Exploring Efficient Adder Compressors for Power-Efficient Sum of Squared Differences Design

This work explores the 8-2 adder compressor in the addition tree of the Sum of Squared Differences (SSD) architecture. SSD is a distortion metric of the motion estimation in the High-Efficiency Video Coding (HEVC) standard. Distortion metrics are the most time-consuming operations of the encoder. SSD hardware architecture consists of a sum tree that accumulates the calculation of the partial values. The addition tree in the SSD opens an opportunity of exploring efficient addition schemes such as the combinations of efficient adder compressors. The SSD architectures herein presented are compared regarding power dissipation using real video sequences. Our work overcomes the state-of-the-art related work which they investigated different SSD hardware architectures concluding that employing the synthesis tool arithmetic operators are the best choice to reduce the power dissipation. According to our results, we reveal that the SSD employing the 8-2 hierarchical adder compressor combined with a Brent-Kung adder in the final sum saves on average 29.4 % of total power dissipation, when comparing with SSD implemented using the arithmetic operators automatically selected by the synthesis tool.