The High-speed LSP Transformation Algorithm in Vocoder

摘要

The LSP parameter is mainly used in low-rate speech coders because of its constant spectral sensitivity, low spectral distortion, and easy linear interpolation. However, the method of converting the LPC coefficients into the LSP is complicated and takes a long time to calculate.;The present invention relates to a method for reducing the calculation time of a real root method that is mainly used in a speech encoder among LSP conversion methods. The real root method assumes that the polynomial has a real root and converts it to LSP. However, this method takes a lot of computation time because it searches the frequency domain sequentially to find the root. The algorithm of the present invention changes the order of search sections according to the distribution of each LSP parameter. Comparing the existing real root method with the inventive method, the search time was reduced by more than 46% on average.