A Perceptually Based Embedded
B. Tang, Albert Shen, Abeer A. Alwan, Gregory J. Pottie · 1997
A new scheme for robust, high-quality, embedded speech coding based on subband decomposition and percep- tually optimized bit allocation and prioritization is presented. An infinte impulse response (IIR) quadrature mirror filterbank (QMF) performs subband decomposition. A perceptual model, computed using subband spectral analysis, optimizes the coder's perceptual quality. Dynamic bit allocation and prioritization is combined with embedded quantization resulting in little perfor- mance degradation relative to a nonembedded implementation. The coder output is scalable from high quality at higher bit rates to lower quality at lower bit rates, supporting a wide range of service and resource utilization. The lower bit-rate representation is obtained simply through truncation of the higher bit-rate rep- resentation. Since source-rate adaptation is performed through truncation of the encoded stream, interaction with the coder is not required, making the embedded coder ideally suited for rate- adaptive communication systems. Performance for both speech and music was verified through subjective listening tests.