| 摘要 |
PURPOSE: To improve efficiency in gain quantization and to realize excellent tone quality even at a low bit rate. CONSTITUTION: A gain code book retrieval circuit 19A is provided with gain code books 181, 182 respectively storing parameter representing respective gains of an adaptive code vector and a voice source vector corresponding to respective cases short and long for a fixed value of a delay value of delay code CD correspondence and a gain code book selection part 194 selecting either one side of the gain code books 181, 182 by using the delay code CD, and a gain calculation circuit 24A is provided with a gain decoding processing part 242 calculating the gains of the adaptive code vector and the voice source vector by using the delay code CD and a gain code CG, the gain code books 181, 182 and the gain code book selection part 194. |
