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What is Blu-ray Disc?

Blu-ray, also known as Blu-ray Disc (BD) is an optical disc storage medium developed by Blu-ray Disc Association. Blu-ray format was primarily developed to enable recording, rewriting and playback of high-definition video (HD), as well as storing large amounts of data.


Blu-ray disc has the same physical dimensions as standard DVDs and CDs. The name Blu-ray derives from the blue-violet laser used to read and write data. Blu-ray is a combination of “Blue” (blue-violet laser) and “Ray” (optical ray). Letter “e” was intentionally left out so the term could be registered as a trademark.

The correct full name is Blu-ray Disc, not Blu-ray Disk (incorrect spelling).

Blu-ray Storage Capacity

  • Single-layer disc can hold 25GB
  • Dual-layer disc can hold 50GB

Blu-ray can fit over 9 hours of high-definition (HD) video and about 23 hours of standard-definition (SD) video on a 50GB disc.

Blu-ray Vs DVD

Blu-ray DVD
Storage capacity 25GB (single-layer)

50GB (dual-layer)

4.7GB (single-layer)

8.5GB (dual-layer)

Laser wavelength 405nm (blue laser) 650nm (red laser)

Video codecs supported by Blu-ray

  • MPEG-2 – MPEG-2 is the codec used on regular DVDs, which allows backwards compatibility.
  • MPEG-4 AVC – MPEG-4 AVC was developed by MPEG and VCEG , part of the MPEG-4 standard also known as H.264 (High Profile and Main Profile).
  • SMPTE VC-1 – standard based on Microsoft’s Windows Media Video (WMV) technology.

Audio codecs supported by Blu-ray

  • Linear PCM (LPCM) – (mandatory)
  • Dolby Digital (DD) – (mandatory)
  • Dolby Digital Plus (DD+)
  • Dolby TrueHD
  • DTS Digital Surround – (mandatory)
  • DTS-HD High Resolution Audio
  • DTS-HD Master Audio
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