Variable framerate parameter encoding

Abstract

A novel approach to parameter encoding is presented which improves coding efficiency and performance by exploiting the variable rate nature of certain classes of signals. This is achieved using an interpolative variable frame-rate breakpointing scheme referred to as adaptive frame selection (AFS). In the approach described in this report, frame selection is achieved using a recursive dynamic programming algorithm; the resulting parameter encoding system is referred to as adaptive frame selection using dynamic programming (AFS/DP). The AFS/DP algorithm determines optimal breakpoint locations in the context of parameter encoding using an arbitrary objective performance measure, and operates in a fixed bit-rate, fixed-delay context with low computational requirements. When applied to the problem of low bit-rate coding of speech spectral and gain parameters, the AFS/DP algorithm is capable of improving the perceptual quality of coded speech and robustness to quantization errors over fixed frame-rate approaches.