MediaPlayer Serias9 SDK里面怎么控制播放结束？

Question

<OBJECT ID="Player" height="300" width="400"
  CLASSID="CLSID:6BF52A52-394A-11d3-B153-00C04F79FAA6"><PARAM NAME="invokeURLs" VALUE="False">
<PARAM NAME="autoStart" value="false">
</OBJECT>
<INPUT TYPE="BUTTON" NAME="BtnPlay" VALUE="Play" OnClick="StartMeUp()">
<SCRIPT>
/*
 *MediaPlayer版本:Windows Media Player 9.0
 *功能:判断该Music是否播放完.
 *原理:通过判断当前Music位置和Music的总长度的对比.
 *author:wanghr100
 */function startRecordset()
{
    window.timer=window.setInterval("blnend()",1000);
}
function blnend()
{
    var ps = Player.playState;  //播放状态,3为播放.
    var curPosition = parseInt(Player.controls.currentPosition);//当前位置
    var mediaLong = parseInt(Player.currentMedia.duration); //Music总长度
    if(ps==3 && curPosition>=mediaLong-2){
    clearInterval(window.timer);
    alert('Music Over') }
}
function StartMeUp()
{
    Player.URL="you.wma";
    Player.controls.play();
    startRecordset();
}
</SCRIPT>