The Difference Between CDs and DVDs

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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 will probably notice is that a DVD can hold much 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. 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. Consequently you can have more pits in the same amount of surface area on a DVD, which explains the large difference in storage capacity.

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. Pits and lands (no pits) burned onto the surface of the disc are what make up the 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. The information from the laser is converted by way of a microprocessor into digital data that your computer can understand.

The spiral groove on a DVD is also narrower than a CD. This equates to a longer track and subsequently more data storage capacity.  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 a lot more given that they are double sided or dual layered.

A DVD has smaller pits and the lasers need to focus on them so the physical make up of a CD is slightly different to a DVD.  A thinner plastic substrate must be used, giving the laser less material and less depth to get through to the surface.

DVDs will access data at a much faster rate than a CD can.  The difference in speed is huge with a 52X CD drive reading data at 8Mb a second and a DVD 24X drive reading data at 32MB second.

With Blu-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 are still very common and very cheap to purchase but I imagine they will slowly be phased out due to the increasing need for larger and larger amounts of storage space. For more related information on CDs and DVDs in relation to packaging and marketing check out this website Packaging CDs and DVDs.

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