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HD DVD
HD DVD (short for High Density Digital Versatile Disc) is an obsolete high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format, but lost out to Blu-ray, which was supported by Sony and others.
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 its rival, the Blu-ray Disc. Compared to the Blu-ray Disc, the HD DVD was released earlier by a quarter year, featured a lower capacity per layer (compared to 25 GB of Blu-ray), but saved manufacturing costs by allowing existing DVD manufacturing equipment to be repurposed with minimal modifications, and movie playback was not restricted through region codes.
On February 19, 2008, Toshiba abandoned the format, announcing it would no longer manufacture HD DVD players and drives. The HD DVD Promotion Group was dissolved on March 28, 2008.
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.
Besides recordable and rewritable variants, a HD DVD-RAM variant was proposed as the successor to the DVD-RAM and specifications for it were developed, but the format never reached the market.
In the late 1990s, commercial HDTV sets started to enter a larger market, but there was no inexpensive way to record or play back HD content. JVC's D-VHS and Sony's HDCAM formats could store that amount of data, but were neither popular nor well-known. It was known that using lasers with shorter wavelengths would yield optical storage with higher density. Shuji Nakamura invented practical blue laser diodes, but a lengthy patent lawsuit delayed commercial introduction.
Sony started two projects applying the new diodes: UDO (Ultra Density Optical) and DVR Blue together with Philips, a format of rewritable discs which would eventually become Blu-ray Disc (more specifically, BD-RE) and later on with Pioneer a format of read only discs (BD-ROM). The two formats share several technologies (such as the AV codecs and the laser diode). In February 2002, the project was officially announced as Blu-ray Disc, and the Blu-ray Disc Association was founded by the nine initial members.
The DVD Forum (chaired by Sony) was deeply split over whether or not to go with the more expensive blue lasers. 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 Disc 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. 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 adopted by the DVD forum and renamed to HD DVD the next year.
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HD DVD
HD DVD (short for High Density Digital Versatile Disc) is an obsolete high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format, but lost out to Blu-ray, which was supported by Sony and others.
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 its rival, the Blu-ray Disc. Compared to the Blu-ray Disc, the HD DVD was released earlier by a quarter year, featured a lower capacity per layer (compared to 25 GB of Blu-ray), but saved manufacturing costs by allowing existing DVD manufacturing equipment to be repurposed with minimal modifications, and movie playback was not restricted through region codes.
On February 19, 2008, Toshiba abandoned the format, announcing it would no longer manufacture HD DVD players and drives. The HD DVD Promotion Group was dissolved on March 28, 2008.
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.
Besides recordable and rewritable variants, a HD DVD-RAM variant was proposed as the successor to the DVD-RAM and specifications for it were developed, but the format never reached the market.
In the late 1990s, commercial HDTV sets started to enter a larger market, but there was no inexpensive way to record or play back HD content. JVC's D-VHS and Sony's HDCAM formats could store that amount of data, but were neither popular nor well-known. It was known that using lasers with shorter wavelengths would yield optical storage with higher density. Shuji Nakamura invented practical blue laser diodes, but a lengthy patent lawsuit delayed commercial introduction.
Sony started two projects applying the new diodes: UDO (Ultra Density Optical) and DVR Blue together with Philips, a format of rewritable discs which would eventually become Blu-ray Disc (more specifically, BD-RE) and later on with Pioneer a format of read only discs (BD-ROM). The two formats share several technologies (such as the AV codecs and the laser diode). In February 2002, the project was officially announced as Blu-ray Disc, and the Blu-ray Disc Association was founded by the nine initial members.
The DVD Forum (chaired by Sony) was deeply split over whether or not to go with the more expensive blue lasers. 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 Disc 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. 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 adopted by the DVD forum and renamed to HD DVD the next year.