How does it do that?

[tonyromen]

So I have an audigy 2 platinum, and a set of logitech 540s.

Right now I'm listenting to an mp3, and there is the standard stereo coming out of the 2 front to speakers, but the 2 rear speakers have music coming out of them too, only not just a reproduction of what the 2 front speakers are producing....it seems like it's just the drums and guitars....all the vocals are only coming out of the 2 front channels.

My question is....if studio music is mixed down to 2 channels, how does the soundcard know what to strip out to put in the rear channels?

things that make you go...hmmmmm?


-t

[Tomteriffic]

A couple of possibilities: First, it may be that the recording was originally mixed as surround and then matrixed or "folded over" into stereo. If the original foldover encoding was intact and the Audigy or your system had the proper codec, it could be decoded back to the original surround mix.

More likely, though, the Audigy is set for a "matrix" type of surround. That is, it examines the amplitude and phase relationships present in the stereo mix and expands "difference information" and puts it in the rear channels. Since drums are usually recorded with numerous microphones at once, and guitar parts are very commonly double or triple tracked (that is, the same parts are played several times in order to fatten them up, and then they are put in opposite channels in the mix) there may be plenty of difference information to work with with a matrix type decoder.

Can't be more specific than that, but those are two good possibilities.