Blu-ray

Blu-ray
Reverse side of a Blu-ray. Unlike CD and DVD, the reflection has a blue hue. Branded colors include silver, gold, and grey.
Media typeHigh-density optical disc
Encoding
Capacity
  • 25 GB (single-layer)
  • 50, 66 GB (dual-layer)
  • 100, 128 GB (BDXL)
  • (Up to four layers are possible in a standard form BD)
Block size2 KB sector,[1] 64 KB ECC-block[2]
Read mechanism405 nm diode laser, 36 Mbit/s
Write mechanism405 nm diode laser with a focused beam using more power than for reading
Developed by
Dimensions
  • 12 cm (4.7 in) diameter
  • 1.2 mm (0.047 in) thickness[4][a]
Usage
Extended fromDVD
Extended to
ReleasedJune 20, 2006; 18 years ago (2006-06-20)
Optical discs
General
Optical media types
Standards
See also

Blu-ray (Blu-ray Disc or BD) is a digital optical disc data storage format designed to supersede the DVD format. It was invented and developed in 2005 and released worldwide on June 20, 2006, 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 refers to the blue laser (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, resulting in an increased capacity.

The polycarbonate disc is 12 centimetres (4+3⁄4 inches) in diameter and 1.2 millimetres (1⁄16 inch) thick, the same size as DVDs and CDs.[5] Conventional (or "pre-BD-XL") Blu-ray discs contain 25 GB per layer, with dual-layer discs (50 GB) being the industry standard for feature-length video discs. Triple-layer discs (100 GB) and quadruple-layer discs (128 GB) are available for BD-XL re-writer drives.[6]

While the DVD-Video specification has a maximum resolution of 480p (NTSC, 720 × 480 pixels) or 576p (PAL, 720 × 576 pixels),[7] the initial specification for storing movies on Blu-ray discs defined a maximum resolution of 1080p (1920 × 1080 pixels) at up to 24 progressive or 29.97 interlaced frames per second. Revisions to the specification allowed newer Blu-ray players to support videos with a resolution of 1440 × 1080 pixels, with Ultra HD Blu-ray players extending the maximum resolution to 4K (3840 × 2160 pixels) and progressive frame rates up to 60 frames per second. Aside from an 8K resolution (7680 × 4320 pixels) Blu-ray format exclusive to Japan,[8] videos with non-standard resolutions must use letterboxing to conform to a resolution supported by the Blu-ray specification. Besides these hardware specifications, Blu-ray is associated with a set of multimedia formats. Given that Blu-ray discs can contain ordinary computer files, there is no fixed limit as to which resolution of video can be stored when not conforming to the official specifications.

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,[9] and later released its own Blu-ray Disc player in late 2009.[10] According to Media Research, high-definition software sales in the United States were slower in the first two years than DVD software sales.[11] Blu-ray's competition includes video on demand (VOD) and DVD.[12] In January 2016, 44% of U.S. broadband households had a Blu-ray player.[13]

  1. ^ "White Paper Blu-ray Disc Format" (PDF). Blu-ray Disc Association. December 2012. Archived (PDF) from the original on March 13, 2013. Retrieved February 21, 2016.
  2. ^ "Data" (PDF). sutlib2.sut.ac.th. Archived (PDF) from the original on February 22, 2014. Retrieved February 17, 2014.
  3. ^ Blu-ray FAQ Archived October 4, 2006, at the Wayback Machine. Blu-ray.com. Retrieved on December 22, 2010.
  4. ^ "Blu-ray FAQ". Blu-ray.com. Archived from the original on February 14, 2014. Retrieved February 17, 2014.
  5. ^ "6JSC/ALA/16/LC response" (PDF). rda-jsc.org. September 13, 2012. Archived (PDF) from the original on October 14, 2012. Retrieved January 29, 2014.
  6. ^ Butler, Harry (February 23, 2011). "Pioneer BDXL BDR-206MBK Review". bit-tech.net. Archived from the original on April 6, 2014. Retrieved February 17, 2014.
  7. ^ "DVD Frequently Asked Questions (and Answers)". Jim Taylor. June 27, 2013. Archived from the original on August 22, 2009.
  8. ^ Chinnock, Chris (January 22, 2018). "Blu-ray Disc Association Settles on 8K Format". Retrieved August 24, 2023.
  9. ^ "Toshiba Announces Discontinuation of HD DVD Businesses" (Press release). Toshiba. February 19, 2008. Archived from the original on February 25, 2008. Retrieved February 26, 2008.
  10. ^ Yomiuri Shimbun. Page 1. July 19, 2009. Ver. 13S.
  11. ^ "Blu-ray Discs reach 1.5 million sold, HDM still trails DVD's first two years". Engadget. AOL Inc. February 16, 2008. Archived from the original on February 5, 2015. Retrieved July 29, 2014.
  12. ^ "Sony Buys a Facebook Spinoff to Give New Life to Blu-ray". Wired. May 27, 2015. Archived from the original on March 6, 2017. Retrieved March 5, 2017.
  13. ^ Morris, Chris (January 8, 2016). "Blu-ray Struggles in the Streaming Age". Fortune. Archived from the original on January 9, 2017. Retrieved October 3, 2018.


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