Hardwired MPEG-4 repetitive padding

Abstract

We consider two hardwired solutions for repetitive padding, a performance restricting algorithm for real time MPEG-4 execution. The first solution regards application specific implementations, the second regards general purpose processing. For the application specific implementations we propose a systolic array structure. To determine the chip area and speed, we have synthesized its VHDL models for two field-programmable gate array families-Xilinx and Altera. Depending on the implemented configuration, the unit can process between 77 K and 950 K macroblocks per second (MB/s) when mapped on FPGA chips containing less than 10 K logical gates and frequency capabilities below 100 MHz. The second approach regards an augmentation of a general-purpose arithmetic logical units with an extra functionality added to perform repetitive padding. At trivial hardware costs of a few hundred 2/spl times/2 AND-OR logic gates, we achieve an order of magnitude speed-up compared to nonaugmented general purpose processor padding. The proposed hardware solutions meet the requirements of all MPEG-4 visual profile levels. Both approaches have been proven to be scalable and fit into different architectural concepts and operand widths.