Accessing waveform data from external app

[Kaldarah]

Hi there
I am new here so please bear with me.
I have a program written in C++ using openGL and I would like to access winamp data to do some visualisation. I have the sdk and can access data like song length and title, but what I really need is the actual audio, or even better, the frequency data. I can't convert my whole program to a plugin.
I have looked on this site and found only tidbits of relevant information. It seems possible but I just need a bit more info.
I vaguely understand that I have to write a dummy plugin to make the data accessable to the external app.
Has anyone done this before and has just such a plugin? Or can anyone point me in the right direction?

Thanks very much,