The name Blu-ray Disc is derived from the blue-violet laser used to read and write this type of disc. Because of its shorter wavelength (405 nm), substantially more data can be stored on a Blu-ray Disc than on the DVD format, which uses a red, 650 nm laser. A single layer Blu-ray Disc can store 25 GB, over 5 times the size of a single layer DVD at 4.7 GB. A dual layer Blu-ray Disc can store 50 GB, almost 6 times the size of a dual layer DVD at 8.5 GB.
Blu-ray Disc is similar to PDD, another optical disc format developed by Sony (which has been available since 2004) but offering higher data transfer speeds. PDD was not intended for home video use and was aimed at business data archiving and backup.
Blu-ray Disc is currently in a "format war" with rival format HD DVD.
| Media type: | High-density optical disc |
|---|---|
| Encoding: | MPEG-2, H.264, and VC-1 |
| Capacity: | 25 GB (single layer), 50 GB (dual layer) |
| Read mechanism: | 1x@36 Mbit/s & 2x@72 Mbit/s |
| Developed by: | Blu-ray Disc Association |
| Usage: | Data storage, high-definition video and PlayStation 3 Games |
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