HD DVD

HD DVD or High-Definition/Density Digital Versatile Disc is an obsolete high-density optical disc format for storing data and high-definition video.^[1] 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 or drives^[1].

Jump to: navigation, search

HD DVD

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	1× @ 36 Mbit/s & 2× @ 72 Mbit/s
Developed by	DVD Forum
Usage	Data storage, including high-definition video

HD DVD is derived from the same underlying technologies as DVD. Since all variants except the 3× 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 Disc the dominant format for high definition video discs.^[2] The HD DVD Promotion Group was dissolved on 28 March 2008.

Disc structure

HD DVD-ROM has a single-layer capacity of 15 GB, and a dual-layer capacity of 30 GB.

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.^[47] Like the original DVD format, the data layer of an HD DVD 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.^[48]

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

Recording speed

Drive speed	Data rate		Write time for HD DVD Disc (minutes)
	Mbit/s	MB/s	Single Layer	Dual Layer
1×	36	4.5	56	110
2×	72	9	28	55

Audio

HD DVDs 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.^[49] 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.^{[citation needed]}

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.^[50] 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.

Video

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.^[49] HD DVD