Multimodal affective computing for video summarization

• Main Author: Lew, Lincoln Wai Cheong
• Other Authors: Quek Hiok Chai
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Computer and Information Science; Video summarization; EEG emotion recognition
• Online Access: https://hdl.handle.net/10356/174824
• Institution: Nanyang Technological University

This research work attempts to merge affective computing and video summarization, thereby enhancing the latter by integrating cross-disciplinary affective information, termed affective video summarization. Affective video summarization functions by identifying emotionally impactful moments in the video using emotional cues, resulting in summaries to enhance user experiences. Existing visual-based video summarization methods frequently neglect integrating affective information to improve summaries through emotional considerations. Alternatively, they may disregard the visual element and instead utilize alternative modalities, like EEG signals, to generate visual attention or emotion tagging for summarization. The plausible cause is the emotion labels to guide video summarization are costly to acquire and demand extensive labels to overcome the lack of nuanced richness for personalization and emotion subtlety. Therefore, this study attempts to overcome the limitations by addressing the problem of expensive human annotations and scalability for affective video summarization. This thesis proposes using EEG as a secondary modality for emotional cues in video summarization. However, the challenge is demonstrating that EEG features retain affective information after converting it into a latent representation. The thesis thus investigates three areas: 1) Emotion recognition by spatiotemporal modeling to prove that the EEG features contain affective information. This preliminary study introduces Regionally-Operated Domain Adversarial Networks (RODAN), an attention-based model for EEG-based emotion classification. 2) Affective semantics analysis by generative modeling, employing Superposition Quantized Variational Autoencoder (SQVAE), based on an orthonormal eigenvector codebook and spatiotemporal transformer as encoder and decoder, to generate EEG latent representations and features to validate the presence of affective information. 3) Affective semantic guided video summarization with deep reinforcement learning proposes EEG-Video Emotion-based Summarization (EVES), a policy-based reinforcement learning model for integrating video and EEG signals for emotion-based summarization. In the first study, RODAN achieved emotion classification accuracies of 60.75% for SEED-IV and 31.84% for DEAP datasets, indicating the presence of affective information. Subsequently, reconstructed EEG signals using SQVAE on MAHNOB-HCI aligned closely with the original signals, and the emotion recognition results with latent representations validated the presence of affective information. Finally, through multimodal pre-training, EVES produced summaries that were 11.4% more coherent and 7.4% more emotion-evoking compared to alternative reinforcement learning models. Overall, this thesis establishes that EEG signals can encode affective information, and multimodal video summarization enhances summaries’ coherency and emotional impact.