Introduction
The technology Blu-ray is the standard of the optical disk that came up with the proposal of replacing the DVD, both video players and computers. The measures a Blu-ray disc (or BD, for Blu-ray Disc) are the same as that of CDs or DVDs, however, this media is capable of storing very great volumes of the information, allowing the industry to offer films with images high-definition and extra features to be quite interesting. In addition, users can record on a single disk Blu-ray an amount of data that would require multiple media if the recording were to occur in CDs or DVDs. In this article, you will learn about the main features of the Blu-ray, understand how technology can store so much data and experience a little bit of its history.
Technology Blu-ray
The Blu-ray is a standard of optical disk designed for applications of video and data storage in general, as well as the is DVD. However, it has characteristics more advanced that the latter, for which reason it is considered to be his replacement. The main difference is storage capacity: in its simplest version, with a layer, you can save up to 25 GB of data, versus 4.7 GB for DVD. There is also a version with dual-layer capable of storing 50 GB of data. Manufacturers can still create versions with capacities different from these, for specific purposes. In April 2010, for example, the industry has made Blu-ray that can reach up to 128 GB capacity.
The the name Blu-ray gives clues about another feature of this default. The initial idea is that it adopted the term “Blue-ray”, “blue ray” in English. This name was given because the laser beam of the devices responsible by the reading of the discs is blue violet, unlike the CD and DVD, where the beam is red. But this has a good reason and more to the front you will know why. The letter ‘e’ was withdrawal of the designation because the phrase “blue ray” is widely used, which certainly would prevent your registration as a trademark. The full name for the media is Blu-ray Disc.
As is the case with CDs and DVDs, there are Blu-ray discs that can be written and rewritten. The version that comes out of the factory already recorded and does not allow rewriting is called BD-ROM DRIVE. The version that can only be written to once by the user is the BD-R. in turn, the version that can be recorded and re-recorded it is called BD-RE.
In what refers to the speed of data transfer in the recording of a Blu-ray, it will all depend on,essentially, the unit. On its lowest speed, 1X, is possible to get a transfer rate of 36 Mb/s (megabits per second), or about 4.5 megabytes per second. So, just knowing the speed of the device (this information is usually is available on a label or in the product manual) and multiply this value by the equivalent of 1X. For example, if the device works with 8X, simply multiply 8 by 36, which will be equal to 288 Mb/s transfer rate in read operations it follows a similar scheme, with a speed of 36 Mb/s, however, can-if reach 54 Mb/s in execution of the video.
Brief history of Blu-ray
The history of Blu-ray discs began at the end of the decade 1990, when the subject is “high definition videos” began to take shape. At the time, there was no type of disc able to store content with this feature but the situation began to change after the researcher Japanese Shuji Nakamura presented a diode blue laser that would allow the creation of disks of higher density.
On this account, some time after, Sony began to work two technologies of optical media, high density: UDO (Ultra Density Optical) and DVR Blue. The latter was a format rewritable and its development was next to the Pioneer.
The DVR Blue continued to be worked until February 2002 it was renamed to Blu-ray, at which time it was also created the consortium Blu-ray Disc Founders, formed by the companies responsible for the creation of the project and other interested later. Here are some of these members: Sony, Pioneer, LG, Dell, Philips, Samsung and 20th Century Fox.
Although Sony has released the first Blu-ray recorder in 2003, the technical specifications of the technology were completed only in 2004 and, subsequently, some details were reviewed. In the same year, the consortium responsible for the standard changed its name to Blu-ray Disc Association. To date the authority receives the participation of the new companies.
The operation of the Blu-ray
The Blu-ray discs have virtually the same dimensions a disk of CD or DVD, but it stores much more information. Observed this aspect, how is this possible? The secret it is precisely in such “blue ray”. On the devices DVD, the laser beam for reading and recording, in color red has a wavelength of 650 nanometers. Readers CD, this measure is 780 nanometers. In laser blue-violet, the Blu-ray, the wavelength is 405 nanometers. Thanks of this, the beam can focus on the information points of the disk with greater precision, allowing them to be smaller. As are smaller, fit more points in the media.
These points (or cavities) has a width of 0.15 micron in Blu-ray, while in the DVD this size is 0.4 micron. But the “magic” Blu-ray” not boils down to this: the track pitch (something, as a step of the trail), that is, the space that there is between the recording points, it is 0.74 micron on the DVD, while the Blu-ray this measure is 0,32 microns.
Despite having the same thickness as a CD or a DVD (about 1.2 mm), Blu-ray media are constituted differently. On the CD, the recording layer, that is, where the data are “fixed”, is “under” a structure polycarbonate (in a few words, a type of plastic) 1.2 mm. On the DVD, this layer is located between the two structures, polycarbonate 0.6 mm each, that is, in the “middle” of the disk. In turn, the layer recording of Blu-ray is “above” a structure of polycarbonate of 1.1 mm:
This characteristic of Blu-ray has two advantages: first, is that, at least theoretically, the cost of production of these disks is smaller, as the manufacturing process requires a single polycarbonate structure, unlike the DVD, which requires two for its way of manufacturing to remember, comparing roughly, a “sandwich”.
The main advantage, however, is in the reading of the Blu-ray. The way the DVD is made you can do with that, under certain circumstances, the structure of polycarbonate create a situation refractive that divides the beam of laser in two parts, an occurrence that can hinder the reading of the data. In addition, certain irregularities in the surface of media, such as a slight curvature or even dirt, you can do with that the beam from the laser to lose its accuracy because of a consequent distortion.
On Blu-ray, the fact the data layer being closer to laser without the beam has “cross” structure polycarbonate, drastically reduces problems such as those referred to in paragraph previous.
As informed at the beginning of the text, there are also media Blu-ray disc with two recording layers, thus enabling you to the storage of the double data: 50 GB. Thus, it is also possible to find Blu-ray recordable and rewritable with the following acronyms: BD-R DL and BD-RE DL. The ‘DL’ is the acronym for Dual Layer, that is, the “Dual Layer”.
In June 2010, came the official specification BDXL, which makes possible the manufacture of BD-R and BD-RE with three layers, resulting in 100 GB capacity storage, or disks BD-R with four layers and 128 GB. BDXL discs can only be read on devices compatible with this specification.
It is important to highlight that, in addition to the layers of polycarbonate and write, Blu-ray come with other, as the layers of protective and reflective, for example.
High-definition
One of the features of the Blu-ray is its ability to offer videos in high definition (High-Definition – HD), which results in visual content with excellent quality image. In almost any the latest technology in the form of videos, this is a common feature, that causes the terms as “720p” and “1080p” can be found easily. But, what does this mean? These designations make it easier the identification of the amount of pixels (a pixel corresponds a point that represents the smallest part of an image) supported by the the device, in addition to the use of progressive scan or interlaced scan. In progressive scan, all lines of pixels of the screen are updated simultaneously. In turn, in the interlaced scan, the first the lines pairs receive the update, and then the lines odd (or rather, a schema of the type: line yes, line not). In general, the mode progressive scan provides the best quality image.
Thus, the letter ‘p’ existing in 720p, 1080p and other resolutions, indicates that the mode used is progressive scan. If it is used for interlaced scan, the letter used is ‘i’ (for example, 1080i). The number, in turn, indicates the amount of lines of pixels in the horizontal. This means that the resolution to 1080p, for example, account with 1080 horizontal lines, and works with progressive scan. Here are some examples resolution:
1080i = 1920×1080 pixels with interlaced scan;
1080p = 1920×1080 pixels with progressive scan;
720i = 1280×720 pixels with interlaced scan;
720p = 1280×720 pixels with progressive scan.
Blu-ray versus HD-DVD
The choice of the market by Blu-ray as the successor to the DVD not occurred an hour to the other. The standard, in fact, they played in the preference industry with other formats, especially the HD-DVD, acronym for High-Definition DVD (also called High Density DVD). The “feud” between these two technologies lasted about 4 years old. On one hand, the Sony supported Blu-ray from a consortium format for dozens of companies, among them, Apple, LG, Philips, Dell and the Panasonic. On the other, the Toshiba championed HD-DVD, also with the support of several companies, such as Intel, NEC, and Universal Pictures.
In the laser of the HD-DVD, the wavelength is 400 nanometers, therefore, like with the Blu-ray disc (405 nanometers). The color of the beam it is also bluish, and the dimensions of the discs healthy the same. In addition, the technology is also able to to offer high-definition content. However, the HD-DVD loses in terms of capacity: a disk with a data layer stores 15 GB, and a media dual layer stores up to 30 GB. This is because the cavities of the layer data of the HD-DVD has a 0.2 micron(remember, on Blu-ray this measurement is 0.15 micron) and the your track pitch is 0.40 micron (compared to 0,32 micron the Blu-ray disc).
However, this disadvantage was not decisive for the “victory” of Blu-ray discs because the capacity of the HD-DVD is enough for the purposes of the entertainment industries, not to mention that, at least theoretically, the production cost of media this format is smaller. What happened was that the support to the Blu-ray by part manufacturers, film distributors and other companies has been increasing in such a way that eventually became clear to the market which default if you become the winner.
The “final blow” against the HD-DVD was given when Toshiba announced, in February 2008, which would no longer manufacture products with the technology. In August 2009, the company has applied for membership in the consortium Blu-ray Disc Association, as shown in this note published in the AbbreviationFinder News.
Control geographic
As with the DVD, Blu-ray for movies feature control geographic to hinder distribution practices illegal. With this scheme, a Blu-ray disc manufactured for a particular the region will only work on devices produced for this area, or in devices that accept all divisions. However, while the DVD has 6 regions (Brazil, for example, is region 4 and Uk is region 2), the Blu-ray has only three:
– Region 1 (or A): for all over the American continent and to Central Asia;
a Region 2 (or B): for Europe, the Middle East, Africa and Oceania;
– Region 3 (or C): to China, to Russia, Asia the south and Asia to the island.
Therefore, when Brazil is applied to region 1, while that Portugal is destined for region 2.
Protection against copies
The Blu-ray not only has the control geographic to handle with alleged illegal copies. The standard can also rely on other means of protection. Here is a brief description of them:
– AACS (Advanced Access Content System): technology that “protects” the content of the media of movies through encryption to avoid copies undue disks. For this, the manufacturers of Blu-ray drives receive decryption keys that serve as communication with an existing key in the media. Thus, the device can execute the contents of the disk. Getting the last key, it is possible to make copy of the content, but obtaining it usually depends on from the manufacturer key. If this is “captured” and become so known, Blu-ray media manufactured subsequently may not be performed on devices that use this key. As this measure may penalize innocent users, the industry states use the AACS only in industrial devices. This technology it was also employed in the HD-DVD;
– BD+: based on a system called Self-Protecting Digital Content, uses a “virtual machine” for verify cryptographic keys on the disks, and thus identify which are original. Copies of undue will incorrect codes, preventing the perfect use of the content;
– ROM Mark: also called BD-Rom Mark, it is a special kind of watermark that should be present in all Blu-ray original, and that should be read by any device player. It is necessary a special mechanism for that this tag is inserted in the media of the copy;
– ICT (Image Constraint Token): this feature limits the resolution the video from the Blu-ray transfer is not protected and that, therefore, may allow copies of undue. Technical controversy, because it may harm the user who uses a cable more simple to connect your Blu-ray player to the tv, for example.
In fact, all of these mechanisms are considered controversial, since it can harm the user’s experience with the technology Blu-ray. In addition, these resources are not infallible: the AACS and BD+, for example, have already been “broken”.
Blu-ray 3D
Cinemas with 3D projection are emerging in a number of countries. At the time of closing of this article, the Brazil already had a room of the kind in the city of São Paulo (SP) and another one in Curitiba (PR). But how about being able to see videos with 3D effects to be quite interesting on the screen of your TV? This is the proposal of the Blu-ray 3D.
This is a specification adopted by the Blu-ray Disc Association at the end of 2009 able to take advantage of the full potential of technology Blu-ray to play 3D content on high definition (full HD).
For this, the Blu-ray 3D makes use of the codec, Multiview Video Coding (VMC), a sort of evolution of the ITU-T H. 264/MPEG-4, the standard used in Blu-ray “normal”. The VMC is able to provide a resolution of 1080p for each eye and also to optimize certain effects that reinforce still more the sense of three-dimensionality.
An interesting feature of the Blu-ray 3D is that the movies in this technology, generally, can be run on Blu-ray, “normal”, but obviously without the three-dimensional effects.
The only problem is the screen: the user needs to use monitors or tvs compatible with the reproductions in 3D, which is hard to find, at least for a while, there may be also the need of use of special glasses to the perfection of the visualization of the images.
Ending
The Blu-ray may have won the contest to become the successor to DVD, but your chances of that does not reach the same success that this last are great. And there are a number of reasons for this. For a start, the excess protection causes some users “torçam the nose” for the technology, not to mention that all of this apparatus anticópias can increase the costs of production, at least in theory. In addition, Internet connections are getting faster, which causes a lot of people prefer to receive videos in high definition over the Internet. There still is the fact that pay TV services are also offering high-definition content, especially in first world countries. This even adds to the devices that allow a user to record these videos channels and watch later. What will happen, in fact, only we will know with all the time.
