We haven't discussed multispeaker setups at all. In fact, most of our audio examples were only mono. While stereo is just straightforward and sends signals to multiple audio outputs too, what if we'd like to have some more sophisticated control about the spatialization in a, say, four-speaker setup? This can get really complex, so we rely on some externals here.
There are multiple techniques to approach the problem of how to perceptually position an acoustic phenomenon in 3D space. One of them is called ambisonics. For ambisonics, the following three different libraries are available: