Central Blurb

Blue Ray vs. HD-DVD

Introduction of optical storage devices such as CDs and DVDs has revolutionized the entire concept of storage. It is now possible to store volumes of information in one single device. Till date, DVDs have been the most preferred devices for storage. However, these technologies had to be revised with the introduction of high-definition televisions. Just to have a brief idea, in order to store a 2hour high-definition video with data compression, almost 22GB of storage space is required. However, DVDs that are currently available have a maximum storage capacity of 17GB. Apart from this, another factor that prohibits usage of DVDs for storing high-definition videos is the resolution. A DVD supports resolution up to 720 x 480 pixels, while a high-definition TV requires a resolution of 1920 x 1080 pixels.

So as to allow higher data storage capacity that is required to support high-definition contents, two phenomenal optical storage technologies have been introduced, which are Blu-Ray and HD-DVD that are considered to be an upgraded version of DVD capable of storing much more than one can now imagine.

Comparing both these technologies is possible only when one understands them completely including their features, advantages and disadvantages. Below outlined are some important details about Blu-Ray and HD-DVD technologies.

Blu-ray technology was developed by a consortium of companies that include Sony, Apple, Dell, Hitachi, HP, JVC, LG, Mitsubishi, Panasonic, Pioneer, Philips, Samsung, Sharp, TDK and Thompson. Blu-ray is based on the proprietary high-end PDD pro-format developed by Sony. On the other hand, the HD-DVD technology has been developed jointly by Toshiba and NEC and has recently received support from Microsoft, HP and Intel. HD-DVD technology uses the concept that is being used for existing DVDs.

Both these devices use a 0.40um Blue-Purple laser beam in order to read and write information present on the disc. The wavelength of this light is smaller in comparison to the red laser that is currently being used in DVD players. As a result, it is now possible to have a higher recording density. Information on the discs is stored in the form of pits or burnt areas and lands or un-burnt regions. In a way similar to DVDs, all these lands and pits are arranged into a single spiral track. This track usually starts from the center of the disc and ends at the border. So as to read the information, both these formats use the transition period between the light emitted from the pits and light coming from the lands. Data is represented in the form of optical bits. In case of HD-DVD, Eight to Twelve modulation technique, also known as ETM, is used to convert optical bits into data bits. Blue-Ray devices use the 17PP modulation technique for such a conversion.

There are very subtle differences that exist between both these technologies. Most important is the storage capacity offered by these devices. While a Blu-Ray device offers a 25GB storage capacity on a single layer, the storage capacity of HD-DVD is 15GB. On a dual layer, the capacity of Blu-Ray becomes more than double, which is 54 GB. On the other hand, dual layer capacity for a HD-DVD is 30GB. While the pit width in a Blu-Ray format is 0.13um, it is 0.20um in a HD-DVD format. However, the base technology is almost similar in both these formats.

Apart from these, there are certain other intricate similarities and differences that make these technologies to be considered as the next-generation packaged media formats.