COZI: crowdsourced and content-based zoomable video player

We present a new user interface designed to allow easy yet effective zooming and panning into high-definition videos for playback on low resolution displays. Our system first applies state-of-the-art video analysis algorithms to detect salient regions of interest and recommends them to users. These recommendations help users to quickly identify important regions in the video and zoom into the regions with a single mouse click. The salient regions may moves according to the movement of track objects, further reducing the need for users to manually pan to track an object of interests. To further improve the relevance of the recommended regions, users' interactions are logged and analyzed. The actual regions selected and viewed by users serve as a feedback and is integrated into the system to improve the recommendations. We have implemented a Web-based version of the user interface, running on modern browsers supporting HTML5. We describe the algorithms and optimizations used to implement and improve the system.