基于定点DSP的MP3解码器的系统级仿真与实现

System Level Simulation and Implementation of the Fixed-point DSP Based MP3 Decoder

便携式MP3播放器目前非常流行。在定点DSP上实现MP3解码的关键在于处理有限字长效应。该文介绍了一种用OCAPI对MP3解码算法进行基于C + +的系统级定点仿真的方法。通过对各个处理步骤迭代求精 ,从而引出各数据处理步骤中间运算结果及滤波系数的最佳字长及Q值。最后 ,在DSP5 685 8上实时地实现了与C + +仿真代码比特精准的汇编代码。测量得到的解码输出的信号 /量化噪声比约为 87dB ,总的MIPS开销约为 60。

The portable MP3 player is now very popular. The key to realize the MP3 decoder on fixed-point DSP is to deal with the finite word-length effects. A C++ based system level fixed-point simulation method of the MP3 decoder algorithm via OCAPI is introduced. After iterative refinement of each processing step, the optimal word-length and Q-Value of each intermediate results and coefficients are evolved. Finally, the bit-exact assemble code is implemented on DSP56858 in real-time. The SQNR of the decoded output is measured, about 87 dB, with the overall MIPS overhead about 60.