Blu-Ray Disc

ByAshish EbenApurv TodkarOmkar

IntroductionBlu-Ray Disc[official acronym BD] is an optical disc storage[Data storage,1080p High Definition video & audio, Stereoscopic 3D(PS3 video games)].The capacity is from 25-50GB[Single layered] & 50-100GB[Dual layered].

This media type is appropriately named after the blue laser being used to write data. The first blue laser was was developed in 1996 by Shuji Nakamura.The letter “e” is not been used in the word’Blu’ due to trademark restrictions.In the year an alliance was formed called as Blu-ray Disc Association[Sony, Philips, Samsung, Sharp, Hewlett-Packard, Warner Bros., etc.]which represented a group of makers of consumer electronics, computer hardware and motion pictures.

As of June 2009, more than 1,500 Blu-ray Disc titles are available in Australia and the United Kingdom, with 2,500 in Japan, the United States and Canada. The encoding for video formats is MPEG-2, H.264/MPEG-4 AVC, and VC-1.

Origins of its Existence

Sony or Philips started two projects applying i.e. UDO[Ultra Density Optical] & DVR Blue(with Pioneer) for a format of rewritable discs that would eventually became Blu-ray Disc (more specifically, BD-RE).

1st of prototypes of DVR blue were reviled at the CEATEC exhibition in Oct’ 2000 & later on in Feb’ 2002,the project was officially called as Blu-Ray Disc. A group formed named as Blu-Ray Disc Founders, which was founded by nine initial members.

The first consumer was available in stores at April 10,2003 called as the Sony BDZ-S77 & the BD-RE recorder was available only in Japan & price was US $ 3800. there was no standard for pre-recorded video, and no movies were released for this player.

Hollywood studios wouldn’t accept it due to it’s Blu-ray Disc standards ,as being new it needed more secure Digital Right Management system & they didn’t wanted to repeat the failure of the Content Scramble System used on standard DVDs.

In October 4,2004 the Founders group was officially changed to Blu-ray Disc Association[BDA] & even 20th Century Fox joined the Board of Directors.

Software Standards

CODECSThe BD-ROM specification mandates certain codec compatibilities for both hardware decoders (players) and movie software (content).

VIDEOFor video, all players are required to support MPEG-2 Part 2, H.264/MPEG-4 AVC, and SMPTE VC-1.[64] MPEG-2 is the codec used on regular DVDs, which allows backwards compatibility. MPEG-4 AVC was developed by MPEG, Sony, and VCEG. VC-1 is a codec that was mainly developed by Microsoft. BD-ROM titles with video must store video using one of the three mandatory codec's; multiple codec's on a single title are allowed.

The choice of codec's affects the producer's licensing/royalty costs as well as the title's maximum run time, due to differences in compression efficiency. Discs encoded in MPEG-2 video typically limit content producers to around two hours of high-definition content on a single-layer (25 GB) BD-ROM. The more-advanced video codec's (VC-1 and MPEG-4 AVC) typically achieve a video run time twice that of MPEG-2, with comparable quality.

AUDIOFor audio, BD-ROM players are required to support Dolby Digital (AC-3), DTS, and linear PCM. Players may optionally support Dolby Digital Plus and DTS-HD High Resolution Audio as well as lossless formats Dolby TrueHD and DTS-HD Master Audio.[65] BD-ROM titles must use one of the mandatory schemes for the primary soundtrack. A secondary audiotrack, if present, may use any of the mandatory or optional codec's.

BIT RATEFor users recording digital television programming, the recordable Blu-ray Disc standard's initial data rate of 36 Mbit/s is more than adequate to record high-definition broadcasts from any source (IPTV, cable/satellite, or terrestrial). BD Video movies have a maximum data transfer rate of 54 Mbit/s, a maximum AV bitrate of 48 Mbit/s (for both audio and video data), and a maximum video bit rate of 40 Mbit/s. This compares to HD DVD movies, which have a maximum data transfer rate of 36 Mbit/s, a maximum AV bitrate of 30.24 Mbit/s, and a maximum video bitrate of 29.4 Mbit/s.

Digital Rights ManagementThe Blu-ray Disc format employs several layers of digital rights management.

BD+ Such programs can: was developed by Cryptography Research Inc. and is based on their concept of Self-Protecting Digital Content. BD+, effectively a small virtual machine embedded in authorized players, allows content providers to include executable programs on Blu-ray Discs.

The Advanced Access Content System (AACS) is a standard for content distribution and digital rights management. It was developed by AS Licensing Administrator, LLC (AACS LA), a consortium that includes Disney, Intel, Microsoft, Panasonic, Warner Bros., IBM, Toshiba, and Sony.

BD-ROM Mark is a small amount of cryptographic data that is stored separately from normal Blu-ray Disc data. Bit-by-bit copies that do not replicate the BD-ROM Mark are impossible to decode

Characteristics of the Disc

120mm

The diameter of the disc is 120mm & thickness 1.2mm which is same as normal DvD. The centre hole diameter is 15mm

120mm

The disc uses blue-violet laser, which operates at 405nm wavelength to read & write the data. The laser’s diameter is .1mm & is used to read block size of 640Kb ECC[Elliptic Curve Cryptography].Diode used is InGaN[Indium Gallium Nitride].

Due to data layer being closer to the surface of the disc the disc had to be scratch resistible, at 1st they made use of cartridges but it was raising the cost of an already expensive medium.

Drive speed

Data rate Theoretical Write time for Blu-ray Disc (minutes)

Mbit/s MB/s Single-Layer Dual-Layer

1× 36 4.5 90 180

2× 72 9 45 90

4× 144 18 22.5 45

6× 216 27 15 30

8× 288 36 11.25 22.5

10× 360 45 9 18

12×[61] 432 54 7.5 15

Recording Speed

So they picked up a technology called Hard-Coating. TDK was very 1st company to use this technology & named it Durabis. See this both Sony & Panasonic replicated the trademark hard-coating technology methods & named Spin-Coating. Verbatim’s recordable and rewritable Blu-ray Discs use their own proprietary hard-coat technology, called ScratchGuard.

The power conservation allows the development of multi-layer platforms and high-speed recording.

BD-ROM has two layers that are single & dual layer. Its capability can go above dual layer[4,6 & 8 layer]which has been proven.In future it can store data upto 200GB.

The recommended resolutions it can support are 1920x1080p & 1280x720p,in future 2160p.Resolution Frame rate1 Aspect ratio Video format restrictions

1920×1080 59.94-i 16:09 1920×1080 50-i 16:09 1920×1080 24-p 16:09 1920×1080 23.976-p 16:09 

1440×1080 59.94-i 16:9 (anamorphic) MPEG-4 AVC / SMPTE VC-1 only

1440×1080 50-i 16:9 (anamorphic) MPEG-4 AVC / SMPTE VC-1 only

1440×1080 24-p 16:9 (anamorphic) MPEG-4 AVC / SMPTE VC-1 only

1440×1080 23.976-p 16:9 (anamorphic) MPEG-4 AVC / SMPTE VC-1 only1280×720 59.94-p 16:09 1280×720 50-p 16:09 1280×720 24-p 16:09 1280×720 23.976-p 16:09 720×480 59.94-i 4:3/16:9 (anamorphic)  720×576 50-i 4:3/16:9 (anamorphic)  

Blu-Ray and HD-DVD both use blue lasers, which operate at lower wavelengths (405 nanometers) than current red lasers (650 nanometers).

That microscopic difference goes a long way. Longer wavelengths suffer more diffraction, which limits their ability to focus tightly on a surface.

But a blue laser's shorter wavelength allows it to read and write data over a much tighter surface area, which in turn allows storage of far more data on a disc that's roughly the same diameter of current DVDs.

While consumers won't have to worry about obsolescence when it comes to their old DVD collections, the format war brewing between new Blu-Ray and HD-DVD discs does present an age-old problem that evokes the VHS vs. Beta fiasco of the 1980s.

The HD-DVD format—like the VHS format that won out over Beta—could become far more widely available to consumers sooner and at a lower price (at least initially) than Blu-Ray discs.

That's because the HD-DVD format utilizes manufacturing techniques very similar to those used for the current generation of DVDs.

• Shorter distance to travel forsame amount of data results infaster data seek times

• Important for randomaccess of data

• Better for video game andPC data applications

On the other hand, Blu-Ray discs require an entirely new manufacturing process with transition costs borne largely by duplicators (unless Blu-Ray backers devise a subsidy system.

That, along with other issues, is expected to delay the introduction of Blu-Ray discs until sometime in 2006, which could hand a major advantage to the HD-DVD format. (add hard return here)

"In this kind of battle, the guy who is out there first and cheaper is going to be the winner," says Fariborz Ghadar, director for the Center for Global Business Studies at Penn State University.

"The more expensive and later one is going to be the loser."

(The Blu-Ray camp contends that it will bring manufacturing costs nearly in line with HD-DVD during the next year.