Effect: Audio Visualizer - JavaFX Special Effects - page 181

An AudioInputStream is an InputStream and works just like other InputStream objects, so we can just
read the content to an AudioInputStream like we would any other InputStream . In this case, we read the
content from decodedInputStream and write the data to the ByteArrayOutputStream object's baos . The
variable baos is a temporary variable whose content is dumped into the variable decodedAudio . This is
our end goal—to have the entire song decoded and stored in memory. This not only allows us to play the
music but also give us the ability to stop and start playing the song form any point.
Working with the Audio Data
The last thing that the method init does is use the AudioSubsystem class again to create a DataLine . A
DataLine object allows us to actually make sound come out of the speakers; the class SoundRunnable , as
shown in Listing 9-3, does this in a separate thread.
Listing 9-3. SoundRunnable
private class SoundRunnable implements Runnable {
public void run() {
try {
byte[] data = new byte[bytesPerChunk];
byte[] dataToAudio = new byte[bytesPerChunk];
int nBytesRead;
while (true) {
if (isPlaying) {
while (isPlaying && (nBytesRead = decodedAudio.read(data, 0,
data.length)) != -1) {
for (int i = 0; i < nBytesRead; i++) {
dataToAudio[i] = (byte) (data[i] * volume);
}
line.write(dataToAudio, 0, nBytesRead);
audioConsumer.writeAudioData(data);
currentChunk++;
}
}
Thread.sleep(10);
}
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
In Listing 9-3 we can see that the class SoundRunnable implements Runnable , which requires the
method run to be implemented. In the run method there are two while loops. The outer loop is used to
toggle whether sound should be playing or not. The inner loop does the real work; it reads a chunk of