Q: I have spent a while trying to figure out how to play sounds in Java. Sun has some audio classes, but they are unsupported and not very flexible. Is there any other way to play sounds in Java?

A: Yes. Using QuickTime for Java, you can easily play sounds stored in a variety of formats. The following application example simply plays a local sound file:

import quicktime.QTSession;
import quicktime.app.QTFactory;
import quicktime.app.players.QTPlayer;

public class Application
{
    static QTPlayer player; // static so it is not garbage collected

    static public void main (String[ ] args) {
        try {
            QTSession.open();
            String soundLocation = QTFactory.findAbsolutePath(
                 "sin440.aif"  ).getPath();
            //this call works with a file://, http://, rtsp:// located movies

            player = (QTPlayer)QTFactory.makeDrawable (
                "file://"  + soundLocation);
            player.startTasking();
            player.setRate(1);
        }
        catch (Exception e) {
            e.printStackTrace();
            QTSession.close();
        }
    }
}

In this example, we initialize QuickTime by calling the static open( ) method from the QTSession class. It is important to call QTSession.open( ) before making any QuickTime for Java calls and QTSession.close( ) before the applet or application terminates.

Next, we load the file by using the QTFactory utility class to generate a URL from a local file path. This location is simply a string. If you are using an applet, you may wish to format the string to specify a file from an http server (this also works with applications). Next, we create a drawable object from the string. This may seem counter-intuitive since we are dealing with a sound and not a movie. This is because QuickTime treats sound and media files, as well as other time-based formats, in a consistent manner. By making a drawable object, we are preparing the file to be presented by the QTPlayer. This is also important, because your application may want to display a controller for controlling the playback of the sound file. In this case, you would create a QTCanvas and add the QTPlayer to it.

Then, we call the startTasking( ) of the QTPlayer inherited from the Taskable class. This creates a task that is responsible for handling the periodic data. Setting the rate of the movie to 1 plays the movie (or sound in this case). The rate is a floating point value that specifies how to play the media. The value "1" means normal speed, "0.5" denotes half speed, and "-1" denotes full speed backwards. Setting the rate to "0" stops playback.

We chose this methodology to play sound files because it is fairly robust, allows files to be located on disk, on the web, or streamed, and supports a variety of sound file formats including AIFF, wav, au, and MP3.

QuickTime for Java is an excellent way to have rich media support if you are targeting your application for deployment on Windows and Macintosh. For more information, see the QuickTime for Java Overview.

[Oct 25 1999]

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