DVD Demystified

DVD Overview
Figure 4.5
Layers and sides
RULE OF THUMB: It takes about 2 gigabytes to store 1 hour of
average video.
A single-sided, single-layer DVD holds 4.7 billion bytes of data (4.37 gigabytes),
7 times more than a CD-ROM, which holds over 650 megabytes. 5 A
double-sided, dual-layer DVD holds just over 17 billion bytes (15.9 gigabytes),
which is 25 times what a CD-ROM holds. See “Units and Notation” in Chapter
1 for a discussion of the difference between billions of bytes and gigabytes.
At the end of 1999, approximately 80 percent of DVD video titles were
released on DVD-5, with about 10 percent on DVD-9 and 10 percent on
DVD-10. The share of DVD-14 and DVD-18 discs was insignificant. In terms
of actual disc production, the percentage of DVD-9 discs is much higher.
Hybrids
185
A hybrid disc is one that combines the features of one or more formats. Anyone
who speaks in general terms of a hybrid disc is being dangerously
vague because as many potential hybrids exist as physical and logical formats.
Table 4.8 lists some of the more common DVD hybrids.
Hybrid players are also available: video-capable audio players (DVD-
Audio players with video output) and universal players (players that can
play both DVD-Video and DVD-Audio). New convergence devices such as
digital satellite receivers with DVD players built in are also known as
hybrids.
5 The loose tolerance of the CD standard tracks enables to be placed more tightly together, so CDs
actually can hold 750 megabytes or more. An example is the so-called 84-minute CD.