Chapter 17. Sound
On systems that support it, sound can
be an important part of many
applications.
Sound can be used to notify the user that her attention is required,
to add the extra dimension of aural feedback to visual GUIs, or for
entertainment purposes. Other applications—such as
media players,
recorders, and editors—are sound-centric and therefore require
advanced sound capabilities.
This chapter illustrates Java's sound capabilities,
from the simple to the complex:
Example 17-1 shows how to ring the terminal bell. A
simple beep is all that some applications need to attract the
user's attention in case of errors or urgent
conditions. Example 17-2 shows how to play simple audio clips
with the java.applet.AudioClip class. This example
illustrates a very simple technique that is sufficient to add sounds
to many applications, but does not give any control over the playback
of the sound. Example 17-3 shows how to use the
javax.sound.sampled and
javax.sound.midi packages to load and play sound
clips, how to monitor and change the playback position within the
clip, and how to set audio parameters such as volume, balance, and
tempo for the clips. Example 17-4 shows how to play streaming sounds in
both sampled audio and MIDI formats. Example 17-5 reads a simple musical score and
converts it into a MIDI Sequence, which is then
either played on a Sequencer or saved to a file. Example 17-6 shows how to make music by directly
controlling a MidiChannel of a
Synthesizer, bypassing the
Sequence and Sequencer used in
Example 17-5.
The Java
Sound API is a low-level interface to sound, and the default
implementation does not support compressed formats such as MP3. In
this chapter we'll be working with simple
audio files,
with types such as .wav,
.aiff, and
.au. Note that, although Java Sound supports
the recording of sounds, there is no recording example in this
chapter: setup and configuration problems on different platforms make
sound recording a topic that is beyond the scope of this chapter.
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