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How Blu-ray Discs Work

        Tech | HDTV

Blu-ray Competitors
Samsung BD-P1000 Blu-ray player
Samsung BD-P1000 Blu-ray player
Photo courtesy photo courtesy Samsung

Will Blu-ray replace previous DVDs? Its manufacturers hope so. In the meantime, JVC has developed a Blu-ray/DVD combo disc with an approximate 33.5-GB capacity, allowing for the release of video in both formats on a single disc. But Blu-ray is not alone in the marketplace. A few other formats are competing for a share of the DVD market.

The other big player is HD-DVD, also called AOD (Advanced Optical Disc), which was developed by electronics giants Toshiba and NEC. HD-DVD was actually in the works before regular DVD, but it didn't begin real development until 2003.

The advantage to HD-DVD is that it uses the same basic format as the traditional DVD and can therefore be manufactured with the same equipment, saving on costs. HD-DVD matches the storage capacity of Blu-ray. A rewritable, single-layer HD-DVD can hold 15 GB of data, a double-layer disc can hold 30 GB, and a triple-layer disc can hold 45 GB (that's compared to 27 GB and 50 GB for Blu-ray). The read-only versions hold slightly less data. Also, HD-DVD offers the interactive capabilities of Blu-ray, with HDi.  For more information on HD-DVD, check out How HD-DVD Works.

Blu-ray and HD-DVD are the two major competitors in the market, but there are other contenders, as well. Warner Bros. Pictures has developed its own system, called HD-DVD-9. This system uses a higher compression rate to put more information (about two hours of high-definition video) on a standard DVD. Taiwan has created the Forward Versatile Disc (FVD), an upgraded version of today's DVDs that allows for more data storage capacity (5.4 GB on a single-sided disc and 9.8 GB on a double-sided disc). And China has introduced the Enhanced Video Disc (EVD), another high-definition video disc.

There are also professional versions of the blue laser technology. Sony has developed XDCAM and ProData (Professional Disc for Data). The former is designed for use by broadcasters and AV studios. The latter is primarily for commercial data storage (for example, backing up servers).

It seems that the future holds a whole lot more than 25 to 54 GB on a single disc. According to T3: Pioneer goes beyond Blu-Ray, Pioneer is developing an optical disc that will blow away the hard disc in most of our PCs in terms storage capacity, holding 500 GB of data. How so? Pioneer's lasers are ultraviolet, which have an even shorter wavelength than the blue.

For more information on Blu-ray and related topics, check out the links on the next page.