Optimal variable fractional delay filters in time-domain L-infinity norm

This paper presents an efficient implementation of the variable fractional-delay (VFD) filter, which is optimal in the time-domain L-infinity norm. The proposed filter has two stages. The first consist in computing the conventional Lagrange interpolator from the signal samples, but weighted using a set of fixed coefficients. And the second consists in multiplying the result of the previous step by a smooth function, which can be well approximated by a polynomial. The paper includes a numerical evaluation of this interpolator and a low-complexity, low-latency implementation based on multiplications.