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HD DVD, or '''High-Definition DVD''' is a high-density Optical Disc format designed for the storage of data and High-definition Video . HISTORY The format had previously been called the "Advanced Optical Disc" (AOD). 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 HD DVD-RAM is not yet fully finalized. The first HD DVD-ROM drives were released in late 2006, and the first HD DVD Recorders were released mid 2007 in Japan.3 HD DVD is currently in a Format War with rival format Blu-ray Disc . TECHNICAL SPECIFICATIONS Disc structure HD DVD has a single-layer capacity of 15 of the optical pick-up head is 0.65, compared with 0.6 for DVD. All HD DVD players are backward compatible with DVD and CD. Hybrid formats There are two types of hybrid formats which contain standard DVD-Video format video for playback in regular DVD players, and HD DVD video for playback in high definition on HD DVD players. The Combo disc is a dual sided disc with one side DVD and the other HD DVD, each of which can have up to two layers. The Twin disc is a single sided disc that can have up to three layers, with up to two layers dedicated to either DVD or HD DVD.4 These hybrid discs make retail marketing and shelf space management easier. Another advantage is hardware cross-compatibility. The average consumer doesn't have to worry about whether or not they can play a hybrid DVD disc: any standard home DVD player can access the DVD encoded content and any HD DVD player can access both the DVD and the HD DVD encoded content. 3x DVD The HD DVD format can also be applied to current red laser DVDs which offers a lower-cost option for distributors; this type of disc is called "3x DVD" as it is capable of up to three times the bandwidth of regular DVD-Video . 3x DVDs are physically identical to normal DVDs, which explains why the cost is lower for the physical media. While 3x DVDs provide the same high definition content, the trade off is that playback time is limited. For instance, on an 8.5 GB DVD you could fit about 85 minutes of 1080p video encoded with VC-1 or AVC at an average Bitrate of 13 Mbit/s. This makes the format suitable for subjects such as training videos and home movies, but not suitable for typical wide release studio movies. Ongoing development Although the HD DVD standard has been finalized, engineers continue working to advance the technology. At the . There is no guarantee that the triple-layer format will work in existing players as it was not part of the original mandatory specifications. File systems Like previous optical disc formats, HD DVD supports several File System s, like ISO 9660 and Universal Disk Format (UDF). Currently, all HD DVD titles use UDF version 2.5 as the file system. Audio HD DVD discs support encoding in up to 24-bit/192 kHz for two channels, or up to eight channels of up to 24-bit/96 kHz encoding.8 For reference, even new big-budget Hollywood films are mastered in only 24-bit/48 kHz, with 16-bit/48 kHz being common for ordinary films. All HD DVD players are required to decode and DTS-HD Master Audio . For the highest-fidelity audio experience, HD DVD offers content-producers the choice of linear PCM, Dolby TrueHD and DTS-HD Master Audio. Due to the high-bandwidth requirements of linear-PCM, lossless audio on HD DVD movies has thus far been delivered in the Lossless format Dolby True-HD. Video The HD DVD format supports a wide variety of resolutions, from low-resolution CIF and SDTV , all video resolutions supported by the DVD-Video standard, and up to HDTV formats such as 720p , 1080i and 1080p . HD DVD supports video encoded in MPEG2 which is what is used in DVDs as well as the new formats VC-1 and AVC which are more efficient. All movie titles released so far have had the feature encoded in 1080p, with most supplements in 480i or 480p . Almost all titles are encoded with VC-1 , and most of the remaining titles encoded with AVC . DIGITAL RIGHTS MANAGEMENT See Also: Advanced Access Content System HD DVD content is protected by the Advanced Access Content System ('''AACS''') a standard for Content Distribution and Digital Rights Management . It is developed by '''AACS Licensing Administrator, LLC''' ('''AACS LA'''), a Consortium that includes Disney , Intel , Microsoft , Matsushita (Panasonic), Warner Brothers , IBM , Toshiba and Sony . One of the advantages over CSS , the content protection system for DVDs, is that AACS allows content providers to revoke an individual player device if its cryptographic keys have been compromised (meaning that it will not be able to decrypt subsequently released content). There is no Region Coding in the existing HD DVD specification, which means that titles from any country can be played in players in any other country. This is likely to give the format some advantage in Europe and other places where consumers are now used to using multi-region players to play DVDs purchased in the US or through the extensive grey market. Since appearing in devices in 2006, several successful attacks have been made on the format. The first known attack relied on the Trusted Client problem. In addition, decryption keys have been extracted from a weakly protected player ( WinDVD ). Notably, a ''Processing Key'' was found that could be used to decrypt all HD content that had been released at the time.10 The processing key was widely published on the Internet after it was found and the AACS LA sent multiple DMCA Takedown notices in the aim of censoring it.11 This caused trouble on some sites that rely on user-submitted content, like Digg and Wikipedia , when administrators tried to remove any mentions of the key.1213 AACS has also been circumvented by SlySoft with their program AnyDVD HD, which allows users to watch HD DVD movies on non- HDCP -compliant PC hardware. Slysoft has stated that AnyDVD HD uses several different mechanisms to disable the encryption, and is not dependent on the use of a single compromised encryption key.14 INTERACTIVE CONTENT HD DVDs use the HDi Interactive Format to allow interactive content to be authored for discs. HDi is based on web technologies such as HTML , XML , CSS , SMIL , and ECMAScript ( JavaScript ), so authoring in HDi should be a fairly easy transition for web developers. No existing DVD authoring experience is required. In contrast, Blu-ray Disc content is authored using either a scripting environment for basic content, or a Java-based platform ( BD-J ) for advanced content. DVD video discs utilize pre-rendered MPEG segments, selectable subtitle pictures, and simple programmatic navigation which is considerably more primitive. HARDWARE Compatibility Backward Compatibility will be available with all HD DVD players, allowing users to have a single player in their homes to play all types of HD DVD, DVD and CD discs. There is also a hybrid HD DVD format 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 movies, and letting consumers with only DVD drives still use the 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. HD DVD standalone players On 31 March 2006 , Toshiba released their first HD DVD player in Japan at ¥110,000 ( US$ 934).15 HD DVD was released in United States on 18 April 2006 ,16 with players priced at $499 and $799. On April 18 2006 , Toshiba released the first HD DVD players for the United States, the Toshiba HD-A1 and Toshiba HD-XA1 . Both players sold out within days of their release. The HD-A1 was also Rebranded by RCA and sold as the HDV5000. |
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