Multiband-excited linear predictive coder with a two-sided short-term predictor

Abstract

Abstract A multiband-excited linear predictive coder with a two-sided short-term predictor is proposed. A two-sided predictor (TSP), which predicts on the basis of past and future samples within the frame, is used to reconstruct the spectral envelope. The coder is a completely frame-based, fixed bit-rate, frequency-domain coder. The excitation spectrum is split into bands whose width depends on the pitch frequency, and each of these bands is coded independently using vector quantisation techniques. Dynamic bit allocation is employed for each band based on the speech energy in that band. The synthetic spectrum is obtained as the product of the excitation spectrum and the spectral envelope. This coder combines some of the benefits of sub-band coding with those of CELP-type techniques. The coder has a highly parallel structure, and pitch periodicity is exploited effectively although the coding is independent in each frame. A 4.8 kbit/s coder was designed and tested and the performance was seen to be promising.