Developing an objective quality assessment model for user-generated content (UGC) videos is significant for multimedia applications, and also a challenge due to the diversity of video content and unpredictability of distortions. To predict the perceived quality, it is necessary to consider the human visual system, in which attention in visual and memory domains is an essential component. With the idea that the stimulus-driven bottom-up mechanism and cognition-driven top-down mechanism work in synergy to generate quality-aware attention, we propose an end-to-end blind video quality assessment (VQA) algorithm based on visual and memory attention modeling. First, a quality-aware visual attention module is established to obtain spatial-temporal attention-guided representations for frame-level quality perception. Specifically, an attention selection and confluence method is developed by circularly integrating the quality-aware attention information to spatial-temporal content features. Then, with the aid of a quality-aware memory attention module, the video-level attention-guided features are inferred through the dimension and attention reshaping of frame-level representations. The video quality is predicted with the guidance of frame-level visual attention and video-level memory attention in an end-to-end structure. Experimental results on five UGC-VQA databases (CVD2014, LIVE-Qualcomm, KoNViD-1 k, LIVE-VQC and Youtube-UGC) demonstrate the effectiveness of our modules.

With the widespread usage of video capture devices and social media videos, videos are dominating the multimedia landscape. There is an emerging need for video quality assessment (VQA) that forms the backbone of advanced video systems. Night-time videos play an important role in user capturing, hence being able to accurately assess their quality is critical. However, the characteristics of night-time videos differ from those of general in-capture videos; and VQA algorithms that have been developed for general-purpose videos cannot accurately assess the quality of night-time videos. Research is needed to gain a better understanding of how humans perceive the quality of night-time videos, and use this new understanding to develop reliable VQA algorithms. To this end, we construct a large-scale night-time VQA database, namely Mobile In-capture Night-time Database for Video Quality (MIND-VQ), containing 1181 night-time videos, 435 subjects, and over 130000 opinion scores. We perform thorough analyses to reveal subjective quality assessment behaviors of night-time videos. Furthermore, we propose a new VQA model, namely Visibility-based Night-time Video Quality Assessment Network, VINIA. Spatial and temporal visibility-aware components are characterized to reflect properties of human perception of night-time VQA task. A series of experiments are conducted to compare our VINIA with other existing VQA algorithms using our new MIND-VQ database and other public VQA databases. Experimental results show that our subjective VQA database provides new insights and our new VINIA model achieves superior performance in accessing night-time video quality.