Original URL: http://www.theregister.co.uk/2004/02/27/dvd_forum_approves_rewriteable_hddvd/

DVD Forum ‘approves’ rewriteable HD-DVD spec

Another win for NEC and Toshiba's blue laser tech

By Tony Smith

Posted in Storage, 27th February 2004 11:35 GMT

The guardians of the DVD specification have approved a rewriteable version of the standard that supports high definition images.

The DVD Forum approved the HD-DVD-RW (our name for it) format in Tokyo this week, according to an official of one of the member companies, cited by IDG News.

However, officially, the organisation will only say: "The DVD Forum has so far made no decision to adopt or reject any proposed format for blue laser optical disc applications."

The approved/not approved spec. details a standard-sized, single-sided disc that can hold up to 20GB of data. Today's DVDs, by contrast, hold up to 4.7GB per side.

The alleged approval of the rewriteable version follows last November's Forum vote in favour Toshiba and NEC's blue laser-based technology as the basis of the HD-DVD spec. That technology is also used in the RW spec, which although submitted last November failed at that time to win sufficient support from other Forum members.

The Toshiba-NEC read-only system won the November vote 8:6, thanks to new voting rules that ignore abstentions. It's backward-compatibility with the current DVD spec appears to have clinched the win. That compatibility not only makes it easier for next-generation players to cope with today's DVDs, but will make it possible to re-tool existing DVD production lines for the new technology. Rival HD specifications would have required entirely new production facilities.

The approval of the HD-DVD-RW standard doesn't mean that rival technologies will vanish, of course. Sony's Blu-ray system, for instance, has already started to ship, under the company's Professional Disc for Data (PDD) trademark. PDD offers higher capacities than HD-DVD-RW - up to 23GB of uncompressed data - but encases its 12cm discs inside a cassette. Sony is pitching PDD as a replacement for high-end magneto-optical storage systems.

Blue light is used in both PDD and HD-DVD because it has a shorter wavelength than the red light lasers found in today's CD and DVD drives. The upshot is that the laser can be focused to a smaller spot on the disc's surface, so more spots can be crammed in. Since each spot equates to a single bit of data, so the blue light discs have a higher data capacity than their red-light predecessors.

The DVD Forum has in place a sub-committee tasked with working on ways to bring Blu-ray and its HD-DVD spec. into alignment. It is also researching a second generation of blue laser systems that can read 0.1µm spots rather than the 0.6µm spots of the Toshiba-NEC and Sony systems. To date, no 0.1µm technology has been proposed to the Forum, the organisation said. ®

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