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What is a Blu-ray Disc?

Blu-ray disc (also known as BD) is a relatively new optical disc format developed by the members who constitute the Blu-ray Disc Association (BDA). The BDA is essentially an association of world leading personal computer manufacturers, consumer electronics producers, and media organisations, and includes: Apple, Dell, Hitachi, Hewlett-Packard, JVC, LG, Mitsubishi, Panasonic, Philips, Samsung, Sharp, Sony, TDK and Thomson. BD was originally conceived of as the disc format that would supersede the DVD format owing to its vastly increased storage capacity and advanced video and audio codec technologies.

The Blu-ray disc conforms to specifications standardised by Compact Disc (CD) format, and reinforced by DVD: the BD is 1.2mm thick and 120mm in diameter. The advantage that Blu-ray enjoys over the CD and DVD formats lies, primarily, in the technology developed in terms of the disc’s reader. The Blu-ray reader, as is suggested by the format’s name, uses a blue-violet laser to read information contained on the disc, whereas the DVD, DVD-R, and DVD-RW are all read by red lasers. The blue-violet laser is of a shorter wavelength (405 nanometres) than the red laser (650 nanometres). The shorter wavelength allows the laser spot to be focussed with a greater degree of accuracy than the red wavelength, which in turn makes it possible to pack information on the Blu-ray disc more densely than on the DVD formats.

The greater precision of the blue-violet laser also means that Blu-ray readers are backwards compatible: they are able to read discs developed for red laser technology, but red laser readers are unable to accurately read the condensed information contained on BD. The result of the new technology is that Blu-ray discs contain a massive 25GB per layer of information; 50 GB discs (dual layer discs) are the norm for commercially released feature length films; triple layer discs have a storage capacity of 100 GB; and quadruple layer discs can contain up to 128 GB of information. The latter two types of disc (the triple and quadruple layer BD) are available for the BD-XL rewriter drives.

Blu-ray discs are popularly used for high capacity data storage, high definition video files, high definition audio files, stereoscopic 3-D, and PlayStation 3 games. Notably, Microsoft has refused to install a Blu-ray reader on the Xbox, and Windows cannot read Blu-ray even if the relevant desktop, laptop or netbook has a Blu-ray reader as part of its hardware specifications. This strategic omission by Microsoft (and its consequent resistance to using BD) is designed to strengthen the market presence of Blu-ray’s competitor, HD-DVD. The latter antagonism between HD-DVD (supported by Toshiba and Microsoft) and BD was termed “the high definition optical disc format war”. Whereas the “war” is often said to be remnant of the past, Microsoft’s influence on the market is still palpable. Blu-ray has, however, made significant advances over HD-DVD, and in 2008, Toshiba resigned itself to the fact that it would have to release its own Blu-ray player. With the support of all of the major Hollywood studios, the Blu-ray format, first commercially released in Japan in 2003, currently has over 3 500 titles available for consumption, and is currently the preferred format for HD video and audio in the digital entertainment industry.