Although both CD and DVD discs have the same size and shape of the media, the things they have in common stops there. There are a lot of different things between the two, as they hold and how they hold.

Data wells and lasers
A disc has microscopic grooves that moves along a spiral around the disc. CD and DVD both these grooves, with breams applied to laser scan these grooves. As you may know, digital information is represented in ones and zeros. Within these discs, highly reflective tiny bumps known as the land and non-reflective holes known as pits, which are adjacent grooves, reflect both the ones and zeros of digital information. By reducing the wavelength of the laser 625mm or more infrared light, DVD technology has been able to write in mass graves smaller compared to the standard technology of CDs. This will allow a larger quantity of data per track on the DVD.

The minimum length allowed for a pit in a single layer DVD-R is .4 microns, which is obviously more than the micron .0834 offers a CD. Traces of a DVD are closer together, allowing more tracks per drive, which has resulted in more capacity than a CD. The average single layer DVD holds 4.5 GB of data, while a holder of a mere 700 MB CD

Couches
As indicated above, a DVD has more small bites of lasers and the need to focus on them. This is actually achieved by using a thin plastic substrate in a CD, meaning that the laser must pass through a thin layer, with less depth to reach the wells. This reduction in the thickness that the head of the discs which were only 0.6mm thick – which is half that of a CD.

Speeds data access
DVD will be able to access data at a much faster rate than a CD can. On average, 32X CD-ROM drive reads data at 4 megabytes per second, while a DVD player reads 1X to 1.38MB one second. This is even faster than a CD-ROM 8X.

Universal data format
The recording formats of CD and DVD are quite different, such as the use of DVD UDF, or the Universal Data Format. This format allows data, video, audio, or even a combination of all three to be stored in a single file structure. The advantage of this file is anything can be consulted by any player, computer, video or even consumers. CDs, however, are not compatible with this format.

Related Articles