i wrote a plugin for mmfcontrol
afer calling openfile(fn,uid) from util's interface, the frame will call adddatasink(..) and adddatasource(..) in my plugin.
but how to cast mdatasource to cmmffile?

or anybody can expain to me for this flow,how can i setup any config in my plug-in to play the file using my pulgin.

I could not file the header for it~

help me ~ thx.