Blu-ray (not Blue-ray) also known as Blu-ray Disc (BD), is the name of a new optical disc format jointly developed by the Blu-ray Disc Association (BDA), a group of the world’s leading consumer electronics, personal computer and media manufacturers (including Apple, Dell, Hitachi, HP, JVC, LG, Mitsubishi, Panasonic, Pioneer, Philips, Samsung, Sharp, Sony, TDK and Thomson). The format was developed to enable recording, rewriting and playback of high-definition video (HD), as well as storing large amounts of data. The format offers more than five times the storage capacity of traditional DVDs and can hold up to 25GB on a single-layer disc and 50GB on a dual-layer disc.

While current optical disc technologies such as DVD, DVD±R, DVD±RW, and DVD-RAM rely on a red laser to read and write data, the new format uses a blue-violet laser instead, hence the name Blu-ray. Despite the different type of lasers used, Blu-ray products can easily be made backwards compatible with CDs and DVDs through the use of a BD/DVD/CD compatible optical pickup unit. The benefit of using a blue-violet laser (405nm) is that it has a shorter wavelength than a red laser (650nm), which makes it possible to focus the laser spot with even greater precision. This allows data to be packed more tightly and stored in less space, so it’s possible to fit more data on the disc even though it’s the same size as a CD/DVD. This together with the change of numerical aperture to 0.85 is what enables Blu-ray Discs to hold 25GB/50GB.

This blu ray technology is now available in specified sony laptops in india….

BLU -RAY DISC

How much video can you fit on a Blu-ray disc?

Over 9 hours of high-definition (HD) video on a 50GB disc.
About 23 hours of standard-definition (SD) video on a 50GB disc.

What is the difference between Blu-ray and DVD?

Parameters

 

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)
Numerical aperture (NA) 0.85 0.60
Disc diameter
Disc thickness
120mm
1.2mm
120mm
1.2mm
Protection layer
Hard coating
0.1mm
Yes
0.6mm
No
Track pitch 0.32µm 0.74µm
Data transfer rate (data)
Data transfer rate (video/audio)
36.0Mbps (1x)
54.0Mbps (1.5x)
11.08Mbps (1x)
10.08Mbps (<1x)
Video resolution (max)
Video bit rate (max)
1920×1080 (1080p)
40.0Mbps
720×480/720×576 (480i/576i)
9.8Mbps
Video codecs MPEG-2
MPEG-4 AVC
SMPTE VC-1
MPEG-2

Audio codecs Linear PCM
Dolby Digital
Dolby Digital Plus
Dolby TrueHD
DTS Digital Surround
DTS-HD
Linear PCM
Dolby Digital
DTS Digital Surround


Interactivity BD-J DVD-Video

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