Many audio applications also provide a graphical " level meter,” which is an on-screen display of the loudness or softness of certain frequencies within the audio. In QuickTime Player, this is shown as a set of bars on the right side of the control bar, as seen in Figure 7-2.
Figure 7-2. Audio level meter in QuickTime Player
The intensity of lower frequencies, like bass, is shown in the leftmost columns, while higher frequencies are to the right.
provides two key methods:
to set up monitoring and
to actually get the data.
setSoundEqualizerBands( ) indicates which
frequencies you want to monitor for your graphics display. These are
passed in the form of a
object, which is built up by
constructing it with the number of bands you intend to monitor, then
to indicate which frequency a given band will monitor.
Unfortunately, most of the level-metering methods are officially undocumented.
As the audio plays, you can repeatedly call
getSoundLevelMeterLevels( ), which returns an
ints representing the measured levels.
Example 7-4 creates a basic audio level meter in an AWT Canvas.
Run this example with ant run-ch07-levelmeterplayer.
Example 7-4. Providing an audio level meter
package com.oreilly.qtjnotebook.ch07; ...