Swing Hacks

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Chapter 10, Audio

#77 Show Audio Information While Playing Sound

HACK

H A C K

#77

Show Audio Information While Playing SoundHack #77

Providing visual feedback for JavaSound audio, or at least trying to….

You might want to play a clip without any corresponding visuals; for exam-

ple, if you were using it to signal the end of a long-running process such as

uploading a file. On the other hand, if the sound is the focus of the applica-

tion, as in a music-player application, you might need to show the user some

information about the audio he’s playing.

The Code

You already know how to play audio from a file or stream [Hack #76]; building

on that, you can create a simple GUI that shows some of the basic traits of

the audio, by pulling fields out of the

AudioFormat object, which can be

retrieved from the

Line once it has been created. These fields include the

audio format, bits/sample, frame size and rate, and endianness (which indi-

cates how two-byte values are to be interpreted: big-endian means the first

byte is more significant, and little-endian means the second is).

More impressively,

DataLine provides a getLevel( ) method that returns the

current level of the audio being played, as a float from

0.0 (silence) to 1.0

(maximum volume). You can use this to create a graphical level meter by

getting the level and coloring in that percentage of a component. For exam-

ple, if the level is

0.5, you’d fill in ...