HD DVD

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Image:HD-DVD.svg HD DVD (High Density Digital Versatile Disc or High Definition Digital Video 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-size (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, HP [1], and Intel. HD DVD may be non-exclusively backed by three major studios: Paramount Pictures, Universal Studios and Warner Bros. Toshiba announced the first sales of HD DVD players set for March 2006 with models priced at $499 and $799, though studios are not planning movie releases until April. [2] At CES 2006, Microsoft announced that there will be an external add-on HD DVD drive for the Xbox 360 game console, due sometime this year.

At the Las Vegas CES 2006, "companies backing HD DVD said that nearly 200 titles would be available for the format by the end of the year." [3] On March 31, 2006, Toshiba released their first HD DVD player in Japan at ¥110,000 ($934) [4] HD DVD was released in United States on April 18, 2006.[5]

1 Overview
2 History
3 Common disc structure
4 The blue laser
5 Copy restriction technology
6 Interactive content
7 First released movies
8 First released players
9 See also
10 External links
- 10.1 News

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Overview

HD DVD has a single layer capacity of 15 GB and a dual-layer capacity of 30 GB. Toshiba has announced that a triple-layer disc is in development, which would offer 45GB of storage. This is less than its primary competitor Blu-ray Disc, which supports 25GB for one layer, 50GB for two layers as presently released. BD 100GB for four, 200GB for eight layers have been demonstrated in a laboratory but have not yet been released to the market. HD DVD proponents point out that multi-layer Blu-ray discs are still in development. The surface layer of an HD DVD disc is 0.6 mm thick, the same as DVD but 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. Both formats will be backwards compatible with DVDs and both employ the same video compression techniques: MPEG-2, Video Codec 1 (VC1, based on the Windows Media 9 format) and H.264/MPEG-4 AVC.

Physical size	Single layer capacity	Dual layer capacity
12 cm	15 GB	30 GB

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History

On November 19, 2003, the DVD Forum decided with a seven-to-eight vote 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" (AOD). Blu-ray Disc was developed outside of the DVD Forum, and was never submitted to the forum for consideration. This is however a not very surprising extension of the previous DVD-R/RW versus DVD+R/RW war, where - (dash) was the format defended by DVD Forum, and + (plus) the format defended by the [[DVD+RW Alliance]]. The DVD Forum generally has focus on CE (Consumer Electronic) and Japanese market development (where CE happens to be very strong). The [[DVD+RW Alliance]] has invested more on the PC market with technologies such as Background Formatting and defect management through "Mount Rainier" (unreleased).

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. The actual product launch of both CE and PC units occurred in 2006.

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Common disc structure

There are many advantages to the fact that HD DVD discs will be the same size as current DVD discs. Backward compatibility will be available with all HD DVD players allowing consumers to only require a single player in their homes to play both HD DVD and DVD discs. DVD disc replication companies can continue using their current production equipment with only minor alterations when changing over to the format of HD DVD replication. Due to the structure of the single-lens optical head, both red and blue laser diodes can be used in smaller, more compact HD DVD players. Additionally there is hybrid HD DVD which contains both DVD and HD DVD versions of the same movie on a single disc, providing smoother transition for the studios in terms of publishing the movies.

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The blue laser

HD DVD uses a blue-violet 405 nm laser to read information from the disc (DVDs use red 650 nm lasers).

Image:CD DVD BD HDDVD.gif

The shorter wavelength reduces diffraction and maintains a smaller spot size of the laser. This allows data to be read from a higher density on the disc surface. While DVDs and HD DVDs will be the same size physically, the ability to store data at a higher density results in a larger total data capacity in HD.

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Copy restriction technology

Commercialized HD DVDs will integrate copy restriction technology that is expected to be developed by AACS LA (Advanced Access Content System License Administrator). "Audio Watermark Protection" is also being created for use on HD DVD. All HD DVD players will have a sensor that listens for inaudible watermarks in the soundtrack of movies, and will be included in the soundtracks of all major movies. If a DVD player detects the code, the disc must be a copy made by copying a film to video, or using a camcorder and microphone on a cinema screen and will cause the player to refuse to play the disc. The mark is made by varying the waveform of speech and music in a regular pattern to convey a digital code. These variations, while being too subtle to be heard by the human ear, can easily be neutralized by the HD DVD players as well as by audio editing software. Another variation of this system can be used to prevent the playback of discs created by using a camcorder and microphone on a home entertainment center playing a legitimate disc purchased by a consumer. This variation for home entertainment utilizes a watermark that differs from the cinema mark that the player will be able to use to check whether the disc is authorized or not.

Manufacturers have also discussed plans to make players accessible for online monitoring like a digital cable box; any attempt to crack a machine, play a cracked disc, or another region's disc would disable the machine.

In addition, HD DVD players must follow AACS guidelines pertaining to outputs over non-encrypted interfaces. This is set by a flag called the Image Constraint Token (ICT), which restricts the resolution for outputs without HDCP to 960×540. The decision to set the flag to restrict output ("down-convert") is left to the content provider. Warner Pictures is a proponent of ICT, and it is expected that Paramount and Universal will implement down-conversion as well [6]. As of March 2006, 5 of the 6 studios releasing HD DVD content have announced they will not use ICT/down-conversion for the time being [7]. AACS guidelines require that any title that implements the ICT must clearly state so on the packaging.

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Interactive content

HD DVDs will use the iHD Interactive Format to allow interactive content to be authored for discs. In contrast, Blu-ray makes use of Java technology for its interactive content.

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