Play 2 different frequencies alternatively in Java

Question

I am a newbie in Java Sounds. I want to play 2 different frequencies alternatively for 1 second each in a loop for some specified time. Like, if I have 2 frequencies 440hz and 16000hz and the time period is 10 seconds then for every 'even' second 440hz gets played and for every 'odd' second 16000hz, i.e. 5 seconds each alternatively.

I have learned a few things through some examples and I have also made a program that runs for a single user specified frequency for a time also given by the user with the help of those examples.

I will really appreciate if someone can help me out on this. Thanks.

I am also attaching that single frequency code for reference.

  import java.nio.ByteBuffer;
  import java.util.Scanner;
  import javax.sound.sampled.*;

  public class Audio {

   public static void main(String[] args) throws InterruptedException, LineUnavailableException {
    final int SAMPLING_RATE = 44100;            // Audio sampling rate
    final int SAMPLE_SIZE = 2;                  // Audio sample size in bytes

    Scanner in = new Scanner(System.in);
    int time = in.nextInt();                      //Time specified by user in seconds
    SourceDataLine line;
    double fFreq = in.nextInt();                         // Frequency of sine wave in hz

    //Position through the sine wave as a percentage (i.e. 0 to 1 is 0 to 2*PI)
    double fCyclePosition = 0;

    //Open up audio output, using 44100hz sampling rate, 16 bit samples, mono, and big 
    // endian byte ordering
    AudioFormat format = new AudioFormat(SAMPLING_RATE, 16, 1, true, true);
    DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);

    if (!AudioSystem.isLineSupported(info)) {
        System.out.println("Line matching " + info + " is not supported.");
        throw new LineUnavailableException();
    }

    line = (SourceDataLine) AudioSystem.getLine(info);
    line.open(format);
    line.start();

    // Make our buffer size match audio system's buffer
    ByteBuffer cBuf = ByteBuffer.allocate(line.getBufferSize());

    int ctSamplesTotal = SAMPLING_RATE * time;         // Output for roughly user specified time in seconds

    //On each pass main loop fills the available free space in the audio buffer
    //Main loop creates audio samples for sine wave, runs until we tell the thread to exit
    //Each sample is spaced 1/SAMPLING_RATE apart in time
    while (ctSamplesTotal > 0) {
        double fCycleInc = fFreq / SAMPLING_RATE;  // Fraction of cycle between samples

        cBuf.clear();                            // Discard samples from previous pass

        // Figure out how many samples we can add
        int ctSamplesThisPass = line.available() / SAMPLE_SIZE;
        for (int i = 0; i < ctSamplesThisPass; i++) {
            cBuf.putShort((short) (Short.MAX_VALUE * Math.sin(2 * Math.PI * fCyclePosition)));

            fCyclePosition += fCycleInc;
            if (fCyclePosition > 1) {
                fCyclePosition -= 1;
            }
        }

        //Write sine samples to the line buffer.  If the audio buffer is full, this will 
        // block until there is room (we never write more samples than buffer will hold)
        line.write(cBuf.array(), 0, cBuf.position());
        ctSamplesTotal -= ctSamplesThisPass;     // Update total number of samples written 

        //Wait until the buffer is at least half empty  before we add more
        while (line.getBufferSize() / 2 < line.available()) {
            Thread.sleep(1);
        }
    }

    //Done playing the whole waveform, now wait until the queued samples finish 
    //playing, then clean up and exit
    line.drain();
    line.close();
}

}

Answer 1

Your best bet is probably creating Clips as shown in the sample code below. That said, the MHz range is typically not audible—looks like you have a typo in your question. If it's no typo, you will run into issues with Mr. Nyquist.

Another hint: Nobody uses Hungarian Notation in Java.

import javax.sound.sampled.*;
import java.nio.ByteBuffer;
import java.nio.ShortBuffer;

public class AlternatingTones {

    public static void main(final String[] args) throws LineUnavailableException, InterruptedException {

        final Clip clip0 = createOneSecondClip(440f);
        final Clip clip1 = createOneSecondClip(16000f);

        clip0.addLineListener(event -> {
            if (event.getType() == LineEvent.Type.STOP) {
                clip1.setFramePosition(0);
                clip1.start();
            }
        });
        clip1.addLineListener(event -> {
            if (event.getType() == LineEvent.Type.STOP) {
                clip0.setFramePosition(0);
                clip0.start();
            }
        });
        clip0.start();

        // prevent JVM from exiting
        Thread.sleep(10000000);
    }

    private static Clip createOneSecondClip(final float frequency) throws LineUnavailableException {
        final Clip clip = AudioSystem.getClip();
        final AudioFormat format = new AudioFormat(AudioFormat.Encoding.PCM_SIGNED, 44100f, 16, 1, 2, 44100, true);
        final ByteBuffer buffer = ByteBuffer.allocate(44100 * format.getFrameSize());
        final ShortBuffer shortBuffer = buffer.asShortBuffer();
        final float cycleInc = frequency / format.getFrameRate();
        float cyclePosition = 0f;
        while (shortBuffer.hasRemaining()) {
            shortBuffer.put((short) (Short.MAX_VALUE * Math.sin(2 * Math.PI * cyclePosition)));
            cyclePosition += cycleInc;
            if (cyclePosition > 1) {
                cyclePosition -= 1;
            }
        }
        clip.open(format, buffer.array(), 0, buffer.capacity());
        return clip;
    }
}