CDs
By:Ronnique Louvier
A CD, an abbreviation for compact disc, is a storage medium that can be used to store, record, and play audio and videos. The storage medium got into the market in late 1982, and it remained as the medium for commercial recording until 2006. It can also store other forms of digital content. Below is an image of a CD.
An audio compact comprises either single or multiple stereo tracks stored using PCM coding at a sampling rate of 44.1 kHz. The diameter of the disc is either 120mm or 80mm, with their storage capacity differing depending on their diameter. A compact disc of 120mm can hold an audio file for approximately 80 minutes, while 80mm can hold audio for about 20 minutes. By the time the CDs started to get out of the market, more than thirty billion discs had been sold worldwide.
A CD works by focusing on a 780-nanometer wavelength semiconductor laser onto a single disc track. As the disc rotates, the laser beam measures difference in the way light is reflected off the polycarbonate layer on the bottom of the disc converting it into sound. The digital data on a CD starts at the center of the disc as it proceeds outwards to the edge. This allows for adaptations to the different available size formats.
There are two standard sizes of discs, one of 120mm diameter and able to store data of about 700 MB and that of 80mm diameter and which stores data of about 180MB data. Producers of the data in the CD would include an extra track in the CD to entice the buyers to buy it purposely to benefit from the extra track.
audio recordings. He filed for a product resembling a combination of laser, digital recording, and optical disc technologies in 1966. However, in 1980, Sony Corp and Philips Electronics obtained the license of the technology. The first CD player was released in the market in 1982, and it was the same time the format started to be used all over the world. The cost was high initially since only two factories manufactured them. Philips and Sony owned these factories. CDs were read-only but later started to allow people to record in them.
A CD comprises the smallest entity known as a frame, which can accommodate six complete 16-stereo samples. A-frame comprises 33 bytes, with 24 of them comprised of audio. Eight of the remaining nine bites serve as CIRC-generated error correction bytes, while the other one is the subcode byte.
CDs were common in the 1980s, and early 1990's when PCs could only store about 10 MBs of data. Since the development of computers that can store a lot of data, their use has greatly declined. However, their use started to decline effectively in 2010. However, the introduction of the DVDs in the market in 1995 started to outdo the CDs, hence their decline in demand.