSampleCounts() {
		return sampleCounts;
	}

	public long[] getSampleDeltas() {
		return sampleDeltas;
	}
}