Optimization manner of statistical oscillation code vector, multi-stage code oscillation linear prediction encoder and multi-stage code oscillation linear prediction decoding vessel

摘要

PURPOSE:To optimize a statistical excitation code vector so that a total distor tion becomes small enough by synthesizing an adaptive excitation code vector and a statistical excitation code vector subjected to center clipping processing, at the time of encoding processing of an input voice vector. CONSTITUTION:An adaptive excitation code vector Va outputted from an adaptive excitation code book 20 is multiplied by an amplitude coefficient (ga) by a multiplier 23 and given to an adder 24. On the other hand, a statistical excitation code vector Vs outputted from a statistical excitation code book 21 is subjected to center clipping through a center clipping processing circuit, multiplied by an amplitude coefficient (gs) by a multiplier 25 and given to the adder 24. Subsequently, from the adder 24, a composite vector V of the vectors Va and Vs subjected to amplitude adjustment is obtained. In such a way, by enhancing relatively a degree of contribution of the vector Va in the vector V, a fluctuation of the vector Vs is made not to influence to the utmost an optimization processing of the vector Vs.