HD DVD
HD DVD (short for High Density Digital Versatile Disc)[1] is an obsolete[2][3][4][5] high-density optical disc format for storing data and playback of high-definition video.[6] Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format, but lost to Blu-ray, supported by Sony and others.
Media type
High-density optical disc
15 GB (single layer)
30 GB (dual layer)
405 nm laser:
1× @ 36 Mbit/s & 2× @ 72 Mbit/s
405 nm laser:
1× @ 36 Mbit/s & 2× @ 72 Mbit/s
Data storage, 1080p high-definition video
March 31, 2006
March 28, 2008
(1 year, 11 months and 28 days)
HD DVD employed a blue laser with a shorter wavelength (with the exception of the 3× DVD and HD REC variants), and it stored about 3.2 times as much data per layer as its predecessor (maximum capacity: 15 GB per layer compared to 4.7 GB per layer on a DVD). The format was commercially released in 2006 and fought a protracted format war with rival Blu-ray. On February 19, 2008, Toshiba abandoned the format,[7] announcing it would no longer manufacture HD DVD players and drives.[6] The HD DVD Promotion Group was dissolved on March 28, 2008.[8]
The HD DVD physical disc specifications (but not the codecs) were used as the basis for the China Blue High-definition Disc (CBHD) formerly called CH-DVD.
Interactive content[edit]
HD DVDs use Advanced Content to allow interactive content to be authored for discs. Microsoft's implementation of Advanced Content is the HDi Interactive Format, and "HDi" is frequently used to refer to the Advanced Content system. Advanced Content is based on web technologies such as HTML, XML, CSS, SMIL, and ECMAScript (JavaScript), so authoring in Advanced Content should be a fairly easy transition for web developers. No existing DVD authoring experience is required. In comparison, Blu-ray Disc content is authored using either a scripting environment (BDMV) or a Java-based platform (BD-J). DVD video discs use pre-rendered MPEG segments, selectable subtitle pictures, and simple programmatic navigation which is considerably more limited.
Hardware[edit]
Compatibility[edit]
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. 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 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. However, HD DVD discs can't be played on standard DVD players.
Development[edit]
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).[92] No movies had been scheduled for this disc type, and Toshiba had declined to say whether the 51 GB disc was compatible with existing drives and players. Specification 2.0 Part 1 (Physical Specification) for triple layer HD DVD had been approved in November 2007.[93]
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. A major obstacle to implementing this technology in either format (150 GB HD DVD will not be developed due to HD DVD's discontinuation) is that reader-writer technology available may not be able to support the additional data layers.[94]
NEC,[95] Broadcom,[96] Horizon Semiconductors, and STMicroelectronics[96] 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[edit]
HD DVD-R / -RW / -RAM[edit]
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.[97] 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 1× media, and 73 Mbit/s (8.71 MB/s) and a recording time of 28 minutes for 2×.
The Toshiba SD-L902A for notebooks was one of the first available HD DVD writers, although it was not meant for retail.[98][99] Burning HD DVD (including Dual Layer) with a 1× 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,[100] 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.[101]
HD DVD-RW is the rewritable disc variant of HD DVD with equal storage capacity to an 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. The dual-layer variant was never released and the single-layer variant was, but it is among the rarest of optical media.
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. This variant of HD DVD was never released.
DVD / HD DVD hybrid discs[edit]
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.[102] These hybrid discs make retail marketing and shelf space management easier. Another advantage is hardware cross-compatibility. The average consumer does not have to worry about whether or not they can play a hybrid DVD: any standard home DVD player can access the DVD-encoded content and any HD DVD player can access both the DVD- and HD DVD-encoded content.
HD DVD / Blu-ray Disc hybrid discs[edit]
Warner Bros. officially announced Total Hi Def (THD or Total HD) at CES 2007. THD hybrid discs were to support both HD DVD and Blu-ray Disc, with HD DVD on one side (up to two layers) and Blu-ray Disc on the other side (up to two layers). In November 2007, Warner Bros. cancelled THD's development.[103]
3× DVD[edit]
The HD DVD format also applies to current red laser DVDs; this type of disc is called "3× DVD", as it is capable of three times the bandwidth of regular DVD-Video.
3× DVDs are physically identical to normal DVDs. Although 3× DVDs provide the same high definition content, their playback time is less. For example, an 8.5 GB DVD DL can hold about 90 minutes of 1080p video encoded with VC-1 or AVC at an average bitrate of 12 Mbit/s, which corresponds with the average length of Hollywood feature-films. If quality is compromised slightly, and good compression techniques are used, most feature films could be encoded with 3× DVD. Due to its much greater resolution, HD-Video also has significantly more redundant information than DVD which newer compression standards can encode more efficiently.
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.[104] The 3× DVD is comparable to Blu-ray Disc BD5 and BD9 formats.
CBHD[edit]
The China Blue High-definition Disc (CBHD), a high-definition optical disc format, was based upon the HD DVD format. Like the HD DVD, CBHD discs have a capacity of 15 GB single-layer and 30 GB dual-layer and can use existing DVD production lines.