High-Level Synthesis FPGA Implementation of Fractional Motion Estimation for HEVC and VVC

Abstract

The rapid deployment of modern video coding standards underscores the need for hardware implementations that enable real-time coding, support interoperability across codecs, and are openly accessible to community. This paper presents the first known high-level synthesis (HLS) implementation of an accurate full-search fractional motion estimation (FME). The proposed FME core is released as open-source and is compatible with High Efficiency Video Coding (HEVC) and Versatile Video Coding (VVC) standards. It implements 1) an accurate multiplierless constant multiplication (MCM) unit that performs quarter-pixel interpolation over 9 × 9 pixels at a time; 2) a transform-exempted sum of absolute transformed differences (TE-SATD) unit that is optimized for area and speed; and 3) fixed-point Lagrangian optimizations for rate-distortion optimization (RDO). On an Intel Arria 10 FPGA, the FME core consumes 122 kALUTs and operates at up to 210 MHz. Our profiling results show that a single FME core can support practical HEVC and VVC encoding of 2160p video at 30–120 fps, depending on the video content and encoder preset.