HD DVD (short for High Definition 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.
On February 19, 2008, after a protracted format war with rival Blu-ray, 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.
Because all variants except 3× DVD and HD REC employed a blue laser with a shorter wavelength, HD DVD 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).
In the late 1990s, commercial HDTV sets started to enter a larger market, but there was no inexpensive way to record or playback 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 well 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 that 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 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 mishandling 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.
The HD DVD Promotion Group was a group of manufacturers and media studios formed to exchange thoughts and ideas to help promote the format worldwide. Its members comprised Toshiba as the Chair Company and Secretary, Memory-Tech Corporation and NEC as Vice-Chair companies, and Sanyo Electric as Auditors; there were 61 general members and 72 associate members in total. The HD DVD promotion group was officially dissolved on March 28, 2008, following Toshiba's announcement on February 19, 2008, that it would no longer develop or manufacture HD DVD players and drives.