VECTOR QUANTIZATION METHOD OF LINE SPECTRUM FREQUENCY USING LOCALIZATION CHARACTERISTICS, ESPECIALLY SEARCHING OPTIMUM CODE BOOK INDEX USING CALCULATED DISTORTION

摘要

PURPOSE: A vector quantization method of a line spectrum frequency(LSF) using localization characteristics is provided, which adopts a spectral distortion measurement considering the localization characteristics of LSFs in order to provide further improved sound quality. CONSTITUTION: According to the method, a line spectrum frequency vector of P dimension is converted into a line spectrum frequency vector of (P-1) dimension, and minimum distortion and optimum code book index and code book index are initialized(300). A quantized line spectrum frequency vector of index k is searched in the code book using the code book index k(320). Localization restriction rate is determined(330), and distortion of the quantized line spectrum frequency of index k is measured. And minimum distortion is updated by replacing the minimum distortion with the distortion and replacing the optimum code book index with the index k(360). If the code book index k is larger than the size of the code book M, the optimum code book index is output(370), and otherwise, the code book index k is replaced with (k+1)(380).