What is a Blu-ray Disc?
Blu-ray Discs (or BDs) are optical discs used for storing data, movies and video games. Blu-ray Discs are the natural successor to DVDs, thanks to their vastly increased storage capacity and the fact that they're the same size as DVDs and CDs, which allows for easy backwards compatibility.
- Blu-ray Discs are capable of storing either 25 gigabytes or 50 gigabytes, depending on whether they're dual or single layered.
Blu-ray Discs get their names from the fact that data is read from the disc using a blue laser. Because they use a blue laser, Blu-ray Discs are capable of storing data more densely than would be possible using a DVD, which uses a red laser.
When it was first introduced, the Blu-ray Disc format competed with a similar technology called the HD-DVD. That format has since failed, and Blu-ray is now recognised as the successor to DVDs.
What are the differences between Blu-ray and DVDs?
Beyond the technical differences, the main, and most practical difference between DVDs and Blu-ray discs is their storage capacity. Where a standard, single-layered DVD is capable of storing 4.7 gigabytes, an equivalent Blu-ray Disc can hold 25 gigabytes of data. This allows Blu-ray Discs to be used to store and play full HD 1080p movies and movies encoded in 3D, making the most of the display capabilities of modern flat panel televisions and projectors.
Another advantage to this is their suitability for modern video games, which continue to become more detailed, use larger files and require a greater amount of storage.
Blu-ray Discs also use a far more complex menu system based on a software platform called Java, and may contain special features using capabilities called BD-Live and Bonus View that are only accessible if the player has an Internet connection. These include scheduled chats with the director, bonus content, quizzes and the like.
How are Blu-ray Discs used?
Just like DVDs, Blu-ray Discs are mostly used to play movies and video games, and to store data. As is the case with DVDs, practically all devices that contain a Blu-ray drive can play Blu-ray movies. These systems include standalone Blu-ray movie players, video game consoles (in particular the PlayStation 3), and Blu-ray drives in computers.
Blu-ray region compatibility
Like DVDs, Blu-ray Discs are region code protected so that they can only be played on players in a specific part of the world. Having said that, with Blu-ray there are only three regions (as opposed to six), and about 70% of the movies released on BD to date don't contain any region protection. Australian discs are designated as Region B discs - this region also covers most European, African and Southwest Asian countries, as well as New Zealand.
All video games distributed on Blu-ray Discs, at the time of writing, are region-free.
Digital rights management and hardware compatibility
Blu-ray Discs and players employ a range of different methods to prevent unauthorised copying of the content they contain. While this won't necessarily affect anyone not trying to copy them, some players do use what's called High-bandwidth Digital Content Protection (HDCP). When used with a disc that enforces this measure, the movie will be played at a low resolution unless every bit of hardware being used (display, speakers) is HDCP compliant.