High-level synthesis implementation of transform-exempted SATD architectures for low-power video coding

This paper presents the first known high-level synthesis (HLS) implementation for the Sum of Absolute Transformed Differences (SATD) calculation. The proposed hardware architecture is designed for two SATD algorithms: a widespread Fast Walsh-Hadamard Transform (FWHT-SATD) and a recently introduced Transform Exempted scheme (TE-SATD). This 2-stage architecture is made up of two 1-D Walsh-Hadamard Transform (WHT) stages and a transpose buffer (TB) between them. The chosen HLS approach cuts down design time over contemporary design methods and thereby made it feasible to implement a set of dedicated FWHT-SATD and TE-SATD architectures for 4×4, 8×8, and 16×16 pixel blocks. All these six architectures were synthesized for 28 nm and 45 nm standard cell technologies, and their area and energy consumptions were analysed. TE-based implementations provide 6.0-8.3% total cell area savings and 6.9-12.7% better energy-efficiency than traditional FWHT approaches. Our proposal is the first to introduce TE-SATD architectures for up to 16×16 blocks and each of these tailored architectures was shown to provide better trade-off between silicon area and performance than their reference implementations.