Compact Disc

Audio CDs tend to be more forgiving than CDs that will be read by computers. The audio CD player can fill in any missing data on the disc because audio data are easily interpolated, with the result that scratches do not have much effect on the quality of the sound produced when the CD is played.

Computer data are less predictable than audio data. Consequently, it is not as easy to interpolate when data are missing. Because computer data are digital (either 0s or 1s), the computer cannot represent missing data by an "average" value lying somewhere between 0 and 1. Because small scratches are inevitable, the CD-ROM incorporates a scheme that makes it possible to reconstruct any bit from the surrounding data. This scheme is called Error Correction Code (ECC). ECC permits the CDROM to undergo some surface damage and still remain usable, but it does not replace the need to exercise care when handling a disc.