Variable rate speech coding for umts
Luca Cellario, Daniele Sereno · 2005
A variable rate speech codec with seven operating rates ranging from 400 bit/s to 16 kbit/s and a 10 ms algorithmic delay is presented in this paper. The current rate is chosen according to an open-loop speech classification followed by a closed-loop quality evaluation. The rate selection can be source-controlled or network-controlled. The codec is based on a CUP algorithm with a variable number of excitations. The innovations have a deterministic structure allowing a very efficient search procedure and are orthogonalized to the long-term contribution. The algorithm will be implemented in the testbed of one RACE II project: CODIT (COde DIvision Testbed) [1].