Research And Realization Of Low Rate Speech Coding Algorithm Based On Waveform Interpolation

Recently~ there is the great interest in developing toll-quality speech coders at rates of 4kbps and below, and which are expected to be widely exploited in applications such as visual telephone~ mobile and personal communications. In this paper, a speech coder at 3.75kbps is developed based on the waveform interpolation scheme (WI), and has been simulated in floatingpoint C language.In the WI coder, the speech signal is represented by an evolving characteristic waveform (CW) . The CW is decomposed into a slowly evolving waveform and a rapidly evolving waveform, representing the quasi-periodic and non-periodic components of speech respectively,which are quantized separately.Informal subjective listening tests indicated that the unquantized WI coder is comparative with the 8kbps G.729 standard under clean input speech conditions. After quantized, the speech quality of WI coder at 3.75kbps is closed to that of G.723.l at 5.3kbps.