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]
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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] by their respective developers.
.mw-parser-output .citationword-wrap:break-word.mw-parser-output .citation:targetbackground-color:rgba(0,127,255,0.133)^ a These maximum storage capacities apply to currently released media as of January 2012. First two layers of Blu-ray have a 25 GB capacity, but the triple layer disc adds a further 50 GB making 100 GB total. The fourth layer adds a further 28 GB. ^ b All HD DVD players are required to decode the two primary channels (left and right) of any Dolby TrueHD track;[4][5] however, every Toshiba made stand-alone HD DVD player released thus far decodes 5.1 channels of TrueHD.^ c On November 1, 2007 Secondary video and audio decoder became mandatory for new Blu-ray Disc players when the Bonus View requirement came into effect. However, players introduced to the market before this date can continue to be sold without Bonus View.^ d There are some differences in the implementation of Dolby Digital Plus (DD+) on the two formats. On Blu-ray Disc, DD+ can only be used to extend a primary Dolby Digital (DD) 5.1 audiotrack. In this method 640 kbit/s is allocated to the primary DD 5.1 audiotrack (which is independently playable on players that do not support DD+), and up to 1 Mbit/s is allocated for the DD+ extension. The DD+ extension is used to replace the rear channels of the DD track with higher fidelity versions, along with adding additional channels for 6.1/7.1 audiotracks. On HD DVD, DD+ is used to encode all channels (up to 7.1), and no legacy DD track is required since all HD DVD players are required to decode DD+.^ e On PAL DVDs, 24 frame per second content is stored as 50 interlaced frames per second and gets replayed 4% faster. This process can be reversed to retrieve the original 24 frame per second content. On NTSC DVDs, 24 frame per second content is stored as 60 interlaced frames per second using a process called 3:2 pulldown, which if done properly can also be reversed.^ f As of July 2008, about 66.7% of Blu-ray discs are region free and 33.3% use region codes.[6]^ g DVD supports any valid MPEG-2 refresh rate as long as it is packaged with metadata converting it to 576i50 or 480i60, This metadata takes the form of REPEAT_FIRST_FIELD instructions embedded in the MPEG-2 stream itself, and is a part of the MPEG-2 standard. HD DVD is the only high-def disc format that can decode 1080p25 while Blu-ray and HD DVD can both decode 1080p24 and 1080p30. 1080p25 content can only be presented on Blu-ray as 1080i50.^ h Linear PCM is the only lossless audio codec that is mandatory for both HD DVD and Blu-ray disc players, only HD DVD players are required to decode two lossless sound formats and those are Linear PCM and Dolby TrueHD. Dolby TrueHD and DTS-HD Master Audio have become sound format of choice for many studios on their Blu-ray titles but ever since Blu-ray won the format war, it has not become clear if they are now Mandatory for all new Blu-ray disc players since the end of the format war.
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.[6] 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.[6] 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.
At the Consumer Electronics Show, on 4 January 2007, 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 0.1 millimetres (100 μm) and 0.5 millimetres (500 μm) 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.[18]
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.[citation needed]
Some film titles that were exclusive to Blu-ray in the United States such as Sony's xXx, Fox's Fantastic Four: 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.[21]
The Blu-ray Disc (BD), often known simply as Blu-ray, is a digital optical disc data storage format. It was invented and developed in 2005 and released on June 20, 2006 worldwide. It is designed to supersede the DVD format, and capable of storing several hours of high-definition video (HDTV 720p and 1080p). The main application of Blu-ray is as a medium for video material such as feature films and for the physical distribution of video games for the PlayStation 3, PlayStation 4, PlayStation 5, Xbox One, and Xbox Series X. The name "Blu-ray" refers to the blue laser (which is actually a violet laser) used to read the disc, which allows information to be stored at a greater density than is possible with the longer-wavelength red laser used for DVDs.
High-definition (HD) video may be stored on Blu-ray Discs with up to 19201080 pixel resolution, at 24& 50/60 progressive or 50/60 interlaced frames per second. DVD discs were limited to a maximum resolution of 480 (NTSC, 720480 pixels) or 576 lines (CCIR 625/50, 720576 pixels, commonly used with PAL).[7] Besides these hardware specifications, Blu-ray is associated with a set of multimedia formats.
The BD format was developed by the Blu-ray Disc Association, a group representing makers of consumer electronics, computer hardware, and motion pictures. Sony unveiled the first Blu-ray Disc prototypes in October 2000, and the first prototype player was released in Japan in April 2003. Afterward, it continued to be developed until its official worldwide release on June 20, 2006, beginning the high-definition optical disc format war, where Blu-ray Disc competed with the HD DVD format. Toshiba, the main company supporting HD DVD, conceded in February 2008,[8] and later released its own Blu-ray Disc player in late 2009.[9] According to Media Research, high-definition software sales in the United States were slower in the first two years than DVD software sales.[10] Blu-ray faces competition from video on demand (VOD) and the continued sale of DVDs.[11] In January 2016, 44% of U.S. broadband households had a Blu-ray player.[12] For playback of 4K content, the BDA introduced a variant of Blu-ray called Ultra HD Blu-ray.
The information density of the DVD format was limited by the wavelength of the laser diodes used. Following protracted development, blue laser diodes operating at 405 nanometers became available on a production basis, allowing for development of a denser storage format that could hold higher-definition media, with prototype discs made with diodes at a slightly longer wavelength of 407 nanometers in October 1998.[13][14] Sony commenced two projects in collaboration with Panasonic, Philips, and TDK,[15] applying the new diodes: UDO (Ultra Density Optical),[16] and DVR Blue (together with Pioneer),[17] a format of rewritable discs that would eventually become Blu-ray Disc (more specifically, BD-RE). The core technologies of the formats are similar. The first DVR Blue prototypes were unveiled by Sony at the CEATEC exhibition in October 2000.[18] A trademark for the "Blue Disc" logo was filed on February 9, 2001.[19] On February 19, 2002, the project was officially announced as Blu-ray Disc,[20][21] and Blu-ray Disc Founders was founded by the nine initial members. 2ff7e9595c
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