Multimodal Graph Conditioned Diffusion Model for Video Captioning

Video captioning aims to describe the content of a given video with condensed natural language sentences. Such a captioning task is full of challenges since the high requirements for visual-textual relevance and multimodal fusion understanding. Previous works primarily focus on visual content modeling, often overlooking the rich semantic correlations between visual and textual modalities, which results in incomplete understanding of the multimodal context and suboptimal caption accuracy. In this paper, we propose a multimodal graph conditioned diffusion model for video captioning, named MGCDVc. The idea behind our model is to incorporate graph-based relational reasoning with diffusion-based generative modeling to jointly model cross-modal relationships and capture latent semantic structure. Specifically, we learn a set of latent concept anchors to bridge the visual and textual modality nodes, enabling the construction of a weighted multimodal graph. Then we introduce the graph conditioned diffusion strategy which generates the textual semantic nodes and associated edges under the graph structure awareness condition. Furthermore, a soft pruning mechanism is designed to filter out low-quality nodes, thus further refining the generated multimodal graph to provide more accurate semantic structural guidance for caption generation. Experimental results on several popular datasets demonstrate that our model achieves better performance in video captioning task.