Parhi Research efforts are directed towards the design of dedicated, high-performance digital signal and image processors. The emphasis is on real-time processing, where samples are processed as they are received from the source, as opposed to being stored in buffers and then processed in batch. Design of algorithm topologies for recursive signal processing algorithms were once considered a major challenge. Using the relaxed look-ahead technique, new concurrent algorithms and topologies for adaptive LMS and lattice filters, cascade and lattice recursive digital filters, and predictive speech and image coders have been developed. Design of concurrent topologies for wave digital filters, decision-feedback equalizers, and adaptive differential vector quantizers are being pursued. The decoding speed in Huffman and arithmetic coders (used for lossless compression) is limited due to the feedback. For the Huffman decoder, the codeword length multiplicity constraint is being exploited to design codes where multiple bits can be simultaneously decoded in parallel. The performance of these decoders is further improved by the use of conditional coding. Novel approaches for design of parallel arithmetic coders are also being pursued.
