Audio Effects

268 Audio Effects: Theory, Implementation and Application

Block- Based Convolution

There are at least two main approaches to performing fast convolution on

a real- time signal: the overlap and add method and the overlap and save

method. They both rely on cutting the input signal into blocks. Here, we will

describe the overlap and add method, which is slightly simpler to under-

stand, and is discussed in more detail in Chapter8. The input signal s is cut

into blocks of length N. The kth block s

kN:(k+1)N–1

= s[kN], …, s[(k + 1)N– 1] is

convolved with the impulse response h of length N, as shown in Figure11.9.

This convolution is performed by zero ...