Clicking noise when streaming sound to SourceDataLine

Question

Hello,
I'm trying to stream sound to the PC's speakers using SourceDataLine, but I have trouble getting rid of a clicking noise.
It seems to occur when sourceDataLine.available() equals sourceDataLine.getBufferSize(). Is there a way to avoid this?
I am dealing with an audio of indeterminate length. Here's the test code:
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.LineEvent;
import javax.sound.sampled.LineListener;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.SourceDataLine;
public class PlaybackLoop implements LineListener {
   SourceDataLine sourceDataLine;
   AudioFormat format;
   public PlaybackLoop() throws LineUnavailableException {
      AudioFormat.Encoding
          encoding = AudioFormat.Encoding.PCM_SIGNED;
      int sampleRate = 8000; // samples per sec
      int sampleSizeInBits = 16; // bits per sample
      int channels = 1;
      int frameSize = 2;  // bytes per frame
      int frameRate = 8000; // frames per sec
      // size of 1 sample * # of channels = size of 1 frame
      boolean bigEndian = true;
      format = new AudioFormat(
            encoding,
            sampleRate,
            sampleSizeInBits,
            channels,
            frameSize,
            frameRate,
            bigEndian);
      // PCM_SIGNED 8000.0 Hz, 16 bit, mono, 2 bytes/frame, big-endian
      DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
      sourceDataLine = (SourceDataLine) AudioSystem.getLine(info);
   public synchronized void play() throws LineUnavailableException,
                                          InterruptedException {
      int bytesPerSec = (int) format.getFrameRate() * format.getFrameSize();
      int intervalMs = 200;
      int loop = 50;
      int bytesSize = bytesPerSec * intervalMs / 1000;
      byte[] bytes = new byte[bytesSize];
      // creates a high pitched sound
      for (int i = 0; i < bytesSize / 2; i++) {
         if (i % 2 == 0) {
            writeFrame(bytes, i, 0x05dc);
         } else {
            writeFrame(bytes, i, 0x059c);
      sourceDataLine.open(format, 16000);
      sourceDataLine.addLineListener(this);
      int bufferSize = sourceDataLine.getBufferSize();
      System.out.println(format.toString());
      System.out.println(bufferSize + " bytes of line buffer.");
      long nextTime = System.currentTimeMillis() + intervalMs;
      sourceDataLine.start();
      for (int i = 0; i < loop; i ++) {
         int available = sourceDataLine.available();
         if (available == bufferSize) {
            // clicking noise occurs here
            System.out.println("*");
         int w = sourceDataLine.write(bytes, 0, bytesSize);
         long currentTime = System.currentTimeMillis();
         if (w != bytesSize) {
            System.out.println("Not all written.");
            // TODO
         // time adjustment , to prevent accumulated delay.
         long delta = (nextTime - currentTime);
         long wait = intervalMs + delta;
         if (0 < wait) {
            this.wait(wait);
            nextTime += intervalMs;
         } else {
            nextTime = currentTime + intervalMs;
      System.out.println();
      System.out.println("End play()");
   public static void main(String[] args) throws LineUnavailableException,
                                                 InterruptedException {
      new PlaybackLoop().play();
   public static void writeFrame(byte[] bytes, int halfwordOffset, int value) {
      writeFrame(bytes, 0, halfwordOffset, value);
   public static void writeFrame(byte[] bytes, int byteOffset,
                                 int halfwordOffset, int value) {
      byteOffset += 2 * halfwordOffset;
      bytes[byteOffset++] = (byte) (value >> 8);
      bytes[byteOffset++] = (byte) (value >> 0);
   public void update(LineEvent event) {
      System.out.println();
      System.out.print("Update:");
      System.out.println(event.getType().toString());
}

Answer 1

I have modified the code so that it shows how the audio goes out of synch
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.LineEvent;
import javax.sound.sampled.LineListener;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.SourceDataLine;
public class PlaybackLoop implements LineListener {
     SourceDataLine sourceDataLine;
     AudioFormat format;
     public PlaybackLoop() throws LineUnavailableException {
          AudioFormat.Encoding
                encoding = AudioFormat.Encoding.PCM_SIGNED;
          int sampleRate = 8000; // samples per sec
          int sampleSizeInBits = 16; // bits per sample
          int channels = 1;
          int frameSize = 2;  // bytes per frame
          int frameRate = 8000; // frames per sec
          // size of 1 sample * # of channels = size of 1 frame
          boolean bigEndian = true;
          format = new AudioFormat(
                    encoding,
                    sampleRate,
                    sampleSizeInBits,
                    channels,
                    frameSize,
                    frameRate,
                    bigEndian);
          // PCM_SIGNED 8000.0 Hz, 16 bit, mono, 2 bytes/frame, big-endian
          DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);
          sourceDataLine = (SourceDataLine) AudioSystem.getLine(info);
     public synchronized void play() throws LineUnavailableException, InterruptedException {
          int bytesPerSec = (int) format.getFrameRate() * format.getFrameSize();
          int intervalMs = 200;
          int loop = 400;
          int bytesSize = bytesPerSec * intervalMs / 1000;
          byte[] bytes = new byte[bytesSize];
          // creates a high pitched sound
          for (int i = 0; i < bytesSize / 2; i++) {
               if (i % 2 == 0) {
                    writeFrame(bytes, i, 0x05dc);
               } else {
                    writeFrame(bytes, i, 0x059c);
          sourceDataLine.open(format, 16000);
          sourceDataLine.addLineListener(this);
          int bufferSize = sourceDataLine.getBufferSize();
          System.out.println(format.toString());
          System.out.println(bufferSize + " bytes of line buffer.");
          long nextTime = System.currentTimeMillis() + intervalMs;
          sourceDataLine.start();
          for (int i = 0; i < loop; i ++) {
               int available = sourceDataLine.available();
               if (available == bufferSize) {
                    // clicking noise occurs here
                    System.out.println("*");
               int w = sourceDataLine.write(bytes, 0, bytesSize);
               if (w != bytesSize) {
                    System.out.println("Not all written.");
                    // TODO
               // printing time drift
               if (i % 100 == 0) {
                    long currentTime = System.currentTimeMillis();
                    // this number increases
                    System.out.println(nextTime - currentTime);
               nextTime += intervalMs;
          System.out.println();
          System.out.println("End play()");
     public static void main(String[] args) throws LineUnavailableException, InterruptedException {
          new PlaybackLoop().play();
     public static void writeFrame(byte[] bytes, int halfwordOffset, int value) {
          writeFrame(bytes, 0, halfwordOffset, value);
     public static void writeFrame(byte[] bytes, int byteOffset,
                                         int halfwordOffset, int value) {
          byteOffset += 2 * halfwordOffset;
          bytes[byteOffset++] = (byte) (value >> 8);
          bytes[byteOffset++] = (byte) (value >> 0);
     public void update(LineEvent event) {
          System.out.println();
          System.out.print("Update:");
          System.out.println(event.getType().toString());
}The output looks like this:
PCM_SIGNED 8000.0 Hz, 16 bit, mono, 2 bytes/frame, big-endian
16000 bytes of line buffer.
Update:Start
200
1200
1450
1700
End play()
The printed number keeps on rising. (Maybe I'm not sending enough information to the audio input stream?)
The printed number should be stable if in synch, but it continues to rise, signifying that it's playing audio faster than it's being provided. When the audio input source is from a network streamed audio (instead of the test audio source in this example), it results in a buffer under run, which causes the clicking sound.