What is the difference between a CD and DVD media?

Although the CD and DVD media the same size and shape, the similarity ends there. A number of points difference between the two is as follows:

Data pits and lasers

microscopic grooves on a disc to move in a spiral around the disc. Both CDs and DVDs these grooves. A laser beam is used to scan these grooves. As you may know, information is represented in digital ones and zeros. In these discs, very tiny reflective bumps (called & # 145; lands & # 146;) and non-reflective holes (called & # 145; pits & # 146;), grooves located along which reflect the ones and zeroes of digital information.

There is a difference & # 150; reducing the wavelength of the laser (the 780mm infrared light used in CD) to 625mm or more infrared light, DVD technology has been a smaller letter & # 145; pits & # 146; than a standard CD. This allows a greater amount of data per track. The minimum pit length of a single-layer DVD-RAM [http://computer-information.info] 0.4 microns, compared to 0.834 microns with a CD.

In addition, the DVD tracks are narrower, allowing for more tracks on one disc, which is again reversed more capacity than a CD.


as explained above, DVDs, small & # 145; & # 146 pits; and lasers need to focus on them. This is done by a plastic substrate thinner than the CD, which means that the laser to pass through a thinner layer of less depth to reach the pits. This is the reduction in thickness, which was responsible for the plates, which are only 0.6 mm thick & # 150; half that of a CD.

The data access speed

DVD access data much faster to do CDs. Here is a comparison of & # 150; a 32X CD-ROM drive reads data of 4M bytes per second while a 1X DVD drive reads 1.38 bytes per second. That & # 146; and even faster than an 8x CD drive!

UDF (Universal Data Format)

Recording formats of CDs and DVDs is quite different. The DVD's UDF (Universal Data Format [http://pda-devices.info]). This allows the data, video, audio or a combination of all three, to be stored in a single file structure. This has the advantage that any file can be accessed for any drive, computer or consumer video. CDs, however, are not compatible with this format.

Source by Logan Rokwild

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