SRC with multiple sets of filter coefficients in memory and a high order coefficient interpolator

A system comprising:

• a coefficient interpolator;
• a filter selection register;
• a memory coupled to the coefficient interpolator;
• and
• a sample rate estimator configured to estimate a sample rate of an audio input signal;
• a convolution engine coupled to the coefficient interpolator;
• wherein the memory is configured to store multiple independent sets of filter coefficients, wherein each set of filter coefficients defines a different polyphase filter function, wherein each of the different polyphase filter functions would result in at least some modifying of a signal if the signal were filtered in accordance with the polyphase filter function, and wherein each of the different polyphase filter functions would result in modifying of a signal in a different manner than the other polyphase filter functions;
• and
• wherein the coefficient interpolator is configured to interpolate a selected single one of the independent sets of filter coefficients, in dependence on the estimated sample rate of the audio input signal, to thereby produce interpolated polyphase filter coefficients;
• and
• wherein the selected single of one of the independent sets of filter coefficients is selected based on contents of the filter selection register, independent of the audio input signal received, and independent of a filtered audio output signal produced;
• wherein the same single one of the sets of filter coefficients selected is used to produce the filtered audio output signal;
• and
• wherein the convolution engine is configured to convolve the audio input signal with the produced interpolated polyphase coefficients corresponding to the selected single one of the sets of filter coefficients to produce the filtered audio output signal that differs from the audio input signal regardless of which one of the sets of filter coefficients is selected.

A method comprising:

• storing a plurality of independent sets of filter coefficients in a memory, wherein each set of filter coefficients defines a different polyphase filter function, wherein each of the different polyphase filter functions would result in at least some modifying of a signal if the signal were filtered in accordance with the polyphase filter function, and wherein each of the different polyphase filter functions would result in modifying of a signal in a different manner than the other polyphase filter functions;
• storing a value in a filter selection register;
• selecting a single one of the sets of filter coefficients based on the value stored in the filter selection register;
• receiving an audio data signal and frame sync signals associated with the audio data signal;
• estimating, based on the frame sync signals, a sample rate of the audio data signal;
• interpolating the single one selected set of filter coefficients, in dependence on the estimated sample rate of the received audio data signal, to thereby produce interpolated polyphase filter coefficients;
• and
• convolving the produced interpolated polyphase filter coefficients with the received audio data signal to produce a filtered audio data signal that differs from the received audio data signal regardless of which single one of the sets of filter coefficients is selected;
• wherein said selecting the single one of the independent sets of filter coefficients is performed prior to receiving the audio data signal, independent of the audio data signal received, and independent of the filtered audio data signal produced;
• and
• wherein the same single one of the sets of filter coefficients selected is used to produce the filtered audio data signal.