A lattice low-delay code-excited linear prediction speech coder at 16 kb/s

Abstract

This paper presents a lattice low-delay code-excited linear prediction speech coder (LLD-CELP) based on the analysis-by-synthesis configuration. The coder achieves a one-way coding delay of less than 2 ms by making both the LPC predictor and the excitation gain backward-adaptive, and by using a small excitation vector size of four samples. The introduction of a lattice filter as a short term predictor, and a perceptual weighting filter has significant advantages, such as fast tracking of speech signal nonstationarities, simple stability verification, and uniform distribution of the computation load. The introduction of backward adaptive prediction gain imbedded in the excitation codebook achieves a lower complexity with the same quality and with the same bit rate.