Dumb 5.1-on-SACD question

I feel like the answer to this should be obvious, but I'm probably missing something.

Is there any reason why the redbook layer of a hybrid SACD couldn't be 5.1 encoded? Perhaps with dts surround? Then you could essentially have a disc that has a hi-rez multichannel mix on the "SA" layer, with what would be the equivalent of a "dts 5.1 music CD" on the redbook layer.

Or does this violate the definition of "redbook?" (Obviously the CD layer would be unlistenable w/o a dts decoder.) Or, to take it down another step, any reason the redbook layer couldn't be at least Dolby Surround (Pro Logic) encoded, to extract some sort of surround? Maybe there simply isn't enough storage space.

I was thinking of this with Dark Side Of The Moon (SACD) & the general buying public in mind. Seems that if your redbook layer is stereo only, you're missing an opportunity to entice the public to buy into SACD if you can't give them a taste of surround. Rather, without SACD equipment, they are just looking at the latest stereo remaster to repurchase for the umpteenth time.

I know, it sounds like I'm just trying to force the DVD-A options onto SACD, but it seems like SACD could run DVD-A right outta town if they could also accomplish surround sound at a backward-compatible level, like Dolby Digital (DVD-V) soundtracks on a DVD-A, without investing in additional equipment (cheap as SACD is!).

Mark

 

There is no reason why they could not encode the "stereo" track with something like Dolby Pro Logic II, however, that might upset some purists.

 

DTS discs are basically redbook CDs with DTS info on them. You can copy the discs just like any other CD.

 

They made Dolby Surround discs... very few of them, but there were some made.

 

You mean those Pro Logic discs? Yeah, got some of them. I never got the feeling they sounded different than a normal stereo mix run through a Pro Logic decoder.

I had to mix a couple of tunes for different soundtracks in Pro Logic. I complained so much that one of the movies was switched to 5.1. Of course, it was 1999 and the time of Pro Logic was over. It's just a cheap gimmick. The stereo image collapsed a lot and there was just a bunch of random stuff in the surround channel. Sounded like everything was coming through the center channel.

 

RCA took dozens of their Quad tapes and remastered for Pro Logic--four channel, but the back channels are mono, not quite the Quad experience.
These don't sound bad, but they're not exactly honest, either. The Tomita titles, some classical, some soundtrack things. Kind of outmoded technology now.

ED