/*************************************************************************
* Compilation: javac StdAudio.java
* Execution: java StdAudio
*
* Simple library for reading, writing, and manipulating .wav files.
*
* Limitations
* -----------
* - Does not seem to work properly when reading .wav files from a .jar file.
* - Assumes the audio is monaural, with sampling rate of 44,100.
*
*************************************************************************/
import java.applet.*;
import java.io.*;
import java.net.*;
import javax.sound.sampled.*;
import java.util.HashMap;
/**
* Standard audio. This class provides a basic capability for
* creating, reading, and saving audio.
*
* The audio format uses a sampling rate of 44,100 (CD quality audio), 16-bit, monaural.
*
*
* For additional documentation, see Section 1.5 of
* Introduction to Programming in Java: An Interdisciplinary Approach by Robert Sedgewick and Kevin Wayne.
*
* @author Robert Sedgewick
* @author Kevin Wayne
*
* Changes by Keith Vertanen:
* 1) Caching of loaded AudioClip objects, default is caching is on, change by calling setCaching
*/
public final class StdAudio {
/**
* The sample rate - 44,100 Hz for CD quality audio.
*/
public static final int SAMPLE_RATE = 44100;
private static final int BYTES_PER_SAMPLE = 2; // 16-bit audio
private static final int BITS_PER_SAMPLE = 16; // 16-bit audio
private static final double MAX_16_BIT = Short.MAX_VALUE; // 32,767
private static final int SAMPLE_BUFFER_SIZE = 4096;
private static SourceDataLine line; // to play the sound
private static byte[] buffer; // our internal buffer
private static int bufferSize = 0; // number of samples currently in internal buffer
private static HashMap clipCache = new HashMap(); // map filename to audio clip
private static boolean clipCaching = true; // turns audio caching on/off
// Turn clip caching on or off, by default caching is on.
// This helps prevents glitches if sounds are played frequently.
public static void setCaching(boolean caching)
{
clipCaching = caching;
if (!clipCaching)
clipCache.clear();
}
// do not instantiate
private StdAudio() { }
// static initializer
static { init(); }
// open up an audio stream
private static void init() {
try {
// 44,100 samples per second, 16-bit audio, mono, signed PCM, little Endian
AudioFormat format = new AudioFormat((float) SAMPLE_RATE, BITS_PER_SAMPLE, 1, true, false);
DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
line = (SourceDataLine) AudioSystem.getLine(info);
line.open(format, SAMPLE_BUFFER_SIZE * BYTES_PER_SAMPLE);
// the internal buffer is a fraction of the actual buffer size, this choice is arbitrary
// it gets divided because we can't expect the buffered data to line up exactly with when
// the sound card decides to push out its samples.
buffer = new byte[SAMPLE_BUFFER_SIZE * BYTES_PER_SAMPLE/3];
} catch (Exception e) {
System.out.println(e.getMessage());
System.exit(1);
}
// no sound gets made before this call
line.start();
}
/**
* Close standard audio.
*/
public static void close() {
line.drain();
line.stop();
}
/**
* Write one sample (between -1.0 and +1.0) to standard audio. If the sample
* is outside the range, it will be clipped.
*/
public static void play(double in) {
// clip if outside [-1, +1]
if (in < -1.0) in = -1.0;
if (in > +1.0) in = +1.0;
// convert to bytes
short s = (short) (MAX_16_BIT * in);
buffer[bufferSize++] = (byte) s;
buffer[bufferSize++] = (byte) (s >> 8); // little Endian
// send to sound card if buffer is full
if (bufferSize >= buffer.length) {
line.write(buffer, 0, buffer.length);
bufferSize = 0;
}
}
/**
* Write an array of samples (between -1.0 and +1.0) to standard audio. If a sample
* is outside the range, it will be clipped.
*/
public static void play(double[] input) {
for (int i = 0; i < input.length; i++) {
play(input[i]);
}
}
/**
* Read audio samples from a file (in .wav or .au format) and return them as a double array
* with values between -1.0 and +1.0.
*/
public static double[] read(String filename) {
byte[] data = readByte(filename);
int N = data.length;
double[] d = new double[N/2];
for (int i = 0; i < N/2; i++) {
d[i] = ((short) (((data[2*i+1] & 0xFF) << 8) + (data[2*i] & 0xFF))) / ((double) MAX_16_BIT);
}
return d;
}
/**
* Play a sound file (in .wav, .mid, or .au format) in a background thread.
*/
public static void play(String filename) {
AudioClip clip = null;
if (clipCaching)
clip = clipCache.get(filename);
if (clip == null)
{
URL url = null;
try {
File file = new File(filename);
if (file.canRead()) url = file.toURI().toURL();
}
catch (MalformedURLException e) { e.printStackTrace(); }
// URL url = StdAudio.class.getResource(filename);
if (url == null) throw new RuntimeException("audio " + filename + " not found");
clip = Applet.newAudioClip(url);
if (clipCaching)
clipCache.put(filename, clip);
}
clip.play();
}
/**
* Loop a sound file (in .wav, .mid, or .au format) in a background thread.
*/
public static void loop(String filename) {
AudioClip clip = null;
if (clipCaching)
clip = clipCache.get(filename);
if (clip == null)
{
URL url = null;
try {
File file = new File(filename);
if (file.canRead()) url = file.toURI().toURL();
}
catch (MalformedURLException e) { e.printStackTrace(); }
// URL url = StdAudio.class.getResource(filename);
if (url == null) throw new RuntimeException("audio " + filename + " not found");
clip = Applet.newAudioClip(url);
if (clipCaching)
clipCache.put(filename, clip);
}
clip.loop();
}
// return data as a byte array
private static byte[] readByte(String filename) {
byte[] data = null;
AudioInputStream ais = null;
try {
// try to read from file
File file = new File(filename);
if (file.exists()) {
ais = AudioSystem.getAudioInputStream(file);
data = new byte[ais.available()];
ais.read(data);
}
// try to read from URL
else {
URL url = StdAudio.class.getResource(filename);
ais = AudioSystem.getAudioInputStream(url);
data = new byte[ais.available()];
ais.read(data);
}
}
catch (Exception e) {
System.out.println(e.getMessage());
throw new RuntimeException("Could not read " + filename);
}
return data;
}
/**
* Save the double array as a sound file (using .wav or .au format).
*/
public static void save(String filename, double[] input) {
// assumes 44,100 samples per second
// use 16-bit audio, mono, signed PCM, little Endian
AudioFormat format = new AudioFormat(SAMPLE_RATE, 16, 1, true, false);
byte[] data = new byte[2 * input.length];
for (int i = 0; i < input.length; i++) {
int temp = (short) (input[i] * MAX_16_BIT);
data[2*i + 0] = (byte) temp;
data[2*i + 1] = (byte) (temp >> 8);
}
// now save the file
try {
ByteArrayInputStream bais = new ByteArrayInputStream(data);
AudioInputStream ais = new AudioInputStream(bais, format, input.length);
if (filename.endsWith(".wav") || filename.endsWith(".WAV")) {
AudioSystem.write(ais, AudioFileFormat.Type.WAVE, new File(filename));
}
else if (filename.endsWith(".au") || filename.endsWith(".AU")) {
AudioSystem.write(ais, AudioFileFormat.Type.AU, new File(filename));
}
else {
throw new RuntimeException("File format not supported: " + filename);
}
}
catch (Exception e) {
System.out.println(e);
System.exit(1);
}
}
/***********************************************************************
* sample test client
***********************************************************************/
// create a note (sine wave) of the given frequency (Hz), for the given
// duration (seconds) scaled to the given volume (amplitude)
private static double[] note(double hz, double duration, double amplitude) {
int N = (int) (StdAudio.SAMPLE_RATE * duration);
double[] a = new double[N+1];
for (int i = 0; i <= N; i++)
a[i] = amplitude * Math.sin(2 * Math.PI * i * hz / StdAudio.SAMPLE_RATE);
return a;
}
/**
* Test client - play an A major scale to standard audio.
*/
public static void main(String[] args) {
// 440 Hz for 1 sec
double freq = 440.0;
for (int i = 0; i <= StdAudio.SAMPLE_RATE; i++) {
StdAudio.play(0.5 * Math.sin(2*Math.PI * freq * i / StdAudio.SAMPLE_RATE));
}
// scale increments
int[] steps = { 0, 2, 4, 5, 7, 9, 11, 12 };
for (int i = 0; i < steps.length; i++) {
double hz = 440.0 * Math.pow(2, steps[i] / 12.0);
StdAudio.play(note(hz, 1.0, 0.5));
}
// need to call this in non-interactive stuff so the program doesn't terminate
// until all the sound leaves the speaker.
StdAudio.close();
// need to terminate a Java program with sound
System.exit(0);
}
}