G.729 standard has been widely used in the VoIP system. But the computational complexity is too large to real-time work via software implementation on embedded devices. Even though the G.729A, it is still hard to implement. This paper will focus on the computational reduction of the quantization procedure of LSP coefficients. Thus, the hybrid two-stage VQ is proposed to replace the original structure. Experimental results confirm that more than 80% of computations can be eliminated in comparison with the conventional G.729 as well as the performance of speech quality is still good. The proposed approach can be successfully used in LSP quantization procedure and the efficiency is excellent.
