Decoding Dolby DTS from SPDIF input using software?

[343N]

I've got my xbox hooked up to my PC through SPDIF In and I can use Dolby AC3 or DTS, only problem is my input device doesn't support decoding those formats. Is it possible I can use software to decode it? I know FFDShow can decode it for video/audio files but that's not what I really want.

Thanks.

[editline]ass[/editline]

or is there a convenient way to get my setup to support my xbox one surround sound? cause right now my setup is this

xbox > optical to usb sound card > to pc > out from pc to speakers (but sound card doesn't support DTS/AC3 which is why i asked the initial question)
speakers have 3 3.5mm jacks as input only

the xbox can do 5.1 hdmi output aswell but my monitor only has a single 3.5mm jack out so it can only output stereo
i cant think of a way to get surround to work without a bunch of other components