Language-aware Visual Semantic Distillation for Video Question Answering
Authors: Bo Zou, Chao Yang, Yu Qiao, Chengbin Quan, Youjian Zhao

Significant advancements in video question answering (VideoQA) have been made thanks to thriving large image-language pretraining frameworks. Although these image-language models can efficiently represent both video and language branches they typically employ a goal-free vision perception process and do not interact vision with language well during the answer generation thus omitting crucial visual cues. In this paper we are inspired by the human recognition and learning pattern and propose VideoDistill a framework with language-aware (i.e. goal-driven) behavior in both vision perception and answer generation process. VideoDistill generates answers only from question-related visual embeddings and follows a thinking-observing-answering approach that closely resembles human behavior distinguishing it from previous research. Specifically we develop a language-aware gating mechanism to replace the standard cross-attention avoiding language's direct fusion into visual representations. We incorporate this mechanism into two key components of the entire framework. The first component is a differentiable sparse sampling module which selects frames containing the necessary dynamics and semantics relevant to the questions. The second component is a vision refinement module that merges existing spatial-temporal attention layers to ensure the extraction of multi-grained visual semantics associated with the questions. We conduct experimental evaluations on various challenging video question-answering benchmarks and VideoDistill achieves state-of-the-art performance in both general and long-form VideoQA datasets. In Addition we verify that VideoDistill can effectively alleviate the utilization of language shortcut solutions in the EgoTaskQA dataset.