What is SACD and DVD-A and now Blu-Ray?
SACD is an abbreviation for Super Audio Compact Disc, and DVD-A is an abbreviation for Digital Versatile Disc-Audio, and Blu-Ray is a new proposed format with higher data storage, that requires a blue laser to read the disc.
SACD is also referred to as DSD or Direct Streamed Digital. SACD is a single bit system that was launched by Philips and Sony at the end of the 25 year period of royalties paid to them from standard CD recordings. It is a new higher frequency sampled system (96kHz) as opposed to standard CD at 44.1kHz. The discs are usually available as hybrids, containing up to three formats on a single disc including; a standard CD recording of 44.1kHz, a two channel DSD @ 96kHz and a multi channel surround sound recording up to 5.1 channels. The material is usually re-mixed from original analogue tapes or 48kHz DAT masters onto the DSD format. Not many discs are in production, approx. 2000 titles, mainly re-issues.
The DVD-A disc in its full glory should deliver 2 channels at 192kHz 24 bits. Most discs have been re-mastered taking the original 48kHz master and recording at 2 channels @ 96kHz resolution. Also there are some surround discs, which feature up to 5.1 channels @96kHz. Very few recordings feature an original digital master at 192kHz, none we know of. Very few discs are in production, most are mainly experimental hardly any mainstream product.
Blu-Ray is a new proposed format. The chief advantage here is very large data storage up to 50 giga-bytes dual layer, the standard DVD is approx. 9.5 gigabytes dual layer. So Blu-ray is essentially a video format and games console format which can support multi-channel DVD-A quality plus video information. There is no proposed format for audio only. There is already a format war in progress similar to VHS versus Betamax between industry giants Toshiba and Sony. So a single format has not been proposed. A new type of player is required to read Blu-Ray as the new blue laser has a wavelength of 450nm compared to the red laser of 650nm.