AC3 output over s/pdif
 

I found out that when I want to play a movie encoded in ac3 5ch audio bs player wir decode only the left and right channel and not the center and surround channels. they are not mixed but just forgoten. I would like to know if there's any thing i can do to make the Intervideo ac3 decoder actualy use the s/pdif and not direct 3dsound.