Scalable VLSI architecture for variable block size integer motion estimation in H.264/AVC

Because of the data correlation in the motion estimation (ME) algorithm of H.264/AVC reference software, it is difficult to implement an efficient ME hardware architecture. In order to make parallel processing feasible, four modified hardware friendly ME workflows are proposed in this paper. Based on these workflows. a scalable full search ME architecture is presented, which has following characteristics: (1) The sum of absolute differences (SAD) results of 4 × 4 sub-blocks is accumulated and reused to calculate SADs of bigger sub-blocks. (2) The number of PE groups is configurable. For a search range of M×N pixels, where M is width and N is height, up to M PE groups can be configured to work in parallel with a peak processing speed of N×16 clock cycles to fulfill a full search variable block size ME (VBSME). (3) Only conventional single port SRAM is required, which makes this architecture suitable for standard-cell-based implementation. A design with 8 PE groups has been realized with TSMC 0.18 μm CMOS technology. The core area is 2.13mm × 1.60 mm and clock frequency is 228 MHz in typical condition (1.8 V, 25°C).