| 摘要 |
PURPOSE: To effectively encode a sound waveform in a low bit rate area by preparing a pulse retrieval period exceeding a spectrum envelope parameter updating (interpolating) period. CONSTITUTION: The pulse retrieval period exceeding the direct updating or approximate updating period, i.e., interpolating period, of an LPC coefficient A type spectrum envelope parameter e.g. is prepared. In order to obtain detailed spectrum envelope information at the time of encoding an inputted sound signal to a multi-pulse, interpolation or LPC analysis for an LPC coefficient signal to be one of the information is executed plural times and LPC coefficients B to D are obtained in each period obtained by dividing one frame into plural periods. Consequently the expression of a spectrum envelope is increased and communication of fine tone quality can be executed even by the transmission of a low bit rate. |
