| 摘要 |
<p>An improved excitation vector generation and search technique is described for a code-excited linear prediction (CELP) speech coder (100) using a codebook of excitation code vectors. A set of M basis vectors vm(n) are used along with the excitation signal codewords (i) to generate the codebook of excitation vectors ui(n) according to a "vector sum" technique (120) of converting the selector codewords into a plurality of interim data signals, multiplying the set of M basis vectors by the interim data signals, and summing the resulting vectors to produce the set of 2M codebook vectors. The entire codebook of 2M possible excitation vectors is efficiently searched by using the vector sum generation technique with the basis vectors - without ever having to generate and evaluate each of the code vectors themselves. Furthermore, only M basis vectors need to be stored in memory (114), as opposed to all 2M code vectors.</p> |
