| 摘要 |
PROBLEM TO BE SOLVED: To prevent quality deterioration in a section wherein an adaptive sound source code book does not function, e.g. where a speech rises as to a CELP type speech encoding device used for a portable telephone, etc. SOLUTION: An extended adaptive sound source code hook 103 where past features of a driving sound source are held is newly provided. The driving sound source is represented as the sum of the output of the adaptive sound source code book 105 or the output of the extended adaptive sound source code book 103 and the output of a fixed sound source code book 108 to select an optimum sound source between the adaptive sound source and extended adaptive sound source. An extended adaptive sound source code book 103 consists of >=1 code book vectors of size larger than encoded sound source vector length and the extended adaptive sound source code book is updated by determining a section similar to past driving sound source vectors in the extended adaptive sound source code book by searching and weighting and adding the driving sound source vector to the section. |
