Audio Signal Processing and Coding

2.1 INTRODUCTION

The signal processing theory described here will be restricted only to the concepts that are relevant to audio coding. Because of the limited scope of this chapter, we provide mostly qualitative descriptions and establish only the essential mathematical formulas. First, we briefly review the basics of continuous-time (analog) signals and systems and the methods used to characterize the frequency spectrum of analog signals. We then present the basics of analog filters and subsequently describe discrete-time signals. Coverage of the basics of discrete-time signals includes: the fundamentals of transforms that represent the spectra of digital sequences and the theory of digital filters. The essentials of random and multirate signal processing are also reviewed in this chapter.