How to play an m4a sound file - actionscript-3

Question

The code below imports and controls an mp3 sound file. When I change from an mp3 to an m4a file the code does not work. Do I need to use a different class to play an m4a file?
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" minWidth="955" minHeight="600" creationComplete="init()" >
<mx:Script>
<![CDATA[
import mx.events.ItemClickEvent;
import mx.rpc.events.ResultEvent;
private var sound:Sound;
private var soundChannel:SoundChannel = new SoundChannel;
private var loaderContext:SoundLoaderContext;
private var trackPosition:Number = 0;
private var timer:Timer;
private var leftGraphic:Sprite;
private var rightGraphic:Sprite;
private function init():void{
var audioFile:String = "recording.mp3";
sound = new Sound(new URLRequest(audioFile));
sound.addEventListener(Event.COMPLETE, onSoundLoaded);
function onSoundLoaded(event:Event):void{
maxTime.text = convertMillesecs(sound.length)
trackSlider.y-= 5;
trackSlider.maximum = sound.length;
}
}
private var counter:Number
private function soundComplete( e:Event ):void{
maxTime.text = convertMillesecs(soundChannel.position);
maxTime.text = convertMillesecs(sound.length)
}
private function checkTrack(event:Event):void{
// manage track counter
trackSlider.value = soundChannel.position;
currentVal.text = String(convertMillesecs(soundChannel.position));
}
private function convertMillesecs(time:Number):String{
var h:Number = new Number(Math.floor(time/1000/60/60));
var m:Number = new Number(Math.floor(time/1000/60)-(h*60));
var s:Number = new Number(Math.floor(time/1000)-(m*60));
var hours:String;
var minutes:String;
var seconds:String
//minutes and seconds always two digits
if(m.toString().length == 1) {
minutes = "0"+m;
} else {
minutes = m.toString();
}
if(s.toString().length == 1) {
seconds = "0"+s;
} else {
seconds = s.toString();
}
// last two digits represent actual seconds
seconds = seconds.slice(seconds.length-2, seconds.length);
return minutes + ":" + seconds;
}
private function controlChange1(event:MouseEvent):void{
var optionString:String;
switch(event.target.id){
case "playButton":
play();
break;
case "pauseButton":
pause();
break;
default:
break;
}
}
private function play():void{
playButton.visible = false;
pauseButton.visible = true;
timer = new Timer(100);
timer.addEventListener(TimerEvent.TIMER, checkTrack);
soundChannel.stop();
soundChannel = sound.play(pausePosition);
timer.start();
}
private var pausePosition:int
private function pause():void{
pausePosition = soundChannel.position;
soundChannel.stop();
playButton.visible = true;
pauseButton.visible = false;
}
private function onTrackSliderChange(e:Event):void{
soundChannel.stop()
soundChannel = sound.play(e.target.value * sound.length / trackSlider.maximum);
playButton.visible = false;
pauseButton.visible = true;
}
private function formatButton(val:String):String{
return convertMillesecs(soundChannel.position)
}
]]>
</mx:Script>
<mx:HBox backgroundColor="0x000000" horizontalCenter="0" verticalCenter="0" verticalAlign="middle" horizontalScrollPolicy="off" verticalScrollPolicy="off" >
<mx:Canvas id="controlBar1" paddingLeft="1" buttonMode="true" useHandCursor="true" >
<mx:Button id="pauseButton" width="40" height="40" click="controlChange1(event)" visible="false" color="0x0B333C"/>
<mx:Button id="playButton" width="40" height="40" click="controlChange1(event)" color="0x000000" />
</mx:Canvas>
<mx:Label id="currentVal" text="00:00" color="0xffffff"/>
<mx:HSlider id="trackSlider" height="10" width="500" liveDragging="false" change="onTrackSliderChange(event);"
dataTipFormatFunction="formatButton" showTrackHighlight = "true" mouseEnabled="true" useHandCursor="true" />
<mx:Label id="maxTime" text="00:00" color="0xffffff"/>
</mx:HBox>
</mx:Application>

Answer 1

The Sound class can play one of two formats: mp3 and the raw format AS3 records to. So it is impossible to use the Sound class to play m4a, unfortunately.
Fortunately, it is possible to play m4a using another class: NetStream. You may or may not have as fine of control over it without the SoundTransform and SoundMixer classes, but you can still play the file no problem (I've done it in the past, though it didn't end up working quite the way I was hoping for so I ended up going with mp3s instead)
Adobe Article on m4a playback