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.
- The two
discs are molded.
- The
recording layer is added to one of the discs.
- 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.
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
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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