1. A signal processing method based on multiple textures, comprising: dividing an input signal that includes a video signal and an audio signal into unit component signals, and selecting one from a plurality of frames of each unit component signal as a seed signal; detecting a plurality of texture points from the seed signal; tracking the plurality of texture points from the plurality of frames of the unit component signal and then calculating spatio-temporal location transform variables for the respective texture points; defining a plurality of texture signals using texture points at which the spatio-temporal location transform variables correspond to one another; defining each of the plurality of texture signals as a sum of a plurality of texture blocks that are outputs of texture synthesis filters that respectively receive video audio excitation signals as inputs; and merging texture signals, which have spatio-temporal location transform variables for which similarities calculated by obtaining correlation characteristics between texture signals have values falling within a preset threshold value, among the plurality of texture signals, into a single texture signal, thus approximating the texture signals.