CD Vs DVD
CD and DVD both use the same storage media as well, but the similarities with regard to format stop there. The CD and DVD use different optical technologies where the data accessed by the use of light namely, x-rays and ultraviolet light are focused onto the CD or DVD using special lasers to read the data stored in the form of its bits and to encode the data into the required pattern. Once the data is encoded, it is read by the relevant CD or DVD player/DVD burners and subsequently read by the DVD recording machines. DVD recording machines also read the DVD data and encodes it into the required pattern as well.
While CDs and DVDs both employ the same storage media as well, they differ in their methods of encoding and the manner in which the data is stored. As a result, while the CD media supplies pictures, audio, lyrics, and so forth, the DVD media supplies video, sound, and so forth. This is because the production of a CD is somewhat dependent upon the dimensions and shape of a DVD disc. While it would be fairly easy to just create a CD from a DVD, it may be more difficult to manufacture a DVD from a CD if the two media are not of similar size and shape.
While CDs are generally made in ‘bulk’, a small hole (pit) is left at the top edge of each disc for the recording of the data. Because the holes in the top surface of a CD prevent the recording of sound for the recording of music, the top layer of the CD contains pits (also called spindles). However, when the recording of a CD is done, the pits get filled up with dust and the recording is completed. Thus, as a result, the top surface of a CD is generally coated with a plastic, which prevents the recording of dust, but also preserves the quality of the sound.
Nowadays, however, a number of high-tech printers have been designed for the production of CD and DVD. Instead of being covered with plastic, the top surface of a CD is printed with a transparent plastic, known as an ‘odette’. The printing on the Odette protects the CD from scratches, thus producing a warmer, clearer, and much more audiophile sound from the music or movie CD. These modern day printers work by ‘printing’ on the surface of the CD, rather than recording on paper which involves the recording of data on paper and pressing this paper into a disc. Modern day discs also contain information on the depth and width of the stereo channels, the master copy number, the manufacturer and the date created on the back of the CD.
Finally, although there are similarities between the CD and the DVD, there are differences as well. For instance, the case of both a CD and a DVD should not be transparent, as this adds to the visual effect of the picture. Therefore, if you want a good quality picture on a CD, you will need a transparent CD case, whereas on DVD, transparent cases do not help matters. The printing on a CD also lacks the special effects that are commonly found on the DVD. In fact, the image on a CD is of better quality than on the DVD.
Both a CD and a DVD can have their data saved on a CD by means of a CD-R, but there are certain limitations as far as the transfer of the data is concerned. As the data is stored in a small area on a small disc, the time taken to create each particular CD is considerably longer than that of a DVD. Further, the process of CD burning does not remove any scratches from the CD. To remove scratches from a CD, one has to buy an optical disc cleaning machine. As for the DVD, all you have to do is use an anti-static substance.