oggstream.java

来自「java语言开发的P2P流媒体系统」· Java 代码 · 共 238 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;

import p2pradio.*;
import p2pradio.packets.*;
import java.io.*;
import java.util.*;


public class OggStream
{	
	public static byte[] readVorbisHeader(OggPage firstPage, InputStream input, Metadata metadata) throws IOException, OggException
	{
		// The raw data of all the pages that belong to the header
		byte[] pagesData = new byte[PacketFactory.STREAM_PACKET_MAX_SIZE - DataPacket.getMaxLength()];
		int pagesSize = 0;
		
		boolean firstPacketOfSet = true;
		
		// Comment header
		byte[] commentData = new byte[PacketFactory.STREAM_PACKET_MAX_SIZE - DataPacket.getMaxLength()];
		int commentSize = 0;
		boolean readingCommentHeader = true;
		
		// Setup header
		boolean readingSetupHeader = false;
		
		
		// Read the identification header
		OggPage identificationHeader = firstPage;
		
		if (!identificationHeader.isBeginOfLogicalBitstream())
		{
			throw new OggException(Messages.getString("OggStream.NOT_BEGINNING_OF_A_STREAM")); //$NON-NLS-1$
		}
		
		if (identificationHeader.data.length != 58)
		{
			throw new OggException(Messages.getString("OggStream.WRONG_IDENTIFICATION_HEADER_SIZE")); //$NON-NLS-1$
		}
		
		LinkedList packets = identificationHeader.oggPackets;
		if (packets.size() != 1)
		{
			throw new OggException(Messages.getString("OggStream.INVALID_IDENTIFICATION_HEADER")); //$NON-NLS-1$
		}
	
		OggPacket packet = (OggPacket)packets.getFirst();
		if (!packet.isVorbisPacket() || (packet.getVorbisPacketType() != OggPacket.VORBIS_IDENTIFICATION_HEADER) || (packet.isContinuedInNextPage()))
		{
			throw new OggException(Messages.getString("OggStream.INVALID_IDENTIFICATION_HEADER")); //$NON-NLS-1$
		}
		
		pagesSize = identificationHeader.data.length;
		System.arraycopy(identificationHeader.data, 0, pagesData, 0, pagesSize);
		

		// Read the comment and setup headers
		
		OggPage nextPage;
		do
		{
			nextPage = new OggPage(input);
						
			if (pagesSize + nextPage.data.length > pagesData.length)
			{
				throw new OggException(Messages.getString("OggStream.HEADER_IS_TOO_LONG")); //$NON-NLS-1$
			}
			
			// Copy page
			System.arraycopy(nextPage.data, 0, pagesData, pagesSize, nextPage.data.length);
			pagesSize += nextPage.data.length;
			
			// Look at all packets in the current page
			Iterator iterator = nextPage.oggPackets.iterator();
			while(iterator.hasNext())
			{
				packet = (OggPacket)iterator.next();
				
				if (firstPacketOfSet)
				{
					if (readingCommentHeader)
					{
						if (!packet.isVorbisPacket() || (packet.getVorbisPacketType() != OggPacket.VORBIS_COMMENT_HEADER))
						{
							throw new OggException(Messages.getString("OggStream.INVALID_COMMENT_HEADER")); //$NON-NLS-1$
						}
					}
					else if (readingSetupHeader)
					{
						if (!packet.isVorbisPacket() || (packet.getVorbisPacketType() != OggPacket.VORBIS_SETUP_HEADER))
						{
							throw new OggException(Messages.getString("OggStream.INVALID_SETUP_HEADER")); //$NON-NLS-1$
						}
					}
					else
					{
						// Yet another packet was found
						throw new OggException(Messages.getString("OggStream.INVALID_PACKET_IN_HEADER")); //$NON-NLS-1$
					}
					
					firstPacketOfSet = false;
				}
			
				if (readingCommentHeader)
				{
					// Copy the part of the comment header
					System.arraycopy(packet.parent.data, packet.dataStartPos, commentData, commentSize, packet.dataLength);
					commentSize += packet.dataLength;
				}
				
				if (!packet.isContinuedInNextPage())
				{
					firstPacketOfSet = true;
				
					if (readingCommentHeader)
					{
						readingCommentHeader = false;
						readingSetupHeader = true;
					}
					else if (readingSetupHeader)
					{
						readingSetupHeader = false;
					}
				}
			}
		}
		while (readingCommentHeader || readingSetupHeader);
		
		readCommentHeader(commentData, metadata);
		
		// Create a new array with the exact size
		byte[] pagesDataResult = new byte[pagesSize];
		System.arraycopy(pagesData, 0, pagesDataResult, 0, pagesSize);
		
		return pagesDataResult;
	}
	
	public static void readCommentHeader(byte[] commentHeader, Metadata metadata) throws OggException
	{
		try
		{	
			// Skip the marker byte and the "vorbis" signature
			int readPos = 7;
			
			// Skip the vendor string
			readPos += 4 + getInt(commentHeader, readPos);
						
			int numberOfEntries = getInt(commentHeader, readPos);
			readPos += 4;
		
			String artist = null;
			String title = null;
		
			for (int i=0; i < numberOfEntries; i++)
			{
				int length = getInt(commentHeader, readPos);
				readPos += 4;
				
				String entry = new String(commentHeader, readPos, length, "UTF-8"); //$NON-NLS-1$
				readPos += length;
			
				// It's possible that there are more than one artists
				// in the comment header. Only look at the first artist
				if (artist == null)
				{
					if (entry.toUpperCase().startsWith("ARTIST=")) //$NON-NLS-1$
					{
						artist = entry.substring(7);
					}
				}
				
				if (title == null)
				{
					if (entry.toUpperCase().startsWith("TITLE=")) //$NON-NLS-1$
					{
						title = entry.substring(6);
					}
				}
			}
		
			// Check the framing bit
			if ((commentHeader[readPos] & 0x01) == 0)
			{
				throw new OggException(Messages.getString("OggStream.INVALID_COMMENT_HEADER")); //$NON-NLS-1$
			}
			
			if ((title != null) && (title.length() != 0))
			{
				if ((artist != null) && (artist.length() != 0))
				{
					metadata.setSongTitle(artist + " - " + title); //$NON-NLS-1$
				}
				else
				{
					metadata.setSongTitle(title);
				}
			}
		}
		catch (Exception e)
		{
			e.printStackTrace();
			throw new OggException(Messages.getString("OggStream.INVALID_COMMENT_HEADER")); //$NON-NLS-1$
		}
	}
	
	private static int getInt(byte[] array, int offset)
	{
		int ch1 = (array[offset + 0] & 0xff);
		int ch2 = (array[offset + 1] & 0xff);
		int ch3 = (array[offset + 2] & 0xff);
		int ch4 = (array[offset + 3] & 0xff);

		return ((ch1 << 0) + (ch2 << 8) + (ch3 << 16) + (ch4 << 24));
	}
}