tasynchronousfilteredaudioinputstream.java

kaffe Java 解释器语言,源码,Java的子集系统,开放源代码

/*
 *	TAsynchronousFilteredAudioInputStream.java
 */

/*
 *  Copyright (c) 1999, 2000 by Matthias Pfisterer <[e-mail]>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library 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 Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this program; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */


package	org.tritonus.share.sampled.convert;


import	java.io.ByteArrayInputStream;
import	java.io.IOException;

import	javax.sound.sampled.AudioFormat;
import	javax.sound.sampled.AudioInputStream;

import	org.tritonus.share.TDebug;
import	org.tritonus.share.TCircularBuffer;


/** Base class for asynchronus converters.
    This class serves as base class for
    converters that do not have a fixed
    ratio between the size of a block of input
    data and the size of a block of output data.
    These types of converters therefore need an
    internal buffer, which is realized in this
    class.

    @author Matthias Pfisterer
*/
public abstract class TAsynchronousFilteredAudioInputStream
	extends TAudioInputStream
	implements TCircularBuffer.Trigger
{
	private static final int	DEFAULT_BUFFER_SIZE = 327670;
	private static final int	DEFAULT_MIN_AVAILABLE = 4096;
	private static final byte[]	EMPTY_BYTE_ARRAY = new byte[0];


	private TCircularBuffer		m_circularBuffer;
	private int			m_nMinAvailable;
	private byte[]			m_abSingleByte;



	/** Constructor.
	    This constructor uses the default buffer size and the default
	    min available amount.

	    @param lLength length of this stream in frames. May be
	    AudioSystem.NOT_SPECIFIED.
	*/
	public TAsynchronousFilteredAudioInputStream(AudioFormat outputFormat, long lLength)
	{
		this(outputFormat, lLength,
		     DEFAULT_BUFFER_SIZE,
		     DEFAULT_MIN_AVAILABLE);
	}



	/** Constructor.
	    With this constructor, the buffer size and the minimum
	    available amount can be specified as parameters.

	    @param lLength length of this stream in frames. May be
	    AudioSystem.NOT_SPECIFIED.

	    @param nBufferSize size of the circular buffer in bytes.
	 */
	public TAsynchronousFilteredAudioInputStream(
		AudioFormat outputFormat, long lLength,
		int nBufferSize,
		int nMinAvailable)
	{
		/*	The usage of a ByteArrayInputStream is a hack.
		 *	(the infamous "JavaOne hack", because I did it on June
		 *	6th 2000 in San Francisco, only hours before a
		 *	JavaOne session where I wanted to show mp3 playback
		 *	with Java Sound.) It is necessary because in the FCS
		 *	version of the Sun jdk1.3, the constructor of
		 *	AudioInputStream throws an exception if its first
		 *	argument is null. So we have to pass a dummy non-null
		 *	value.
		 */
		super(new ByteArrayInputStream(EMPTY_BYTE_ARRAY),
		      outputFormat,
		      lLength);
		if (TDebug.TraceAudioConverter) { TDebug.out("TAsynchronousFilteredAudioInputStream.<init>(): begin"); }
		m_circularBuffer = new TCircularBuffer(
			nBufferSize,
			false,	// blocking read
			true,	// blocking write
			this);	// trigger
		m_nMinAvailable = nMinAvailable;
		if (TDebug.TraceAudioConverter) { TDebug.out("TAsynchronousFilteredAudioInputStream.<init>(): end"); }
	}


	/** Returns the circular buffer.
	 */
	protected TCircularBuffer getCircularBuffer()
	{
		return m_circularBuffer;
	}



	/** Check if writing more data to the circular buffer is recommanded.
	    This checks the available write space in the circular buffer
	    against the minimum available property. If the available write
	    space is greater than th minimum available property, more
	    writing is encouraged, so this method returns true.
	    Note that this is only a  hint to subclasses. However,
	    it is an important hint.

	    @return true if more writing to the circular buffer is
	    recommanden. Otherwise, false is returned.
	*/
	protected boolean writeMore()
	{
		return getCircularBuffer().availableWrite() > m_nMinAvailable;
	}



	public int read()
		throws	IOException
	{
		// if (TDebug.TraceAudioConverter) { TDebug.out("TAsynchronousFilteredAudioInputStream.read(): begin"); }
		int	nByte = -1;
		if (m_abSingleByte == null)
		{
			m_abSingleByte = new byte[1];
		}
		int	nReturn = read(m_abSingleByte);
		if (nReturn == -1)
		{
			nByte = -1;
		}
		else
		{
			//$$fb 2001-04-14 nobody really knows that...
			nByte = m_abSingleByte[0] & 0xFF;
		}
		// if (TDebug.TraceAudioConverter) { TDebug.out("TAsynchronousFilteredAudioInputStream.read(): end"); }
		return nByte;
	}



	public int read(byte[] abData)
		throws	IOException
	{
		if (TDebug.TraceAudioConverter) { TDebug.out("TAsynchronousFilteredAudioInputStream.read(byte[]): begin"); }
		int	nRead = read(abData, 0, abData.length);
		if (TDebug.TraceAudioConverter) { TDebug.out("TAsynchronousFilteredAudioInputStream.read(byte[]): end"); }
		return nRead;
	}



	public int read(byte[] abData, int nOffset, int nLength)
		throws	IOException
	{
		if (TDebug.TraceAudioConverter) { TDebug.out("TAsynchronousFilteredAudioInputStream.read(byte[], int, int): begin"); }
		//$$fb 2001-04-22: this returns at maximum circular buffer
		// length. This is not very efficient...
		//$$fb 2001-04-25: we should check that we do not exceed getFrameLength() !
		int	nRead = m_circularBuffer.read(abData, nOffset, nLength);
		if (TDebug.TraceAudioConverter) { TDebug.out("TAsynchronousFilteredAudioInputStream.read(byte[], int, int): end"); }
		return nRead;
	}



	public long skip(long lSkip)
		throws	IOException
	{
		// TODO: this is quite inefficient
		for (long lSkipped = 0; lSkipped < lSkip; lSkipped++)
		{
			int	nReturn = read();
			if (nReturn == -1)
			{
				return lSkipped;
			}
		}
		return lSkip;
	}



	public int available()
		throws	IOException
	{
		return m_circularBuffer.availableRead();
	}



	public void close()
		throws	IOException
	{
		m_circularBuffer.close();
	}



	public boolean markSupported()
	{
		return false;
	}



	public void mark(int nReadLimit)
	{
	}



	public void reset()
		throws	IOException
	{
		throw new IOException("mark not supported");
	}
}



/*** TAsynchronousFilteredAudioInputStream.java ***/