BLU RAY DISC - A SEMINAR

 

1. INTRODUCTION

          Blu-ray disc (BD) is appropriately named after the blue laser used to write the data. The first blue laser was developed in 1996 by Shuji Nakamura (Nichia Corporation).In 2002, an alliance was formed, called the Blu-ray Disc Association, including the likes of Sony, Samsung, Sharp, Hewlett-Packard, and Royal Phillips. The “e” is intentionally left out of the name due to trademark restrictions.

          In the mid 1990s, commercial HDTV sets were finally starting to enter a larger market. However, there was no good, cheap way to record or play back HD content. Indeed, there was no media that could store that amount of data, except JVC's Digital VHS and Sony's HD Betacam. However, it was well known that using lasers with shorter wavelengths would enable optical storage with higher density. When Shuji Nakamura invented practical blue laser diodes, it was a sensation, although a lengthy patent lawsuit delayed commercial introduction.


2. History of Blu-ray Disc

          When the CD was introduced in the early '80s, it meant an enormous leap from traditional media. Not only did it offer a significant improvement in audio quality, its primary application, but its 650 MB storage capacity also meant a giant leap in data storage and retrieval. For the first time, there was a universal standard for pre-recorded, recordable and rewritable media, offering the best quality and features consumers could wish for themselves, at very low costs.

          Although the CD was a very useful medium for the recording and distribution of audio and some modest data applications, demand for a new medium offering higher storage capacities rose in the '90s. These demands lead to the evolution of the DVD specification and a 5-10 x increase in capacity. This enabled high quality, standard definition video distribution and recording. Furthermore, the increased capacity accommodated more demanding data applications. At the same time, the DVD spec used the same form factor as the CD, allowing for seamless migration to the next generation format and offering full backwards compatibility.

          Now, in the next millennium, high definition video demands a new solution. History proved that a significant 5-10 x increase in storage capacity and the ability to play previous generation formats are key elements for a new format to succeed. This new format has arrived with the advent of Blu-ray Disc, the only format that offers a considerable increase in storage capacity with its 25 to 50 GB data capacity. This allows for the next big application of optical media: the distribution and recording of high definition video in the highest possible quality. In fact, no other proposed format can offer the data capacity of Blu-ray Disc, and no other format will allow for the same high video quality and interactive features to create the ultimate user experience. As with DVD, the Blu-ray Disc format is based on the same, bare disc physical form factor, allowing for compatibility with CD and DVD.


3.Blu-ray Disc format finalized and launched

          The Blu-ray Disc physical specifications were finished in 2004. In January 2005, development of a hard coating polymer for Blu-ray Discs was announced. The cartridges, no longer necessary, were scrapped. The BD-ROM specifications were finalized in early 2006. AACS LA, a consortium founded in 2004, had been developing the DRM platform that could be used to securely distribute movies to consumers. However, the final AACS standard was delayed, and then delayed again when an important member of the Blu-ray Disc group voiced concerns.


4. Evolution

         

          The figure shows the evolution of Blu Ray Discs from CD’s and DVD’s.

 


5. Building a Blu-ray Disc

 

          Blu-ray discs not only have more storage capacity than traditional DVDs, but they also offer a new level of interactivity. Users will be able to connect to the Internet and instantly download subtitles and other interactive movie features. With Blu-ray, you can:

  • Record high-definition television (HDTV) without any quality loss
  • Instantly skip to any spot on the disc
  • Record one program while watching another on the disc
  • Create playlists
  • Edit or reorder programs recorded on the disc
  • Automatically search for an empty space on the disc to avoid recording over a program
  • Access the Web to download subtitles and other extra features

          Discs store digitally encoded video and audio information in pits -- spiral grooves that run from the center of the disc to its edges. A laser reads the other side of these pits -- the bumps -- to play the movie or program that is stored on the DVD. The more data that is contained on a disc, the smaller and more closely packed the pits must be. The smaller the pits (and therefore the bumps), the more precise the reading laser must be.

          Unlike current DVDs, which use a red laser to read and write data, Blu-ray uses a blue laser (which is where the format gets its name). A blue laser has a shorter wavelength (405 nanometers) than a red laser (650 nanometers). The smaller beam focuses more precisely, enabling it to read information recorded in pits that are only 0.15 microns (µm) (1 micron = 10-6 meters) long -- this is more than twice as small as the pits on a DVD. Plus, Blu-ray has reduced the track pitch from 0.74 microns to 0.32 microns. The smaller pits, smaller beam and shorter track pitch together enable a single-layer Blu-ray disc to hold more than 25 GB of information -- about five times the amount of information that can be stored on a DVD.

 

         

          Each Blu-ray disc is about the same thickness (1.2 millimeters) as a DVD. But the two types of discs store data differently. In a DVD, the data is sandwiched between two polycarbonate layers, each 0.6-mm thick. Having a polycarbonate layer on top of the data can cause a problem called birefringence, in which the substrate layer refracts the laser light into two separate beams. If the beam is split too widely, the disc cannot be read. Also, if the DVD surface is not exactly flat, and is therefore not exactly perpendicular to the beam, it can lead to a problem known as disc tilt, in which the laser beam is distorted. All of these issues lead to a very involved manufacturing process.


6. How Blu-ray Reads Data

 

          The Blu-ray disc overcomes DVD-reading issues by placing the data on top of a 1.1-mm-thick polycarbonate layer. Having the data on top prevents birefringence and therefore prevents readability problems. And, with the recording layer sitting closer to the objective lens of the reading mechanism, the problem of disc tilt is virtually eliminated. Because the data is closer to the surface, a hard coating is placed on the outside of the disc to protect it from scratches and fingerprints.

 

 

          The design of the Blu-ray discs saves on manufacturing costs. Traditional DVDs are built by injection molding the two 0.6-mm discs between which the recording layer is sandwiched. The process must be done very carefully to prevent birefringence.

  1. The two discs are molded.
  2. The recording layer is added to one of the discs.
  3. The two discs are glued together.

          Blu-ray discs only do the injection-molding process on a single 1.1-mm disc, which reduces cost. That savings balances out the cost of adding the protective layer, so the end price is no more than the price of a regular DVD.


7. Disc Structure

 

Laser and Optics

          Blu-ray uses a "blue" (technically violet) laser operating at a wavelength of 405 nm to read and write data. Conventional DVDs and CDs use red and near infrared lasers at 650 nm and 780 nm respectively.

          The blue-violet laser's shorter wavelength makes it possible to store more information on a 12 cm CD/DVD sized disc. The minimum "spot size" on which a laser can be focused is limited by diffraction, and depends on the wavelength of the light and the numerical aperture of the lens used to focus it. By decreasing the wavelength, increasing the numerical aperture from 0.60 to 0.85 and making the cover layer thinner to avoid unwanted optical effects, the laser beam can be focused to a smaller spot. This allows more information to be stored in the same area. In addition to the optical improvements, Blu-ray Discs feature improvements in data encoding that further increase the capacity.

 


Hard-Coating Technology

          Since the Blu-ray data layer is closer to the surface of the disk, compared to the DVD standard, it was at first more vulnerable to scratches. The first discs were housed in cartridges for protection. Later a company developed a working scratch protection coating for Blu-ray discs. Sony's rewritable media are sprayed with a scratch-resistant and antistatic coating.

 


8. Software standards

 

Codecs

          Codecs are compression schemes that store audio and video more efficiently, either giving longer play time or higher quality per megabyte. There are both lossy and lossless compression techniques.

          The BD-ROM specification mandates certain codec compatibilities for both hardware decoders (players) and the movie-software (content). For video, all players are required to support MPEG-2, H.264/AVC, and SMPTE VC-1. MPEG-2 is the codec used on regular DVDs, which allows backwards compatibility. H.264/AVC was developed by MPEG and VCEG as a modern successor of MPEG-2. VC-1 is another MPEG-4 derivative codec mostly developed by Microsoft.

          For audio, BD-ROM players are required to support Dolby Digital AC-3, DTS, and linear PCM. BD-ROM titles must use one of the mandatory schemes for the primary soundtrack. A secondary audio track, if present, may use any of the mandatory or optional codecs. 

 


Java Software Support

          As a mandatory part of the standard, it was announced that Sun Microsystems' Java cross-platform software environment would be included in all Blu-ray Disc players. Java is used to implement interactive menus on Blu-ray Discs, as opposed to the method used on DVD video discs, which uses pre-rendered MPEG segments and selectable subtitle pictures, which is considerably more primitive and less seamless. Java creator James Gosling, at the conference, suggested that the inclusion of a Java Virtual Machine as well as network connectivity in BD devices will allow updates to Blu-ray Discs via the Internet, adding content such as additional subtitle languages and promotional features that are not included on the disc at pressing time.

Digital Rights Management (DRM)

          BD+ was developed by Cryptography Research Inc. and is based on their concept of Self-Protecting Digital Content. BD+ is effectively a small virtual machine embedded in authorized players. It allows content providers to include executable programs on Blu-ray Discs. Such programs can:

  • Examine the host environment, to see if the player has been tampered with. Every licensed playback device manufacturer must provide the BD+ licensing authority with memory footprints that identify their devices.
  • Verify that the player's keys have not been changed.
  • Execute native code, possibly to patch an otherwise insecure system.
  • Transform the audio and video output. Parts of the content will not be viewable without letting the BD+-program unscramble it.

          If a playback device manufacturer finds that its devices have been hacked, it can potentially release BD+-code that detects and circumvents the vulnerability. These programs can then be included in all new content releases.


10. Blu-ray Disc Key Characteristics


- Broadest Industry Support
- Lifespan
- Content Protection
- Cost
- Capacity
- Robustness of Disc 

 

Broadest Industry Support

          History has shown that unified industry support for a particular format is most likely to lead to success. Therefore, the participation of the world's most renowned consumer electronics manufacturers and IT companies are leading in the success of the best standard for next-generation storage: Blu-ray Disc. Blu-ray Disc is supported by leading hardware manufacturers across the CE and IT fields from the U.S., Europe, Japan and Korea, including Dell, HP, Hitachi, LG Electronics, Matsushita (Panasonic), Mitsubishi, Pioneer, Philips, Samsung, Sharp, Sony and Thomson/RCA. Finally, major blank media manufacturers including TDK are supporting the Blu-ray Disc format as the successor of DVD. This broad industry support will lead to a broad selection of Blu-ray Disc products, including home video decks, PC drives, PCs line-fitted with Blu-ray Disc drives and blank media, to be available when the format is launched in the various regions in the world.

 

Lifespan

          The Blu-ray Disc format is designed to stay relevant for at least 10 to 15 years. Its high storage capacity of 25 to 50 GB allows for the best-possible High Definition video quality and satisfies even the most demanding data storage needs. As we have seen with DVD in the past, most premium titles require two discs. This is why Blu-ray Disc incorporates the additional storage space that is required for a High Definition feature film including bonus bonus material in the new standard from the beginning. Formats with a lesser capacity are only suitable as interim solutions, requiring them to be replaced much sooner than a format that takes tomorrow's data storage needs into account from day one. This will of course require multiple investments in production equipment, and will lead to increased consumer confusion.  

Content Protection

          Blu-ray Disc provides some of the strongest copy protection methods ever developed for any consumer format. It makes Blu-ray Disc the best choice for any content publisher wanting assurance that their valuable assets are protected from piracy. Based on feedback from the content industry and taking a cue from the lessons learned by other formats, the Blu-ray Disc format incorporates a robust copy protection mechanism, which not only relies on implementation at the playback device, but which also includes precautions at replicator level, which will be strictly controlled. Unlike the voluntary implementation of CSS protection in DVD, the copy protection mechanism for Blu-ray Disc is mandatory and will be governed by strict licensing procedures.

Cost

          Blu-ray Disc is developed to offer the best long-term profitability model for content providers. Although it might require a nominal investment in advance, it provides greater and longer-term profit potential. This is because the format is designed to last for a period of at least 10 to 15 years. Due to its enormous storage capacity, short term replacement of the technology is unnecessary, unlike other format proposals that might require less investment in advance, but higher investments in the long term due to the replacement of the technology when it becomes outdated. At comparable volumes, Blu-ray Disc production costs are within 10% of DVD production costs, although a Blu-ray Disc offers 5-10 x the capacity. It is by far the cheapest format measured in cost per GB. Since Blu-ray Disc requires fewer slots in a replication line compared to other formats, it will bring costs on par with DVD, or even cheaper, much sooner. Production facilities can produce many more Blu-ray Discs in the same time period as DVDs. Also, contrary to some rumors circulating, Blu-ray Discs do not require cartridges for any of the format variations (BD ROM, BD RE, and BD R).

Capacity

          The Blu-ray Disc format offers the highest capacity of any consumer media format to date, also greatly surpassing the capacity of other format proposals. Blu-ray Disc's huge capacity allows not only for the highest quality High Definition video to be recorded at large bitrates (thereby eliminating the need for tight compression that could affect picture quality), it also opens the doors to new and existing applications. Think of extra sessions on a disc that could be unlocked when a user's Blu-ray Disc player connects to the Internet to validate authorization. Or what about bonus material and special features that will eventually also be recorded in High Definition quality? With Blu-ray Disc's large capacity, these extras can be included in high quality on the same disc, so there is no need for separate bonus discs to accompany the movie title. Only Blu-ray Disc will be able to offer these value-added options.

Robustness of Disc

          As the result of recent breakthroughs in the development of hard coating for Blu-ray Disc, the discs offer much stronger resistance to scratches and fingerprints than other existing and proposed formats. Hard-coated Blu-ray Discs do not require a cartridge and can be used as a bare disc, similar to DVD and CD. This avoids extra production costs, and allows for small form factor applications, such as the implementation of Blu-ray Disc drives in a notebook computer. The hard-coating technology is used for BD ROM discs, giving them the same bare disc look and feel consumers know from DVD, and it can be applied to rewritable and recordable Blu-ray Discs as well.


11. Backward compatibility

          While it is not compulsory for manufacturers, the Blu-ray Disc Association recommends that Blu-ray Disc drives should be capable of reading standard DVDs for backward compatibility. For instance, Samsung's first Blu-ray Disc drive can read CDs, regular DVDs, and Blu-ray Discs. All other Blu-ray Disc players that have been released so far are also capable of DVD playback, though not all support CD playback.

 

 

 


12. Blu-ray Disc / HD DVD comparison

 

          The primary rival to Blu-ray Disc is HD DVD. Due to the format war, both sides are currently vying to promote their format as the best choice for studios and consumers. Both formats are intended as successors to DVD, capable of higher quality video and audio playback, and of greater capacity when used to store video, audio, and computer data. Blu-ray and HD DVD share most of the same methods of encoding media onto disks with each other, resulting in equivalent levels of audio and visual quality, but differ in other respects such as storage capacity, interactive capabilities, Internet integration, usage control and enforcement, and even in the degree to which their specifications are fixed.


13. Ongoing development

 

Front side of an experimental Blu-ray Disc

          Although the Blu-ray Disc specification has been finalized, engineers continue working to advance the technology. Quad-layer (100 GB) discs have been demonstrated on a drive with modified optics and standard unaltered optics. Hitachi stated that such a disc could be used to store 7 hours of 32 Mbit/s video (HDTV) or 3.5 hours of 64 Mbit/s video. Furthermore TDK announced in August 2006 that they have created a working experimental Blu-ray Disc capable of holding 200 GB of data on a single side, using six 33 GB data layers.

          Also behind closed doors at CES 2007, Ritek has revealed that they had successfully developed a High Definition optical disc process that extends the disc capacity of both competing formats to 10 layers. That increases the capacity of the discs to 250 GB for Blu-ray compared to 150 GB for HD DVD using the same process. However, they noted that the major obstacle is that current reader and writer technology does not support the additional layers.

          JVC has developed a three layer technology that allows putting both standard-definition DVD data and HD data on a BD/DVD combo. If successfully commercialized, this would enable the consumer to purchase a disc which could be played on current DVD players, and reveal its HD version when played on a new BD player. This hybrid disc does not appear to be ready for production and no titles have been announced that would utilize this disc structure.

          In January 2007, Hitachi showcased 100 GB Blu-ray Disc, which consists of four layers containing 25 GB each. Unlike TDK and Panasonic's 100 GB disc, they claim this disc is readable on standard Blu-ray drives that are currently in circulation, and it is believed that a firmware update is the only requirement to make it readable to current players and drives.

 

 


14. Variants Released

 

BD9 / Mini-Blu-ray Disc

          BD9 is a red laser DVD with BD contents on it. This disc should be rotated at 3x speed or more to satisfy the minimum transfer rate of 30.24 Mbit/s. These disks can be used for private storing. BD9 was originally proposed by Warner Home Video, as a cost-effective alternative to regular Blu-ray discs. It is similar to HD DVD's 3x DVD

 

AVCREC

          AVCREC is a standard for storing BD content on red laser DVDs using H.264/MPEG-4 AVC compression. It is similar to HD REC for HD DVD.

 

Blu-ray Disc Recordable

          Blu-ray Disc recordable refers to two optical disc formats that can be recorded with an optical disc recorder. BD-R discs can be written to once, whereas BD-RE can be erased and re-recorded multiple times. As of January 2008, BD-R/RE drives up to 6x speed are available from retailers for about US$450, and 4x single-layer BD-R discs, with a capacity of 25 GB, can be found for around US$12. The theoretical maximum speed for Blu-ray Discs is about 12x as the speed of rotation (10,000 rpm) causes too much wobble for the discs to be read properly, similar to the 20x and 52x respective maximum speeds of DVDs and CDs.

          Consumers should be aware that most commercial players, like the Samsung BD-UP5000, will not play a BD-R or BD-RE disk at all. In other words, the only media they will play are commercial Blu-ray movie disks, not movies made on a computer Blu-ray recorder. As a result, consumers cannot buy a Blu-ray disk recorder for their home movies and watch them on most commercial Blu-ray players. Some early -player models permitted this, but after a grace period, new versions of player firmware prohibit it.

 

HD DVD / Blu-ray hybrid discs

          Total Hi Def (Total HD) hybrid discs support both HD DVD and Blu-ray, HD DVD on one side (up to two layers) and Blu-ray on the other side (up to two layers). The project was finally cancelled in January 2008 when declaration of dropping HD DVD in favour of publishing exclusively on Blu-ray was made - thus eliminating the need for a hybrid disk.


15. Blu-ray Disc Applications


- High Definition Television Recording
- High Definition Video Distribution
- High Definition Camcorder Archiving
- Mass Data Storage
- Digital Asset Management and Professional Storage

          The Blu-ray Disc format was designed to offer the best performance and features for a wide variety of applications. High Definition video distribution is one of the key features of Blu-ray Disc, but the format's versatile design and top-of-the-line specifications mean that it is suitable for a full range of other purposes as well.

 

High Definition Television Recording

          High Definition broadcasting is vastly expanding in the U.S. and Asia. Consumers are increasingly making the switch to HDTV sets to enjoy the best possible television experience. The Blu-ray Disc format offers consumers the ability to record their High Definition television broadcasts in their original quality for the first time, preserving the pure picture and audio level as offered by the broadcaster. As such it will become the next level in home entertainment, offering an unsurpased user experience. And since the Blu-ray Disc format incorporates the strongest copy protection algorithms of any format or proposal to date, the format allows for recording of digital broadcasts while meeting the content protection demands of the broadcast industry.

 

High Definition Video Distribution

          Due to its enormous data capacity of 25 to 50 GB per (single-sided) disc, the Blu-ray Disc format can store High Definition video in the highest possible quality. Because of the huge capacity of the disc, there is no need to compromise on picture quality. Depending on the encoding method, there is room for more than seven hours of the highest HD-quality video. There is even room for additional content such as special features and other bonus material to accompany the High Definition movie. Furthermore, the Blu-ray Disc movie format greatly expands on traditional DVD capabilities, by incorporating many new interactive features allowing content providers to offer an even more incredible experience to consumers. An Internet connection may even be used to unlock additional material that is stored on the disc, as there is enough room on the disc to include premium material as well.

 


High Definition Camcorder Archiving

          As the market penetration of High Definition TV sets continues to grow, so does the demand of consumers to create their own HD recordings. With the advent of the first HD camcorders, consumers can now for the first time record their own home movies in a quality level unlike any before. As these camcorders are tape-based, consumers cannot benefit from the convenience and direct access features they are used to from DVD players and recorders. Now, the Blu-ray Disc format, with its unprecedented storage capacity, allows for the HD video recorded with an HD camcorder to be converted and recorded on a Blu-ray Disc. When the HD content is stored on a Blu-ray Disc, it can be randomly accessed in a way comparable to DVD. Furthermore, the disc can be safely stored for many years, without the risk of tape wear.

Mass Data Storage

          In its day, CD-R/RW meant a huge increase in storage capacity compared to traditional storage media with its 650 MB. Then DVD surpassed this amount by offering 4.7 to 8.5 GB of storage, an impressive 5-10 x increase. Now consumers demand an even bigger storage capacity. The growing numbers of broadband connections allowing consumers to download vast amounts of data, as well as the ever increasing audio, video and photo capabilities of personal computers have led to yet another level in data storage requirements. In addition, commercial storage requirements are growing exponentially due to the proliferation of e-mail and the migration to paperless processes. The Blu-ray Disc format again offers 5-10 x as much capacity as traditional DVD resulting in 25 to 50 GB of data to be stored on a single rewritable or recordable disc. As Blu-ray Disc uses the same form factor as CD and DVD, this allows for Blu-ray Disc drives that can still read and write to CD and DVD media as well.

Digital Asset Management and Professional Storage

          Due to its high capacity, low cost per GB and extremely versatile ways of transferring data from one device to another (because of Blu-ray Disc's extremely wide adoption across the industry), the format is optimized for Digital Asset Management and other professional applications that require vast amounts of storage space. Think of medical archives that may contain numerous diagnostic scans in the highest resolution, or catalogs of audiovisual assets that need to be instantly retrieved in a random manner, without the need to "restore" data from a storage carrier. One Blu-ray Disc may replace many backup tapes, CDs, DVDs or other less common or proprietary storage media. And contrary to network solutions, the discs can be physically stored in a different location for backup and safekeeping.


16. CONCLUSION

 

 

          The next generation optical media battle is on going. Blu-ray seems to have the upper hand but the next two years will tell which one wins.

 

          The Blu-ray Disc format for movie distribution offers two profiles for the creation of titles. It was designed to allow for the streamlined development of Blu-ray Disc (HD) and DVD-Video (SD) titles at the same time, if needed. Basic menus and navigation can be identical. It also offers many new functions that will benefit the author by offering flexible ways of creating disc content and the end users by offering new functionality compared to DVD-Video.


REFERENCES

 

 

1.     http://en.wikipedia.org./wiki/Blu-ray_Disc

2.     http://www.linkroll.com/Blu-ray/the-most-notable-blu-ray-features.php

3.     http://www.blu-raydisc.com/general_information/Section-13576/Section-13577/Index.html

4.     http://www.blu-ray.com/info/

5.     http://electronics.howstuffworks.com/blu-ray.htm

 

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