Swing Hacks

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Chapter 10, Audio

#76 Play Non-Trivial Audio

HACK

This hack shows you how to do all of the sample conversion

and painting you need to display a waveform very simplisti-

cally. However, you should address a few key issues before

using this in an audio application; for example, this only

deals with 16-bit audio. You probably would want to build

something a little more generic to deal with other sample

sizes. You may also want to deal with compression, so you

can display waveforms for MP3 files. That said, this hack

still gives you a good idea of how to dig into raw audio data

and get your audio visualization on.

—Jonathan Simon

H A C K

#76

Play Non-Trivial Audio Hack #76

When loading an entire audio clip into memory is a bad idea (or just

impossible), you have to take JavaSound responsibilities into your own

hands.

Playing JavaSound audio with a Clip [Hack #71] is a pretty convenient way to

play a short sound, like a sound effect for a desktop application. The only

problem is that the

Clip loads all the audio into memory, which could have

a couple of bad side effects:

• It makes your application use more memory, which could cause problems.

• The audio you need might not fit into memory at all.

You might have run into this second point if you tried to load a really big

audio file into a

Clip. For example, I took a 3 minute, 45 second track from

a CD and converted it to 8-bit mono PCM in an AIFF file, which ended up

being 9.4 MB. You can guess what happened:

[aeris:HacksBook/Media/52] cadamson% java CoreJavaSound

javax.sound.sampled.LineUnavailableException: Failed to allocate clip data:

Requested buffer too large.

at com.sun.media.sound.MixerClip.implOpen(MixerClip.java:536)

at com.sun.media.sound.MixerClip.open(MixerClip.java:161)

at com.sun.media.sound.MixerClip.open(MixerClip.java:249)

at CoreJavaSound.<init>(CoreJavaSound.java:39)

at CoreJavaSound.main(CoreJavaSound.java:17)

Unfortunately, most of the JavaSound code you’ll find on the Web deals

with

Clips only and not with getting a Line for larger files, or potentially

endless streams for that matter. Why? Perhaps because JavaSound doesn’t

do it for you—you are responsible for reading bytes and feeding them to

JavaSound!