Pipelined implementation of AI-based Loeffler DCT

Abstract

We propose a pipelined implementation of the eight-point Loeffler discrete cosine transform (DCT) for portable applications. The pipelined structure produces one DCT coefficient per clock cycle, which meets the limited memory bandwidth of many portable devices. Two-dimensional algebraic integer (AI) encoding and the shift-and-add approach were used to make the implementation multiplication-free. A hardware cost reduction of approximately 40% was achieved by trading off the precision of the adders against a negligible amount of error in the reconstructed images.