ABSTRACT
A CD stores sound as numbers, 0’s and 1’s. These numbers are packaged together with redundant information, so, if the disc gets scratched, enough information remains for the CD player to reconstruct the original sound. The CD player can correct errors in the data on the CD because the data is represented using an error-correcting code. This chapter provides a brief discussion of codes in general, but quickly restrict to linear codes, and to the even smaller class of cyclic codes. It examines a specific set of cyclic codes, the Reed-Solomon codes, which includes the codes used on CDs. The chapter shows how to construct codes that can correct multiple errors, yet are still fairly easily to decode: the BCH codes. It concludes with a discussion on the mechanics of audio CD recording and encoding.
