Tech Talk

A line has been drawn in the sand. Negotiations between Sony and Toshiba to reach a consensus on a unified next-generation optical disc format broke down this summer. Both companies and their supporters are pushing what they think should replace the DVD format. Technophiles…prepare for the next format war.

The two new major competing formats are Blu-ray and HD DVD. Promoting Blu-ray is the Blu-ray Disc Association. The format was founded by Sony and Philips. Some of the big names backing it include Fox, EA, MGM, Dell, Apple and Sun Microsystems.

Behind HD DVD are the DVD Forum and the HD DVD Promotional Group. The format was founded by Toshiba and Hitachi. Some of its major supporters include New Line Cinema, Paramount Pictures, Warner Bros., Microsoft, NEC and Sanyo.

As for upcoming Hollywood releases, 35 per cent will be in Blu-ray format and 40 per cent will be HD DVD.

The war will also be fought on the next generation of videogames consoles. Sony has confirmed that the PlayStation 3 will use Blu-ray and it is rumoured Microsoft’s Xbox 360 will use HD DVD.

This new generation of optical storage is based upon the transition from red lasers to blue lasers. These new blue lasers have a shorter wavelength than the red lasers which allows them to read and write much smaller 1s and 0s on discs. The smaller the 1s and 0s on the disc, the more data you can fit onto it.

The main argument against Blu-ray is its cost of production, which will be, at least in the short-term, higher than HD DVD. This is because it’s easier to convert DVD production lines to HD DVD than to retrofit for Blu-ray.

Both Blu-ray and HD DVD support the same video compression techniques and devices designed to play either format will be backwards compatible with DVDs and CDs. On the other hand, it looks like devices designed to play Blu-ray Discs will not play HD DVDs or vice-versa. Both formats will have the same diameter as a CD, 12 cm.

Blu-ray discs offer 25 GB of storage on a single-layer disc and 50 GB on a dual-layer disc. They have a theoretical eight-layer capacity of 200 GB.

HD DVD has a capacity of 15 GB on a single-layer disc and 30 GB on a dual-layer disc, with a theoretical double-sided dual-layer capacity of 60 GB.

Blu-ray discs have a higher per layer data capacity than HD DVD because of the lens used to focus the laser of Blu-ray drives. This lens has a numerical aperture of 0.85 while HD DVD’s lens has a numerical aperture of 0.65. The higher the numerical aperture, the smaller the 1s and 0s a laser can read and write on a disc, which of course means more data can be fit on a disc.

Both formats have reached data transfer speeds of 2x, equivalent to about 9 MB/sec. Data transfer speeds measure how quickly a computer can read the data on a disc. To give you a reference point, conventional DVD drives have data transfer speeds of about 21 MB/sec. Since Blu-ray discs store information closer together, they don’t have to spin as fast as HD DVDs to achieve the same data transfer speeds. Because optical drives have a maximum rotational speed of 10,000 RPM, Blu-ray can reach a transfer rate of 12x while HD DVD can only reach a speed of 9x.

New, more aggressive compression techniques such as MPEG-4 AVC allow a dual-layer HD DVD to store up to 8 hours of high-definition video. This compression technique allows more video to fit in a smaller space, supposedly without any discernible degradation of quality. So HD DVDs will be able to store a feature film and all the extras with no trouble. For comparison’s sake, a dual-layer Blu-ray disc can store over 13 hours of high-definition video.

HD DVD uses the standard 0.6 mm protective coating that is found on DVDs to physically protect data. Blu-ray has a 0.1 mm protective coating developed by TDK called “Durabis.” The coating is supposed to allow for easy removal of fingerprints and be highly scratch-resistant. The downside of this coating is that it adds significantly to production costs.

As usual, some players and media for these new formats are already available in Japan. The rest of us will have to wait until at least early 2006 for products to reach the North American market.

In the end this war comes down to a simple dichotomy: Blu-ray has storage capacity and performance, but HD DVD is cheaper. It looks certain that both formats will be around for at least the next couple years, so which format eventually wins will be largely dependant on whether consumers are willing to pay a premium for Blu-ray.

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