Sunday, March 10, 2013

Blu-ray: The King of Optical Storage Technology

Let's turn towards the era of multimedia. IT has played a very leading role in digital multimedia, movies, music etc. The chief requirement in this field is 'storage'. This storage must be rich, reliable, secure, easily available and easy to handle. The first handy storage for computers was 'floppy disc' invented by IBM in 1971. The floppy had a little data storage capacity of 1.44 MB which was not fit to store multimedia files.
Later in 1982, Sony Inc. of Japan invented a new medium to store a huge information. This was 'Compact Disc' simply called as CD. CD was originally invented for storage and playback of digitally recorded sound. CD was later allowed to store other digital files. CD is still used as standard physical medium for storage of digital sound. The capacity of CD is 700 MB. It can store 80 minutes of uncompressed digital audio with high bitrate of 1441 kbps. CD is still very popular and widely used medium for data. Sony also developed a special format of CD to store video also. This format was VCD (Video Compact Disc) which is still used. VCDs contain 80 minutes of moderate-quality video with CIF resolution and MPEG-1 as video codec. VCDs also got popular all over the world.

In the same time, the capacity of computers was highly increasing and it was found that CD cannot store this much data. Also, it was not possible to watch full-length high-quality movies on CD due to its insufficient capacity. So, there was a need of new invention. So, technicians developed a new media similar to CD in dimensions but 7 times high storage capacity. This media was DVD (Digital Video/Versatile Disc). DVD was primarily developed for storing high-quality full-length movies or videos with 4CIF resolution and MPEG-2 as video codec. DVD is now used for delivering high-quality movies. DVD has a capacity of 4.7 GB with a single layer and it almost completely fulfills all the technical requirements.

Let's turn towards our main subject. Why there was the need of new invention though DVD fulfills all requirements sufficiently? This is because of the invention of HDTV (High Definition Television) sets. These HDTV sets began to appear in 1999. HDTVs are the television sets that can support video signal of very highest resolution with improved picture, sound clearity and frame-rate. HD video files require very high memory space for storage and playback. Even though this much resolution is not available on some screens, this resolution is included as a part of signal. So, it was found that DVDs are really unable to store this HD video which requires a much more as compared to space on DVDs.

This new invention was done in 2004 by Toshiba. They invented a new media similar to CD and DVD. This invention was HD DVD. It had a capacity of 15 GB per layer. So, it could store HD movies. But at the same time, the similar invention was being done by Blu-ray disc association. This association developed a similar optical disc to CD and DVD having a rich data storage capacity of 25 GB per layer which is also much higher than HD DVD. This was 'Blu-ray Disc' officially called as BD.
So, the battle between HD DVD and Blu-ray Disc began to get permanently located in market. This battle is called as 'Optical Disc Format War' which got ended in 2008. So, BD was the winner of this war. The commercial Blu-ray Disc Player was released in 2010.


Let,s discuss about specifications of Blu-ray Disc. We will simply call it as BD throughout the rest of this article. As discussed earlier, BD can store 25 GB of data per layer. It can store this much data because it uses a laser of very shorter wavelength or color as compared to CD or DVD. In CD/DVD, the red laser of wavelength 650 nanometer is used to read/write. On the other hand, BD uses a laser of 405 nanometer. Though the name suggests 'Blue' color, the actual color of laser comes in 'Violet' region of spectrum. Due to this mechanism, BD stores 5 times more data than that allowed by DVD.











The writing speed of BD varies from 1x (4.5 MB/s) upto 12x (54 MB/s). It has the same dimensions as that of CD/DVD. BD has been released in two formats namely, recordable and rewritable. Recordable or blank BDs are called as BD-RE's. Rewritable BD's are especially developed for HD camcorders.
BDs are primarily developed to store High Definition full-length movies. They can store 1080p HD video with new and efficient codec MPEG-4 AVC or H.264. This is very popular and commonly used video codec now a days. It is also used on streaming videos of YouTube. Its official media container is .MP4.
All the Hollywood movies are nowadays delivered in both DVDs and BDs and many PC or notebook vendors are including Blu-ray Disc Drive in-built in their products.

Right now, the only drawback of BDs is that they are very costly and not affordable to common man. I think their market prices will get down very shortly. But, still we have to wait for its arrival and let's enjoy with our traditional DVDs!

Thanks and regards,
Nitish R. Muley