A mixer is an audio device with one or more lines. It need not be designed for mixing audio signals. A mixer that actually mixes audio has multiple input (source) lines and at least one output (target) line. The former are often instances of classes that implement
, and the latter,
objects, too, are either source lines or target lines. A mixer can accept prerecorded, loopable sound as input, by having some of its source lines be instances of objects that implement the
Through methods of the
Line interface, which
Mixer extends, a mixer might provide a set of controls that are global to the mixer. For example, the mixer can have a master gain control. These global controls are distinct from the controls belonging to each of the mixer's individual lines.
Some mixers, especially those with internal digital mixing capabilities, may provide additional capabilities by implementing the
A mixer can support synchronization of its lines. When one line in a synchronized group is started or stopped, the other lines in the group automatically start or stop simultaneously with the explicitly affected one.