用Real Player的控件播放ram，Mp3文件，怎样才能知道它的时间长度？

//用getlength得到的就是总长度（单位是毫秒吧，0.001秒），当前播放时间也就一样啦
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, OleCtrls, RealAudioObjects_TLB;type
  TForm1 = class(TForm)
    RealAudio1: TRealAudio;
    Button1: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.DFM}
procedure GetTotalTime(var RealAudio1: TRealAudio; var vMin,vSecond:Integer);
var
  temp:integer;
begin
  temp:=round(realaudio1.GetLength/1000);//ÎÒÕâÀïÖ»¾«È·µ½Ãë
  vMin:=temp div 60;
  vSecond:=temp - vMin*60;
end;procedure TForm1.Button1Click(Sender: TObject);
begin
realaudio1.SetSource('C:\1222\jacky06.mp3');
realaudio1.DoPlay;
end;procedure TForm1.Button2Click(Sender: TObject);
var
  ff,mm:integer;
begin
  GetTotalTime(realaudio1,ff,mm);
  showmessage(inttostr(ff)+'·Ö'+inttostr(mm)+'Ãë');end;end.