WireItRight
home theatre installation and pre-wire services
What is HDTV?
High-definition television (HDTV)
Advantages of HDTV
Recording and compression
Blu-Ray
HD DVD
Dolby
What is
HD DVD ?
The HD DVD disc is designed to be the successor to the standard DVD format. It can store about three times as much data as its predecessor (15 GB per layer instead of 4.7 GB). The HD DVD standard was jointly developed by Toshiba and NEC.[2] On 19 November 2003, the DVD Forum voted to support HD DVD as the high definition successor of the standard DVD. At this meeting, they also renamed it HD DVD. HD DVD stands for "High Definition Digital Versatile Disc".[1] The format had previously been called the "Advanced Optical Disc" (AOD).
At CES[2] 2006, companies backing HD DVD said that nearly 200 titles would be available for the format by the end of the year.
On 31 March 2006, Toshiba released their first HD DVD player in Japan at ¥110,000 ($934).[3] HD DVD was released in United States on 18 April 2006,[4] with players priced at $499 and $799.
In November 2006 Microsoft released an external add-on HD DVD drive for the Xbox 360 game console which was previously announced at CES 2006.
The current specification version for HD DVD-ROM and HD DVD-Rewritable is version 1.0. The specification for HD DVD-R is currently at 0.9, the HD DVD-RAM is not yet fully finalized. The first HD DVD-ROM drives were released in late 2006.
HD DVD is currently in a format war with rival format Blu-ray Disc.
Technical specifications
Disc structure
HD DVD has a single-layer capacity of 15 GB and a dual-layer capacity of 30 GB, the HD DVD-RAM has a single-layer capacity of 20 GB and a dual-layer capacity of 40 GB. Like the original DVD format, the data layer of an HD DVD disc is 0.6 mm below the surface physically protecting 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.
Audio
HD DVD discs 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.[9] 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.[10] 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 True-HD.
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.[9] HD DVD supports video encoded in MPEG2 which is what is used in DVDs as well as the new formats VC-1 and AVC which are more efficient. All movie titles released so far have had the feature encoded in 1080p, with most supplements in 480i or 480p. Almost all titles are encoded with VC-1, and most of the remaining titles encoded with AVC.
HD DVD / Blu-ray disc comparison
Main article: Comparison of high definition optical disc formats
The primary rival to HD DVD is Blu-ray, championed by Sony. Blu-ray has a higher disc capacity per layer (25 GB vs 15 GB). However the majority of Blu-ray titles released before 2007 are in the 25 GB single layer format while almost all HD DVD movies are in the 30 GB dual layer format. [47] The first 50GB release for Blu-Ray was not made until November 2006. So far in 2007 approx half of the new releases for Blu-ray movies were released in 25GB Discs with the other half being released in 50GB dual layer format.[48]
In terms of audio/video compression, HD DVD and Blu-ray are similar on the surface: both support MPEG-2, VC-1, and H.264 for video compression. Virtually every HD DVD released uses an advanced codec (VC-1 or H.264) for video compression, reducing the required space for equivalent quality video. The first generation of Blu-ray Disc movies however used the legacy video codec MPEG-2, and many new titles still do. In terms of audio, there are many differences. With HD DVD support for the new Dolby Digital Plus audio codec is mandatory at a maximum of 3.0 Mbit/s, but for Blu-ray players it is optional at a maximum of 1.7 Mbit/s.[10] Furthermore HD DVD players must be able to decode the new lossless audio codec Dolby True HD, but this is optional for Blu-ray players.
Both HD DVD and Blu-ray Disc support the 24p (traditional movie) frame rate, but technical implementations of this mode are different among the two formats. Blu-ray Disc supports 24p with its native timing, while HD DVD uses 60i timing for 24p (encoded progressively, replacing missing fields with "repeat field flags"). Decoders can ignore the “flags” to output 24p.[49] There is no impact on picture resolution or storage space as a result of this, as the HD DVD format uses the exact same video information — it simply adds notational overhead
