Blu Ray Disc

Blu-Ray Disc And HD-DVD

The HD-DVD format, originally called AOD or Advanced Optical Disc, is based on much of today's DVD principles and as a result, suffers from many of its limitations. The format does not provide as big of a technological step as Blu-ray Disc. For example, its pre-recorded capacities are only 15 GB for a single layer disc, or 30 GB for a double layer disc. Blu-ray Disc provides 67% more capacity per layer at 25 GB for a single layer and 50GB for a double layer disc. Although the HD-DVD format claims it keeps initial investments for disc replicates and media manufacturers as low as possible, they still need to make substantial investments in modifying their production equipment to create HD-DVDs. But what's more important is that HD-DVD can be seen as just a transition technology, with a capacity not sufficient for the long term. It might not offer enough space to hold a High Definition feature along with bonus material in HD quality and additional material that can be revealed upon authorization via a network. When two discs are needed, this will degrade the so-called cost benefit substantially.

Different Formats of Blu-ray Disc

BD-ROM   : a read only format developed for prerecorded content

BD-R         : a write once format developed for PC storage

BD-RW     : a rewritable format developed for PC storage

BD-RE       : a rewritable format developed for HDTV recording

Data Management Parameters

 The logical organization of data on the disk and how those data are used are considerations for data management. Data management considerations have important implications in the application of optical disk technology to storage for HDTV. For example, simply using a more advanced error correction scheme on DVDs allows a 30% higher disk capacity compared to CDs. Data rate, video format, bit-rate scheme and HDTV play time are all data management issues.  There is a basic difference in data management between CDs and DVDs. Since CDs were designed for audio, data are managed in a manner similar to data management for magnetic tape. Long, contiguous files are used that are not easily subdivided and written in a random access pattern. Efficient data retrieval is accomplished when these long files are read out in a contiguous fashion. To be sure, CDs are much more efficient that magnetic tape for pseudorandom access, but the management philosophy is the same. On the other hand, DVDs are more like magnetic hard disks, where the file structure is designed to be used in random-access architecture. That is, efficient recovery of variable length files is achieved. In addition, the Original error correction strategy for CDs was designed for error concealment when listening to audio, where DVDs utilize true error correction. Later generations of optical disks also follow the DVD model.

Applications

·       High Definition Television Recording

     ·       High Definition Video Distribution

     ·       High Definition Camcorder Archiving

     ·       Mass Data Storage

     ·       Digital Asset Management and Professional Storage

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 to 10 times increase. Now consumers demand an even bigger storage capacity. The growing number 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 has lead 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 to 10 times as much capacity as traditional DVD resulting in 25 to 50 GB of data to be stored on a single rewritable or recordable disc.

Conclusion

           The BD represents a major advancement in capacity as well as data transfer rate. It would be an ideal choice for the secondary storage purposes.The semiconductor storage for secondary memory is large, consumes more power and is more expensive. HDTV video recording and reproducing would essentially require the large storage capacity and data transfer rates, as offered by the Blu-ray disc. The Blu-ray disc has a wide variety of applications and is the ultimate storage device that would lead to digital convergence, ultimately leading to the convergence of the PC and CE technologies. In the opinion of many researchers (including those at the BDF group themselves), BD possibly represents the last of the plastic-based, visible laser optical disc systems.