DVD Technology
November 18th, 2010 | Author: admin
The Differences between CDs and DVDs are Microscopic even though both CD and DVD disks have the same media size and shape, the things they have in common end there. There are many differences between the two, such as what they hold and how much they can hold.
The reason for the big difference in the amount of data storage will become apparent when you understand how data is written to or burned to CDs and DVDs. A laser is used to burn pits around a spiral groove in the disc. Lasers have a wave length and the longer the wave length the bigger the pit. DVD lasers have a substantially smaller wave length than a CD laser. A smaller pit obviously takes up less space and ultimately resulting in the ability to store more information in the same amount of surface area.
Digital data is data that is stored as a series of ones and zeros. DVDs and CDs are digital data storage mediums so everything, including audio and video, is stored as ones and zeros. The pits and lands (where there are no pits) on the DVDs and CDs represent ones and zeros. When the disc is read the laser moves around the discs surface and is reflected off the lands but not off the pits. Microprocessors in the disc drive take the information from the laser and convert it into a digital format that your PC can easily understand.
The tracks of a DVD are narrower as well, which allows for more tracks per disc and translates into more capacity than a CD. The common single layer DVD holds 4.5 GB of data, while a CD holds only 700 MB. As the pits on a DVD are smaller the physical make up of a DVD has to be different to a CD in order to allow the laser to focus on them. The DVD has a thinner plastic substrate than a CD making it easier for the laser to pass through and get reflected back.
DVD technology also has a much faster rate of reading and processing data. The difference in speed is very large with a 52X CD drive reading data at 8Mb a second and a DVD 24X drive reading data at 32MB second. With Blue-Ray being the new kid on the block and because it has such a massive storage ability DVDs will slowly be phased out as will CDs. CDs will be available for a while yet but as Blue-Ray prices come down and storage needs continually spiral upwards I can’t see them lasting forever.
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