Enhanced Spectral Envelope Coding Based On NLMS for G.729.1

In this paper, a new encoding algorithm of spectral envelope based on NLMS 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 quantization algorithm based on NLMS is proposed. Also, reduced bits are used to enhance sound quality. The performance of the proposed algorithm is evaluated by sound quality and bit reduction rates in clean and frame loss conditions.

• Keunseok Cho
• Sangbae Jeong
• Hyungwook Chang
• Minsoo Hahn

• G.729.1
• MDCT coefficient
• NLMS
• spectral envelope.

[1] ITU-T Rec. G. 729.1, "G.729 based embedded variable bit-rate coder: An
8-32 kbit/s scalable wideband coder bitstream interoperable with G.729,"
2006.
[2] D. Massaloux et al, "An 8-12 kbit/s embedded CELP coder interoperable
with ITU-T G.729 coder: First stage of the new G.729.1 standard," in
Proc. ICASSP, May 2007.
[3] Slock, D.T.M., "On the convergence behavior of the LMS and the
normalized LMS algorithms", IEEE Transactions on Signal Processing,
Volume 41, Issue 9, pp.2811 - 2825, Sep. 1993.
[4] K. Cho, S. Jung, H. Kim, M. Hahn, "Frame error-robust MDCT bit
reduction scheme using inter-frame correlation for G.729.1.," in Proc.
ICASSP, May 2011.
[5] ITU-T Rec. G. 191, "ITU-T Software Tool Library 2005 User's manual,"
2005.
[6] S. Wang, A. Sekey and A. Gersho, "An objective measure for predicting
subjective quality of speech coders," IEEE Trans. Selected Areas in
Comm., Vol. 10, No. 5, pp. 819-829, June 1992.
[7] M. Hayes, Statistical Digital Signal Processing and Modeling, Prentice
Hall, 1996.