FFT and IFFT for 16-bits wave, you can use this instead of convolution calculate, input samples must be 2^n. If its not 2^n samples just stuff zero in last array. I already make it to C++ class you can new a calss and do it easy

FFT快速傅里叶变换程序语言。频率抽选基FFT和IFFT子程序,FFT Fast Fourier Transform programming language. Frequency-based FFT and IFFT selected subroutine