Sound capturing - what is in there?

[Nelson37]

When a movie (on digital cable, if it makes any difference) says it has surround sound, what exactly does that mean? I'm a little unclear on Dolby Prologic, AC3, 5.1, DTS, etc. My amp only does Dolby Prologic or simulated surround, plus I only have 2.1 speakers but hoping for the future. I have noticed that Prologic always muddies and muffles the sound, while simulated surround seems to improve it somewhat, dramatically on some movies.
Are any broadcasts in 4-channel? Would a 4-channel card help? How about encoding methods?
I have seen some discussion of similar topics but only concerning DVD rips, I'm just trying to get the max sound capabilities from a TV capture, Thanks All!

[jbwill]

Check out the info center @ crutchfield.com. Dolby Prologic means that the source has 4 discrete sound channels that consist of a Left Front, Right Front, Center channel and a single Rear channel. Attempting to play all four of these channels through a 2.1 system will muddle the sound because the system is attempting to play the center and rear sounds through the front speakers, in my opinion that spells big trouble no matter what size speakers you have. A simulated signal may sound clearer because the system is more than likely selecting a stereo track and and creating a rear and center single from it.

Dolby Prologic is transmitted via RCA audio cables. Using a video card that has the RCA audio inputs should be able to capture the Dolby format. Good luck.