Science Fair Project Encyclopedia
HD-DVD
HD-DVD (for High-Density Digital Versatile Disc) is a digital optical media format which is being developed as one standard for high-definition DVD. HD-DVD is similar to the competing Blu-ray Disc, which also uses the same CD sized (120 mm diameter) optical data storage media and 405 nm wavelength blue laser. HD-DVD is promoted by Toshiba, NEC, and Sanyo, and backed by four major film studios. It is currently engaged in a format war with the Blu-ray Disc proposed by Sony.
HD-DVD has a capacity of 15 GB (for dual-layer HD-DVD capacity would be 30 GB). The surface layer is 0.6 mm thick, the same as for DVD and much thicker than the Blu-ray Disc's 0.1 mm layer. The numerical aperture of the optical pick-up head is 0.65, compared with 0.6 for DVD. These factors mean that HD-DVD media is less expensive to manufacture than Blu-ray discs which require re-tooling of DVD disc production lines. Existing DVD media are playable on HD-DVD drives with only minor modification of the optical pickup. Blu-ray Disc players however, are now also expected to include backward compatibility with DVDs. The two formats employ nearly identical video compression techniques, including MPEG-2, Video Codec 1 (VC1, based on the Windows Media 9 format) and H.264/MPEG-4 AVC.
On November 19, 2003, the DVD Forum decided with eight to six votes, that the HD-DVD will be the HDTV successor of the DVD. At this meeting they renamed it to HD-DVD, while it had been previously called the "Advanced Optical Disc". Blu-ray Disc was never submitted to the DVD Forum for consideration.
The current specification version for HD-DVD-ROM and HD-DVD-Rewritable is version 1.0. The specification for HD-DVD-R is currently at 0.9. The first HD DVD-ROM drives were expected to be unveiled by Q4 2004, with mass production to start in Q1 2005.
In April 2005, Apple Computer updated its version of DVD Studio Pro to support authoring HD content. DVD Studio Pro allows for the burning of HD-DVD content to both standard DVD's and HD-DVD media (even though no burners are available). For playing back HD-DVDs burnt onto a standard DVD, Apple requires a PowerPC G5, Apple DVD Player v4.6, and Mac OS X v10.4 or later.
Supporting film studios
See also
- Blu-ray Disc
- Enhanced Versatile Disc
- Versatile Multilayer Disc
- Digital Multilayer Disk
- Holographic Versatile Disc - a proposed next generation disc after HD-DVD and Blu-ray
External link
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