Dolby® Digital (AC3) Decoding Built-in allows the 5.1 channels (front right, front left, rear right, rear left, center and subwoofer) of sound to be decoded and then passed on to a receiver with 6-channel inputs. All Dolby® Digital decoders can also decode Dolby® ProLogic sound tracks. A very high percentage of home DVD-videos come with Dolby Digital soundtracks. It is also used in many digital TV channels and broadcasts, including HDTV.
DTS Decoding like Dolby® Digital, DTS is a 5.1-channel digital surround format that provides a separate channel of sound to five speakers (right, center, left, right surround, left surround) and a subwoofer. DTS is not the standard for most DVD-videos, but many people claim the sound quality is higher than that of Dolby.
Virtual surround sound attempts to create the illusion of surround sound through just the speakers on your television.