In the fir_mem_up filter, the inner loop does a mac on the y0, y1, y2, y3 variables. What is the range of values of those variables? I would like to move the SHR 1 outside the loop after the mac has been done. Will this result in a 32 bit overflow of the y0, y2, y2 and y3 variables? -Fritz On2 Technologies, Inc. http://www.on2.com