APPARATUS AND A METHOD FOR TRANSCODING DATA BETWEEN SPEECH CODECS HAVING DIFFERENT CELP TYPES TO REDUCE QUANTITY OF CALCULATION AND OFFER SPEECH WITH HIGH QUALITY

摘要

PURPOSE: An apparatus and a method for transcoding data between speech codecs having different CELP(Code Excited Linear Prediction) types are provided to reduce quantity of calculation and offer speech with high quality by utilizing one transcoding filter instead of a post-processing filter and a perception weighting filter. CONSTITUTION: A decoding process part(321) converts a bitstream with an input CELP codec format into a speech signal, wherein the bitstream is formed by coding an input speech signal. A transcoding filter(323) filters the decoded speech signal by filter characteristics calculated by adopting an optimal weighting value for minimum spectrum distortion. A transcoding filter design part(322) extracts the optimal weighting value from a weighting value set comprised of a plurality of weighting value pairs. A coding process part(324) codes the speech signal processed by the transcoding filter and thereby generates a bitstream of an output CELP codec format.