SampleGroupDescriptionBox.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.MP4InputStream;
import net.sourceforge.jaad.mp4.boxes.BoxFactory;
import net.sourceforge.jaad.mp4.boxes.BoxImpl;
import net.sourceforge.jaad.mp4.boxes.BoxTypes;
import net.sourceforge.jaad.mp4.boxes.FullBox;
import net.sourceforge.jaad.mp4.boxes.impl.samplegroupentries.*;
import java.io.IOException;
import net.sourceforge.jaad.mp4.boxes.Box;

/**
 * This description table gives information about the characteristics of sample
 * groups. The descriptive information is any other information needed to define
 * or characterize the sample group.
 *
 * There may be multiple instances of this box if there is more than one sample
 * grouping for the samples in a track. Each instance of the
 * SampleGroupDescriptionBox has a type code that distinguishes different sample
 * groupings. Within a track, there shall be at most one instance of this box
 * with a particular grouping type. The associated SampleToGroupBox shall
 * indicate the same value for the grouping type.
 *
 * The information is stored in the sample group description box after the
 * entry-count. An abstract entry type is defined and sample groupings shall
 * define derived types to represent the description of each sample group. For
 * video tracks, an abstract VisualSampleGroupEntry is used with similar types
 * for audio and hint tracks.
 *
 * @author in-somnia
 */
public class SampleGroupDescriptionBox extends FullBox {

	private long groupingType, defaultLength, descriptionLength;
	private SampleGroupDescriptionEntry[] entries;

	public SampleGroupDescriptionBox() {
		super("Sample Group Description Box");
	}

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

		groupingType = in.readBytes(4);
		defaultLength = (version==1)?in.readBytes(4):0;

		final int entryCount = (int) in.readBytes(4);

		//TODO!
		/*final HandlerBox hdlr = (HandlerBox) parent.getParent().getParent().getChild(BoxTypes.HANDLER_BOX);
		final int handlerType = (int) hdlr.getHandlerType();
		
		final Class<? extends BoxImpl> boxClass;
		switch(handlerType) {
		case HandlerBox.TYPE_VIDEO:
		boxClass = VisualSampleGroupEntry.class;
		break;
		case HandlerBox.TYPE_SOUND:
		boxClass = AudioSampleGroupEntry.class;
		break;
		case HandlerBox.TYPE_HINT:
		boxClass = HintSampleGroupEntry.class;
		break;
		default:
		boxClass = null;
		}
		
		for(int i = 1; i<entryCount; i++) {
		if(version==1&&defaultLength==0) {
		descriptionLength = in.readBytes(4);
		left -= 4;
		}
		if(boxClass!=null) {
		entries[i] = (SampleGroupDescriptionEntry) BoxFactory.parseBox(in, boxClass);
		if(entries[i]!=null) left -= entries[i].getSize();
		}
		}*/
	}

	/**
	 * The grouping type is an integer that identifies the SampleToGroup box
	 * that is associated with this sample group description.
	 */
	public long getGroupingType() {
		return groupingType;
	}

	/**
	 * The default length indicates the length of every group entry (if the
	 * length is constant), or zero (0) if it is variable.
	 */
	public long getDefaultLength() {
		return defaultLength;
	}

	/**
	 * The description length indicates the length of an individual group entry,
	 * in the case it varies from entry to entry and default length is therefore 0.
	 */
	public long getDescriptionLength() {
		return descriptionLength;
	}
}