How StereoMono.split() splits a channel.
type StereoSplitMode = "left-right" | "mid-side";
Used by StereoMono.split().
"left-right": the first branch carries (L, 0), the second (0, R). Default."mid-side": the first branch carries the mid (M, M), the second the side (S, -S), with M = (L + R) / 2 and S = (L - R) / 2.Both splits add up to the original signal when the branches are sent to the same channel.