This document summarizes Dr. Li Song's research on perceptual video coding. It discusses using perceptual cues from the human visual system in video coding to discard superfluous data that humans cannot perceive. Recent research areas covered include just-noticeable distortion based rate-distortion optimization, SSIM based RDO, and analysis-completion frameworks. While perceptual metrics have improved coding performance over PSNR, bridging the gap between metrics and perceived quality remains an ongoing challenge.