circularvibes wrote:Actually, there are Dolby matrix encoded CD's and they do conform to RBCD standards. They are playable in 2 channel, or using a Dolby decoder, it will be 5.1. There are also quad matrix encoded CD's as well, but you likely need a knowledgeable list to tell you which ones they are. The only thing not utilised in the RBCD standard was the 4 channel discrete format. This is because quad as a popular format was regrettably dead by 1980. There were also DTS encoded cd's in the RBCD standard, but you require a DTS decoder to hear them. You get loud white noise otherwise. They are not 2 channel compatible, but conform only because the sound is still in the 2 channels waiting for decoding. Most older DVD players and multichannel receivers had DTS built in.
With any matrix encoded CD they already confirm to the Red Book standard as they are matrix based audio and have no impact on the two channel signal on regular CD's. Unless you use a matrix based decoder (QS, SQ, Dolby Pro Logic) to listen to them you'd never know there was any "surround" material there.
Any sound other than the two front channels is derived and is not a discrete signal.
DTS audio and Dolby Digital are discrete systems and do not use any matrixing whatsoever.