Flash sound not playing

I have a code as below

import flash.media.Sound;
import flash.media.SoundChannel;

flash.system.Security.allowDomai开发者_运维百科n("*");

var request:URLRequest = new URLRequest('beep.mp3');
var beepSound:Sound = new Sound();
beepSound.load(request);

function playBeep() {
    var channel:SoundChannel = beepSound.play();
}

ExternalInterface.addCallback("beep", playBeep);

The problem is that when I try to play this beep using JS, I get the following error:

Error calling method on NPObject! [plugin exception: Error in Actionscript. Use a try/catch block to find error.].

If I directly add "playBeep()" in the AS3 code, then it plays the sound. Any clue why? I have added allowscriptaccess=always in the embed code.

---

Is it possible that you're calling the beep function from your Javascript before the beep.mp3 has completely loaded in the swf? You can get an error by calling .play() on a Sound object that is not ready.

Try either wrapping the call to .play() in a try/catch block, or perhaps put the ExternalInterface.addCallback declaration inside of an onLoadComplete handler for the sound object.

beepSound.addEventListener(Event.COMPLETE, onLoadComplete);
beepSound.load(request);

function onLoadComplete(e:Event):void{
    ExternalInterface.addCallback("beep", playBeep);
    beepSound.removeEventListener(Event.COMPLETE, onLoadComplete);
}

EDIT: Of course, this doesn't account for the next question - How does the Javascript know that the mp3 has loaded? In that case, the onLoadComplete handler could also call

ExternalInterface.call("notifyJSThatMP3isHere", "someArgs");

In which notifyJSThatMP3isHere is a function you've defined in your Javascript that lets it know that it's now okay to try to call the swf's exposed "beep" function.