Song Duration

Question

Hi;

I have made a Windows Media Player, but i would like to know how to know the duration of the song,
somebody said: that i must know the song BitRate.
can anyone help me to get the BitRate of the song, or help me of all the problem (get the duration of the song)
am using these segments to play the song(the song name+path are stored on ComboBox comboBox1)

MediaPlayer.settings.autoStart = true;

MediaPlayer.URL = comboBox1.SelectedItem.ToString();

if any Body can help me quickly
thanx alot