Proposed Modifications in the Excitation Codebook Structure of ITU-T CS-ACELP Speech Codec and Its Overall Comparative Performance Analysis with CELP-Based AMR-NB Speech Codec

摘要

The paper addresses the tactic of using forward mode excitation codebook structure of extended G.729 (ITU-T. Recommendation, 2007 [1]) consuming two non-zero pulses in each track in ITU-T 8 Kbps CS-ACELP speech codec (ITU-T. Recommendation, 2007 [1]). The proposed modification in legacy speech codec for determining optimized excitation codebook codevector using least significant search engine avoids two different codebook structures to minimize the complexity of search engine. Modification in the excitation codebook structure of the legacy speech codec triggers the bit rate of 11.6 Kbps. Comparative performance analysis is performed between the proposed speech codec and CELP-based speech codec using different subjective and objective quality assessment parameters.