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Beyond DVD Page 5

Inside the Formats

Supporters stress the differences between Blu-ray and HD DVD, but each format relies on a common component: new "blue" lasers. Like all optical discs, the new formats encode data as small pits in a spiral track from the center of the disc outward. To increase capacity without increasing disc size, the pits and "lands" (the flat spaces between the pits) have to be made smaller. But a DVD player's red laser can't read pit tracks smaller than on a DVD, so HD DVD and Blu-ray use shorter-wavelength blue lasers.

Players in both formats will likely be compatible with DVDs and will support the MPEG-2 video standard used for DVDs as well as the MPEG-4 AVC and Microsoft Windows Media 9 compression, which allow the discs to hold even more high-def content.

But a Blu-ray disc can hold much more than an HD DVD, with a single-layer Blu-Ray disc maxing out at 25 gigabytes (GB) and a dual-layer at 50 GB, compared with 15 and 30 GB, respectively, for HD DVDs. Blu-ray rewritable (BD-RE) discs will come in 23-, 25-, and 27-GB single-layer and 50-GB dual-layer sizes, while HD DVD will have 20-GB single-layer and 32-GB dual-layer rewritable discs.

To achieve this capacity, Blu-ray not only has smaller data pits than HD DVD but also puts the recording layer closer to the disc's surface. The recording layer on HD DVDs rests between two 0.6-mm layers of plastic. Sony plans to release a four-layer 100-GB Blu-ray disc in 2007 and is working on an eight-layer, 200-GB version. The HD DVD camp hasn't discussed larger capacities.
Spider-Man vs. The Matrix
A war between the high-def Blu-ray and HD DVD discs could mean that your favorite movies will wind up on two different formats. The studio most strongly associated with Blu-ray - Columbia TriStar - produces the Spider-Man films, while Warner Bros., which spearheaded the launch of both DVD and HD DVD, makes the Matrix series. Also, Sony Pictures, which owns Columbia TriStar, recently bought MGM/UA, spiderman matrix
whose catalog includes The Wizard of Oz, Gone with the Wind, and the Pink Panther and James Bond series. Disney, with its collection of classic movies, is in the Blu-ray camp, and 20th Century Fox (the Star Wars franchise) was leaning toward Blu-ray at press time. Meanwhile, Paramount (the Godfather films), New Line (The Lord of the Rings), and Universal (Jurassic Park, Back to the Future ) all support HD DVD. Without a last-minute compromise, or universal players, watching your favorite films on high-def discs could mean having to make room for two players on your rack. (For more on what kind of compromises are possible, see David Ranada's commentary " Peace Entreaties ," filed from the Consumer Electronics Show.)

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