Lag-indexed VQ for pitch filter coding

The presence of a pitch predictor is critical to low-rate performance of CELP coders. Unfortunately the rate required for high-quality encoding of pitch filter parameters is often a large fraction of the available bandwidth. Moreover, the application of analysis-by-synthesis techniques to pitch filter optimization can require excessive computation. We present a vector quantization (VQ) approach for coding pitch filter parameters which maintains a subjective quality equivalent to other coding schemes while requiring lower (variable) rate with less closed-loop computation than other VQ techniques