SwinLip: An Efficient Visual Speech Encoder for Lip Reading Using Swin Transformer
Young-Hu Park, Rae-Hong Park, Hyung-Min Park
TL;DR
SwinLip tackles the computational burden of visual speech encoders by leveraging a lightweight Swin Transformer and introducing a 3D Spatio-Temporal Embedding Module plus a Conformer-inspired 1D Attention block to capture temporal cues. The approach is validated across English and Mandarin lip reading benchmarks (LRW, LRW-1000, LRS2, LRS3), achieving state-of-the-art performance on Mandarin LRW-1000 with lower FLOPs and enabling streaming inference by removing certain temporal components. Key contributions include configuring a Swin Transformer for small lip-reading inputs, integrating temporal embeddings without compromising patch-based processing, and demonstrating compatibility with diverse backends while delivering substantial efficiency gains. The results support SwinLip as a practical, high-performance visual speech encoder suitable for real-time lip reading and AVSR systems, with clear potential for integration with audio-based models and knowledge-distillation frameworks.
Abstract
This paper presents an efficient visual speech encoder for lip reading. While most recent lip reading studies have been based on the ResNet architecture and have achieved significant success, they are not sufficiently suitable for efficiently capturing lip reading features due to high computational complexity in modeling spatio-temporal information. Additionally, using a complex visual model not only increases the complexity of lip reading models but also induces delays in the overall network for multi-modal studies (e.g., audio-visual speech recognition, speech enhancement, and speech separation). To overcome the limitations of Convolutional Neural Network (CNN)-based models, we apply the hierarchical structure and window self-attention of the Swin Transformer to lip reading. We configure a new lightweight scale of the Swin Transformer suitable for processing lip reading data and present the SwinLip visual speech encoder, which efficiently reduces computational load by integrating modified Convolution-augmented Transformer (Conformer) temporal embeddings with conventional spatial embeddings in the hierarchical structure. Through extensive experiments, we have validated that our SwinLip successfully improves the performance and inference speed of the lip reading network when applied to various backbones for word and sentence recognition, reducing computational load. In particular, our SwinLip demonstrated robust performance in both English LRW and Mandarin LRW-1000 datasets and achieved state-of-the-art performance on the Mandarin LRW-1000 dataset with less computation compared to the existing state-of-the-art model.
