1. A method for asynchronous sample rate conversion, the method comprising: receiving an input signal, in the form of a sample stream at an input sample rate; determining a relationship between the input sample rate and an output sample rate; responsive to the determining step determining that the input sample rate is lower than the output sample rate, converting the sample rate of the input signal to the output sample rate according to a first sample rate conversion algorithm; responsive to the determining step determining that the input sample rate is higher than the output sample rate, converting the sample rate of the input signal to the output sample rate according to a first sample rate conversion algorithm; determining a phase offset of a current output sample at the output sample rate relative to the samples of the input signal; and calculating digital filter coefficients for use in the converting steps by evaluating polynomial expressions for the digital filter coefficients responsive to the phase offset of the current output sample.