What is Blu-ray?

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

What is Blu-ray?

What is Blu-ray Disc?

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

Competition

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

It is a memory card, although others point out that the successor of the DVD will not be an optical disc. However, work is ongoing on HVD or Versatile Holographic Disc with 3.9 TB. The capacity limit on SD/MMC format cards is currently 128 GB and has the advantage of being rewritable for at least 5 years.

In February 2008, after HD DVD support fell, Toshiba decided to quit player production and research to improve its format.

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

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

Working Principle

The Blu-ray disc uses a blue laser beam with a wavelength of 405 nanometers, unlike the red laser used in DVD players with a 650-nanometer wavelength. This, together with other technological advances, allows the storage of significantly more information than a DVD on a disk of the same size and appearance.

Blu-ray gets its name from the blue color of the laser beam. The letter e, which is blue from the original word, has been removed because in some countries a common word for a trade name cannot be registered. Developed jointly by a group of technology companies called Blu-ray Disc Association (BDA), managed by Sony and Philips.

The DVD offered high quality because it can offer 720×480 (NTSC) or 720×576 (PAL) resolution, which is much more than 1920×1080 (1080p) high definition capacity offered by Blu-ray.

The second is the format used by the studios, which were previously converted into a format to be exported, to archive their production. This will no longer be necessary, so the digital cinema industry will not have to spend effort and time to change the movie resolution, which will reduce costs.

Capacity and Speed

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

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

 Drive Speed
 Transfer Speed
 Transfer Speed
 Theoretical writing time (minutes)
 Mbit/s
MB/s
Double Layer
Double Layer
 1x
 36
 4,5
 90
 180
 2x
 72
 9
 45
 90
 4x
 144
 18
 22,5
 45
 6x
 216
 27
 15
 30
 8x
 288
 36
 11,25
 22,5
 12x
 432
 54
 7,5
 15

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

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

Technology

The size of the minimum spot 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-purple laser used in Blu-ray discs, the wavelength is shorter compared to previous technologies, therefore increasing the numerical aperture.

Thanks to this and the dual-lens system and a thinner protective cover, the laser beam can focus much more clearly on the disc surface.

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

DVD had two problems trying to solve with Blu-Ray technology, so the structure is different. First of all, to read on DVD, the laser must pass through a layer of 0.6mm polycarbonate, where the laser can break into two beams of light. This prevents the disc from being read if the diffraction is high, for example, if it is scratched.

However, having only a 0.1mm layer, this disc avoids this problem because it travels less to the data layer; Also, this layer is scratch resistant. Secondly, if the disc is bent, in the case of the DVD, for the same reason as the previous problem, the distortion of the laser beam will cause errors to be read in the wrong position. Thanks to the proximity of the lens and the rapid convergence of the laser, distortion is lower and possible reading errors can be avoided.

Another important feature of Blu-ray discs is their scratch and dirt resistance. The fine gap between the reading layer and the disc surface made these discs more susceptible to scratches and dirt than normal DVDs.

So it was first thought to market them in some kind of case or Caddy. The idea was scrapped by the TDK, called Durabis, thanks to the development of a protective substrate that not only compensates for fragility but also provides extra protection against the scratches of the disc in question. These protected DVD discs are also available but are not so necessary because of the larger layer thickness that separates the data from the disc surface by 0.6 mm.

Region Codes

Each Blu-ray disc contains one or more region codes indicating where each distribution of the world is directed to. Sometimes region codes are called regions. The characteristics of each reproductive equipment indicate which region they can reproduce.

Theoretically, this allows movie studios to control various aspects of the release, including content, date, and price based on region acquisition. In practice, various players allow you to play any disc or can be changed for this purpose. Unlike data encryption, region codes allow regional blocking from the video game industry.

Region Code
Area
A/1
America, East Asia (excluding mainland China and Mongolia),
Southeast Asia and other countries
B/2
Africa, Southwest Asia, Europe (excluding
Belarus, Russia and Ukraine), the Middle East, Oceania and other countries.
C/3
Central Asia, East Asia (Mainland China and Mongolia
only), South Asia, Central Eurasia (including Russia) and other countries.

Today, many multi-region players manage to unlock and unlock regional lock and RCE by defining and selecting the region supported by Blu-Ray or by allowing the user to select a specific region.

Others are skipping to fully control the area. Some player manufacturers now freely provide information on how to disable the regional lock, and some recent models seem to be disabled by default.

This practice is a violation of the trade agreements of the World Trade Organization for many people, although there is no defined law in this area.

Codec Components and BD-J

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

MPEG-2 format is preserved for backward compatibility; It is almost not used, 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 coding time.

SMPTE VC-1 belongs to a consortium of companies dominated by Microsoft. This makes the codec’s degree of application unbalanced and prefers HD DVD. Nevertheless, Microsoft has made remarkable efforts by organizing seminars for companies in the industry that have increased the acceptance of VC-1.

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

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

For example, subtitles in certain languages, special content, cutting scenes, among others. On the other hand, there are detractors who say it is unnecessarily complicated and usage copyrights are excessive.

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 major 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.

LPCM
DTS
Dolby Digital
DD True HD
DTS-HD
Transfer Rate
27Mbps
1536Kbps
640Kbps
18Mbps
18Mbps (HD DVD) 24,5Mbps (Blu-ray)
Discrete Channels
8
8
6
8
8
 Quantification
24b
24b
24b
24b
24b
Sampling Rate
192KHz
48KHz
48KHz
192KHz
192KHz

Copy Protection

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

   AACS

It is an improvement over the CSS of DVD, a product of the initiative of AACS, Disney, Sony, Microsoft, IBM, Intel, Panasonic, Toshiba, and Warner Brothers. Its main function is to control the distribution of the content. One consequence of this is that this anti-copy method creates a register blacklist.

This system allows a key to be given to each engraving model. This makes it easy to keep track of which keys are decrypted and which recorders allow copies; the result will be to cancel the key and not include it in subsequent players and to guarantee incompatibility with the recorder.

This possibility led to a huge controversy because, if 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 bulk copying.

The system could theoretically even allow each player to provide a set of keys for that system that could revoke the keys and only prevent them from playing.

Initially, the Blu-Ray Disk Association decided to include the restrictive managed copy (MC). The computer companies that were involved immediately protested due to their high restrictions.

Eventually, they decided that the content distribution control was a mandatory managed copy (MMC) used on the HD DVD, which allowed at least one copy of a disc to be sent to other devices.

This decision was influenced by the fact that the HD DVD adopted it, as the user could choose a less restrictive system in this regard.

   BD+ and Rom-Mark

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

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

At the request of HP, the possibility of a limited number of copies of a disk purchased by a user to purchase these keys and copyrights from users using this format has been added. BD+ can also check if the hardware has been replaced and prevent playback.

BDs were also accepted to carry digital watermarks. Under the name of Rom-Mark, this technology will be available on all original disks and will require a special hardware component licensed on certain recorders to add the watermark when copying. All Blu-ray readers should search for this brand. In this way, the BDA aims to stop a large copy of this disk.

   SPDG

SPDG is an acronym for Self-Protecting Digital Content and is a program to be included in players.

It has a behavior similar to that of an operating system and prevents recorders from recording watched movies.

This is also controversial, not only because of the excessive copy prevention policy but also because operating systems are susceptible to computer viruses, which can create a serious security vulnerability.

   ICT

ICT (Image Constraint Token) is a signal that prevents high-resolution content from traveling in unencrypted environments and therefore can be copied.

In practice, if the cable from the player to the television is analog, even though the player is in high definition, it is to limit the video output to 960×540 resolution.

ICT is not compulsory, each company freely decides whether or not it should be added to their headlines. For example, while Fox is in favor of using Warner, Fox is against it.

Compatibility

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

JVC (Japan Victor Company) is developing a three-layer DVD/BD combination that ensures that the standard DVD and BD are on the same disc. This way, you can buy a movie that can be seen on existing DVD players and also be high definition if it is placed on a Blu-ray player.

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

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

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

First, related studies decided not to gain degrees in this method. But rival HD DVD has released titles with this possibility, which allows users to purchase movies to watch on DVD players and later on HD DVD players. Blu-Ray studios have been withdrawn and there are already launches in this method since late 2006.

HD Ready, Full HD and HDMI

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

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

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

Adaptation means a conversion that includes a loss in audio and/or video signal. The latter includes HDMI, a connector that allows the sending of the local high definition signal to guarantee maximum fluidity and quality of the scenes.

All other analog or digital connections will need to adapt to logical results. Even if it has an HDMI connector, it is recommended to look at devices with version 1.3 since 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 media used to connect the player to the display device must be HDCP compliant (HDMI) before converting the signal to DVD quality. As you can see, those who decide to define high should look for players with HDMI 1.3 connectors and devices with Full-HD.

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

Finally, the codec affected the effects, the companies used in the first use released the MPEG-2; From the beginning, it was mainly coded in VC-1. The audio transfer rate is also higher than the HD DVD on Blu-ray.

To understand the differences between Blu-ray and HD DVD, you need to realize that while the first one is a new technology that tries to improve performance, the second wants to greatly improve DVD support.

Therefore, when new and expensive production equipment needs to be installed on Blu-ray, HD DVD is in favor of a few changes in DVD production equipment.

So the album has a lot to lose because the prices are higher, which is reflected, for example, to the readers. HD DVD players cost about half of Blu-ray, but at the beginning of 2007, this gap decreased. On the contrary, films have a similar cost.

When it comes to hybrid titles, the Blu-ray system looks better and allows you to assign each format to a layer without changing faces.

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