HD DVD

(High Definition DVD) A relatively short-lived high-capacity optical disc that holds four hours of high-definition video on a single-sided, single-layer 15GB disk. Sanctioned by the DVD Forum in 2003 and based on the Advanced Optical Disc (AOD) technology from Toshiba and NEC, HD DVD used a blue-violet laser that read pits half the size of a DVD on tracks that were packed tighter together. HD DVD supported the more advanced H.264 and VC-1 video encoding algorithms (codecs) as well as MPEG-2, which is used for DVD. It also supported 1080p, the highest HDTV resolution. See H.264 and VC-1.

A distinct advantage of HD DVD for the media manufacturer was that HD DVDs were an evolution of the standard DVD. Unlike the competing Blu-ray format, which requires new machinery to make the disks, traditional DVD stamping machines needed only minor modifications to make HD DVDs.

The first HD DVD drives were introduced in the U.S. in 2006, and Microsoft offered an HD DVD drive option for its Xbox 360 video game console in that same year. Despite all its features and initial support, however, in 2008, the majority of movie studios and retail outlets chose Blu-ray over HD DVD, and the "format war" was over.

HD DVD-ROM, HD DVD-R and HD DVD-RW
Like CD, DVD and Blu-ray media, there were read-only, write-once and rewritable options. Used for HD movies, HD DVD-ROMs were pre-recorded discs that could not be changed. HD DVD-R media could be "burned" once by the user, and HD DVD-RW disks could be rewritten over and over.

HD DVD Hybrids
Hybrid HD DVD disks were read-only media that stored a movie in both HD DVD and standard DVD. There were two types: combination hybrids used both sides, each side containing a different format, and Twin Format hybrids used only one side of a dual or triple layer disk, storing the different formats in separate layers.

In late 2006, Warner Home Video announced a hybrid disc that held HD DVD and Blu-ray on one side and DVD on the other. In 2007, LG introduced the Super Blu, the first dual-format player, supporting both HD DVD and Blu-ray media. However, the multiple choices confused buyers, and adoption of both HD formats was sluggish, even with reduced player prices. See high-def DVD formats, Blu-Ray, DVD and DTV. See also HD DVR.

   FULL-SIZE HD DVD DISK (120 mm) CAPACITIES

            SINGLE SIDED     DOUBLE SIDED

                     HD                 HD
   Layers   Storage  Hours     Storage  Hours

   Single    15GB     4

   Dual      30GB     8         38.5GB   8HD/4SD

   Triple    51GB    14