Method of implementing dual-mode audio decorder and filter therefor

摘要

A method of implementing a dual-mode audio decoder and filter is provided. The inverse modified discrete cosine transform (IMDCT) method and circuit for a dual-mode audio decoder perform the IMDCT with respect to a signal encoded using either the MPEG or Dolby AC-3 standard by utilizing a shared fast Fourier transform (FFT) circuit thereby simplifying the necessary hardware construction. Also, the number of IMDCT outputs used for windowing is reduced by utilizing the properties of the IMDCT outputs of the MPEG bit stream and thus the size of memory necessary for storing the IMDCT outputs is reduced.