Efficient architectures of MDCT/IMDCT implementation for MPEG audio codec

Efficient architectures for realizing MDCT/IMDCT are presented. Based on the symmetry property of trigonometric functions, N-point MDCT formula was transferred into an odd-even index paralleling process which can be achieved by two different types of decomposition, recursive formed DCT-II kernel or FFT-based DCT-IV kernel. Then a butterfly unit is employed to accelerate the computational speed. Furthermore, these new architectures are suitable for the computations of both MDCT and IMDCT, which improve the hardware efficiency. For verification, an experiment of MPEG2 AAC using this optimized FFT-based MDCT architecture on Altera Stratix FPGA is implemented. The analyzed results show the proposed structure provides a superior performance in terms of the computation rate, the data throughput and the hardware utilization. In addition, these MDCT/IMDCT architectures can be employed in many international audio standard systems.