Speaker.java

package de.bse.vm;

import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.SourceDataLine;

public class Speaker {

  private static float SAMPLE_RATE = 8000f;

  private static void tone(int hz, int msecs, double vol)
      throws LineUnavailableException {
    byte[] buf = new byte[1];
    AudioFormat af = new AudioFormat(SAMPLE_RATE, // sampleRate
        8, // sampleSizeInBits
        1, // channels
        true, // signed
        false); // bigEndian
    SourceDataLine sdl = AudioSystem.getSourceDataLine(af);
    sdl.open(af);
    sdl.start();
    for (int i = 0; i < msecs * 8; i++) {
      double angle = i / (SAMPLE_RATE / hz) * 2.0 * Math.PI;
      buf[0] = (byte) (Math.sin(angle) * 127.0 * vol);
      sdl.write(buf, 0, 1);
    }
    sdl.drain();
    sdl.stop();
    sdl.close();
  }

  public static void tone(int hz, int msecs) throws LineUnavailableException {
    tone(hz, msecs, 1.0);
  }

}