About Blu-ray


In February 2002 a group of nine leading electronics companies formed what is now known as the Blu-ray Disc Association. The Association's primary aims are to develop and promote the Blu-ray standard. Since then the Association has grown to more than 250 supporters.

A Blu-ray Disc (BD) is very similar to a Standard DVD (SDVD) in shape, size and construction and similarly is particularly well suited for the distribution of feature films. BDs are designed to be the successor to the SDVD format in response to a need for increased disc capacity. Blu-ray Discs have over 5 times the storage capacity of SDVDs as well as increased data transfer rates making them much better suited to the storage and playback of high-definition video.

The name Blu-ray is trademark of Sony Corp. and is derived from the blue color of the laser used to read and write BDs.

Key Features

Key features include:

  • High capacity storage of video and data – Up to 9 hours of high definition video or 23 hours of standard definition video or up to 50GB of data. This is over 5 times the capacity of SDVDs making Blu-ray discs particularly well suited for the distribution of high-definition feature films.
  • 1080p high definition video support – Full support for the 1920 x 1080p high definition video standard ensures highest quality video reproduction.
  • Uncompressed surround sound – Ensures highest quality sound reproduction
  • Increased data transfer rate – BDs spin faster to allow for an increased data transfer rate. A SDVD has a data transfer rate of about 1.3MB per second as compared to the Blu-ray data transfer rate of 4.2MB bytes per second
  • Improved interactive features – network and Internet connectivity and enhanced menu navigation help provide a more seamless viewing experience.
  • Backward compatibility – Most players support both SDVDs and CDs
  • Better scratch resistance – Recent advancements in coating technology have provided for increased resistance to damage caused by scratches
  • Well supported within industry – The Blu-ray standard was developed by the Blu-ray Disc Association. Headed by Sony, this group includes many prominent companies within the consumer electronics and computer industries. This helps to ensure the competitiveness of Blu-ray products and more choice for consumers.
  • Cost effective – Although BD media currently cost more than SDVD media, the capability to store over 5 times the data on a Blu-ray disc results in a lower cost per GB than for SDVDs.


BDs provide the highest capacity of data storage of any consumer level optical disc available today. Blu-ray discs can store up to 25GB of data on a single layer disc or up to 50 GB on a dual layer disc. This translates into about 4.5 hours of high-definition video at full-resolution (1920 x 1080p) in high-quality (minimal compression) for a single layer disc or 9 hours for a dual layer disc. Competitor standard HD DVDs have about 60% of the capacity of BDs.

Capacity Comparison for BD, HD DVD, DVD, CD Discs
  Blu-ray Disc HD DVD DVD
Data Capacity
(Single Layer)
25GB 15GB 4.7GB
Data Capacity
(Dual Layer)
50GB 30GB 9.4GB
HD Video Capacity*
(Single Layer)
4.5H 2.7H NS
HD Video Capacity*
(Dual Layer)
9H 5.4H NS
SD Video Capacity*
(Dual Layer)
11H 7H 2H
SD Video Capacity*
(Dual Layer)
23H 14H 4.3H

NS - Not Supported
H - Hours
GB - Gigabytes
SD - Standard Definition
HD - High Definition d

*Video capacity is dependent on the type and amount of compression applied to the video image. The times provided here are approximate and representative of high quality video typically used for the distribution of feature length movies.

This capacity of BDs is ideal for the distribution of high definition feature films. The increased capacity not only allows for the inclusion of the entire high definition film on one disc but provides enough space to include extra features such as 'making-of' documentaries and extra scenes.

The High Definition Standard

High definition is the new video standard for disc and broadcast distribution. Although the standard has been around for some time it is just now starting to see wide acceptance. Currently there are 3 recognised standards that can be identified as being high definition: 1080i, 1080p and 720p. The numbers refer to the number of horizontal lines in the image.

Comparison of high definition video resolutions
Comparison of HD and SD Video Resolutions

The 'i' and 'p' after the numbers refer to whether the video is an 'interlaced' image or 'progressively scanned' image. When video is interlaced, each frame in the video sequence is drawn to the screen in two passes referred to as fields (standard definition televisions display interlaced video). When video is progressively scanned, each frame is drawn to the screen in one pass (computer monitors use progressive scanning). The ability of televisions to display different video standards depends on the capabilities of the specific television model.

All HD video standards are widescreen (have a screen aspect ratio of 16:9) whereas SD video has an aspect ration of 4:3.

Uncompressed Surround Sound

The Blu-ray standard supports fully uncompressed surround sound allowing for the best possible sound reproduction.

Data transfer rate

The speed at which data is transferred and processed from a disc is referred to as the data transfer rate. SDVD drives have a data transfer rate of about 1.3MB per second. The playback of full-resolution high-definition video requires a system that has a data transfer rate of about 4.2MB per second. To achieve this increased transfer rate Blu-ray discs spin faster than SDVDs.

Improved interactivity

Enhancements in interactivity such as the ability to connect to a network or the Internet provide opportunities for content producers to directly interact with users while they are viewing the content. This also provides the facility to download additional or updated content over the internet to the players internal memory.


Although Blu-ray standards do not require backward compatibility, most players currently in production allow for playback of SDVDs and CDs as well as BDs. There are also several hybrid systems that will play both Blu-ray and competitor format HD DVD.

The Blue Ray

The Blu-Ray standard takes its name from the blue laser used to read and write data within the drive mechanism. The laser operates at a wavelength of 405 nm making it somewhere in the order of two thirds the wavelength of the lasers used to read conventional DVDs (red - 650nm) and CDs (infrared – 780nm). The shorter wavelength allows the laser to read data that is compacted into a smaller space.

The ability of the laser to read more compact data is further enhanced though improvements in the focusing lens mechanism and a reduction in the thickness of the outer cover layer on the disc. These three enhancements ultimately allow for the laser to focus on a much smaller area resulting in the ability to store more data in the same area.

Industry Support

The Blu-ray standard was developed by the Blu-ray Disc Association whose membership includes many prominent consumer electronics, IT and video distribution companies. The board of directors is comprised of:

  • Apple
  • Dell
  • HP
  • Hitachi (Founder)
  • LG (Founder)
  • Mitsubishi Electric (Founder)
  • Panasonic
  • Pioneer (Founder)
  • Philips (Founder)
  • Samsung (Founder)
  • Sharp (Founder)
  • Sony (Founder)
  • Sun Microsystems
  • TDK
  • Thomson (Founder)
  • Twentieth Century Fox
  • Walt Disney
  • Warner Bros.

For a full list of supporters visit the Blu-ray Disc Association website.

This broad base of support was essential in ensuring Blu-ray's dominance as the standard of choice for the distribution of high definition video and PC data storage. It is also essential in ensuring competitiveness and a variety of products from manufacturers and distributors around the world.


Blu-ray's only competitor - HD DVD has suffered major set-backs including the discontinuation of HD DVD products by its primary supporters - Toshiba, Universal Studios and Paramount Studios. It is safe to say, Blu-ray has become the technology of choice for disc based distribution of feature films, music, games and other home entertainment titles as well as the storage and distribution of computer data.

The HD DVD standard was developed by Toshiba and NEC. Prominent supporters include:

  • Toshiba
  • NEC
  • DVD Forum
  • HP
  • Microsoft
  • Intel
  • Warner Bros.
  • HBO
  • New Line Cinema
  • Paramount Pictures
  • Universal Studios

Note: Some companies supported both standards.

Disc Construction

BDs are the same size, shape and general construction as SDVDs. However they hold more data because the data is written to the disc in a more compact form.

As part or the quest to fit more data into the same area, it became necessary to have the data layer surface closer to the outer cover surface of the disc making Blu-ray discs more susceptible to damage caused by scratches. To overcome this, manufacturers such as TDK Corporation developed a hard clear polymer for use as the outer coating of the disc, making BDs more resistant to scratches than SDVDs. This extra protection is also likely to improve the longevity of discs.

Disc and Drive Costs

Blu-ray discs are the same physical size and shape as DVDs and CDs but require a special hard outer coating layer. Assembly lines need to be redesigned to accommodate this, leading to an increase in cost of BD production. HD DVDs do not require a special hard coating and can be manufactured in much the same way as SDVDs.

As initial investment costs are offset, prices are expected to drop to levels more in line with current SDVDs.

Content Protection

Blu-ray discs are required to use the Advanced Access Content System (AACS) the most comprehensive copy protection currently available. This increased protection makes this format particularly attractive to distributors trying to combat a multi-billion dollar content piracy industry.


Blu-ray Disk Association
The Authoritative Blu-ray Disc (BD) FAQ