Iterative triangular inequality elimination algorithm for codebook search of vector quantization

Abstract

This paper presents an iterative triangular inequality elimination (ITIE) algorithm for vector quantization (VQ) codebook search, which is then applied to the quantization of ISF coefficients in an AMR‐WB+ audio codec. Most of the codewords are ruled out as candidates using the ITIE rejection criterion, leading to considerable computational complexity reduction but with a well‐maintained coding quality. With a full search algorithm as the benchmark, this work gives a reduction in the total number of operations above 74%, a figure far beyond the 60% using the TIE algorithm with a dynamic and an intersection mechanism (DI‐TIE) and 65% using the equal‐average equal‐variance equal‐norm nearest neighbor search (EEENNS) algorithm. Furthermore, this work is expected to meet the energy‐saving requirement when implemented on an AMR‐WB+ audio codec of mobile devices. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.