The Differences Between CDs and DVDs

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Posted by jimcook | Posted in Uncategorized | Posted on 18-05-2010

A few Of The Differences Between CDs And DVDs

CDs and DVDs possess the same shape and size but that is where the similarities end. The differences lie in the make up of the surface of the disc which are invisible to the naked eye.  The biggest difference that you can notice is that a DVD can hold far more data than a CD.

When you discover how the data storage is implemented on both CDs and DVDs you will understand how the big difference in capacities is achieved.  By moving a laser across a spinning disc pits are burned into a spiral groove that covers the complete surface. A laser is an intensely focused beam of light and all lasers operate on a particular wave length. A smaller wave length will produce a smaller pit. 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.

DVDs and CDs are digital storage mediums which basically means that all data is stored as ones and zeros. Pits and lands (no pits) burned onto the surface of the disc are what make up the ones and zeros. The laser light will reflect off the lands but not off the pits when the disc is being read. Optical technology reads the data and converts into the ones and zeros that your computer can then understand.

Because the spiral groove is narrower on a DVD than a CD it is subsequently longer and able to hold more data.  The most common DVD format can hold 4.5GB of data which is approximately six times more than a CD which only holds 700MB. Other DVD formats can hold much more because they are double sided or dual layered.

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.  This is achieved by using a thinner plastic substrate than in a CD, which means that the laser needs to pass through a thinner layer, with less depth to reach the pits.

DVD drives are also capable of much higher data throughput than a CD drive.  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.

DVD’s are currently the format of choice for most consumers these days but expect them to get taken over by Blu-Ray discs in the next few years. CDs will be available for a while yet but as Blu-Ray prices come down and storage needs continually spiral upwards I can’t see them lasting forever. For additional information on Compact disks and DVDs in regards to presentation and marketing visit the following website CD and DVD Packaging

Guide on how to convert files to pdf format at How to PDF


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