HPCNet: Hybrid Pixel and Contour Network for Audio-Visual Speech Enhancement with Low-Quality Video

To advance audio-visual speech enhancement (AVSE) research in low-quality video settings, we introduce the multimodal information-based speech processing-low quality video (MISP-LQV) benchmark, which includes a 120-hour real-world Mandarin audio-visual dataset, two video degradation simulation methods, and benchmark results from several well-known AVSE models. We also propose a novel hybrid pixel and contour network (HPCNet), incorporating a lip reconstruction and distillation (LRD) module and a contour graph convolution (CGConv) layer. Specifically, the LRD module reconstructs high-quality lip frames from low-quality audio-visual data, utilizing knowledge distillation from a teacher model trained on high-quality data. The CGConv layer employs spatio-temporal and semantic-contextual graphs to capture complex relationships among lip landmark points. Extensive experiments on the MISP-LQV benchmark reveal the performance degradation caused by low-quality video across various AVSE models. Notably, including real/simulated low-quality videos in AVSE training enhances its robustness to low-quality videos but degrades the performance of high-quality videos.The proposed HPCNet demonstrates strong robustness against video quality degradation, which can be attributed to (1) the reconstructed lip frames closely aligning with high-quality frames and (2) the contour features exhibiting consistency across different video quality levels. The generalizability of HPCNet also has been validated through experiments on the 2nd COG-MHEAR AVSE Challenge dataset.