MediaPlayer.Duration wird angemeckert

[Delphi.Narium]

Weils Duration beim Mediaplayer nicht gibt, dafür aber Length?

Delphi-Quellcode:

procedure GetVideoDuration(const VideoFileName: string);
var
  MediaPlayer: TMediaPlayer;
begin
  MediaPlayer := TMediaPlayer.Create(nil);
  try
    MediaPlayer.FileName := VideoFileName;
    MediaPlayer.Open;
    try
      ShowMessage('Video-Dauer: ' + IntToStr(MediaPlayer.Length) + ' ms');
    finally
      MediaPlayer.Close;
    end;
  finally
    MediaPlayer.Free;
  end;
end;