Need help! How to draw waveform of the sound when playing video!

[C# Programming]

I use Microsoft.DirectX.AudioVideoPlayback for video player, and I don't know how to get frequencies and amplitude of the sound (when playing video) to draw a waveform. I can't find any-code about it. Somebode help me please!! http://www.barakasoft.com/script/Forums/Images/smiley_biggrin.gif
Thank you for your help.