A fast MPEG-audio layer III algorithm for a 32-bit MCU

This paper describes a fast MP3 algorithm for a 32-bit microcontroller unit (MCU) with DRAM to realize a real-time MP3 software decoder. Effective methods of reducing the amount of operations by using the IMDCT coefficients' symmetry and appropriate multiplication size, and storing data to use the DRAM effectively are proposed. As a result, the proposed methods make it possible to cut the processing speed requirement in half and a decoding time of approximately 20 msec per frame for joint stereo data with a sampling frequency of 44.1 kHz has been obtained, that is to say, real-time decoding can be realized.