Blu-ray
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.
Media type
- Data encoding: CLV or Zoned CAV pits-and-lands with interleaved error correction code
- BDMV Video encoding:
- H.262/MPEG-2 Part 2
- H.264/MPEG-4 AVC
- VC-1
- H.265/HEVC (only Ultra HD Blu-ray)
405 nm diode laser, 36 Mbit/s
405 nm diode laser with a focused beam using more power than for reading
June 20, 2006
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 Blu-ray specification 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 a 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.
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]
Data format standards[edit]
Filesystem[edit]
Blu-ray Disc specifies the use of Universal Disk Format (UDF) 2.50 as a convergent-friendly format for both PC and consumer electronics environments. It is used in the latest specifications of BD-ROM, BD-RE, and BD-R.[158][159][160] In the first BD-RE specification (defined in 2002), the BDFS (Blu-ray Disc File System) was used. The BD-RE 1.0 specification was defined mainly for the digital recording of high-definition television (HDTV) broadcast television. The BDFS was replaced by UDF 2.50 in the second BD-RE specification in 2005, to enable interoperability among consumer electronics Blu-ray recorders and personal computer systems. These optical disc recording technologies enabled PC recording and playback of BD-RE.[160][161][162] BD-R can use UDF 2.50/2.60.[163]
The Blu-ray Disc application for recording of digital broadcasting has been developed as System Description Blu-ray Rewritable Disc Format part 3 Audio Visual Basic Specifications (BDAV). The requirements related with computer file system have been specified in System Description Blu-ray Rewritable Disc Format part 2 File System Specifications version 1.0 (BDFS).[164] Initially, the BD-RE version 1.0 (BDFS) was specifically developed for recording of digital broadcasts using the Blu-ray Disc application (BDAV application). But these requirements are superseded by the Blu-ray Rewritable Disc File System Specifications version 2.0 (UDF) (a.k.a. RE 2.0) and Blu-ray Recordable Disc File System Specifications version 1.0 (UDF) (a.k.a. R 1.0). Additionally, a new application format, BDMV (System Description Blu-ray Disc Prerecorded Format part 3 Audio Visual Basic Specifications) for High Definition Content Distribution was developed for BD-ROM. The only file system developed for BDMV is the System Description Blu-ray Read-Only Disc Format part 2 File System Specifications version 1.0 (UDF) which defines the requirements for UDF 2.50.[160][164] All BDMV application files are stored under a "BDMV" directory.[165][166][167][168]
Backward compatibility[edit]
The Blu-ray Disc Association recommends but does not require that Blu-ray Disc drives be capable of reading standard DVDs and CDs, for backward compatibility.[234] Most Blu-ray Disc players are capable of reading both CDs and DVDs; however, a few of the early Blu-ray Disc players released in 2006, such as the Sony BDP-S1, could play DVDs but not CDs.[235][236][237] In addition, with the exception of some early models from LG and Samsung, Blu-ray players cannot play HD DVDs, and HD DVD players cannot play Blu-ray Discs. Some Blu-ray players can also play Video CDs, Super Audio CDs, and/or DVD-Audio discs. All Ultra HD Blu-ray players can play regular Blu-ray Discs, and most can play DVDs and CDs. The PlayStation 4 and PlayStation 5 do not support CDs.[238]
