AC3和dolby digital是一回事dolby surround = stereo front + mono surround dolby pro logic / II = stereo front + mono surround + center dolby digital / DTS = stereo front + stereo surround + center + woofer dolby digital surround EX / DTS EX MATRIX 6.1 = stereo front + stereo surround + center + "matrixed surround center" + woofer