|Media type||High-density optical disc|
|Encoding||VC-1, H.264, and MPEG-2|
|Capacity||15 GB (single layer) |
30 GB (dual layer)
|Read mechanism||1x@36 Mbit/s & 2x@72 Mbit/s|
|Developed by||DVD Forum|
|Usage||Data storage, including high-definition video|
HD DVD or High-Definition Digital Versatile Disc is a high-density optical disc format designed for the storage of data and high-definition video. HD DVD was designed principally by Toshiba, and was envisaged to be the successor to the standard DVD format. However, in February, 2008, Toshiba abandoned the format, announcing it would no longer develop or manufacture HD DVD players.
HD DVD is derived from the same underlying technologies as DVD. Since all variants except the 3x DVD employed a blue laser with a shorter wavelength, it can store about 3¼ times as much data per layer as its predecessor (maximum capacity: 15 GB per layer instead of 4.7 GB per layer).
Much like the VHS vs. Betamax format war during the late 1970s and early 1980s, HD DVD was in a "format war" with rival format Blu-ray Disc to determine which of the two formats would become the leading carrier for high-definition content to consumers. In 2008, major content manufacturers and key retailers began withdrawing their support for the format. Toshiba's withdrawal from the format ended the high definition optical disc format war, effectively making rival Blu-ray the dominant format for high definition video discs. The HD DVD Promotion Group dissolved on March 28.
|Optical disc authoring|
|Optical media types|
Origins and competition from Blu-ray Disc
Sony started two projects applying the new diodes: UDO (Ultra Density Optical) and DVR Blue (together with Pioneer), a format of rewritable discs which would eventually become Blu-ray (more specifically, BD-RE). The core technologies of the formats are essentially similar. The first DVR Blue prototypes were unveiled at the CEATEC exhibition in October 2000. In February 2002, the project was officially announced as Blu-ray, and the Blu-ray Disc Association was founded by the nine initial members.
The DVD Forum (which was chaired by Toshiba) was deeply split over whether to go with the more expensive blue lasers or not. Although today's Blu-ray Discs appear virtually identical to a standard DVD, when the Blu-ray Discs were initially developed they required a protective caddy to avoid mis-handling by the consumer. (Early CD-Rs also featured a protective caddy for the same purpose.) The Blu-ray prototype's caddy was both expensive and physically different from DVD, posing several problems. In March 2002, the forum voted to approve a proposal endorsed by Warner Bros. and other motion picture studios that involved compressing HD content onto dual-layer DVD-9 discs. However, in spite of this decision, the DVD Forum's Steering Committee announced in April that it was pursuing its own blue-laser high-definition solution. In August, Toshiba and NEC announced their competing standard Advanced Optical Disc. It was finally adopted by the DVD forum and renamed to HD DVD the next year, after being voted down twice by Blu-ray Disc Association members, prompting the U.S. Department of Justice to make preliminary investigations into the situation. Three new members had to be invited and the voting rules changed before the vote finally passed.
Attempts to avoid a format war
In an attempt to avoid a costly format war, the Blu-ray Disc Association and DVD Forum attempted to negotiate a compromise in early 2005. One of the issues was that Blu-ray's supporters wanted to use a Java-based platform for interactivity (BD-J based on Sun Microsystem's Java TV standards), while the DVD Forum was promoting Microsoft's "iHD" (which became HDi). A much larger issue, though, was the physical formats of the discs themselves; the Blu-ray Disc Association's member companies did not want to risk losing billions of dollars in royalties as they had done with standard DVD. An agreement seemed close, but negotiations proceeded slowly and ultimately stalled.
On August 22, 2005, the Blu-ray Disc Association and DVD Forum announced that the negotiations to unify their standards had failed. Rumors surfaced that talks had stalled; publicly, the same reasons of physical format incompatibility were cited. In the end of September, Microsoft and Intel jointly announced their support for HD DVD.
Hewlett Packard (HP) made a last ditch attempt to broker a peace between the Blu-ray Disc Association and Microsoft by demanding that Blu-ray association adopt Microsoft's HDi instead of its own Java solution and threatening to support HD DVD instead. However, the Blu-ray Disc group did not accept HP's proposal.
On March 31, 2006, Toshiba released their first consumer-based HD DVD player in Japan at ¥110,000 (US$934), beating Blu-ray to the market by about three months. HD DVD was released in United States on April 18, 2006, with players priced at $499 and $799.
The first HD DVD titles were released on April 18, 2006. They were The Last Samurai, Million Dollar Baby, and The Phantom of the Opera by Warner Home Video and Serenity by Universal Studios. The first independent HD film released on HD DVD was One Six Right.
In the middle of 2007, the first HD DVD Recorders were released in Japan.
In November 2007, the Toshiba HD-A2 was the first high definition player to be sold at a sale price of less than US$100; this was done through several major retailers to make room for the new HD-A3 models. These closeout sales lasted less than a day each due to both limited quantities and high demand at that price point. In the same month, the HD DVD promotion group announced that 750,000 HD DVD players had been sold, which included stand-alone players and the Xbox 360 add-on.
On 4 January 2008 citing consumer confusion and indifference as a reason for lackluster high-definition software sales, Warner Bros. announced they would stop supporting HD DVD by June 2008, and the company would release software only on Blu-ray Disc. This was followed by news of Netflix phasing out support for the format, and Best Buy's decision to recommend Blu-ray Disc over HD DVD in its retail locations. Finally, Wal-Mart announced that they would be supporting only Blu-ray by June 2008. On February 19, 2008, Toshiba announced their decision to discontinue development and marketing of the HD DVD format. The company cited "recent major changes in the market". According to Toshiba, HD DVD Player (playback only) had sold approx. 10,000 sets in Japan and approx. 700,000 worldwide. TV broadcasting program recordable HD DVD recorders sold approx. 20,000 in Japan. HD DVD Drive for PC, add-on for Microsoft Xbox 360 and others is approx. 20,000 in Japan and approx. 300,000 worldwide. Toshiba will continue support by holding spare parts for eight years after sales have stopped. Shipments of HD DVD machines to retailers will be reduced and will stop by the end of March 2008. As of February 2008, Toshiba has announced plans to discontinue development, marketing and manufacturing while still providing product support and after-sale service to consumers of the format. 
HD DVD-R and HD DVD-RW have a single-layer capacity of 15 GB, a dual-layer capacity of 30 GB. HD DVD-RAM has a single-layer capacity of 20 GB. Like the original DVD format, the data layer of an HD DVD disc is 0.6 mm below the surface to physically protect the data layer from damage. The numerical aperture 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.
|Physical size||Single layer capacity||Dual layer capacity|
|12 cm, single sided||15 GB||30 GB|
|12 cm, double sided||30 GB||60 GB|
|8 cm, single sided||4.7 GB||9.4 GB|
|8 cm, double sided||9.4 GB||18.8 GB|
|Drive speed||Data rate||Write time for HD DVD Disc (minutes)|
|Mbit/s||MB/s||Single Layer||Dual Layer|
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. 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 linear (uncompressed) PCM, Dolby Digital AC-3, Dolby Digital EX, DTS, Dolby Digital Plus and Dolby TrueHD. A secondary soundtrack, if present, can be stored in any of the aforementioned formats, or in one of the HD DVD optional codecs: DTS-HD High Resolution Audio 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 TrueHD.
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 MPEG-2 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
If a publisher wishes to restrict use of their HD DVD content, they may use the Advanced Access Content System (AACS) although this is not required for normal disc playback. AACS is 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 Bros., IBM, Toshiba and Sony. One of the advantages over CSS, the content restriction 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 was 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. 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. 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.
- For more details on this topic, see AACS encryption key controversy.
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. Other AACS circumvention programs have become available, like DVDFab HD Decrypter.
Backward compatibility is available with all HD DVD players, allowing users to have a single player 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 a smooth transition for the studios in terms of publishing movies, and allowing consumers with only DVD players to 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.
General purpose computers
HD DVD drives can also be used with a desktop/laptop personal computer (PC) running Windows XP, Windows Vista, Mac OS X v10.5 "Leopard", and many varieties of Linux. Third-party player software for Windows and Linux have successfully played HD DVD titles using the add-on drive. First-party (Apple, Inc.) player software is included with Leopard, making it the first operating system (OS) to ship with native HD DVD playing software, albeit limited to HD DVD disks authored by DVD Studio Pro.
- For more details on this topic, see Xbox 360 HD DVD Player
Released at the end of November 2006, the Microsoft HD DVD drive for the Xbox 360 game-console gives the Xbox 360 the ability to play HD DVD movies. The drive was announced with an MSRP of US$199 and includes a USB 2.0 cable for connection to the console. The first drives also included Peter Jackson's King Kong on HD DVD. The final "regular" for the drive was US$129.99 as of February 25, 2008. On February 23, 2008 Microsoft discontinued the Xbox 360 HD DVD player. On February 26, 2008, Microsoft "officially" announced that the Xbox 360 HD DVD add on drive would reflect a heavily discounted price down to $49.99.
Two manufacturers (LG and Samsung) produced standalone consumer players that could read both HD DVD and Blu-ray discs. Because these allowed the buyer to sidestep the obsolescence of any outcome in the format wars, they were sold at premium prices, and failed to sell in large quantities. Some reviewers also reported that although the drives could read each format, their playback quality was slightly lower than a dedicated player for either.
HD DVD / Blu-ray disc comparison
HD DVD competed primarily with Blu-ray Disc. Both formats were designed as successors to DVD, capable of higher quality video and audio playback, and of greater capacity when used to store video, audio, and computer data. Blu-ray and HD DVD share most of the same methods of encoding media onto disks with each other, resulting in equivalent levels of audio and visual quality, but differ in other respects such as interactive capabilities, Internet integration, usage control and enforcement, and even in the degree to which their specifications are fixed. The storage size also varies: A dual-layer HD DVD holds a maximum of 30 GB of data (although there had been an announcement of a 51 GB version), and a comparable Blu-ray Disc holds a maximum of 50 GB.
Even after finalizing the HD DVD standard, engineers continued developing the technology. A 51 GB triple-layer spec was approved at the DVD Forums 40th Steering Committee Meeting (held on November 15, 2007). However, no movies are currently scheduled for this disc type, and Toshiba has declined to say whether the 51 GB disc is compatible with existing drives and players. Specification 2.0 Part 1 (Physical Specification) for triple layer HD DVD has been approved in November 2007. At the CES 2007, Ritek revealed their high definition optical disc process that extended both competing high definition formats to ten layers, increasing capacity to 150 GB for HD DVD and 250 GB for Blu-ray Disc. However, a major obstacle to implementing this technology is that current reader-writer technology may not support the additional data layers.
NEC, Broadcom, Horizon Semiconductors, and STMicroelectronics have separately developed a single chip/laser that can read both the HD DVD and the Blu-ray disc standard. Broadcom and STMicroelectronics will be selling their dual-format single chip/laser solution to any OEM willing to develop a product based on the chip.
Variants and Media
HD DVD-R / -RW / -RAM
HD DVD-R is the writable disc variant of HD DVD, available with a single-layer capacity of 15 GB or a dual-layer capacity of 30 GB. Write speeds depend on drive speed, with a data rate of 36.55 Mbit/s (4.36 MB/s) and a recording time of 56 minutes for 1x media, and 73 Mbit/s (8.71 MB/s) and a recording time of 28 minutes for 2x.
The Toshiba SD-L902A for notebooks was one of the first available HD DVD writers, although it was not meant for retail. Burning HD DVD (including Dual Layer) with a 1x write speed, it could also burn DVDs and CDs. In a test of the SD-L902A by C't computer magazine with Verbatim discs, the written HD DVD-Rs suffered from high noise levels; as a result, the written discs could not be recognized by the external HD DVD drive of the Xbox 360, though they could be read back by the SD-L902A.
HD DVD-RW is the rewritable disc variant of HD DVD with equal storage capacity to a HD DVD-R. The primary advantage of HD DVD-RW over HD DVD-R is the ability to erase and rewrite to an HD DVD-RW disc, up to about 1,000 times before needing replacement, making them comparable with the CD-RW and DVD-RW standards. This is also of benefit if there are writing errors when recording data, as the disc is not ruined and can still store data by erasing the faulty data.
HD DVD-RAM was the proposed successor to DVD-RAM for random access on optical media using phase-change principals. It would hold 20 gigabytes per layer instead of 15 gigabytes for HD DVD-R, due to differences in recording methods used, yielding a higher density disc. The future of this format is uncertain, given Toshiba's announcement of withdrawal of support for the HD DVD format as a whole.
DVD / HD DVD hybrid discs
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. 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.
HD DVD / Blu-ray hybrid discs
Warner Bros. officially announced Total Hi Def (THD) at CES 2007. Total Hi Def (Total HD) hybrid discs were to support both HD DVD and Blu-ray, with HD DVD on one side (up to two layers) and Blu-ray on the other side (up to two layers). However, in November of 2007, Warner Brothers cancelled development of the Total HD discs.
The HD DVD format also applies to current red laser DVDs; this type of disc is called "3x DVD", as it is capable of three times the bandwidth of regular DVD-Video.
3x DVDs are physically identical to normal DVDs. Although 3x DVDs provide the same high definition content, their playback time is less. For example, an 8.5 GB DVD can hold about 85 minutes of 1080p video encoded with VC-1 or AVC at an average bitrate of 13 Mbit/s, suitable for short subjects (training films, home movies, very short feature films), but unsuitable for most feature film-length content.
It is technically possible for consumers to create HD DVD compatible discs using low cost DVD-R or DVD+R media. At least one such guide exists. The 3x DVD is comparable to Blu-ray BD5 and BD9 formats.
HD Rec is an extension of the HD DVD format for storing HD content on regular red laser DVDs using H.264/MPEG-4 AVC compression. It was approved by the DVD Forum on September 12, 2007 It is comparable to Blu-ray's AVCREC.