HD DVD

High definition DVD, often known as HD-DVD (which actually stands for High Density

DVD), is of competing high definition storage format - the other being Blu-ray.

The necessity for a new, high capacity storage format, has been primarily brought about by the fast

rise in popularity of HDTV in Japan & the US. HDTV has much higher bandwidth

than either NTSC or regular DVD discs, so in order to record programs from HD-

DVD higher capacity discs, of at least 30GB, are necessary.

High definition video is also being used increasingly to make Hollywood movies as it

offers comparable quality to film at much less cost. Therefore, the studios plan to

release future movies on or both high definition formats.

HD-DVD was developed by Toshiba & NEC & has the support of the DVD Forum,

along with lots of Hollywood studios. Currently those studios which have

announced support for HD-DVD are; Universal Studios, Paramount Studios, Warner

Bros. & New Line Cinema. It is a capacity of 15GB for single-sided discs &

30 GB for double-sided. It doesn't need a caddy or cartridge & the cover layer is

the same thickness as current DVD discs, 0.6mm. The numerical aperture of the

Optical pickup head is also the same as DVD, 0.65mm.

Because of its similarities to current DVD, high definition DVD is cheaper to

manufacture than Blu-ray, because it doesn't need giant changes in the production

line set up. Both HD-DVD & Blu-ray have backward compatibility with existing

DVDV discs. That is that current DVDs will play in HD-DVD player, although new

High definition DVD won't play in older DVD players.

High definition DVD currently supports lots of compression formats, including

MPEG-2, VC1 (based on Microsoft's Windows Media 9), & H.264 which is based on

MPEG-4 & will be supported by the next version of Apple's QuickTime program,

Which will be included with Mac OS X Tiger.