Blu-ray Disc

Capacity and speed

A disc Blu-ray simple layer contains 23,3 Go is 86 minutes with a flow of 4,5 Mo/s with the audio and videos coded with the format MPEG-2, and a disc double-layer can contain 46,6 Go. The rate of transfer is of 36 Dry Mbits/(either 4,5 Mo/s), but of the prototypes of readers with a rate of transfer of 72 Dry Mbits/(either 9 Mo/s) are under development. The standard BD-RE (rewriteable disc) is currently available, and will be followed by formats BD-R (recordable) and BD-ROM in 2006 even in 2007, as a part of the specifications Blu-ray 2.0. Recorded discs pre BD-ROM will be available at the beginning of 2007; the first BD-ROM was engraved in November 2005 (Sony Pictures Home Entertainment). Projects of discs with capacity of 100 Go and 200 Go are currently being studied, respectively using four and eight layers; TDK developed a prototype with six layers adding up 200 Go (33 Go by layer).

Codecs

Format BD-ROM specifies three codecs for the video: MPEG-2 (the standard currently used for DVDs), the codec H.264/MPEG-4 AVC, and the codec VC-1 based on the codec Microsoft Windows Media 9. The first codec authorizes only two hours of contents in high-definition on a simple Blu-ray disc sleep, but with the others codecs a disc simple layer can contain approximately four hours. The MPEG-2 high-definition has a rate of transfer of approximately 25 Mbit/s, whereas the two others have a rate of transfer of approximately 15 Mbit/s for the video and 3 Mbit/s for the audio.

Discs BD-RE (and by extension discs BD-R) currently do not support a codecs other than the MPEG-2. Since standard MPEG-2 is currently used for the diffusion HDTV, the recorders write this flow high-definition directly on the disc. No recorder available for the general public not being able to transcribe with stolen flow MPEG-2 towards another codec which can be used for discs BD-RE, the MPEG-2 is the only format used on discs BD-RE.

The methods of encoding of the audio stream include linear PCM, the Dolby DIGITAL, SDR and the dts++ (compression without loss). Association Blu-ray Disc seeks codecs higher than those used by specification DVD.

Variations

A specification for a Blu-ray disc of 8 cm was already finalized and approved. It results a disc from it from 8 simple cm sleeps with a face, able to contain 15 Go, is once and half the capacity of a DVD normal double-layer of 12 cm. This format would be adapted for the portable small apparatuses, like the video players or the numeric cameras.

A hybrid disc Blu-ray/DVD was developed by JVC and LG and waits to be recognized by association Blu-ray Disc. That would make it possible to use the same disc in readers Blu-ray and DVD. The users could buy only one disc which can be read either in normal definition or in high-definition, according to the material used. Users not having that a simple reader DVD will be able to look at to it video of normal resolution, then in high-definition when they buy a Blu-ray reader.

Sony proposes in its range VAIO AR of the portable PC equipped right now with engraver Blu-ray double-layer.

Technology

Wavelength of the laser

This technology uses a laser Diode blue (in fact blue purplished) functioning with a Wavelength of 405 Nm for reading and writing the data. CDs and DVDs conventional use red lasers and oranges with respectively 780 Nm and 650/635 Nm.

On the level of the comparison of the colors, the visible color of a tube of black light is dominated by the emissions purplished of the mercury to 435,8 Nm. The laser diode purplished blue used for the Blu-ray discs function with 405 Nm, which is definitely more purple (nearer to the violet end of the Specter of the visible light) than the visible part of the black light. An side effect owing to the fact that the wavelength is very small is that several materials become fluorescent, and the ray appears white bluish if it is reflected on a white surface (like a sheet of paper). If future technologies project the use of fluorescent supports, the Blu-ray discs function in a way similar to that of CDs and of DVDs and do not use the fluorescence of the supports to read the data.

The purplished blue laser has a wavelength shorter than that of the systems CD or DVD, and this reduction makes it possible to store more data on an of the same disc cuts (12 cm). The minimal size of the point on which the laser can be focused is limited by the Diffraction, and depends on the wavelength of the light and the numerical Ouverture on the lens used to develop it. By decreasing the wavelength (while approaching the violet end of the spectrum), by using a system with double lens with a better numerical opening (better quality) and while making the disc finer in order to avoid certain optical effects, the laser can be focused much more precisely on the surface of the disc. More precise luminous pointings are obtained, and thus it can store more information on the disc in the same space. In addition to the optical improvements, the Blu-ray disc present of the improvements with regard to the encoding of the data and the bringing together of the tracks between them, which makes it possible to store even more data. (see the article on the “Compact disk” for information on the optical structure of the disc)

Technology of reinforced protection

The introduction of TDK within the Blu-ray foundation, announced on March 19th, 2004, was accompanied by a great number of indications which can improve to a significant degree the future of the Blu-ray disc. The technology of reinforced protection of TDK would make it possible the Blu-ray discs to better resist the stripes, and would allow them to be cleaned prints of fingers with a simple fabric, process which leaves microstripes on CD or a normal DVD.

Manufacture of a Blu-ray disc

The Blu-ray discs follow, with some exceptions, the same stages of manufacture of a disc DVD. A software master is initially created by the editor. It is transferred towards the manufacturing plant which engraves the data on a master of physical glass. This master is used to create negative: the mother. The latter is used as copy for the future wafers which will be generated in mode copies of the mother. In Europe, it is Sony DADC which holds the monopoly of the manufacture of the Blu-ray discs. It is thus necessary obligatorily to pass by the company to publish a disc in this format. More details and images are available here: Manufacture of a Blu-ray disc.

The War of supports HD

This association of TDK and Sony naturally aims at making the data base less expensive to manufacture for better competing with the competitor HD DVD which certainly has maximum capacities of storage lower than Blu-ray (15Go by layer for the HD-DVD against 25Go by layer for the BRD) but which with the advantage of being able to be manufactured on the current chains of assembly of DVD. The intervention of TDK is thus likely to be decisive because, within sight of the conflicts between the multinationals of cinema industry which divide the ones in favor exclusively of Blu-ray and the others exclusively in favor of HD DVD, that certainly will decide each one with better choosing the destination of the supports… Indeed, before the progress of TDK, the consumer would have been well annoyed because the two supports being incompatible between them from a point of view of reading, it would have been necessary to buy a reader data base and a reader HD DVD to be able to look at films of one or others. The first solution considered was to intend Blu-ray for data-processing storage and HD DVD for films. This solution was copied on a similar problem having opposed VHS to the Betamax. This last was of a quality higher than that of VHS, but its capacity of recording was less. Of advantage of manufacturers adopted the format invented by JVC: VHS was thus intended for the market general public and the Betamax for a professional use in its Betacam version. By analogy at that time, Sony and TDK thus allow us to have a VHS which with the quality of Beta.

Decreasing costs

The members of the Blu-ray foundation concentrated their efforts on the reduction of the production costs, while exploiting various aspects. April 15th, 2004 for example, Sony and Toppan Printing announced the success of the development of made up a Blu-ray disc to 51 % (in mass) of paper, which could reduce the production costs and improve its environmental side.

Compatibility

The Blu-ray foundation although it is not obligatory for the manufacturers, modified the Blu-ray.Assurant equipment retrocompatibility. This aspect returns more the migration attracting for the users, because they are not obliged to replace their collection of DVD.

Applications

Recorders and game consoles

The first recorder of Blu-ray discs was revealed by Sony on March 3rd, 2003, however, following many delays, the first compatible turntables Blu-ray should not appear before at the end of June 2006. September 1st, 2003, JVC and Samsung Electronics announced products based on Blu-ray technology with IFA, with Berlin, in Germany.

In March 2004, Sony and Matsushita announced the record sales of 50 Go the same year. However, there were then neither readers of living rooms, nor engravers of Blu-ray for Ordinateurs available. Exit in November 2006 at the Japan and the the United States and on March 22nd, 2007 in Europe, the new console of Sony, the PlayStation 3, is equipped in series with a Blu-ray reader. It is one of the first machines of living room to being equipped with this support. With the image of the PlayStation 2 and its reader DVD, Sony wants to make use of popularity of the video games and PlayStation mark to impose the use of Blu-ray.

Data storage for the personal computers

Sony launched a portable PC of the series VAIO which has the first reader/engraver Blu-ray (series AR). The first advertisement of a Blu-ray peripheral was in connection with the OPU81 by Philips, in January 2005 and planned for second half 2005, but was pushed back.

Information and updates: Forums Blu-ray.com “PC Dated Storage”

Criticisms

The need for a so great capacity a priori is not completely justified, in particular by the fact that simple a DVD can contain a film in high-definition provided that it is encodé in X264 (or a of the same format generation). Indeed, the choice of a better encoding than the Mpeg2 (used on the video DVD) makes it possible to increase the quantity of information stored in the same volumes of data.

Nevertheless the contents of the discs evolve/move, and one can S `wait to find more interactivity (in particular the DVD Interactifs which are often plays) or of different catch of sight in films. One can imagine new markets such as films 3D, which could benefit from a great capacity of data.

Support of the studios

As one could have envisaged it, Sony Pictures Entertainment and the studios MGM have both announced their support of the Blu-ray format.

October 3rd, 2004, the group 20th Century Fox announced that it joined the Blu-ray foundation, it did not decide which format yet to support well that it seems that it will be Blu-ray.

December 8th, 2004, the Walt Disney Company (and its division of audio-visual distribution, Buena Vista Home Entertainment) announced an exclusive support of the Blu-ray format.

January 7th, 2005, Vivendi Universal Games (VU Games) and Electronic Arts (EA Games) announced their support of the Blu-ray disc.

March 10th, 2005, Apple Computers Inc. joined the Blu-ray foundation.

October 20th, 2005, Warner Bros. announced its support with the Blu-ray format.

Alternatives to Blu-ray technology

The main competitor of Blu-ray is HD-DVD, supported by Toshiba and NEC. It has a lower density of data, but is less expensive to produce (because using the same assembly lines as the current DVD), as well as the peripherals of reading and writing.

November 29th, 2004, four Hollywood studios announced their projects of support of the HD-DVD rather than Blu-ray, although this support is not exclusive: New Line Cinema, Paramount Pictures, Universal Studios and Warner Bros. In fact, since August 2006, Paramount Pictures and Warner Bros in parallel produce Blu-ray versions of their films. However, in August 2007, Paramount Pictures suspends its support for Blu-ray; the films of the major will be from now on in a hurry only on discs HD-DVD.

Other competitors:

VMD, successor of EVD, a Chinese technology of optical disk in answer to the cost of licenses DVD.
DMD, technology succeeding the fluorescent Disc multi-layer
FVD (Forward Changeable Disc or general-purpose Disc " of before-garde"), Taiwanese technology using the red laser.
HVD, which stores the data in a numerical hologram.

Future optical media

According to the opinion of many researchers (including those of the Blu-ray foundation), the Blu-ray disc represents surely the last of technologies based on a plastic support and with a visible laser. The waves violets and ultraviolet shorter are strongly absorbed by the plastic used in the manufacture of the discs, and it would be difficult to manufacture with low costs of the lenses of higher quality. The light absorptive by the disc could not be read by the lens. Moreover, the majority of the plastics deteriorate under the ultraviolet rays, changing color and weakening. A system Ultraviolet would destroy the plastic used. Future technologies rather envisage the use of plates of glass (which does not absorb the ultra-violets as much as the plastic), of the ultraviolet lasers and/or the fluorescent media multi-layer.

the use of a media in holographic Mémoire could also take the continuation of the optical disks, the holographic Versatile Disc (hvd - in French general-purpose holographic Disque) could reach capacities of stokages of 3,9 terabytes.

Blu-ray Disc Association

This association gathers the principal partners of Blu-ray technology as well as the inventor of Blu-ray TDK and promotes the performances of this technology, vis-a-vis the rival format HD DVD. At March 15th, 2005, it includes/understands approximately 200 members of which most important are:

Acer
Apple
Dell
Hewlett-Packard
Hitachi - Maxell
LG
Mitsubishi
Panasonic
Philips
Pioneer
Samsung
Sharp
Sony
Sun Microsystems
TDK
Thomson
Twentieth Century Fox
Walt Disney
Warner Bros

See too

Playstation 3
Full-Hd TV
HVD
HD DVD

External bonds

The Authoritative Blu-ray Disc (data base) FAQ by Hugh Bennett
Foundation of the disc Blu-ray
List of the supporteurs of Blu-ray
Blu-ray vs. HD-DVD

Simple: Blu-ray

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