Packet-loss robust scalable speech coding using the discrete wavelet transform

This paper presents a new scalable speech codec for IP networks using the discrete wavelet transform (DWT). The scalable narrowband speech coding scheme based on the internet low bitrate codec (iLBC) was previously presented and achieved speech quality equivalent to G.718 for narrowband signals. Whereas the performance of the core layer was satisfactory, the higher speech quality by the addition of the enhancement layer which employed the modified discrete cosine transform (MDCT) was desired. We propose the utilization of the DWT instead of the MDCT to encode the core-layer coding error in the enhancement layer. The experimental simulation results show that the DWT is a promising technique to use for encoding highly non-stationary signals such as the coding error.