CPSC203 2008Fall T20 Group B: Blu-ray Disc Technology

Group Members
Joey Chan, Rebecca Hawryluk, Jordan Kopperud, Kayla Nagorski, Amanda Vena

Introduction


There is a lot of hype about Blu-ray Technology and this can be very confusing to consumers. Our group wanted to research Blu-ray technology to find out what it was, how it worked and most importantly whether it is reasonable for consumers to switch from DVD usage to Blu-ray usage.

The Origins of Blu-ray Technology
As audio and video technology advanced and increased in quality, the space on discs required to hold the audio and video content increased proportionally. High definition video was a type of video technology advancement; it is characterized by having a higher resolution than standard. Eventually current storage medium (i.e. DVDs) would no longer be enough to hold all the audio and video information and could not play high definition video to its full potential. Thus, a demand for storage medium that could hold the additional audio and video information and play high definition video to its full potential was born.

The Format War
Two storage medium formats capable of satisfying the demand surfaced: HD-DVD (created by the DVD Forum, chaired by Toshiba) and Blu-ray (created by the Blu-ray Disc Association). The two formats competed fiercely until 19 February, 2008, when Toshiba announced that it would “no longer develop, manufacture and market HD DVD players and recorders.” Many people believe that the Playstation 3 played a key part in Blu-ray winning the format “war”.

Name
Current optical technologies such CD or DVD uses red lasers to read and write information. Blu-ray, however uses a newly developed blue-violet laser, which has a shorter wavelength (405nm), as compared to the traditional red laser (650nm). A shorter laser wavelength allows for more precision, and as a result allows for more recording of information. Blu-ray gets its name from the blue-violet laser it uses.

Creators and Release Dates
Philips and Sony started applying this new blue laser technology in DVR Blue, the form of rewritable discs, which would later become Blu-ray. The first prototypes of DVR Blue were revealed in October of 2000. In February 2002, the project name was official announced as Blu-ray and the Blu-ray Disc Association was founded(the developers of Blu-ray) in May of 2002. The Blu-ray Disc Association originally consisted of: Sony, Matsushita, Pioneer, Philips, Thomson, LG Electronics, Hitachi, Sharp, and Samsung, but as of August 2008, there were 192 members. The first mass produced Blu-ray players and disc titles were shipped and released in June of 2006.

Improved Laser
A blue laser is used to record digital and audio information onto a Blu-ray disc. This laser burns tiny pits into the surface of the 1.1mm thick polycarbonate layer. These pits are spiral groves that run from the center of the disc to the edges. The blue laser has a 405 nm (nanometre) wavelength that is much shorter than the 650 nm length of the red laser used for writing CDs and DVDs. This short wavelength allows for a greater level of precision in the transference of information onto the disc. Consequently, the pits are smaller on Blu-ray discs.

Shorter Track Pitch
The track pitch of Blu-ray is only 0.32 microns, making it substantially smaller than the 0.74 micron track pitch of a DVD. The track pitch is the distance between two tracks on a disc.

Increased Storage Capacity
All the improvements mentioned above contribute to allow Blu-ray to store much more information than any other disc made before it. The combination of all these improvements has made it possible for one-sided Blu-ray discs to store 25 GB of information. This is a considerable upgrade compared to the standard 4.7 GB DVD storage capacity. There is so much room for high quality information to be stored on a Blu-ray disc, increasing its usability and convenience. There is often room for more than seven hours of the highest HD quality video. With all this additional space comes the option to include many more additional features that can be accessed through a standard Blu-ray player or the internet.

Data Transfer Rate
Blu-ray has the highest data transfer rate at 36 Mbps (megabits per second). This far surpasses the data transfer rate of DVDs which is 10 Mbps. This means that 25 GB of material can be recorded onto a Blu-ray disc in about 90 min.

High End Security
Blu-ray discs are equipped with a unique encryption system that protects against video piracy and copyright infringement. It provides some of the strongest copy protection ever developed. Many improvements have been made since the voluntary copy write protection of DVD. Copy protection for Blu-ray discs is mandatory which creates an advantage for those producing goods on Blu-ray discs. Their products are protected from piracy which will eliminate lost profits due to illegal copying and distribution of the goods - A problem that is widespread with CDs and DVDs today.

Multi-Functional
Blu-ray discs can hold a wide variety of information. Basically all data that is available on a PC can be recorded onto a Blu-ray disc, making it possible to serve as a removable storage device.

How Data is Read From the Disc
Newer technology has led to greater advances in the process of reading data. Existing problems with DVDs or CDs have now been eliminated due to the Blu-Ray. Many imporovemnents have been made to Blu-Ray espicially in the aspect of reading data.

Data
Blu-Ray relocated the data above a 1.1mm-thick polycarbonate layer at the top of the disc preventing birefringence. Birefringence also known as double refraction, is a light wave splitting into two unequal waves that diffract at different anlges, if the beam is split too widely the disc can no longer be read. Double refraction is a common problem caused when data is placed below the polycarbonate layer, in result can cause the disc not to be read properly. 

Objective Lens
The objective lens is another great improvement with the Blu-Ray discs. The new objective lens has a larger numerical aperture (NA), which calculates the focusing power. With higher focusing power the beam becomes a smaller spot. Blu-Ray's objective lens has a NA of 0.85 whereas DVD's only have a NA of 0.6. Disc tilt is another problem Blu-Ray recognized and fixed that can cause normal DVD's to skip or freeze. When a disc is not perfectly perpendicular to the beam it can create distortion in the beam. To prevent this from happening Blu-Ray placed the objective lens closer to the data. 



Cover Layer
Although the larger NA makes the laser more presice it also has it's downfall. With a large numerical aperture the spot distortion increases due to the warping of the disc. This distortion problem is solved by making the cover layer a lot thinner, by using a resin spin coating process making it from 0.6 to 0.1mm thick. Not only does this solve the problem of distortion it also provides protection for the disc. Since the cover layer is placed on the outside of the disc it also helps prevent scratches and fingerprints. 



Pits
Blu-Ray uses a blue laser which has a higher frequency making the laser more precise, with all the improvements made to Blu-Ray the laser is able to read smaller pits. Smaller pits mean more pits will be able to fit onto the disc which means more information can be stored. 

Speed
Technology has made Blu-Ray able to read and write data faster than ever before. As a result from a larger numerical apenditure (NA), Blu-Ray will require less recording power and rotation speed to aquire the same transfer rate. There are different levels of speed depending on the size of the data. First speed tranfers rate at 36Mbps whereas regular DVDs transfer only at 11Mbps. 

BD-ROM
These discs are pressed at the factories with pre-recorded media, such as movies, games, and software. This type of Blu-ray disc is read-only, meaning no changes can be made to the disc’s content.



BD-R
These are blank discs that you can burn once. This type of disc is recordable (only once) and can be used for video recording, and data storage. 

Versions
This version was created for broadcast recording of HD TV, and for PC recording and playback. This version is PC friendly. 
 * Blu-ray Disc Recordable (R) Format Version 1


 * Blu-ray Disc Recordable (R) Format Version 2

This version was made for broadcast recording of HD TV, and also for PC recording and playback. The blank disc is also completely compatible with the BD-R version 1. 



BD-RE
These are re-writable discs that allow you to record and re-record. These discs can be erased and re-recorded multiple times. These discs can be used for data storage, and video recording. 

Versions

 * Blu-ray Disc Rewritable (RE) Format Version 1

This version of the Blu-ray disc was created mainly for broadcasting recordings of HD TV. It has a unique file system, but is not computer compatible.  This version was created for HD TV broadcasting, as well as PC recording/playback. Some special features of this version are its file system for computer use (meaning it’s PC friendly) and it’s usage of AACS. 
 * Blu-ray Disc Rewritable (RE) Format Version 2


 * Blu-ray Disc Rewritable (RE) Format Version 3

This version of the Blu ray disc was created for PC recording/playback, and recording HD TV. The special features of this version are that camcorder discs were added, and it is backwards compatible with Blu-ray disc Version 2. 

BD/DVD hybrid format
There's also plans for a BD/DVD hybrid format, which combines Blu-ray and DVD on the same disc so that it can be played in both Blu-ray players and DVD players. 

Mini Blu-ray Disc
This variation of the Blu-ray disc is compact, has a 3-inch diameter, provides approximately and hour of continous video on a single side, when high definition is used, and two hours when it is not. This mini blu-ray disc can store up to 7.5 GB of data. 

BD9/BD5 Blu-ray Disc
This version of the Blu ray disc is basically a DVD but with compatible Blu ray video and audio. These discs are cheaper than regular Blu-ray discs, but they are also lower in storage capacity. BD9 uses a dual layer disc, while BD5 uses a single layer disc. 

AVCREC
This version of the Blu ray disc has a lower storage capacity, but, like the BD9 and BD5 versions of the Blu ray disc, it is also cost sensitive. This disc is used for storing Blu-ray Disc compatible content on DVD discs. Currently, the AVREC is being promoted for camcorder usage. 

Consumer Analysis
The question on the minds of consumers is whether upgrading to Blu-ray is worth it or not. Is the price of the discs themselves and the players required to play them comparable to the increased quality in video and audio that is received?

Disc Prices
Purchasing Blu-ray discs can set you back between on average between $5 and $10 more than a traditional DVD of the same movie. The price difference is also clear for blank discs. A BD-R costs approximately $0.44 whereas a DVD-R costs about $0.10.

Price Comparison of Consumer-Writable Discs
Chart is from Wikipedia: http://en.wikipedia.org/w/index.php?title=Comparison_of_high_definition_optical_disc_formats&oldid=252962139#Retail_price_of_consumer-writable_discs, Accessed on Nov 24, 2008.



Blu-ray Player Prices
If you already have a Play-Station 3, then the question of how to play your Blu-ray discs will not arise because the PS3 has Blu-ray playing capabilities. If you are not that fortunate then you will probably have to consider purchasing a Blu-ray specific player. These players can cost upwards of $800 but the prices have been coming down in recent years and you can find them for as low as about $169. The other advantage is that you can still play your old DVDs on Blu-ray players so you will not have to replace all your DVDs.

However, the price increase in discs and players does result in a significant increase in audio and picture quality. The bottom half of the picture on the right is Blu-ray and the top is a traditional DVD image. As you can see, the Blu-ray image is clearer and the lines are more defined.

Although, these prices may seem high, DVD also seemed really expensive when it came out and economist predict that Blu-ray will catch on and be the new DVD of choice for consumers.

Conclusion
Our group decided that it is worth the extra money to upgrade to Blu-ray. The increased storage capacity, security, and video quality make the cost reasonable. However, we also recommend that each consumer do their own analysis and make the decision based on their personal budget and entertainment needs.