What is Blu-ray?

Blu-ray (Blu-ray Disc or BD) is a new generation 12 cm diameter optical disc format such as CD and DVD for high definition video and high-density data storage.

What is a Blu-ray Disc?

Although there is more capacity, storage capacity reaches 25 GB for one layer and 50 GB for a double layer. The PlayStation 3 game console can read double-layer discs.

Competition

Blu-ray, which has dominated HD DVD, has begun to change the DVD standard, as between VHS and Betamax or phonograph and gramophone.

Although others point out that the successor to the DVD will not be an optical disc, it will be a memory card. However, work is ongoing on HVD or Versatile Holographic Disc/Versatile Holographic Disc with 3.9 TB. The capacity limit on SD/MMC format cards is currently 128 GB. Plus, it has the advantage of being rewritable for at least five years.

In February 2008, after HD DVD support was dropped, Toshiba decided to abandon player production and research to develop its format.

There is also a third format, HD-VMD. This should also be called because it focuses on offering a high definition. Its primary disadvantage is that it does not have the support of large companies and is unknown to most of the public.

So, its primary commitment is to offer the same technology as other technologies at a more affordable price. Therefore, it is part of DVD technology (red laser). In the future, when blue laser technology becomes reliable and inexpensive, they plan to adapt it.

Blu-ray Working Principle

The Blu-ray disc uses a blue laser beam with a wavelength of 405 nanometers, as opposed to the red laser used in DVD players, which has a wavelength of 650 nanometers. This, along with other technological advances, allows for significantly more information to be stored on a disc of the same size and appearance as a DVD.

Blu-ray takes its name from the blue color of the laser beam. The blue e was removed from the original word. This is because, in some countries, a common word cannot be registered for a commercial name. It was developed jointly by a group of technology companies called the Blu-ray Disc Association (BDA), led by Sony and Philips.

DVD offered high quality, as it could offer a resolution of 720×480 (NTSC) or 720×576 (PAL). This is much more than the high-resolution capacity of 1920×1080 (1080p) offered by Blu-ray.

The latter is the format used by studios to archive their productions, which have already been converted to an export format. This will no longer be necessary. This will save the digital cinema industry time and effort to change the film resolution, thus reducing costs.

Capacity and Speed

The Blu-ray Disc Layer can hold approximately 25GB or approximately 6 hours of HD video and audio. A dual-layer disc with a capacity of approximately 50GB is also available on the market.

The data transfer rate is 36 Mbit/s (54Mbps for BD-ROM), but prototypes with 2x transfer speed are already in development. The standard BD-RE (rewritable format), BD-R (recordable), and BD-ROM formats are now available as part of version 2.0.

On May 19, 2005, TDK announced a 100GB four-layer Blu-ray Disc prototype. On October 3, 2007, Hitachi announced that it had developed a 100GB BD-ROM prototype that, unlike the TDK and Panasonic versions, was compatible with commercially available readers and required only a firmware upgrade. Hitachi also stated that it was developing a 200GB version.

Pioneer’s latest development allowed it to create a 20-layer Blu-ray disc with a total capacity of 500GB, although it was not compatible with commercially available reader units, as Hitachi did.

Blu-ray Technology

The minimum size of the spot that a laser can focus on is limited by diffraction and depends on the wavelength of the light beam and the numerical aperture of the lens used to focus it. In the case of the blue-violet laser used in Blu-ray discs, the wavelength is shorter than in previous technologies, thus increasing the numerical aperture.

Thanks to this and, the dual lens system, and a thinner protective cover, the laser beam can be focused much more precisely on the disc surface.

In other words, the readable information points on the disc are much smaller, and therefore, the same area can contain much more information. Finally, in addition to the improvements in optical technology, these discs include an improved data encryption system that allows more information to be packed in.

There were two problems that DVD tried to solve with Blu-Ray technology, so the structure is different. First of all, to read on a DVD, the laser has to pass through a 0.6 mm polycarbonate layer, where the laser can be broken into two beams of light. If this diffraction is high, for example, if it is scratched, it prevents the disc from being read.

However, this disc, which has only a 0.1 mm layer, avoids this problem because it travels less to the data layer. In addition, this layer is scratch-resistant. Secondly, if the disc is bent, for the same reason as in the case of DVDs, the distortion of the laser beam will cause errors by reading it in the wrong position. Thanks to the proximity of the lens and the fast convergence of the laser, distortion is lower, and possible reading errors can be avoided.

Another essential feature of Blu-ray discs is their resistance to scratches and dirt. The thin gap between the reading layer and the surface of the disc made these discs more prone to scratches and dirt than the standard DVD.

That is why it was first considered to market them in a kind of case or Caddy. The idea was scrapped thanks to the development by TDK of a protective substrate called Durabis, which not only compensates for the fragility but also provides extra protection against scratches of the disc in question. These protected DVDs also exist, but they are not necessary due to the larger layer thickness of 0.6 mm separating the data from the disc surface.

Region Codes

Each Blu-ray disc contains one or more region codes that indicate the location or areas of the world to which each distribution is directed. Sometimes, region codes are called regions. The specifications of each reproduction equipment indicate which region they can reproduce.

In theory, this allows film studios to control various aspects of the release, including content, date, and price, based on regional acquisition.

In practice, various players will allow you to play any disc, which can be modified for this purpose. Unlike data encryption, region codes allow for regional blocking originating in the video game industry.

Today, many multi-region players manage to bypass region locking and RCE locking by identifying and selecting the area supported by the Blu-Ray or by allowing the user to choose a specific location.

Others skip checking the region altogether. Some player manufacturers now freely provide information on how to turn off region locking. However, it seems to be disabled by default on some recent models.

This practice is, for many people, a violation of the World Trade Organization’s trade agreements despite the fact that there are no defined laws in this area.

Codec Components and BD-J

Blu-ray supports the same file systems as its predecessors, such as UDF and ISO 9660. Thanks to its storage capacity, video is high definition, and audio is up to 8 channels. It supports MPEG-2, MPEG-4, and VC-1 compression formats. MPEG-4 AVC and SMPTE VC-1 formats apply more advanced compression algorithms that provide high quality.

The MPEG-2 format is preserved for backward compatibility; It is almost obsolete, but it is still used to encode most of the first movies released in Blu-Ray format. This is because MPEG-4 AVC has high requirements, resource consumption, and high encoding time.

SMPTE VC-1 belongs to a consortium of companies dominated by Microsoft. This makes the degree of application of the codec unbalanced and favors HD DVD. Despite this, Microsoft has made significant efforts by holding seminars for companies in the industry to increase the acceptance of VC-1.

The inclusion of the Java platform in the Blu-ray recorded movie standard is new. This platform, called BD-J (Blu-ray Disc Java), gives developers more freedom to add content to the film.

It does not allow the display of a menu at any time during playback or the embedment of applications on the disc. The possibility of downloading additional content to the disc from the Internet is also planned.

For instance, this could include subtitles in specific languages, exclusive content, and edited scenes, among other things. On the other hand, some detractors say that it is unnecessarily complicated and that the copyrights of its use are excessive.

The audio compression codecs supported by Blu-ray are LPCM, DTS, Dolby Digital, Dolby True HD, and DTS-HD Master Audio.

The first three are preserved for backward compatibility with video as well as DVD. The last two represent a significant improvement, as they allow lossless compression.

In the table below, you can see how they maintain the same sampling frequency with a high transfer rate.

Blu-ray Copy Protection

Blu-ray systems include four anti-copy systems: AACS, BD+ Rom-Mark, SPDG, and ICT.

1) AACS

AACS is an improvement on the CSS of DVD, a product of Disney, Sony, Microsoft, IBM, Intel, Panasonic, Toshiba, and Warner Brothers initiative. Its primary function is to control the distribution of content. One of the consequences of this method of preventing copying is the creation of a blocklist of records.

This system allows each engraving model to be given a key. This makes it easy to keep track of which keys have been decrypted and which recorders allow copies. The result would be to revoke the key and not include it in subsequent players, guaranteeing incompatibility with the recorder.

This possibility has caused a great deal of controversy because if it were not done, users who never used it illegally would see how their recorders would become unusable. For now, they have announced that they will focus only on industrial players used for mass copying.

The system could even theoretically allow each player to be provided with a set of keys that could revoke the keys for that system and prevent playback on it.

Initially, the Blu-Ray Disc Association decided to include the restrictive managed copy (MC). The computer companies involved immediately protested because of the high restrictions.

They eventually decided that the content distribution control would be a mandatory managed copy (MMC) used in HD DVD, which allowed at least one copy of a disc to be sent to other devices.

The adoption of HD DVD influenced this decision, as the user could choose a less restrictive system in this regard.

2) BD+ and Rom-Mark

Blu-ray discs have a unique copy protection system called BD+ in their standards. This system allows dynamically changing the keys for cryptographic protection of original BDs.

If one of these keys is found, manufacturers only need to change the key. Thus, new units of the product cannot be hacked with the discovered key.

At HP’s request, the possibility was added for a user to purchase these keys to get a limited number of copies of the disc they bought and to obtain copyrights from users who use this format. BD+ can also check if the hardware has been modified and prevent playback.

It was also accepted that BDs carry a digital watermark. Under the name Rom-Mark, this technology will be present on all original discs. It will require a particular hardware component licensed in specific recording devices to add the watermark during copying. All Blu-ray readers must look for this mark. In this way, the BDA aims to stop the massive copying of this disc.

3) SPDG

SPDG is short for Self-Defending Digital Content and is a program that will be included in players.

It has a behavior similar to that of an operating system. Plus, it prevents recorders from recording the movies being watched.

This is also controversial, not only because of the excessiveness of the copy protection policy. It can also present a severe security vulnerability, as operating systems are susceptible to computer viruses.

4) ICT

ICT (Image Constraint Token) is a signal that prevents high-definition content from traveling over unencrypted media and, therefore, can be copied.

In practice, if the player is high definition but the cable from the player to the TV is analog, it limits the video output to 960×540 resolution.

ICT is not mandatory; each company freely decides whether to include it in its titles. For example, Warner is in favor of its use, while Fox is against it.

Compatibility

The BDA recommends that BR players play DVDs that comply with the above definition. Today, you can find hybrid CD, DVD, HD-DVD, and Blu-ray players.

JVC (Victor Corporation of Japan) is developing a triple-layer DVD/BD combination that allows standard DVD and BD to be on the same disc. In this way, you can buy a movie that can be viewed on existing DVD players and also have high definition if inserted into a Blu-ray player.

Two of the layers correspond to a dual-layer DVD (8.6 GB), and the third layer corresponds to a Blu-ray.

Despite the above, there are currently some insurmountable incompatibilities. This problem comes from the assembly lines. Manufacturers have had to invest heavily in their machines to start creating Blu-ray discs.

This is due to the vast difference in technology between this disc and DVD, especially the special protection layer of the former. Creating a Blu-ray takes 5 seconds. There is the possibility of creating hybrid Blu-rays: those with two layers dedicate one to the DVD type.

First, the associated studies decided not to make a degree in this method. However, rival HD DVD has released titles with this possibility, allowing users to purchase movies to watch on their DVD players and later on their HD DVD players. Blu-Ray studios have pulled back, and there have already been launches in this method since late 2006.

HD Ready, Full HD, and HDMI

This section tries to highlight the difference between compatibility and adaptation and how to get the most out of Blu-ray high definition. Compatibility refers to all televisions that allow you to play the content of that disc.

This is achieved with devices that carry the HD Ready or 1080i logo, which does not mean that you will get the most out of the high definition. This is because progressive search only guarantees that the minimum resolution is 720 lines panoramic (1280×720).

If what we want is high definition with a resolution of 1920×1080 in progressive mode, there must be devices marked under the Full-HD or 1080p logo.

Adaptation means a conversion that involves a loss in the audio and video signal. The latter includes HDMI, a connector that allows the native high-definition signal to be sent to guarantee maximum fluidity and quality of the scenes.

Any other connection, whether analog or digital, must adapt to the logical results. Even if it has an HDMI connector, it is recommended to look for devices with version 1.3, as it is currently the only version that supports all audio and video formats and doubles the transfer rate compared to version 1.2.

Any connector and medium used to connect the player to the display device must be HDCP compatible (HDMI) before the signal is converted to DVD quality. As you can see, those who decide on high definition should look for players with HDMI 1.3 connectors and devices with Full-HD.

You can see how Blu-ray technology allows a higher transfer rate for video. This difference has not been used in many cases due to several factors. First, the rate is variable, and choosing which one to use depends on the company, not the most. Second, the rate can have other benefits besides the transmission of the video.

Finally, the codec has had an impact; the companies that used it in the first use introduced MPEG-2. From the beginning, it was mainly encoded in VC-1. The transfer rate of audio is also higher on Blu-ray than on HD DVD.

To understand the differences between Blu-ray and HD DVD, you need to realize that while the former is a new technology that tries to increase performance, the latter aims to improve DVD support significantly.

Therefore, HD DVDs are in favor of Blu-ray, where new and expensive production equipment has to be installed, so a few changes in DVD production equipment are enough.

So, in terms of prices, the album has a lot to lose, as the costs are higher. This is reflected in the readers, for example. HD DVD players cost about half as much as Blu-ray, but this difference has decreased since early 2007. In contrast, movies have a similar cost.

As for hybrid titles, the Blu-ray system seems to be better, allowing you to assign each format to a layer without changing the faces.