Adaptive prediction and bit-assignment in subband coding of speech
José Bernardo Mariño Acebal, Jaume Martí Ros · RECERCAT (Consorci de Serveis Universitaris de Catalunya) · 1985
The combination of time-domain harmonic scaling (TDHS) and sub-band coding (SBC) provides an encoding approach which allows 9.6 Kb/s speech encoding with good communication quality. Starting from this structure, this paper focuses the improvement of earlier designs. It is shown that adaptive prediction and bit-assigment enhances the subband signal coding and, hence, the performance of the overall system. The prediction is realized by an adaptive lattice, the algorithm being GAL2. The dynamic bit allocation takes place from the step-sizes of the backward adaptive quantizers (Jayant) in each sub-band. Improvements as high as 5 dB can be achieved for the average segmented signal to noise ratio.