A fixed-point pipelined processor optimized for decoding MPEG-1 audio layer III (MP3) is presented. Various examination and experiments on the decoding algorithm are exploited to lower the operating frequency by providing efficient instructions and addressing modes, because low frequency is directly related to low power consumption. Accordingly, the dynamic scaling method is used to preserve the precision while computing in fixed-point arithmetic. Also, a novel instruction set tuned for MP3 decoding Is presented. The resulting cycle count required to decode a frame is so small that the proposed processor can operate with 12.8 MHz while decoding in real-time.