// 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];
listeners = new HashSet<AudioEventListener>();
} catch (Exception e) {
System.err.println("Error initializing StdAudio audio system:");
e.printStackTrace();
System.exit(1);
}
// no sound gets made before this call
line.start();
}
/**
* 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;
}
}
/** Close standard audio. */
public static void close() {
line.drain();
line.stop();
}
