Cost-effective VLSI architectures and buffer size optimization for full-search block matching algorithms

This paper presents two efficient very large scale integration (VLSI) architectures and buffer size optimization for full-search block matching algorithms. Starting from an overlapped data flow of search area, both systolic- and semisystolic-array architectural solutions are derived. By means of exploiting stream memory banks, not only input/output (I/O) bandwidth can be minimized, but also processor element efficiency can be improved. In addition, the controller structure for both solutions are very straightforward, making them very suitable for VLSI implementation to meet computational requirements. Moreover, by exploring the dependency graph, we focus on the problem of reducing the internal buffer size under minimal I/O bandwidth constraint to derive guidelines on reducing redundant internal buffer as well as to achieve area-efficient VLSI architectures. Simulation results show that, for N=P=16 (N is the reference block size and P is the search range), I/O bandwidth can be reduced by 2.4 times, while buffer size increases less than 38%. Two prototype chips for N=P=16 have been designed and fabricated. Test results show that clock rate can be up to 90 MHz, implying that more than 87.9-K motion vectors per second can be achieved to meet real-time requirements specified in MPEG-2 MP@ML coding standard.