Mid/Side Processing
摘要
A stereo audio file has two channels, left and right. When these channels play through left and right speakers at an equal level, a phantom centre between the two speakers is created. The phantom centre contains identical information that is present in both the left and right channels—this is the mid part of the signal. Removing this information would leave only the information that differs between the left and right channels—the side information. So, the side information is accessed by subtracting the mid information from the whole signal and vice versa.