ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with sound
Monitoring the sound loading process
Flash Player 9 and later, Adobe AIR 1.0 and later
Sound files can be very large and take a long time to load. While Flash Player and AIR let your application play sounds
even before they are fully loaded, you might want to give the user an indication of how much of the sound data has
been loaded and how much of the sound has already been played.
The Sound class dispatches two events that make it relatively easy to display the loading progress of a sound:
ProgressEvent.PROGRESS and Event.COMPLETE. The following example shows how to use these events to display
progress information about the sound being loaded:
import flash.events.Event;
import flash.events.ProgressEvent;
import flash.media.Sound;
import flash.net.URLRequest;
var s:Sound = new Sound();
s.addEventListener(ProgressEvent.PROGRESS, onLoadProgress);
s.addEventListener(Event.COMPLETE, onLoadComplete);
s.addEventListener(IOErrorEvent.IO_ERROR, onIOError);
var req:URLRequest = new URLRequest("bigSound.mp3");
s.load(req);
function onLoadProgress(event:ProgressEvent):void
{
var loadedPct:uint = Math.round(100 * (event.bytesLoaded / event.bytesTotal));
trace("The sound is " + loadedPct + "% loaded.");
}
function onLoadComplete(event:Event):void
{
var localSound:Sound = event.target as Sound;
localSound.play();
}
function onIOError(event:IOErrorEvent)
{
trace("The sound could not be loaded: " + event.text);
}
This code first creates a Sound object and then adds listeners to that object for the ProgressEvent.PROGRESS and
Event.COMPLETE events. After the Sound.load() method has been called and the first data is received from the sound
file, a ProgressEvent.PROGRESS event occurs and triggers the onSoundLoadProgress() method.
The percentage of the sound data that has been loaded is equal to the value of the bytesLoaded property of the
ProgressEvent object divided by the value of the bytesTotal property. The same bytesLoaded and bytesTotal
properties are available on the Sound object as well. The example above simply shows messages about the sound
loading progress, but you can easily use the bytesLoaded and bytesTotal values to update progress bar components,
such as the ones that come with the Adobe Flex framework or the Adobe Flash authoring tool.
This example also shows how an application can recognize and respond to an error when loading sound files. For
example, if a sound file with the given filename cannot be located, an Event.IO_ERROR event is dispatched by the
Sound object. In the previous code, the onIOError() method executes and displays a brief error message when an
error occurs.
Last updated 6/6/2012
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