Characteristic waveform extraction rate adaptive WI speech coding scheme

This paper presents a Waveform Interpolation (WI) speech coder, which characteristic waveform extraction rate is adaptive to the feature of the input frame. Efficient pitch estimation algorithm is based on the principle of maximizing double weighted Long Time Prediction (LTP) gain and uses the forward pitch detection. The waveform extraction rate and the update rate of SEW (Sulocoly Evoloiuy Waveform) and REW (Rapidly Evolving Waveform) are based on the three features: pitch cycle, voicing degree and stationary degree of waveform surface. Tests indicate that the proposed WI coding algorithm has lower average bit rate and computing complexity compared to the fixed-extraction-rate WI coder and obviously deliver better quality than FS1016 CELP at 4.8 kbps.