Scalable Variable Rate CWI Speech Coding Algorithm Based on Wavelet Transform
Jingming Kuang · Transactions of Beijing Institute of Technology · 2008
A scalable variable rate characteristic waveform interpolation(CWI) speech coding algorithm is proposed based on wavelet transform(WT).The 2-D characteristic waveform surface is decomposed into several spaces with different time-frequency resolution,which serves as the enhancement layers of scalable CWI coding scheme.The basic layer only contains linear prediction parameters,pitch cycle and power normalized factors.The scalable WT-CWI coder obtains variable bit rate.MUSHRA subjective listening test showed that with the coding rate increasing from 1.8kbit/s to 3.6kbit/s,the basic layer of the proposed scalable variable rate CWI coder outputs acceptable speech quality and the enhancement layers improved the speech quality in turn.