FAST COMPUTATION OF FORWARD AND INVERSE MDCT USING CLENSHAW’S RECURRENCE FORMULA

P. Sai chaitanya, P. santhosh

Abstract


The MPEG audio coding standard employs the
dynamically windowed modified discrete cosine transform
(MDCT) to achieve a high-quality performance. Direct
computation of the MDCT in MPEG coding and of the inverse
MDCT (IMDCT) in MPEG decoding are computationally
intensive tasks. Therefore, efficient algorithms for the MDCT
and IMDCT are of prime importance within the audio coding
and decoding process. The forward and inverse modified
discrete cosine transform (MDCT) are two of the most
computational intensive operations in the MPEG audio coding
standard. In this project, we used Clenshaw’s recurrence
formula to transform kernels of the MDCT and IMDCT of the
general length. Clenshaw’s recurrence formula is an efficient
way to evaluate the sum of products of indexed coefficients that
obey recursive relations. Efficient implementations of MDCT
and IMDCT are obtained. The proposed regular structures are
particularly suitable for parallel VLSI realization. Simulation
results are carried out for signal reconstruction by considering
different signals. Further, the proposed approach is applied for
signal compression and the compression results are obtained. It
is observed from the simulation results that the proposed
approach is more efficient that straightforward method.

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