A note on the computational efficiency of the FIR multistage implementations of fractional sampling rate conversion

The question of whether computational savings can generally be achieved in the FIR multistage implementations of fractional sampiing rate conversion over a single-stage implementation is not well answered in the literature. In this correspondence, it is pointed out that there exists a class of fractional sampling rate conversion problems for which FIR multistage implementations have no computational advantage over single-stage implementations. This result is uncommon multistage implementations of integer factor sampling rate conversion. It is important to weigh more carefully the tradeoffs involved in such cases before making a choice between the single-stage and multistage implementations.