Derivation of efficient CELP coding algorithms using the Z-transform approach
Alain Le Guyader, Renaud Di Francesco, Claude Lamblin · 1991
A novel approach for minimizing the CELP (code excited linear prediction) error criterion in the Z-transform domain is presented. A covariance method and an autocorrelation method of CELP coding are derived using the Z-transform formulation. The intermediate signals in the excitation selection are interpreted in terms of digital filtering, (inter)correlations, spectra, and inner products. For each method, specific algebraic codebooks permit fast algorithms in the selection of the excitation signal, leading to low complexity CELP coders for high-quality narrowband (0-4 kHz) and wideband (0-7 kHz) speech coding at reduced bit rates.>