Recently, automatic micro-expression (ME) analysis has attracted increasing attention, since ME is a spontaneous facial expression that can truly reflect the emotional state an individual tries to conceal. As a crucial step in ME analysis, Micro- and Macro-expression (MaE) spotting aims to sequentially identify the occurrence intervals of MEs and MaEs within a long video sequence. However, the subtle spatiotemporal movements of MEs and the scarcity of well-labeled data pose great challenges for accurately spotting them. To this end, this paper proposes a novel spotting framework based on Multi-scale Feature Learning Network with Optical Flow Correction. Specifically, we first integrate the pre-trained VideoMAE and customized convolutional layers as a visual feature extraction module to learn the facial motion features in long video sequences. Then, to comprehensively locate and identify the existing ME and MaE segments, we introduce a multi-scale candidate segment generation method based on the ActionFormer. In particular, a multi-start points optical flow filtering method is proposed to improve the precision of expression spotting. Finally, we conduct comprehensive experiments on the MEGC2024 spotting task, and the experimental results demonstrate the effectiveness of our method, which ranks second in this task. The implemented code is also publicly available at https://github.com/zzy188zzy/megc_spotting_code.

Temporal action detection (TAD) aims to localize the start and end frames of actions in untrimmed videos, which is a challenging task due to the similarity of adjacent frames and the ambiguity of action boundaries. Previous methods often generate coarse proposals first and then perform proposal-based refinement, which is coupled with prior action detectors and leads to proposal-oriented offsets. However, this paradigm increases the training difficulty of the TAD model and is heavily influenced by the quantity and quality of the proposals. To address the above issues, we decouple the refinement process from conventional TAD methods and propose a learnable, proposal-free refinement method for fine boundary localization, named RefineTAD. We first propose a multi-level refinement module to generate multi-scale boundary offsets, score offsets and boundary-aware probability at each time point based on the feature pyramid. Then, we propose an offset focusing strategy to progressively refine the predicted results of TAD models in a coarse-to-fine manner with our multi-scale offsets. We perform extensive experiments on three challenging datasets and demonstrate that our RefineTAD significantly improves the state-of-the-art TAD methods with minimal computational overhead.