Patent ID: 9747916
Date: 2017-08-29
CPC Classifications: G10L

Claim:
1. A Code-Excited Linear Prediction (CELP) type speech coding apparatus, comprising: a receiver that receives an input speech signal for encoding; an adaptive codebook that outputs an adaptive codebook vector representing a periodic component; a fixed codebook that outputs a fixed codebook vector representing a non-periodic component; an adder that generates an excitation signal from the adaptive codebook vector and the fixed codebook vector; a synthesis filter that operates based on a linear prediction coefficient obtained by performing linear prediction analysis on the input speech signal and quantization and that is driven by the excitation signal thereby generating a synthesized speech signal; and a parameter quantizer that selects the adaptive codebook vector and the fixed codebook vector so as to minimize an error between the synthesized speech signal and the input speech signal, wherein the parameter quantizer includes a fixed codebook searcher that switches between an orthogonal fixed codebook search and a non-orthogonal fixed codebook search based on a correlation value between a target vector for the fixed codebook search and the adaptive codebook vector obtained as a result of the process by the synthesis filter, and outputs switching information whether the orthogonal search is used or not, for transmitting the switching information over a communication channel to a decoder.