synthaudioclip.java

java高级使用教程 全书一共分六章

// SynthAudioClip - a synthesized audio clip
//
// Copyright (C) 1996 by Jef Poskanzer <[e-mail]>.  All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// Visit the ACME Labs Java page for up-to-date versions of this and other
// fine Java utilities: http://www.acme.com/java/

package Acme;

import java.io.*;
import java.applet.AudioClip;
import sun.audio.*;

/// A synthesized audio clip.
// <P>
// Generates a synthetic audio tone of a specified frequency and duration.
// <P>
// <A HREF="/resources/classes/Acme/SynthAudioClip.java">Fetch the software.</A><BR>
// <A HREF="/resources/classes/Acme.tar.gz">Fetch the entire Acme package.</A>

public class SynthAudioClip implements AudioClip
    {
    private static final long SAMPLES_PER_SEC = 8000;

    AudioData data;
    InputStream stream;

    /// Constructor.
    // Generates a single tone.
    // @param hz the frequency of the tone
    // @param millis the duration of the tone, in milliseconds
    // @param amplitude the loudness of the tone, from 0 to 32767
    public SynthAudioClip( int hz, long millis, double amplitude )
	{
	int samples = (int) ( millis * SAMPLES_PER_SEC / 1000 );
	byte[] buf = new byte[samples];
	for ( int i = 0; i < buf.length; ++i )
	    buf[i] = toUlaw( (int) (
		amplitude *
		Math.sin( 2.0D * Math.PI * i * hz / SAMPLES_PER_SEC ) ) );
	data = new AudioData( buf );
	}

    /// Constructor.
    // Generates a single tone, with default loudness.
    // @param hz the frequency of the tone
    // @param millis the duration of the tone, in milliseconds
    public SynthAudioClip( int hz, long millis )
	{
	this( hz, millis, 16384.0D );
	}


/*****
    // This is not currently used here, so we comment it out because
    // it compiles to a whole lot of bytecodes.

    private static final int[] ulawTab = {
	-32124, -31100, -30076, -29052, -28028, -27004, -25980, -24956,
	-23932, -22908, -21884, -20860, -19836, -18812, -17788, -16764,
	-15996, -15484, -14972, -14460, -13948, -13436, -12924, -12412,
	-11900, -11388, -10876, -10364,  -9852,  -9340,  -8828,  -8316,
	 -7932,  -7676,  -7420,  -7164,  -6908,  -6652,  -6396,  -6140,
	 -5884,  -5628,  -5372,  -5116,  -4860,  -4604,  -4348,  -4092,
	 -3900,  -3772,  -3644,  -3516,  -3388,  -3260,  -3132,  -3004,
	 -2876,  -2748,  -2620,  -2492,  -2364,  -2236,  -2108,  -1980,
	 -1884,  -1820,  -1756,  -1692,  -1628,  -1564,  -1500,  -1436,
	 -1372,  -1308,  -1244,  -1180,  -1116,  -1052,   -988,   -924,
	  -876,   -844,   -812,   -780,   -748,   -716,   -684,   -652,
	  -620,   -588,   -556,   -524,   -492,   -460,   -428,   -396,
	  -372,   -356,   -340,   -324,   -308,   -292,   -276,   -260,
	  -244,   -228,   -212,   -196,   -180,   -164,   -148,   -132,
	  -120,   -112,   -104,    -96,    -88,    -80,    -72,    -64,
	   -56,    -48,    -40,    -32,    -24,    -16,     -8,      0,
	 32124,  31100,  30076,  29052,  28028,  27004,  25980,  24956,
	 23932,  22908,  21884,  20860,  19836,  18812,  17788,  16764,
	 15996,  15484,  14972,  14460,  13948,  13436,  12924,  12412,
	 11900,  11388,  10876,  10364,   9852,   9340,   8828,   8316,
	  7932,   7676,   7420,   7164,   6908,   6652,   6396,   6140,
	  5884,   5628,   5372,   5116,   4860,   4604,   4348,   4092,
	  3900,   3772,   3644,   3516,   3388,   3260,   3132,   3004,
	  2876,   2748,   2620,   2492,   2364,   2236,   2108,   1980,
	  1884,   1820,   1756,   1692,   1628,   1564,   1500,   1436,
	  1372,   1308,   1244,   1180,   1116,   1052,    988,    924,
	   876,    844,    812,    780,    748,    716,    684,    652,
	   620,    588,    556,    524,    492,    460,    428,    396,
	   372,    356,    340,    324,    308,    292,    276,    260,
	   244,    228,    212,    196,    180,    164,    148,    132,
	   120,    112,    104,     96,     88,     80,     72,     64,
	    56,     48,     40,     32,     24,     16,      8,      0
	};

    private static int toLinear( byte ulaw )
	{
	return ulawTab[ulaw & 0xff];
	}
*****/


    private static final int[] expLut = {
	0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 
	4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 
	5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 
	5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 
	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 
	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 
	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 
	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 
	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 
	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 
	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 
	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 
	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 
	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 
	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 
	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7
	};
    private static final int CLIP = 32635;
    private static final int BIAS = 0x84;

    private static byte toUlaw( int linear )
	{
	int sign, exponent, mantissa;
	byte ulaw;

	// Get the sample into sign-magnitude.
	if ( linear >= 0 )
	    sign = 0;
	else
	    {
	    sign = 0x80;
	    linear = -linear;
	    }
        if ( linear > CLIP )
	    linear = CLIP;	// clip the magnitude

	// Convert from 16 bit linear to ulaw.
	linear = linear + BIAS;
	exponent = expLut[( linear >> 7 ) & 0xFF];
	mantissa = ( linear >> ( exponent + 3 ) ) & 0x0F;
	ulaw = (byte) ( ~ ( sign | ( exponent << 4 ) | mantissa ) );
	return ulaw;
	}


    public synchronized void play()
	{
	stop();
	if ( data != null )
	    {
	    stream = new AudioDataStream( data );
	    AudioPlayer.player.start( stream );
	    }
	}

    public synchronized void loop()
	{
	stop();
	if ( data != null )
	    {
	    stream = new ContinuousAudioDataStream( data );
	    AudioPlayer.player.start( stream );
	    }
	}

    public synchronized void stop()
	{
	if ( stream != null )
	    {
	    AudioPlayer.player.stop( stream );
	    try
		{
		stream.close();
		}
	    catch ( IOException iignore ) {}
	    stream = null;
	    }
	}

    }