A METHOD AND APPARATUS THAT SEARCHES A FIXED CODEBOOK IN SPEECH CODER BASED ON CELP

摘要

A fixed codebook searching apparatus and method in a CELP(Code Excited Linear Prediction)-based speech coder are provided to select an initial fixed codebook suitable for a speech characteristic and decide the number of pulse replacements and a limit in order to improve sound quality and reduce the quantity of unnecessary calculations. A fixed codebook searching apparatus in a CELP-based speech coder includes a speech characteristic information collection unit(310), a speech characteristic determination unit(320), an initial fixed codebook determination unit(330), a fixed codebook search parameter determination unit(340), and a fixed codebook determination unit(350). The speech characteristic information collection unit collects speech information from user's speech by using a CELP speech coder. The speech characteristic determination unit determines a speech characteristic based on the collected speech information. The initial fixed codebook determination unit selects an initial fixed codebook based on the determined speech characteristic. The fixed codebook search parameter determination unit determines various constants required for pulse replacement based on the determined speech characteristic. The fixed codebook determination unit determines a fixed codebook through the pulse replacement by using the selected fixed codebook search parameter and the initial fixed codebook as initial values.