Fast implementation of a general L/M rate changer by a filter bank structure

We show that an L/M rate changer can be realized as a discrete time SISO (L,M) shift invariant system in the form of a two-dimensional kernel function or a filter bank structure. Based on this realization, we can implement an L/M rate changer by a bank of filters with the average number of coefficients in the filters in each channel is 1/L of the original L/M rate changer. Hence, the system is speeded up by L. This helps the designer to design sharp cutoff discrete time FIR filters in an L/M rate changer for real time applications in video systems.