Optimization of 2.4KBPS MELPe based on ARM9

MELPe (Mixed-Excitation Linear Predictive Enhancement) is an enhanced algorithm of MELP, which includes noise pre-processor and achieves better speech quality than MELP. To meet the demand of real-time embedded application, the MELPe algorithm is optimized based on ARM926EJ-S. The detailed process of optimization is presented, including three levels: algorithm optimization, code optimization and embedded assembly optimization. After optimization, the computation complexity is decreased by 87.6% (from 516.8MIPS to 64.1MIPS). And the PESQ test shows that the speech quality doesn't descend. The experiments indicate that the effectiveness of the proposed approaches, which meets the requirement of real-time implementation.