how does Blu-ray technology work? a small introduction to Blu-ray
Blu-ray works in much the same way as DVD. Movies, TV shows, and/or music are stored on a 12cm disc (the same diameter as a standard CD). When you put the disc into a compatible player and press play, a laser reads the data stored on the disc in the form of tiny pits. The pitted and unpitted areas of the disc translate into digital 1s and 0s, which are decoded by the player into video, sound, menus, and interactive bonus materials.
The most significant difference between DVD and Blu-ray is that the latter features much tinier pits—0.15 microns long, as opposed to 0.4 microns for DVD. Thus, far more pits can be squeezed onto the same surface area. Those tinier pits must be read by a more precise laser than DVD’s relatively thick red beam, though, which is where the shorter-wavelength, bluer laser of Blu-ray comes in. That’s also where the format gets its name.
As you may have already guessed, more pits equals more bits, so a Blu-ray Disc can hold a lot more information than a DVD—a single-layer Blu-ray Disc holds 25 GB, compared to a single-layer DVD’s 4.7 GB; a dual-layer Blu-ray tips the scales at 50 GB, while a dual-layer DVD holds roughly 8.5 GB.
That extra storage space, combined with the more advanced video compression techniques used on most new Blu-ray releases, allows each disc to hold as much as four hours worth of ultra high quality high-definition video, which is six times the detail of a standard DVD.
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