javasoundaudiodevice.java

java编写的mp3播放器

/*
 * 06/04/01		Too fast playback fixed. [e-mail]
 * 29/01/00		Initial version. [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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *----------------------------------------------------------------------
 */

package javazoom.jl.player;

import javazoom.jl.decoder.*;

import javax.sound.sampled.*;

/**
 * The <code>JavaSoundAudioDevice</code> implements an audio
 * device by using the JavaSound API.
 *
 * @since 0.0.8
 * @author Mat McGowan
 */
public class JavaSoundAudioDevice extends AudioDeviceBase
{
	private SourceDataLine	source = null;

	private AudioFormat		fmt = null;

	private byte[]			byteBuf = new byte[1024];

	protected void setAudioFormat(AudioFormat fmt0)
	{
		fmt = fmt0;
	}

	protected AudioFormat getAudioFormat()
	{
		if (fmt==null)
		{
			Decoder decoder = getDecoder();
			fmt = new AudioFormat(decoder.getOutputFrequency(),
								  16,
								  decoder.getOutputChannels(),
								  true,
								  false);
		}
		return fmt;
	}

	protected DataLine.Info getSourceLineInfo()
	{
		AudioFormat fmt = getAudioFormat();
		DataLine.Info info = new DataLine.Info(SourceDataLine.class, fmt, 4000);
		return info;
	}

	public void open(AudioFormat fmt) throws JavaLayerException
	{
		if (!isOpen())
		{
			setAudioFormat(fmt);
			openImpl();
			setOpen(true);
		}
	}

	protected void openImpl()
		throws JavaLayerException
	{
	}


	// createSource fix.
	protected void createSource() throws JavaLayerException
    {
        Throwable t = null;
        try
        {
			Line line = AudioSystem.getLine(getSourceLineInfo());
            if (line instanceof SourceDataLine)
            {
         		source = (SourceDataLine)line;
                source.open(fmt, millisecondsToBytes(fmt, 2000));
                /*
                if (source.isControlSupported(FloatControl.Type.MASTER_GAIN))
                {
					FloatControl c = (FloatControl)source.getControl(FloatControl.Type.MASTER_GAIN);
                    c.setValue(c.getMaximum());
                }*/
                source.start();

            }
        } catch (RuntimeException ex)
          {
			  t = ex;
          }
          catch (LinkageError ex)
          {
              t = ex;
          }
          catch (LineUnavailableException ex)
          {
              t = ex;
          }
		if (source==null) throw new JavaLayerException("cannot obtain source audio line", t);
    }

	public int millisecondsToBytes(AudioFormat fmt, int time)
	{
		return (int)(time*(fmt.getSampleRate()*fmt.getChannels()*fmt.getSampleSizeInBits())/8000.0);
	}

	protected void closeImpl()
	{
		if (source!=null)
		{
			source.close();
		}
	}

	protected void writeImpl(short[] samples, int offs, int len)
		throws JavaLayerException
	{
		if (source==null)
			createSource();

		byte[] b = toByteArray(samples, offs, len);
		source.write(b, 0, len*2);
	}

	protected byte[] getByteArray(int length)
	{
		if (byteBuf.length < length)
		{
			byteBuf = new byte[length+1024];
		}
		return byteBuf;
	}

	protected byte[] toByteArray(short[] samples, int offs, int len)
	{
		byte[] b = getByteArray(len*2);
		int idx = 0;
		short s;
		while (len-- > 0)
		{
			s = samples[offs++];
			b[idx++] = (byte)s;
			b[idx++] = (byte)(s>>>8);
		}
		return b;
	}

	protected void flushImpl()
	{
		if (source!=null)
		{
			source.drain();
		}
	}

	public int getPosition()
	{
		int pos = 0;
		if (source!=null)
		{
			pos = (int)(source.getMicrosecondPosition()/1000);
		}
		return pos;
	}

	/**
	 * Runs a short test by playing a short silent sound.
	 */
	public void test()
		throws JavaLayerException
	{
		try
		{
			open(new AudioFormat(22050, 16, 1, true, false));
			short[] data = new short[22050/10];
			write(data, 0, data.length);
			flush();
			close();
		}
		catch (RuntimeException ex)
		{
			throw new JavaLayerException("Device test failed: "+ex);
		}

	}
}