HD DVD (High Density Digital Versatile
Disc or
High Definition Digital Video Disc)
A digital optical media format which is being developed
as one standard for high-definition DVD. HD DVD is
similar to the competing Blu-ray Disc, which also
uses the same CD-size (120 mm diameter) optical data
storage media and 405 nm wavelength blue laser. HD
DVD is promoted by Toshiba, NEC, Sanyo, and, most
recently, Microsoft, HP [1], and Intel.
HD DVD has a dual-layer capacity of 30 GB and
a single-layer capacity of 15 GB. Toshiba has announced
a triple-layer disc which offers 45GB of storage.
HD DVD can offer both the current DVD and HD DVD
formats on one disc, which means that special HD
DVD discs will play in any DVD player, old or the
new high definition players. Blu-ray does not. This
makes retail marketing and shelf space management
easier. For consumers shopping is simplified as they
can simply buy a movie that plays in any DVD player
in their house, standard definition or high definition.
The HD DVD format also can be applied to current
red laser DVDs in 5, 9, 15 and 18 GB capacities which
offers an even lower cost option to content owners
wanting to sell short form content. Blu-ray does
not work with red laser discs.
Blu-ray Disc (BD)
A next-generation optical disc format
meant for high-density storage of high-definition
video and data. The Blu-ray standard was jointly
developed by a group of consumer electronics and
PC companies called the Blu-ray
Disc Association (BDA). It is currently competing
with the HD DVD format for wide adoption as the prefered
next generation optical standard.
The name Blu-ray is derived from the blue-violet laser it
uses to read and write to the disc. A Blu-ray Disc
will be able to store substantially more data than a DVD,
because of the shorter wavelength (405 nm)
of the blue-violet laser (DVDs use a 650-nm-wavelength
red laser and CDs 780
nm), which allows more information to be stored digitally
in the same amount of space. In comparison to HD DVD, which also
uses a blue laser, Blu-ray has more information capacity per layer
(25 gigabytes instead
of 15) but may initially be more expensive to produce. |