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When you listen to the WhiteNoise audio file, you hear the result of transforming those random numbers into electricalcurrents that circulate through the computer speakers. That transformation is accomplished by the call to the playOrFileData method as the last statement in the constructor for the MusicComposer04 class in Listing 4 .
Random numbers don't produce a very pleasant sound. Future modules will populate the melody array with values that are somewhat more interesting than random byte values.
Listing 11 also signals the end of the getMelody method and the end of the WhiteNoise class.
I encourage you to copy the code from Listing 12 through Listing 16 . Compile the code and execute it. Experiment with the code,making changes, and observing the results of your changes. Make certain that you can explain why your changes behave as they do.
This section contains a variety of miscellaneous information.
Financial : Although the OpenStax CNX site makes it possible for you to download a PDF file for the collection thatcontains this module at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, youshould be aware that some of the HTML elements in this module may not translate well into PDF.
You also need to know that Prof. Baldwin receives no financial compensation from OpenStax CNX even if you purchase the PDF version of the collection.
In the past, unknown individuals have copied Prof. Baldwin's modules from cnx.org, converted them to Kindle books, and placedthem for sale on Amazon.com showing Prof. Baldwin as the author. Prof. Baldwin neither receives compensation for those sales nordoes he know who does receive compensation. If you purchase such a book, please be aware that it is a copy of a collection thatis freely available on OpenStax CNX and that it was made and published without the prior knowledge of Prof.Baldwin.
Affiliation : Prof. Baldwin is a professor of Computer Information Technology at Austin Community College inAustin, TX.
Complete listings of the class files required by this program are provided below.
| Listing 12 . The class named AudioPlayOrFile01. |
|---|
/*File AudioPlayOrFile01.java
Copyright 2014, R.G.BaldwinRevised 08/16/14
******************************************************************************/import javax.sound.sampled.*;
import java.io.*;import java.util.*;
public class AudioPlayOrFile01{//An object of this class is used to either play the sound in the array
// named melody or to write it into an audio file of type AU.//The following are general instance variables used to create a// SourceDataLine object.
AudioFormat audioFormat;AudioInputStream audioInputStream;
SourceDataLine sourceDataLine;AudioFormatParameters01 audioParams;
byte[]melody;
String playOrFile;//"play" to play immediately or a fileName to write// an output file of type AU.
//-------------------------------------------------------------------------//public AudioPlayOrFile01(AudioFormatParameters01 audioParams,byte[] melody,String playOrFile){//constructor
this.audioParams = audioParams;this.melody = melody;
this.playOrFile = playOrFile;}//end constructor
//-------------------------------------------------------------------------////This method plays or files the synthetic audio data that has been generated
// and saved in an array.void playOrFileData() {
try{//Get an input stream on the byte array containing the data
InputStream byteArrayInputStream = new ByteArrayInputStream(melody);//Get the required audio format
audioFormat = new AudioFormat(audioParams.sampleRate,audioParams.sampleSizeInBits,
audioParams.channels,audioParams.signed,
audioParams.bigEndian);//Get an audio input stream from the ByteArrayInputStream
audioInputStream = new AudioInputStream(byteArrayInputStream,
audioFormat,melody.length/audioFormat.getFrameSize());
//Get info on the required data lineDataLine.Info dataLineInfo = new DataLine.Info(SourceDataLine.class,
audioFormat);//Get a SourceDataLine object
sourceDataLine = (SourceDataLine)AudioSystem.getLine(dataLineInfo);//Decide whether to play the audio data immediately, or to write it// into an audio file of type AU based on the incoming parameter named
// playOrFile.if(playOrFile.toUpperCase().equals("PLAY")){
//Create a thread to play back the data and start it running. It will// run until all the data has been played back
new PlayAudioThread().start();}else{
//Write the data to an output file with the name provided by the// incoming parameter named playOrFile.
try{AudioSystem.write(audioInputStream,
AudioFileFormat.Type.AU,new File(playOrFile + ".au"));
}catch (Exception e) {e.printStackTrace();
System.exit(0);}//end catch
}//end else}catch (Exception e) {
e.printStackTrace();System.exit(0);
}//end catch}//end playOrFileData
//===========================================================================////Inner class to play back the data that was saved.
class PlayAudioThread extends Thread{//This is a working buffer used to transfer the data between the
// AudioInputStream and the SourceDataLine. The size is rather arbitrary.byte playBuffer[] = new byte[16384];public void run(){
try{//Open and start the SourceDataLine
sourceDataLine.open(audioFormat);sourceDataLine.start();int cnt;
//Get beginning of elapsed time for playbacklong startTime = new Date().getTime();//Transfer the audio data to the speakers
while((cnt = audioInputStream.read(playBuffer,0,playBuffer.length)) != -1){
//Keep looping until the input read method returns -1 for empty// stream.
if(cnt>0){
//Write data to the internal buffer of the data line where it will// be delivered to the speakers in real time
sourceDataLine.write(playBuffer, 0, cnt);}//end if
}//end while//Block and wait for internal buffer of the SourceDataLine to become// empty.
sourceDataLine.drain();//Get and display the elapsed time for the previous playback.
int elapsedTime = (int)(new Date().getTime() - startTime);System.out.println("Elapsed time: " + elapsedTime);//Finish with the SourceDataLine
sourceDataLine.stop();sourceDataLine.close();
}catch (Exception e) {e.printStackTrace();
System.exit(0);}//end catch}//end run
}//end inner class PlayAudioThread//=========================================================================//
}//end AudioPlayOrFile01 class |
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