Online and offline computational reduction techniques using backward filtering in CELP speech coders
Mark Anthony Johnson, T. Taniguchi · IEEE Transactions on Signal Processing · 1992
The authors review the backward filtering algorithm and give a compact proof of its validity using matrix notation. They review the relation between backward filtering and offline perceptual weighting in sparse codebook CELP and show how a combination online/offline parallel weighting algorithm can be used to reduce the search complexity of an overlapped sparse codebook by 30% to 50%.>