Signal processing system for performing real-time pitch shifting and method therefor

A signal processing system for performing real-time pitch shifting, comprising:

• an adaptive pitch estimator having an input for receiving a digital input signal, and an output for providing a buffer size signal corresponding to a fundamental frequency of said digital input signal;
• a variable-size buffer having a data input for receiving said digital input signal, a size input for receiving said buffer size signal, and an output;
• and
• interpolation means coupled to said output of said variable-size buffer, for converting samples from said variable-size buffer from a first pitch to a second pitch according to a pitch-shifting ratio, and for providing a pitch-shifted digital output signal in response thereto.

A method for performing real-time pitch shifting comprising the steps of:

• receiving a digital input signal at a sample dock rate;
• storing said digital input signal at successive locations of a variable-size buffer having a variable size associated therewith;
• adaptively estimating a fundamental frequency of said digital input signal to provide an estimated fundamental frequency;
• changing said variable size of said variable-size buffer in response to said estimated fundamental frequency;
• and
• interpolating said digital input signal stored in said variable-size buffer to provide a digital pitch-shifted output signal.