Supporting region-of-interest cropping through constrained compression
MM '08 Proceedings of the 16th ACM international conference on Multimedia
Supporting zoomable video streams with dynamic region-of-interest cropping
MMSys '10 Proceedings of the first annual ACM SIGMM conference on Multimedia systems
Adaptive encoding of zoomable video streams based on user access pattern
MMSys '11 Proceedings of the second annual ACM conference on Multimedia systems
Supporting region-of-interest cropping through constrained compression
ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP)
Color-plus-depth level-of-detail in 3D tele-immersive video: a psychophysical approach
MM '11 Proceedings of the 19th ACM international conference on Multimedia
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The mismatch between increasingly large video resolution and constrained screen size of mobile devices has led to the proposal of zoomable video systems based on tiled video. In the current system, a tiled video frame is constructed from multiple tiles in a single resolution stream. In this paper, we explore the perceptual effect of mixed-resolution tiles in tiled video, in which tiles within a video frame could come from streams with different resolutions, with the aim to tradeoff bandwidth and perceptual video quality. To understand how users perceive the video quality of mixed-resolution tiled video, we conducted a psychophysical study with 50 participants on tiled videos where the tile resolutions are randomly chosen from two resolution levels with equal probability. The experiment results show that in many cases, we can mix tiles from HD (1920×1080p) stream and tiles from 1600×900p stream without being noticed by the viewers. Even when participants notice quality degradation in videos combined with tiles from HD stream and tiles from 960×540p stream, the majority of participants still accept the degradation when viewing videos with low and medium motion; and greater than 40% of participants accept the quality degradation when viewing video with dense motion.