Inverse modified discrete cosine transform (imdct) co-processor and audio decoder having the same

Abstract

Provided are an IMDCT co-processor and an audio decoder having the same. The IMDCT co-processor includes: an input buffer for storing an input inverse-quantized frequency spectrum sample value; an I/Q separator for dividing the sample value stored in the input buffer into real data I and imaginary data Q; a first operation unit for performing complex-multiplication on the data divided by the I/Q separator and a given twiddle factor; an IFFT unit for performing an inverse fast Fourier transform on the operation result value of the first operation unit; a second operation unit for performing complex-multiplication on the result value from the IFFT unit and a given twiddle factor; a deinterleaver for receiving the operation result value from the second operation unit to arrange data and performing inverse-mapping on a positive value (+) and a negative value (−) of a certain portion of the data to each other to output a final IMDCT time sample value; and a control register for selecting the input inverse-quantized frequency spectrum sample value according to a given window sequence value to determine the final IMDCT time sample value.