1. Technical details
    Capacity/codecs  Interactivity  Disc construction  Hybrid discs  Copy protection  Region coding 

2. References

This article compares the technical specifications of multiple high definition formats, including HD DVD and Blu-ray Disc; two mutually incompatible, high definition optical disc formats that, beginning in 2006, attempted to improve upon and eventually replace the DVD standard. The two formats remained in a format war until February 19, 2008 when Toshiba, HD DVD's creator, announced plans to cease development, manufacturing and marketing of HD DVD players and recorders.^[1]

Other high-definition optical disc formats were attempted, including the multi-layered red-laser Versatile Multilayer Disc and a Chinese made format called EVD. Both appear to have been abandoned {{Citation needed|date=March 2010}}by their respective developers.

Technical details

Mandatory codecs must be supported by the player. Each disc must use one or more of the mandatory codecs.

Capacity/codecs

Blu-ray Disc has a higher maximum disc capacity than HD DVD (50 GB vs. 30 GB for a double layered disc). In September 2007 the DVD Forum approved a preliminary specification for the triple-layer 51GB HD DVD (ROM only) disc though Toshiba never stated whether it was compatible with existing HD DVD players. In September 2006 TDK announced a prototype Blu-ray Disc with a capacity of 200GB.^[6] TDK was also the first to develop a Blu-ray prototype with a capacity of 100GB in May 2005.^[7] In October 2007 Hitachi developed a Blu-ray prototype with a capacity of 100GB. Hitachi has stated that current Blu-ray drives would only require a few firmware updates in order to play the disc.^[8]

The first 50 GB dual-layer Blu-ray Disc release was the movie Click, which was released on October 10, 2006. As of July 2008, over 95% of Blu-ray movies/games are published on 50 GB dual layer discs with the remainder on 25 GB discs.^[9] 85% of HD DVD movies are published on 30 GB dual layer discs, with the remainder on 15 GB discs.^[10][11]

The choice of video compression technology (codec) complicates any comparison of the formats. Blu-ray Disc and HD DVD both support the same three video compression standards: MPEG-2, VC-1 and AVC, each of which exhibits different bitrate/noise-ratio curves, visual impairments/artifacts, and encoder maturity. Initial Blu-ray Disc titles often used MPEG-2 video, which requires the highest average bitrate and thus the most space, to match the picture quality of the other two video codecs. As of July 2008 over 70% of Blu-ray Disc titles have been authored with the newer compression standards: AVC and VC-1.^[5] HD DVD titles have used VC-1 and AVC almost exclusively since the format's introduction. Warner Bros., which used to release movies in both formats prior to June 1, 2007, often used the same encode (with VC-1 codec) for both Blu-ray Disc and HD DVD, with identical results. In contrast, Paramount used different encodings: initially MPEG-2 for early Blu-ray Disc releases, VC-1 for early HD DVD releases, and eventually AVC for both formats.

Whilst the two formats support similar audio codecs, their usage varies. Most titles released on the Blu-ray format include Dolby Digital tracks for each language in the region, a DTS-HD Master Audio track for all 20th Century Fox and Sony Pictures and many upcoming Universal titles, Dolby TrueHD for Disney and Sony Pictures and some Paramount and Warner titles, and for many Blu-ray titles a Linear PCM track for the primary language.^[5] On the other hand, most titles released on the HD DVD format include Dolby Digital Plus tracks for each language in the region, and some also include a Dolby TrueHD track for the primary language.

Interactivity

Both Blu-ray Disc and HD DVD have two main options for interactivity (on-screen menus, bonus features, etc.).

HD DVD's Standard Content is a minor change from standard DVD's subpicture technology, while Blu-ray's BDMV is completely new. This makes transitioning from standard DVD to Standard Content HD DVD relatively simple {{Citation needed|date=December 2007}}—for example, Apple's DVD Studio Pro has supported authoring Standard Content since version 4.0.3. {{Citation needed|date=December 2007}} For more advanced interactivity Blu-ray disc supports BD-J while HD DVD supports Advanced Content.

Disc construction

Blu-ray Discs contain their data relatively close to the surface (less than 0.1 mm) which combined with the smaller spot size presents a problem when the surface is scratched as data would be destroyed. To overcome this, TDK, Sony, and Panasonic each have developed a proprietary scratch resistant surface coating. TDK trademarked theirs as Durabis, which has withstood direct abrasion by steel wool and marring with markers in tests.^[12]

HD DVD uses traditional material and has the same scratch and surface characteristics of a regular DVD. The data is at the same depth (0.6 mm) as DVD as to minimize damage from scratching. As with DVD the construction of the HD DVD allows for a second side of either HD DVD or DVD.

A study performed by Home Media Magazine (August 5, 2007) concluded that HD DVDs and Blu-ray discs are essentially equal in production cost. Quotes from several disc manufacturers for 25,000 units of HD DVDs and Blu-rays revealed a price differential of only 5-10 cents. (Lowest price: 90 cents versus 100 cents. Highest price: $1.45 versus $1.50.)^[13] Another study performed by Wesley Tech (February 9, 2007) arrived at a similar conclusion. Quotes for 10,000 discs show that a 15 gigabyte HD DVD costs $11,500 total, and 25 gigabyte Blu-ray or a 30 gigabyte HD DVD costs $13,000 total.^[14] For larger quantities of 100,000 units, the 30 gigabyte HD DVD was more expensive than the 25 gigabyte Blu-ray ($1.55 versus $1.49).^[15]

Hybrid discs

At the Consumer Electronics Show, on {{start date and age|2007|1|4|df=y|paren=y}}, Warner Bros. introduced a hybrid technology, Total HD, which would reportedly support both formats on a single disc. The new discs were to overlay the Blu-ray and HD DVD layers, placing them respectively {{convert|0.1|mm|um}} and {{convert|0.5|mm|um}} beneath the surface. The Blu-ray top layer would act as a two-way mirror, reflecting just enough light for a Blu-ray reader to read and an HD DVD player to ignore.^[16]

Later that year, however, in September 2007, Warner President Ron Sanders said that the technology was on hold due to Warner being the only company who would publish on it.^[17]

One year after the original announcement, on 4 January 2008, Warner Bros. stated that it would support the Blu-ray format exclusively beginning on 1 June 2008, which, along with the demise of HD DVD the following month, ended development of hybrid discs permanently.{{fact|date=July 2018}}

Copy protection

The primary copy protection system used on both formats is the Advanced Access Content System (AACS). Other copy protection systems include:

• HDCP encrypted digital output
• ROM-Mark watermarking technology (physical layer)
• BD dynamic crypto (BD+)
• Cinavia Digital Mark

• HDCP encrypted digital output

Region coding

The Blu-ray specification and all currently available players support region coding. As of July 2008 about 66.7% of Blu-ray Disc titles are region-free and 33.3% use region codes.^[5]

The HD DVD specification had no region coding, so a HD DVD from anywhere in the world will work in any player. The DVD Forum's steering committee discussed a request from Disney to add it, but many of the 20 companies on the committee actively opposed it.^[18]

Some film titles that were exclusive to Blu-ray in the United States such as Sony's xXx, Fox's Rise of the Silver Surfer and The Prestige, were released on HD DVD in other countries due to different distribution agreements; for example, The Prestige was released outside the U.S. by once format-neutral studio Warner Bros. Pictures. Since HD DVDs had no region coding, there are no restrictions playing foreign-bought HD DVDs in an HD DVD player.^[19]

References

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