快速傅里叶变换
Code in the per_frame section is executed once for each frame, modifying variables which affect different parameters that can be passed to other areas of code. Trigonometric functions which modify MilkDrop's internal looping time variable, systems of logic, and interaction with the audio information received from Winamp or other applicable media player's Fast Fourier transform (FFT) can be used to govern how these parameters evolve through time.