Frame error-robust MDCT bit reduction scheme using inter-frame correlation for G.729.1

In this paper, a new algorithm for encoding spectral envelope in G.729.1 for VoIP is proposed. In the TDAC part of G.729.1, the spectral envelope and MDCT coefficients extracted in the weighted CELP coding error (lower-band) and the higher-band input signal are encoded. In order to reduce allocation bits for spectral envelope coding, a new algorithm using sub-band correlation between adjacent frames is proposed. In addition, a new bit allocation strategy using reduced bits from the proposed algorithm is also proposed. The performance of the proposed algorithm is evaluated by sound quality and bit reduction rates in clean and frame loss conditions.