VMG: Rethinking U-Net Architecture for Video Super-Resolution

The U-Net architecture has exhibited significant efficacy across various vision tasks, yet its adaptation for Video Super-Resolution (VSR) remains underexplored. While the Video Restoration Transformer (VRT) introduced U-Net into the VSR domain, it poses challenges due to intricate design and substantial computational overhead. In this paper, we present VMG, a streamlined framework tailored for VSR. Through empirical analysis, we identify the crucial stages of the U-Net architecture contributing to performance enhancement in VSR tasks. Our optimized architecture substantially reduces model parameters and complexity while improving performance. Additionally, we introduce two key modules, namely the Gated MLP-like Mixer (GMM) and the Flow-Guided cross-attention Mixer (FGM), designed to enhance spatial and temporal feature aggregation. GMM dynamically encodes spatial correlations with linear complexity in space and time, and FGM leverages optical flow to capture motion variation and implement sparse attention to efficiently aggregate temporally related information. Extensive experiments demonstrate that VMG achieves nearly 70% reduction in GPU memory usage, 30% fewer parameters, and 10% lower computational complexity (FLOPs) compared to VRT, while yielding highly competitive or superior results across four benchmark datasets. Qualitative assessments reveal VMG's ability to preserve remarkable details and sharp structures in the reconstructed videos.