A Windowed Search Method for the Pitch Predictor in Celp Coder
Chih-Chung Kuo, Ron-Chuan Pan, Fu-Rong Jean and Hsiao-Chuan Wang Department of Electrical Engineering National Tsing Hua University, Hsinchu, Taiwan, 30043, Republic of China
In analysis-by-synthesis coders, the delay parameters of pitch predictors in consecutive subframes can be encoded efficiently and decoded robustly if there is a smooth pitch contour. In this paper we present a new method called the windowed search (WS) method to obtain a smooth pitch contour. Three types of WS algorithms are proposed and implemented in CELP coders for experiments. The results show that not only a smooth contour but also less computation and slightly better quality as measured by subjective tests are found by using the WS method as compared to other smoothing methods.