Low-delay speech coding with adaptive interframe pitch tracking

The authors present an improved version of a previous 8-kb/s low-delay VXC (vector excitation coding) algorithm, which has been enhanced to maintain high-quality results under clean conditions while adding robustness to channel errors. Periodic resetting of the pitch predictor makes the coder more robust to channel errors but sacrifices some of the advantages of interframe coding in clean channels. A novel adaptive mean-removed pitch tracking scheme was introduced that provides robustness to bit errors while avoiding significant quality degradation under error-free conditions.