Although it has been on the market for some years now, and was initially considered the successor to DVD , the Blu Ray disc is still one of the newest optical disc formats. Of course there are other projects that are intended to replace it, such as the versatile holographic disk, which is capable of storing up to almost 4 TB of information . However, Blu Ray will remain on the market for many years to come thanks to its capabilities, competitive price and constant expansion among users.
Basically, Blu Ray is nothing more than a 12 cm optical storage disc. in diameter, the same size as DVD or CD, and was developed by a consortium called Blu-Ray Disc Association in order to obtain a storage medium capable of containing the large amount of data required by movies made on the spectacular high definition , in addition to other actors inherent to reducing costs.
In most cases, the most common Blu Ray discs are those with a storage capacity ranging from 25 to 50 GB, but Blu Rays of more than 100 GB capacity are also marketed in different layers.
It should be noted that the Blu-Ray in each of its layers can contain around 25 GB of information, which translated means about 6 hours of high definition video plus the corresponding audios . The media with the highest capacity is the four-layer Blu Ray , which can store more than 100 GB.
Blu Ray technical characteristics
While DVD uses a 650 nanometer laser, Blu Ray uses a 405 nanometer , making it possible to record more information on a disc of the same size.
The name Blu Ray (Blue = blue; Ray = lightning) comes from the technology used: a blue laser to read and write data. The “e” in “blue” was removed from the product name because in some regions of the world it is not possible to register a common word as a trade name.
As we mentioned, this optical disc standard was developed by the Blu-ray Disc Association (BDA) , but it was worked together with a group of companies in the electronic, computer and entertainment fields such as Sony, Apple, Samsung and Walt Disney Pictures , among others.
The Blu Ray stopped on the way to its top contenders such as DVD or HD DVD, while the first still is a strong competitor, offering a resolution of 720×480 in NTSC or 720×576 PAL, suitable for playback on most of the equipment present in homes around the world, while the HD DVD format has practically disappeared.
In terms of quality, Blu Ray offers a high definition display quality, that is to say 1920×1080, also called 1080p, an incredibly high jump compared to DVD.
One of the most impressive applications that can be obtained from the Blu Ray disc is the ability to reproduce content in 3D and in 4K quality (ultra high definition) , a feature highly requested at the time by the most important software developers, studios and production companies. cinema.
In addition to the obvious advantages in terms of its storage capacity and high definition display, one of the most outstanding characteristics of Blu Ray is the physical protection that it provides to its contents, since it is provided with a substrate that serves it as a barrier against scratches and scuffs, a technique that prevents damage and ensures good disc playback for many years.
Blu Ray operation and capacity
The Blu Ray optical disc format is one of its kind that offers the greatest storage capacity, which can reach up to 500 Gb, there is even talk of upcoming releases of 1 Tb (Terabyte) , thus far surpassing the rest of its competitors, such as the popular DVD .
To achieve this large storage capacity, the Blu Ray Disc has been developed so that it performs the reading and writing of the data through the use of a blue laser beam , hence the commercial name of the disc.
This blue laser beam used for reading and writing on Blu Rays makes it possible to significantly expand the amount of information stored in the different areas of the medium, due to the fact that it has a shorter wavelength than the conventional one.
Along these lines, unlike the red laser beam used in reading and writing DVDs, which have a wavelength of 650 nanometers, in the case of the blue laser beam, it is characterized by having a wavelength of 405 nanometers.
Amazing storage capacity
Through this technology, and added to a series of advances in terms of Blu-ray manufacturing materials, in this type of media it is possible to store up to 25 GB per layer, allowing a total storage of up to 500 GB in Blu-ray Blu-ray. 20 layers.
Although it may seem implausible, this storage capacity has been achieved in the same physical space and dimensions as the well-known DVD , so many assure that in the near future they will be totally replaced by Blu Ray discs, although today Blu Ray discs must compete with other storage technologies, such as memory cards.
Currently, the most common types of Blu Ray discs that can be purchased on the market are those that allow 25 GB to be stored on a single single layer medium, and up to 50 GB on double layer ones , which can hold approximately 12 hours video in high definition format with its corresponding audio in 5.1. These are used mainly in the world of entertainment, for which today most of the movies can be purchased on Blu Ray.
Regarding the transfer speed with which this type of media works, most of the optical discs of this type reach a data transfer speed of 2x, that is, 72 Mbit per second, although there are other faster ones, but they do It is true that these are the most common on the current market.
Like the DVD format, Blu-ray discs also have lines of the rewritable type, called BD-RE.
How does Blu Ray work?
Unlike DVD, in which the reading is done through a red laser beam that passes through the 0.6 mm thick layer of polycarbonate that the disc has, thus being able to cause a diffraction of the light beams and perform An erroneous reading, in the case of Blu Ray Disc, because it has been manufactured with a thin layer of 0.1 mm, the blue laser beam can perform the reading without errors, even when the medium is placed in an inclined way.
In this way, thanks to the proximity and easy access that the laser has on the medium, it is possible to perform a reading with less probability of distortion and errors in reading.
This precise reading, added to an optimized data coding system, allows the sectors destined to the readable information in the medium to be smaller , therefore the capacity of the disk is greater.
On the other hand, it should be noted that thanks to the incorporation of a much thinner protective layer than that found in DVDs, Blu-ray discs have greater resistance to bumps, scratches and dirt.
Copy protection on Blu Ray discs
In the world of entertainment, Blu Ray optical disc technology can be considered in many cases as the great successor to DVD , not only because of the storage capacities it has and its physical characteristics that make it a more robust medium, but it also has with a complete security method to avoid piracy.
For years, with the massification of the Internet and the possibility that this medium offers for the continuous downloading of audiovisual material from the Internet to any home computer anywhere in the world, the crime of piracy has spread to extreme levels.
Likewise, the ease of making copies of original DVDs through a simple tape recorder on each household’s computer has led to a parallel trade in fraudulent DVDs, known as “tricks.”
Such is the repercussion of this activity, that film production companies are in a constant search for a solution to the scourge of piracy , which can become the main reason for the total collapse of the industry.
In this regard, the Blu Ray disc has come to offer a real solution to the problem that its predecessor, the DVD, has not been able to overcome.
The Blu Ray Disc works with a complete method of copy protection, which consists of five systems , called AACS, BD + and ROM-Mark, SPDG and ICT, each of them with a specific function.
In principle, AACS is a system that has been developed based on the CSS used by DVD , but incorporating significant improvements. Its function consists of controlling the distribution of content, assigning a unique key for each model of Blu Ray disc recorder, in order to allow or not the copies that are made on said equipment.
On the other hand, Blu Rays have an exclusive anti-copy system called BD + , which is based on a cryptographic protection carried out through a key assigned to the Blu Ray disc itself, preventing their reproduction when the system detects that it is. of a copy.
In order to offer complete content protection, Blu Ray discs also have a digital watermark called ROM-Mark made with special devices, which is present on the original discs, and which is sought by players to allow display of content.
A fourth element in this method of copy protection is the SPDG system, which is a small program that Blu-ray disc players include, and by operating similar to any operating system, it makes it impossible to make a copy of the disc. that is inside.
Finally, the Image Constraint Token system, known by its acronym ICT , has also been incorporated , which consists of a signal that does not allow the transport of high definition content through unencrypted media.
However, despite the work done to prevent piracy, the truth is that the Blu Ray Disc also includes a copy management system called MMC , which allows copies of the original disc to be made to be used on other devices.
On the other hand, many assure that despite the arduous and intense work carried out to avoid piracy in the daily use of Blu Rays, there will always be hackers who manage to render the functions of these protection systems useless.
Blu Ray discs and multimedia codecs
Undoubtedly, thanks to the important benefits in terms of storage capacity that Blu Ray-type optical discs allow, we are facing one of the most suitable storage media for storage, especially for the entertainment industry.
There is no doubt that Blu Ray is here to stay, and that is why more and more manufacturers of electronic equipment are launching new products that allow this type of optical disc to be reproduced and recorded.
However, as it is a medium that allows storing ultra-high resolution video and audio of up to 8 channels, many consumers wonder what happens with the codecs that are implemented in many compression of multimedia files.
In principle, it should be clarified that Blu Ray discs can support all the types of files that their predecessors , that is to say that this type of medium can contain compressed files with the most commonly used codecs today, such as MPEG-2 and MPEG-4 .
Most of the Blu Ray movies that are marketed today have generally implemented MPEG-4 AVC AND SMPTE VC-1 codecs, because they use a series of more modern and sophisticated compression algorithms, which make possible to achieve higher image quality, to achieve a level similar to high definition.
Due to the fact that the MPEG-4 AVC video codec has higher requirements, uses a greater consumption of resources and requires a greater amount of time to carry out the encoding , initially the companies in the film industry had decided to launch the first Blu Ray of movies compressed with the MPEG-2 codec, although due to the quality it offers, it is undoubtedly a type of codec that finally became almost totally obsolete, given the possibilities offered by the MPEG-4 AVC.
Blu Ray discs also have support for videos encoded in SMPTE VC-1, although this will not be the codec that will be used the most in the future, due to a series of restrictions on the part of its developer.
It should be noted that the SMPTE VC-1 codec has been created by a group of companies led by Microsoft to support the HD DVD optical disc, which competes with Blu Ray, but because the latter prevailed over HD DVD, the Codec developers have decided to make it available to be supported by the BD.
The videos recorded on Blu Ray discs have incorporated this technology, under a platform called Blu Ray Disc Java (BD-J), which offers the possibility of including multimedia content made in this language within the movies.
This has allowed to create the most modern and advanced navigation menus for discs, which offers fabulous options such as being able to access interactive menus while the movie is playing, and even include some applications in the optical medium.
In addition, with the inclusion of the Java platform, it is possible to download additional content from the Internet to the Blu Ray disc, such as deleted scenes, extra subtitles, documentaries and a great variety of material that is available through the network.
With regard to audio, as we mentioned, Blu Ray Discs can contain sound tracks of up to 8 channels, thus achieving a unique audio quality.
The most used codecs
Among the codecs supported by Blu Ray discs, although they are many, the most widely used are LPCM, which is a type of uncompressed codec, DTS, Dolby Digital, Dolby True HD and DTS-HD Master Audio.
Both Dolby True HD and DTS-HD Master Audio are the most modern technology codecs, which perform lossless compression , allowing to contain 8-channel audio in maximum quality.