Video Quality Assessment: Exploring the Impact of Frame Rate
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Date
2019-05-01
Authors
Mohammadi Nasiri, Rasoul
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
Technology advancements in the past decades has led to an immense increase in data traffic over various networks. Videos constitute a major percentage of this traffic and their share is projected to increase at an accelerating speed in the coming years. Service providers aim to deliver videos that have high quality while at the same time keeping the data rate as low as possible. Effective and efficient objective Video Quality Assessment~(VQA) algorithms are essential in order to provide real time estimate of video quality so that the best compromise between data rate and quality can be achieved. Data rate of video transmission can be altered by controlling different parameters of the video, among which frame rate is one of the most important parameters. So far, only limited works have been done to study the impact of frame rate variations on video quality.
The purpose of this work is to investigate the impact of varying frame rate on the quality of videos and to develop novel VQA models that integrate frame rate variations into the task of quality assessment. In order to achieve this goal, we first construct two new video databases that contain videos of diverse content, and spatial and temporal resolutions. We carry out subjective studies on these databases to obtain human opinions on video quality. The subjective study allows us to evaluate the performance of well known objective VQA algorithms on cross-frame rate videos. The results reveal that there is considerable disparity between the subjective scores and the predictions from state-of-the-art objective models that do not take frame rate into consideration.
We explore statistical models for video quality analysis. In particular, we conduct cross-frame local phase statistical analysis, which provides new insights on video motion smoothness as an important factor that affects video quality across different frame rates. Our evaluations of the proposed motion smoothness metric using the subject-rated databases show that this novel measure provides a new means to capture the impact of frame rate on video quality, and demonstrates strong promise at improving the performance of objective video quality assessment models.
We also propose the notions of perceptual temporal aliasing factor and perceptual spatiotemporal aliasing factor to incorporate the characteristics of human visual contrast sensitivity variations into the framework of spatial and temporal aliasing analysis. We incorporate the proposed aliasing factors into the VQA process to predict the quality of video under frame rate change, resolution change, and lossy compression. Our performance evaluation using the subjective database shows that the proposed perceptual aliasing factors are strong quality predictors across-frame rate, resolution, and data rate, significantly outperforming baseline VQA methods without aliasing modeling.
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Keywords
High frame rate, video quality assessment, Perceptual quality analysis, spatiotemporal aliasing, motion smoothness, Perceptual video processing, cross frame rate video analysis, Subjective evaluation