Digital audio principles
Analog information is made up of a continuum of values of some physical quantity, which at any instant may have any value between the limits of the system. For example, a rotating knob may have one of an inﬁnite number of positions – it is therefore an analog controller (see Figure 2.1). A simple switch, on the other hand, can be considered as a digital controller, since it has only two positions – off or on. It cannot take any value in between. The brightness of light that we perceive with our eyes is analog information and as the sun goes down the brightness falls gradually and smoothly, whereas a household light without a dimmer may be either on or off – its state is binary (that is it has only two possible states). A single unit of binary information is called a bit (binary digit) and a bit can only have the value one or zero (corresponding, say, to high and low, or on and off states of the electrical signal).