ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with sound
import flash.events.Event;
import flash.media.Sound;
import flash.net.URLRequest;
var snd:Sound = new Sound();
var req:URLRequest = new
URLRequest("http://av.adobe.com/podcast/csbu_dev_podcast_epi_2.mp3");
snd.load(req);
var channel:SoundChannel;
channel = snd.play();
addEventListener(Event.ENTER_FRAME, onEnterFrame);
channel.addEventListener(Event.SOUND_COMPLETE, onPlaybackComplete);
function onEnterFrame(event:Event):void
{
var estimatedLength:int =
Math.ceil(snd.length / (snd.bytesLoaded / snd.bytesTotal));
var playbackPercent:uint =
Math.round(100 * (channel.position / estimatedLength));
trace("Sound playback is " + playbackPercent + "% complete.");
}
function onPlaybackComplete(event:Event)
{
trace("The sound has finished playing.");
removeEventListener(Event.ENTER_FRAME, onEnterFrame);
}
After the sound data starts loading, this code calls the snd.play() method and stores the resulting SoundChannel
object in the channel variable. Then it adds an event listener to the main application for the Event.ENTER_FRAME
event and another event listener to the SoundChannel object for the Event.SOUND_COMPLETE event that occurs when
playback is complete.
Each time the application reaches a new frame in its animation, the onEnterFrame() method is called. The
onEnterFrame() method estimates the total length of the sound file based on the amount of data that has already been
loaded, and then it calculates and displays the current playback percentage.
When the entire sound has been played, the onPlaybackComplete() method executes, removing the event listener
for the Event.ENTER_FRAME event so that it doesn’t try to display progress updates after playback is done.
The Event.ENTER_FRAME event can be dispatched many times per second. In some cases, you won’t want to display
playback progress that frequently. In those cases, your application can set up its own timing mechanism using the
flash.util.Timer class; see “Working with dates and times” on page 1.
Stopping streaming sounds
Flash Player 9 and later, Adobe AIR 1.0 and later
There is a quirk in the playback process for sounds that are streaming—that is, for sounds that are still loading while
they are being played. When your application calls the SoundChannel.stop() method on a SoundChannel instance
that is playing back a streaming sound, the sound playback stops for one frame, and then on the next frame, it restarts
from the beginning of the sound. This occurs because the sound loading process is still underway. To stop both the
loading and the playback of a streaming sound, call the Sound.close() method.
Last updated 6/6/2012
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