Low-Delay Speech Coding at 16 kb/s and Below (original) (raw)

Development of network quality speech coders at 16 kb/s and below is an active research area. This thesis focuses on the study of low-delay Code Excited Linear Predictive (CELP) and tree coders. A 16 kb/s stochastic tree coder based on the (M,L) search algorithm suggested by Iyengar and Kabal and a low-delay CELP coder proposed by AT&T (CCITT 16 kb/s standardization candidate) are examined. The first goal is to compare and study the performance of the two coders. Second objective is to analyze the particular characteristics which make the two coders different from one another. The final goal is the improvement of the performance of the coders, particularly with a view of bringing down the bit rate below 16 kb/s. When compared under similar conditions, the two coders showed comparable performance at 16 kb/s. The analysis of the components and particular characteristics of the tree and CELP coders provide new insight for future coders. Higher performance coder components such as predi...