Panning is the process of distributing one or more signals across a series of outputs so that the listener will have the experience of them coming from a particular point or area of the overall listening field.
It is used to create a sense of space and/or a sense of motion in an audio mix. Different signals can be spread out across the space, and moved over time.
The way a panner works depends a great deal on how many signals it is going to process and how many outputs it will send them to. The simplest case is distributing a single signal to 2 outputs, which is the common case when using a "mono" track and a stereo speaker setup.
But panning in Ardour could theoretically involve distributing any number of signals to any number of outputs. In reality, Ardour does not have specific panners for each different situation. Currently, it has dedicated panners for the following situations:
Even for each of these cases, there are many different ways to implement panning. Ardour currently offers just one solution to each of these situations, but in the future will offer more.
In addition to the panners, Ardour has a balance control for subtle corrections to existing stereo images.