Java How to Program Fourth Edition - DCC

1278 Java Media Framework and Java Sound (on CD) Chapter 22
The Java Sound API is a simpler way to incorporate audio media into applications than
the Java Media Framework. The Java Sound API is bundled with Java 2 Software Development
Kit version 1.3. The API consists of four packages—javax.sound.midi,
javax.sound.midi.spi, javax.sound.sampled and javax.sound.sampled.spi.
The next two sections focus on packages javax.sound.midi and
javax.sound.sampled, which provide classes and interfaces for accessing, manipulating
and playing Musical Instrumental Data Interface (MIDI) and sampled audio. The
packages ending in .spi provide developers with the tools to add Java Sound support for
additional audio formats that are beyond the scope of this book.
The Java Sound API provides access to the Java Sound Engine which creates digitized
audio and captures media from the supported sound devices discussed in Section 22.3. Java
Sound requires a sound card to play audio. A program using Java Sound will throw an exception
if it accesses audio system resources on a computer that does not have a sound card.
22.6 Playing Sampled Audio
This section introduces the features of package javax.sound.sampled for playing
sampled audio file formats, which include Sun Audio (.au), Windows Waveform (.wav)
and Macintosh Audio Interchange File Format (.aiff). The program in Fig. 22.5 and
Fig. 22.6 shows how audio is played using these file formats.
When processing audio data, a line provides the path through which audio flows in a
system. One example of a line is a pair of headphones connected to a CD player.
Class ClipPlayer (Fig. 22.5) is an example of how lines can be used. It contains an
object that implements interface Clip, which in turn extends interface DataLine. A
Clip is a line that processes an entire audio file rather than reading continuously from an
audio stream. DataLines enhance Lines by providing additional methods (such as
start and stop) for controlling the flow of data, and Clips enhance DataLines by
providing methods for opening Clips and methods for precise control over playing and
looping the audio.
1 // Fig. 22.5: ClipPlayer.java
2 // Plays sound clip files of type WAV, AU, AIFF
3
4 // Java core packages
5 import java.io.*;
6
7 // Java extension packages
8 import javax.sound.sampled.*;
9
10 public class ClipPlayer implements LineListener {
11
12 // audio input stream
13 private AudioInputStream soundStream;
14
15 // audio sample clip line
16 private Clip clip;
17
Fig. Fig. 22.5 22.5 ClipPlayer plays an audio file (part 1 of 4).