DVDs and CDs – The Differences Explained
May 22nd, 2010
What Are The Major Difference 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. There are many different things between the two, such as what they hold and how much they can hold.
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. As the disc spins a laser is moved across the surface to burn pits in a spiral groove around 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. More pits in the same amount of surface area results in a larger amount of information and explains why a DVD is capable of holding so much more data than a CD.
CDs and DVDs store everything, including audio and video, as a series of ones and zeros which means they are digital data storage mediums. 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. Microprocessors in the disc drive take the information from the laser and convert it into a digital format that your computer can understand.
Because the spiral groove is narrower on a DVD than a CD it is subsequently longer and able to hold more data. The average DVD can hold 4.5GB of data that is 6 times greater than a CD at around 700MB.
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 drives are also capable of much higher data throughput than a CD drive. The average 52X CD-ROM drive reads data at 8MB a second, while a 24X DVD drive reads at 32MB a second.
DVD’s are still the format of choice for most people nowadays but expect them to be 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 more related information on Compact disks and DVDs in relation 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
Categories: Music and Gadget
