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What is HD DVD?
HD DVD (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, Sanyo, and most recently Microsoft, Intel, and is backed by four major studios: New Line Cinema, Paramount Pictures, Universal Studios and Warner Bros.


With the demand for high-definition TVs taking off consumers increasingly expect greater realism and better image quality in visual entertainment. The goal of HD DVD is to deliver that realism via DVD. According to HD DVD supporters it is the future, a new standard for next-generation optical systems that delivers brilliant, high-definition performance.

How it all started:

he DVD Forum develops and defines DVD formats. Its 230-strong membership brings together companies from all over the world, leaders in movies and entertainment, computing, consumer electronics and software. In November 2003, the DVD Forum selected a single technology as the next-generation, post-DVD standard for high capacity, high definition optical discs— HD DVD. Now, HD DVD is poised to become the primary visual medium for the age of high-definition TV.

Features of HD DVD:

HD DVD delivers all the capacity necessary for all sorts of recorded content, including movies and live performances. There are two kinds of single-sided HD DVD discs for content playback: the 15GB single-layer disc, and the dual-layer disc with double the capacity, 30GB. By using the latest compression technologies, the 15GB disc can hold a complete movie and tons of bonus content: extra/deleted original scenes, actor and director interviews.

The DVD Forum has defined the standard for a single-sided, single-layer HD DVD-Rewritable disc with 20GB capacity that can accommodate about 5.5 hours of HD content. And look for more capacity in the forthcoming single-sided, dual-layer disc.

The shared disc structure of HD DVD and DVD offers numerous advantages to consumers and manufacturers alike. Full backward compatibility allows consumers to enjoy their current DVD library and crystal-clear HD video on the same HD DVD player.

DVD and HD DVD share the same basic disc structure: back-to-back bonding of two 120mm diameter substrates, each 0.6mm thick. As a result, HD DVD combines advanced capabilities with essential backward compatibility. The HD DVD standard clearly promotes early and cost efficient disc and hardware production, and assures quality, availability, and marketability.

HD DVD and DVD specification
Disc type DVD-ROM (Read-Only) HD DVD-ROM (Read-Only) HD DVD-R (Recordable) HD DVD-Rewritable (Recordable)
Disc diameter 120mm 120mm 120mm 120mm
Disc structure 0.6mm x 2 substrates 0.6mm x 2 substrates 0.6mm x 2 substrates 0.6mm x 2 substrates
Capacity (Single-sided, single-layer) (Single-sided, dual-layer) 4.7GB 8.5GB 15GB 30GB 15GB 20GB 32GB (Under development)
Playback time* Recording time* 4.7GB, SD resolution: 132minutes 8.5GB, SD resolution: 238minutes 15GB, HD resolution: over 4 hours 30GB, HD resolution: over 8 hours 15GB, HD resolution: over 4 hours 20GB, HD resolution: over 5.5 hours 32GB, HD resolution: over 8.5 hours
Laser Wavelength 650nm (red laser) 405nm (blue laser) 405nm (blue laser) 405nm (blue laser)
Compression technology MPEG-2 MPEG-4 AVC/ VC-1/MPEG-2 MPEG-4 AVC/ VC-1/MPEG-2 MPEG-4 AVC/ VC-1/MPEG-2
User bit rate 11.08Mbps 36.55Mbps 36.55Mbps 36.55Mbps

The blue laser that reads and writes to HD DVD has a shorter wavelength than DVD's red laser. Even though DVD and HD DVD share the same disc structure, the blue laser's shorter wavelength translates into an HD DVD storage capacity dwarfing that of DVD. Single-sided, single-layer DVDs can hold 4.7GB of data. The single-sided dual-layer HD DVD-ROM surpasses that 6.2 times with its 30GB capacity.

With a transfer rate of 36.55Mbps, HD DVD disc drives outperform the 24Mbps maximum transfer rate of digital TV broadcasts. As a result, high-definition images can be recorded and played back, for many hours of viewing pleasure.
2008 - 04 -24