MPEG-4 Book, The

11.5. Introduction to Parametric Audio Coding

The design of an audio coding system is based on model assumptions for the signal source and signal perception [PaiS00]. A coding system designed for these models is able to exploit redundancy and irrelevancy in the audio signal to obtain a compact coded representation of the signal, which can be efficiently transmitted or stored.

Two examples help to illustrate the possible range of abstraction for representing audio signals. From a physical point of view, the temporal sound pressure function x(t) (i.e., the waveform) is an obvious way to represent an audio signal x. On the other hand, the score of a piece of music provides a rather abstract representation of an audio signal. Although there are many ...