MDCT-Domain Packet Loss Concealment for Scalable Wideband Speech Coding

Abstract

In this paper, we propose a modified discrete cosine transform (MDCT) based packet loss concealment (PLC) algorithm in order to improve the quality of decoded speech when a packet loss occurs in scalable wideband speech coders using MDCT as spectral parameters. The proposed PLC algorithm is realized by smoothing MDCT coefficients between the low and high bands for scalable wideband speech coders. In G.729.1, a typical scalable wideband speech coder standardized by ITU-T, two different PLC algorithms are applied to low band and high band in time and frequency domain, respectively. Thus, the MDCT coefficients around the boundary between the low and high band can be mismatched. The proposed PLC algorithm is replaced with the PLC algorithm applied to the high band, and it compensates for the mismatch in the MDCT domain at the boundary. Finally, we compare the performance of the proposed PLC algorithm with that of the PLC algorithm employed in G.729.1 by means of perceptual evaluation of speech quality (PESQ), an A-B preference test, and a waveform comparison under different random and burst packet loss conditions. It is shown from the experiments that the proposed PLC algorithm provides significantly better speech quality than the PLC of G.729.1.