What’s the Blu-ray Disc

What’s the Blu-ray Disc?


Why was the Blu-ray Disc created?
Today’s high-definition video equipment has made it easy to enjoy HD broadcasts and other high-quality content at home. As the content increases in image and sound quality, though, the media for recording and playing it also has to offer larger data capacity and higher speed.
The Blu-ray Disc (BD) is a new-generation optical disc media that responds to these needs.
The Blu-ray Disc is a de facto global standard that is being developed and promoted by a total of 173 companies (as of June 22, 2006) around the world. These include leading electronics companies such as Hitachi, Pioneer, Sony and Sharp, and film studios such as Walt Disney Pictures, Sony Pictures Entertainment, 20th Century Fox and Warner Brothers Entertainment.


What does the high storage capacity of the Blu-ray Disc offer to users?
With its 12-cm diameter, the Blu-ray Disc does not look any different from a DVD disc. There’s a major difference, however, in its storage capacity. The Blu-ray Disc is able to store 50 GB (single-side, double-layer disc) of data, as compared to the 4.7 GB (gigabytes) of the DVD disc. This is enough to record more than four hours of high-definition video with 7.1-channel surround sound onto a single disc..


Basic Blu-ray Technologies


The Incredible Data Capacity of the Blu-ray Disc
The Blu-ray Disc is an optical disc format that was created to meet the needs of high-definition video by storing a huge amount of data.
The Blu-ray Disc has the same dimensions as CD and DVD discs, with a 12-cm diameter, but...
...it features an amazing data storage capacity.
While a DVD disc stores up to 4.7 GB (gigabytes) of data on one side, the Blu-ray Disc can hold as much as 25 GB on a single side, giving it more than five times the storage capacity.
Because each recording layer of a single-side, dual-layer Blu-ray Disc is capable of storing 25 GB of data, the total capacity is an astonishing 50 GB per disc. In other words, one Blu-ray Disc can store as much data as ten DVD discs.

How does the Blu-ray Disc achieve such a large data storage capacity?

Key Technologies for Efficient Use of Limited Space
The Blu-ray Disc is 12 cm in diameter.
To efficiently record a large amount of data in a disc having the same dimensions as CD and DVD discs, it was necessary to develop different technologies from those used in CDs and DVDs.
There are three key points in these technologies.