THE QUANTIZER AND METHOD OF LSF COEFFICIENT IN WIDE-BAND SPEECH CODER USING TRELLIS CODED QUANTIZATION ALGORITHM

摘要

A quantizer and method of an LSF coefficient in a wide-band speech coder using trellis coded quantization algorithm are provided to improve an SD performance and assigned bits by reducing an error transfer as a result of using in parallel both a predictional structure and a non-predictional structure. A quantizer of an LSF coefficient in a wide-band speech coder includes a predictional structure quantizing portion(200), a non-predictional structure quantizing portion(210), and a switching portion(220). The predictional structure quantizing portion calculates a quantized candidate vector by quantizing an LSF coefficient vector, and a predictional quantization final vector of the LSF coefficient vector by trellis coded quantizing the candidate vector with reference to a predicted LSF vector of the LSF coefficient vector. The non-predictional structure quantizing portion calculates a quantized candidate vector by quantizing the LSF coefficient vector, and a non-predictional quantization final vector of the LSF coefficient vector by trellis coded quantizing the candidate vector. The switching portion selects smaller one of differences between the LSF coefficient vector and the predictional and non-predictional quantization final vectors as the final quantization vector of the LSF coefficient vector.