zidaibianma

代码说明：

  设计了镜像滤波器opt_filter函数来实现子带分解与合成。取N=256， nbands=16，调用滤波器函数完成子带分解与合成(Mirror filters are designed to achieve opt_filter function subband decomposition and synthesis. Take N = 256, nbands = 16, call the filter function and achieve Synthesis Subband Decomposition)