Pipelined implementation of AI-based Loeffler DCT

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. Twodimensional 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.