AS3でM4Aファイルを再生するプログラム

PlayM4A.as

package {
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.events.NetStatusEvent;
	import flash.events.UncaughtErrorEvent;
	import flash.media.Sound;
	import flash.media.SoundTransform;
	import flash.net.NetConnection;
	import flash.net.NetStream;

	public class PlayM4A extends Sprite {

		private var nc:NetConnection;
		private var ns:NetStream;
		private var st:SoundTransform;

		public function PlayM4A():void {

			nc = new NetConnection();
			nc.connect(null);

			ns = new NetStream(nc);

			//これしないとエラーでる
			ns.client = { 
				onXMPData: function(data:Object):void { },
				onMetaData: function(data:Object):void { }
			}

			ns.addEventListener(NetStatusEvent.NET_STATUS, netStatusHandler);

			ns.play("MySound.m4a");

			st = ns.soundTransform;
			st.volume -= 0.3;
			ns.soundTransform = st;
		}

		private function netStatusHandler(e:NetStatusEvent):void {
			trace(e.info.code);
		}

	}

}