Blu Ray Discs or HD DVDs ?

Do you remember a 3.5 inches round magnetic tape with plastic covering ? Have you seen it at-least ? Today's computer system doesn't even have that so called Floppy Disks, which could store only one 1024x768 resolution JPG image. Then came CD drives, and then the CD-RW drives. Then the DVDs , DVD-RW. In market, it is difficult to find one CD-R or CD-RW drive these days. Every system comes with a DVD drive or DVD combo drive at-least. With newer technology and very high resolution TVs/screens and surround sound systems, 8.5 GB (Dual Layer DVD) seems not enough to put a movie with the highest quality. Then came the High Definition DVDs (HD-DVDs) and Blu Ray Disc (Note: It is not Blue Ray Disc).

How CDs and DVDs store data? Lasers are used to burn small pits on the surface of Discs. The presence or absence of pits determines the data present in the CD or DVD. Reflection property is used for reading the data.

While CDs and DVDs used red lasers (higher wavelength), Blu ray and HD DVDs used blue lasers (lower wavelength). Lower the wavelength, more closer the pits can be made and hence more data. So Blu-Rays and HD DVDs are able to store many times more data than normal DVDs.

Normal DVDs can store over 2 hours of standard movie quality which we see in Televisions. HD DVDs has a capacity of around 30 GB (dual layer) and can store over 2 hours of high definition video, which is much clearer than normal videos. Blu-Ray Discs are build similar to HD DVDs but has a memory of around 50 GB (dual layer). Blu Ray discs cost much higher than the HD DVDs and since 30 GB is almost enough to put in a Single High Definition movie, HD DVDs are preferred now. Future technology will decide which will survive in the market.

With the trend in the computer market, next generation will most likely do not know what is a CD or DVD.


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