APPARATUS AND A METHOD FOR SEARCHING AN ADAPTIVE CODEBOOK IN A SPEECH CODER TO IMPLEMENT AN EFFICIENT SPEECH CODER

摘要

PURPOSE: An apparatus and a method for searching an adaptive codebook in a speech coder is provided to implement an efficient speech coder by reducing quantity of calculation without decreasing quality of sound. CONSTITUTION: Closed-loop pitch delay and gain which have minimum difference from a target signal of an adaptive codebook are searched through 1-tap prediction(210). A gain table is selected by using the gain searched and a gain which makes minimum difference from the target signal of the adaptive codebook is searched in the gain table selected through 5-tap gain prediction(220). The closed-loop pitch delay searched and the pitch gain searched in the gain table are determined as the result of adaptive codebook search.