Complexity Reduction Algorithm of QCELP Speech Coder

摘要

The present invention is a method of cyclically using a previously calculated value by _{avoiding a} complicated formula having a large amount of calculation used to calculate the energy E _{yy L} and E _yyl obtained in the search of pitch and codebook parameters in the QECLP algorithm. The goal of this method is to implement a cheaper and less MIPS chip for QCELP vocoder implementation. The configuration of the present invention reduces the complexity of calculating E _yyL , which is an energy item found in the pitch parameter search in the QCELP vocoder algorithm.;E _yyL = y _L (n) y _L (n) + S _L (n), where S _L (n) = S _Ll (n) + y _L² (N _h ) -y _Ll² (L _p -l);Where L is pitch delay, y _L (n) is the synthesized speech signal with pitch delay L, N _h is the number of samples used to approximate the impulse response of the weighted synthesis filter, and L _p is the number of samples in the pitch subframe ).;In addition, the computational complexity is reduced to calculate E _yyl , which is an energy item that is found when searching codebook parameters in the QCELP vocoder algorithm.;E _yyl = y _L (n) y _L (n) + S _L (n), where S _l (n) = S _ll (n) + y _l² (N _h ) -y _ll² (L _c -l);Where I is the codebook index y _l (n) is the synthesized speech signal with codebook index I, N _h is the number of samples used to approximate the impulse response of the weighted synthesis filter, and L _c is the sample of the todbook subframe Number).;In addition, when the selected codebook value becomes zero during the codebook parameter search, the complexity of calculating the energy item E _yyl is reduced E _yyl = E _yyl-l -y _l² (L _c -1), where I is the codebook index. y _l (n) is the synthesized speech signal having codebook index I, N _h is the number of samples used to approximate the impulse response of the weighted synthesis filter, and L _c is the number of samples of the todbook subframe.;The effect of the present invention is to reduce the amount of computation by improving the high-energy energy equation calculated during the search of pitch and codebook parameters in the QCELP vocoder algorithm, and to implement the QCELP vocoder using the reduced complexity equation, it is cheaper and more MIPS. The effect is to make a vocoder chip with less.