get sound card output volume in a windows app

I'm developing a application that works the same as the windows 7 system volume tray application, but don't know how to display the "strength" of the music that is playing in the background. The windows tray application does that by dis开发者_Go百科playing a green and a grey line behind a trackbar, it does this even if the sound is muted (gray line).

How could i get the same effect in C#? Is it even possible?

Thanks in advance. Regards J.

You'll have to call some native Win32 methods via P/Invoke. This article goes into detail and uses windows sound as one of the examples.