with other digital data, the music or audio signals on a CD is
stored digitally (in 1's and 0's). However, digial music are encoded
in a format that allows them to be stored on the CD. So, if the
bits of information on the CD player are read off without decoding
it you would not get music.
is necessary because of algorithms that are incorporated in the
music at recording time. Also, because of how the laser detects
ones and zeroes on the CD, there cannot be consecutive ones when
storing the digital information. The solution for this problem
is called eight-to-fourteen modulation (EFM). At the final preparation
of storing the encoded music on the CD, eight bit chunks of information
are transformed to fourteen bits. Also, three merging bits of
zeros are tacked on to each fourteen bit chunk. This final process
ensures that no consecutive ones are present before storage.
encoding of digital audio on CD player is governed by IEC 908.
CD players use parity and interleaving techniques to minimize
the effects of an error on the disk. In theory, the combination
of parity and interleaving in a CD player can detect and correct
a burst error of up to 4000 bad bits -- or a physical defect 2.47
mm long. Interpolation can conceal errors up to 13,700 or physical
defects up to 8.5 mm long.
are the steps that are involved in the encoding process of digital