The basic element of the mixer architecture is an audio line. An audio line consists of one or more channels of data originating from a single source or a system resource. For example, a stereo audio line has two data channels, but it is considered a single audio line because it originates from a single source.
The mixer architecture provides routing services to manage audio lines on a computer. You can use the routing services if you have adequate hardware devices and software drivers installed. The mixer architecture allows several audio source lines to map to a single destination audio line.
Each audio line can have mixer controls associated with it. A mixer control can perform any number of functions (such as control volume), depending on the characteristics of the associated audio line.