Hardware Reference
In-Depth Information
Figure 11.16. The structure of a hybrid SA-CD disc.
Note
Although you can play hybrid SA-CD media in standard players or computer-based drives,
these devices are only playing the CD layer. To enjoy the enhanced audio of SA-CD, you must
use a standalone SA-CD player.
An SA-CD disc (or the SA-CD layer of a hybrid disc) includes the stereo version of the album in its
inner portion, a six-channel surround audio mix in the middle portion, and extra data such as lyrics,
graphics, and video in the outer portion.
For listings of SA-CD albums and players and additional SA-CD information, see
www.sa-cd.net
.
DualDisc
DualDisc, introduced by a consortium of major record labels in the summer of 2004, is a combination
of two different formats—music CD and DVD—on a single two-sided disc. DualDisc (sometimes
referred to as Dual Disc), as the name suggests, is two discs in one: One side is a music CD, typically
featuring support for surround audio or other advanced audio formats, and the other side is a DVD
(using the single-layer DVD-5 format) that can include music videos, concert footage, web links, and
other features.
Although DualDisc is designed to work in standard CD drives and players, it is not completely
compatible with Red Book standards because the CD layer is only 0.9mm, compared to the Red Book
standard of 1.1mm. To compensate for spherical aberration caused by a thinner CD layer, one method
used is to increase the size of the pits on the CD side of a DualDisc, reducing playing time to 60
minutes. (Some later DualDisc media uses different methods to increase playtime.)
The total thickness of a DualDisc is 1.5mm, compared to 1.2mm for standard CD or DVD media,
causing DualDiscs to be incompatible with slot-loading drives in car stereos, PCs, and mega-disc
changers. Because DualDisc media is thicker than normal CD media and because the internal
structure of the CD side is not compatible with Red Book standards, Philips and Sony (the co-
creators of the CD format) do not use the CD logo on DualDisc media, and most DualDisc albums
include warning labels that the disc will not work in slot-loaded drives and mega-disc changers and
