Efficient Pre-selection Method for Fast MP-MLQ Search in G.723.1

For multimedia communications, the low computational complexity of coder is required to integrate services of several media sources due to the limited computing capability of the personal information machine. The Multi-pulse Maximum Likelihood Quantization (MP-MLQ) algorithm with high computational complexity and high quality has been used in the G.723.1 standard codec. To reduce the computational complexity of the MP-MLQ method, this paper presents an efficient pre-selection scheme to simplify the excitation codebook search procedure which is computationally the most demanding. We propose a fast search algorithm which uses an energy function to predict the candidate pulses, and the codebook is redesigned to become the multi-track position structure. Simulation results show that the average of the perceptual evaluation of speech quality (PESQ) is degraded slightly, by only 0.056, and our proposed method can reduce computational complexity by about 52.8% relative to the original G.723.1 MP-MLQ computation load with perceptually negligible degradation. Our objective evaluations verify that the proposed method can provide speech quality comparable to that of the original MP-MLQ approach.