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Toshiba and NEC presented the DVD Forum with a joint proposal for a next generation optical disc format on Thursday, a move that looks set to ensure the road to a higher capacity optical disc is not going to be a smooth one.

This is because the new optical disc format, which has yet to be named, is the second to be proposed this year, after a group of 10 companies disclosed plans for their "Blu-ray Disc" system in February.

With some of the biggest names in electronics already lined up behind each format, and Toshiba and NEC seeking endorsement from the DVD Forum for theirs, the stage is set for a replay of the standards battle that took place in the mid-1990s over the DVD format.

Similar to DVD

The system proposed by Toshiba and NEC shares several features with DVD, including its physical structure: two 4.7 inch diameter, 0.02 inch thick discs bonded back-to-back to form a 0.04 inch thick disc. The companies say this is an advantage because it will be easier for disc manufacturers to modify existing equipment to make the new discs and also allows them to be double layered.

The Toshiba/NEC format is capable of storing 15GB of data on a single-layer prerecorded disc, or 30GB on a two-layer disc. A rewritable version of the format will store 20GB on single-layer discs and 40GB on two-layer discs, making use of the space between data tracks using a technology called land and groove recording.

The Blu-ray format has a capacity of around 27GB.

Both formats make use of blue laser diodes, which is how they are able to have capacities well beyond the 8.5GB of a dual-layer DVD. As the name suggests, the lasers used in the system emit a blue light, which has a shorter wavelength than the red light used in CD and DVD players. This means the size of the laser spot on the disc is smaller and so more data can be fitted in the same space.

At around $1,000 per component, blue laser diodes are prohibitively expensive, but several companies are about to enter mass production of the devices which should drive prices under $100.

Eliminating the Barriers

Although the falling price of laser diodes eliminates one of the cost barriers to mass production, the competing formats could still hamper an early launch while companies make bets on which technology to back. The situation mirrors that of the mid-1990s, before 10 companies working on competing optical disc formats agreed to come together under the DVD Forum. Prior to that agreement, two formats were battling each other: Super Density from Toshiba and Matsushita Electric Industrial, and Multimedia Compact Disc from Sony and Philips Electronics.

The DVD Forum says it is attempting to avoid a battle but has had little success so far.

"The DVD Forum would like to unify with the Blu-ray group if possible, but perhaps it looks like they don't want to unify," says Hideyuki Irie, director of the DVD Forum secretariat office.

There is also the possibility of a third format appearing. When Toshiba and NEC started work on the format proposed Thursday, they also began working on an alternate system based on a disc with a 0.1 millimeter cover layer over the recording layer, which is the same physical design as Blu-ray disc.

The two companies have yet to propose that format to the DVD Forum, which has a separate subgroup studying such a system, although development work on the system is continuing, according to Daniel Mathieson, a spokesperson for NEC.

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