Improved adaptive codebook-based speech compression system

Abstract From the Canadian patent

A speech coding system employing an adaptive codebook model of periodicity is augmented with a pitch-predictive filter (PPF). This PPF has a delay equal to the integer component of the pitch-period and a gain which is adaptive based on a measure ofperiodicity of the speech signal. In accordance with an embodiment of the present invention speech processing systems which include a first portion comprising an adaptive codebook and corresponding adaptive codebook amplifier and a second portion comprising a fixed codebook coupled to a pitch filter are adapted to delay the adaptive codebook gain; determine the pitch filter gain based on the delayed adaptive codebook gain and amplify samples of a …