AfterDawn: Glossary


BD-ROM discs are the physical Blu-Ray Discs. In 2006, many movies and game content (for the PlayStation 3) will be released on BD-ROM discs. A blue-violet laser that will operate at a wavelength of 405nm (much shorter than the 650nm wavelength used by red lasers) to read data from BD-ROM discs. These discs also use a higher numerical aperture than DVDs, 0.85 compared to 0.6 for DVD (whereas HD DVD uses only 0.65). Blu-ray's rivals are skeptical that the higher numerical aperture will lead to reliability issues with BD-ROM discs.

BD-ROM discs can store much more data than DVDs due to the shorter wavelength of the blue-violet laser and the numerical aperture. Typically, BD-ROM discs store 25GB per layer, so one of the main selling points of Blu-ray is the 50GB dual layer discs that will be available. The first discs were enclosed in plastic caddies to protect the surface of the discs. However, it was thought that HD DVD would then have a huge advantage over Blu-ray as HD DVD discs can be handled like DVDs and CDs, which are familiar to consumers. Now instead of using caddies, BD-ROM discs will have a much tougher coating developed by the TDK Corporation. The coating, called Durabis, allows for easier cleaning of the discs. Millions of DVDs and CDs are destroyed each year because consumers do not know how to safely clean them.

The software that will make BD-ROM discs containing high definition movies work is Java-based. It is known as BD-J. Some supporters of Blu-ray would have preferred to see iHD being used for interactivity features to drive down costs for PC manufacturers. The codecs that will be used for video on BD-ROM discs are MPEG-2, MPEG-4 H.264/AVC Codec and VC-1. The initial movies released on BD-ROM discs will use MPEG-2. This is a decision that has been frowned on and questioned by consumers, as it allows for much less high definition content to be stored per layer. LPCM, Dolby Digital, Dolby Lossless, Dolby Digital Plus, DTS and DTS-HD are the audio codecs supported by Blu-ray.

News History for BD-ROM

Panasonic begins pilot production of 50GB BD-ROM discs
On 6th December 2005, Panasonic gave details on how it has started pilot production of 50GB BD-ROM discs.


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