AudioData.java

/*
 * Copyright 1999-2004 Carnegie Mellon University.  
 * Portions Copyright 2002-2004 Sun Microsystems, Inc.  
 * Portions Copyright 2002-2004 Mitsubishi Electric Research Laboratories.
 * All Rights Reserved.  Use is subject to license terms.
 * 
 * See the file "license.terms" for information on usage and
 * redistribution of this file, and for a DISCLAIMER OF ALL 
 * WARRANTIES.
 *
 */

package edu.cmu.sphinx.tools.audio;

import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/** Represents a 16bit, SIGNED_PCM, little endian audio clip with a sample rate specified by AudioFormat. */
public class AudioData {

    protected AudioFormat format;
    protected short[] shorts;
    protected final List<ChangeListener> listeners = new ArrayList<ChangeListener>();
    protected int selectionStart = -1;
    protected int selectionEnd = -1;

    /** No-arg constructor.  Creates an empty clip at 8kHz sample rate. */
    public AudioData() {
        this.format = new AudioFormat(8000f,
                16,    // sample size in bits
                1,     // mono
                true,  // signed
                false); // little endian
        shorts = new short[0];
    }


    /**
     * Creates a new AudioData with the given data and sample rate. Expects the data to be 16bit, little endian,
     * SIGNED_PCM.
     *
     * @param data       the audio samples; one sample per element in the array
     * @param sampleRate the sample rate in Hz
     */
    public AudioData(short[] data, float sampleRate) {
        this.shorts = data;
        this.format = new AudioFormat(sampleRate,
                16,    // sample size in bits
                1,     // mono
                true,  // signed
                false); // little endian
    }


    /**
     * Creates a new AudioData from the given AudioInputStream, converting the data to 16bit, little endian, SIGNED_PCM if
     * needed.
     *
     * @param ais the AudioInputStream
     * @throws IOException if problems happen when reading from ais
     */
    public AudioData(AudioInputStream ais) throws IOException {
        this.shorts = Utils.toSignedPCM(ais);
        this.format = new AudioFormat(ais.getFormat().getSampleRate(),
                16,    // sample size in bits
                1,     // mono
                true,  // signed
                false); // little endian
    }


    /**
     * Gets the SIGNED_PCM 16 bit little endian audio data.  NOTE:  this the actual array held by this object, so only use
     * it as a reference (i.e., don't modify the contents).
     *
     * @return the SIGNED_PCM 16 bit little endian samples
     */
    public short[] getAudioData() {
        return shorts;
    }


    /**
     * Sets the audio data and notifies all ChangeListeners.
     *
     * @param data the new SIGNED_PCM 16 bit little endian samples
     */
    public void setAudioData(short[] data) {
        this.shorts = data;
        fireStateChanged();
    }


    /**
     * Gets the audio format.
     *
     * @return the AudioFormat for the data managed by this object
     */
    public AudioFormat getAudioFormat() {
        return format;
    }


    /**
     * Add a ChangeListener.
     *
     * @param listener the listener to add
     */
    public void addChangeListener(ChangeListener listener) {
        listeners.add(listener);
    }


    /**
     * Remove a ChangeListener.
     *
     * @param listener the listener to remove
     */
    public void removeChangeListener(ChangeListener listener) {
        listeners.remove(listener);
    }


    /** Notify all ChangeListeners of a change. */
    protected void fireStateChanged() {
        ChangeEvent event = new ChangeEvent(this);
        for (ChangeListener listener : listeners)
            listener.stateChanged(event);
    }
}