oggpacket.java

来自「java语言开发的P2P流媒体系统」· Java 代码 · 共 109 行

/* 
 * P2P-Radio - Peer to peer streaming system
 * Project homepage: http://p2p-radio.sourceforge.net/
 * Copyright (C) 2003-2004 Michael Kaufmann <[e-mail]>
 * 
 * ---------------------------------------------------------------------------
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * ---------------------------------------------------------------------------
 */

package p2pradio.sources.ogg;

public class OggPacket
{
	protected OggPage parent;
	protected int dataStartPos;
	protected int dataLength;
	private boolean continuedInNextPage;
	
	public static final int UNKNOWN = 0;
	public static final int VORBIS_IDENTIFICATION_HEADER = 1;
	public static final int VORBIS_COMMENT_HEADER = 2;
	public static final int VORBIS_SETUP_HEADER = 3;
	public static final int VORBIS_AUDIO = 4;
	
	public OggPacket(OggPage parent, int dataStartPos, int dataLength, boolean continuedInNextOggPage)
	{
		this.parent = parent;
		this.dataStartPos = dataStartPos;
		this.dataLength = dataLength;
		this.continuedInNextPage = continuedInNextOggPage;
	}
	
	public boolean isVorbisPacket()
	{
		return ((parent.data[dataStartPos+1] == 'v')
		     && (parent.data[dataStartPos+2] == 'o')
		     && (parent.data[dataStartPos+3] == 'r')
		     && (parent.data[dataStartPos+4] == 'b')
		     && (parent.data[dataStartPos+5] == 'i')
		     && (parent.data[dataStartPos+6] == 's'));
	}
	
	public int getVorbisPacketType()
	{
		byte type = parent.data[dataStartPos];
		
		if ((type & 0x01) == 0)
		{
			return VORBIS_AUDIO;
		}
		
		switch (type & 0x0FF)
		{
			case 1:
			  return VORBIS_IDENTIFICATION_HEADER;
			
			case 3:
				return VORBIS_COMMENT_HEADER;
				
			case 5:
				return VORBIS_SETUP_HEADER;
			
			default:
				return UNKNOWN;
		}
	}
	
	public boolean isContinuedInNextPage()
	{
		return continuedInNextPage;
	}
	
	public String toString()
	{
		String result = "Ogg Packet: "; //$NON-NLS-1$
		
		if (isVorbisPacket())
		{
			result += "Vorbis (type " + getVorbisPacketType() + "), "; //$NON-NLS-1$ //$NON-NLS-2$
		}
		else
		{
			result += "NOT Vorbis, "; //$NON-NLS-1$
		}
		
		result += dataLength + " bytes"; //$NON-NLS-1$
		
		if (continuedInNextPage)
		{
			result += " (continued in next page)"; //$NON-NLS-1$
		}
		
		return result;
	}
}