Fundamentals of Digital Audio
Ken C. Pohlmann · 1992
Abstract The essence of digital audio lies in its numerical basis. A digital audio system converts an analog waveform into numbers, stores, transmits, or processes those numbers, and then converts them back to an analog wave-form. These steps may be divided into the digital audio recording of a music performance, the storage of that performance on a compact disc, and the reproduction of the performance with the CD player. The digital audio chain, from the recording studio or concert hall to your living room, is predicated on several basic phenomena. First, the analog waveform must be discrete-time sampled at a precise, unvarying rate. This divides the waveform into discrete intervals. With sampling, the signal must be filtered to prevent aliasing, a form of distortion. Next, each sample must be converted to a number; this is the process of quantization. To minimize an inevitable error associated with quantization, a dither signal must be introduced. In many digital audio recorders/reproducers these steps take place in a linear pulse code modulation system. This chapter examines all of these fundamental elements.