[AS3]as3取FMS流媒体服务器播放器mp3的问题

草民在做一个播放器，从网上找了个代码，但是有问题，就是读取mp4格式的时候没问题，但读mp3格式的，取不到mp3的总长度。代码如下，各位大大有空的时候来指点指点。

package { 
        import flash.display.Sprite; 
        import flash.events.NetStatusEvent; 
        import flash.events.SecurityErrorEvent; 
        import flash.media.Video; 
        import flash.net.NetConnection; 
        import flash.net.NetStream; 
        import flash.events.Event; 
        import flash.net.ObjectEncoding; 
 
        public class Main142 extends Sprite { 
                private var videoURL:String="mp4:1"; 
                private var nc:NetConnection; 
                private var ns:NetStream; 
 
                public function Main142() { 
                        nc = new NetConnection(); 
                        nc.objectEncoding=ObjectEncoding.AMF0; 
                        nc.addEventListener(NetStatusEvent.NET_STATUS, netStatusHandler); 
                        nc.addEventListener(SecurityErrorEvent.SECURITY_ERROR, securityErrorHandler); 
                        nc.connect("rtmp://localhost/vod/media"); 
                        nc.client=this; 
                } 
                private function netStatusHandler(event:NetStatusEvent):void { 
                        trace("netStatusHandler= " + event.info.code); 
                        switch (event.info.code) { 
                                case "NetConnection.Connect.Success" : 
                                        connectStream(); 
                                        break; 
                                case "NetStream.Play.StreamNotFound" : 
                                        trace("Stream not found: " + videoURL); 
                                        break; 
                        } 
                } 
                private function securityErrorHandler(event:SecurityErrorEvent):void { 
                        trace("securityErrorHandler: " + event); 
                } 
                private function connectStream():void { 
                        ns=new NetStream(nc); 
                        ns.addEventListener(NetStatusEvent.NET_STATUS, netStatusHandler); 
                        var client:Object=new Object(); 
                        client.onMetaData=onMetaData; 
                        ns.client=client; 
                        var video:Video = new Video(); 
                        video.attachNetStream(ns); 
                        ns.play(videoURL); 
                        addChild(video); 
                } 
                public function onBWDone():void { 
                } 
                public function onMetaData(info:Object):void { 
                        trace("CuPlayer.com提示总时间:"+info.duration); 
                } 
        } 
} 

 终于搞定了，在这里保存下，省的以后找不到了，虽然是抄的别人的。
Application.onConnect=function(client)
{
     Application.acceptConnection(client);
}
Client.prototype.getMediaLength=function (mp3_name)
{
     return Stream.length(mp3_name);
}