Home : Video : Formats : DVD : Blu-ray

The Blu-ray Format

Blu-Ray Logo

Blu-ray is an optical disc storage technology. The name refers to the blue laser used (instead of the red laser used in DVD) — blue light has a shorter wavelength so more data can be stored in the same space.

Blu-ray competed with HD-DVD for the post-DVD high-definition market, eventually emerging as the winner in February 2008. See Blu-ray vs HD-DVD for a comparison.

A single-layer Blu-ray disc can hold 25GB of data, a dramatic improvement over DVD's 4.7GB. This is enough for approximately 2.5 hours of high-definition video or 13 hours of standard-definition video. A double-layer Blu-ray disc can hold 50 GB, enough for approximately 4.5 hours of high-definition video or 20 hours of standard-definition video.

Prototypes have been demonstrated which hold up to 100GB with a theoretical limit of 200 GB. However it should not be assumed that these specifications will be available any time soon (or at all).

Blu-ray supports 1080p resolution. This is touted as the best high-definition resolution for consumers, despite the fact that pre-recorded content is not yet widely available. However the inclusion of 1080p is another big tick for Blu-ray.

The Blu-ray format also allows you to:

As far as the corporate game goes, Sony owns Columbia Pictures and MGM, and has the support of a number of big players. It also has PlayStation 3 on it's side which will play Blu-Ray DVDs.

Specifications at a Glance

Capacity: 25GB (single layer), 50GB (dual layer). Tested up to 100GB, the theoretical limit is 200GB.
Compression: MPEG-2, AVC MPEG-4, VC-1
Max Resolution: 1980x1080/24p, 601, 50i
Max Video Bitrate: 40Mbps
Audio Codec: Linear PCM, Dolby Digital, Dolby Digital Plus, Dolby TrueHD, DTS, DTS HD
Max Audio Streams: 32 streams
Backers: Sony, Dell, Hewlett-Packard, Hitachi, LG Electronics, Matsushita (Panasonic), Mitsubishi, Philips, Pioneer, Samsung, Sharp, TDK, Thomson Multimedia. Possibly Microsoft.
Compatibility: Backwards-compatible with standard DVD.
Interactivity: Java-based

See also: