| Summary: | 碩士 === 輔仁大學 === 資訊工程學系碩士班 === 103 === Remote screen recording is a system that records whole actions on a remote computer screen, and displays the actions on a client computer screen at the same time. Traditionally, screen recording are streamed in a video format, which large data usually results in high CPU utilization and heavy network loading. Therefore, in order to reduce CPU utilization and network bandwidth loading, the screen recording system records and only sends the blocks which have updates on the recording screen. A screen update on any part of the recording screen is called a “changed block” in this paper. Only recording and sending the changed blocks definitely reduces the network bandwidth and CPU loading. Because of only sending changed blocks, this study comes up with a media synchronization problem between a video stream and remote screen data stream in a distance learning system due to an unstable network environment. This study proposes a fast skip mechanism, called Fast Media Synchronization (FMS), to match the video stream playback by adjusting the remote screen data stream. The FMS quickly determines whether the changed blocks overlap. In the fast skip mechanism of FMS, overlapping areas among changed blocks in a screen data stream will be effectively deleted. In this paper, four different scenarios web browsing, document editing, slide presentation, and video playback, are designed to test the effectiveness of applying FMS. The experiment results shows that the FMS mechanism approximately reduces 85% of processing time, 57% to 99% of the frequency of pasting times, 70% to 90% the number of comparisons, and 70% to 90% the total pasting area. Furthermore, the proposed FMS mechanism can also be applied to improve the efficiency of different screen recording systems, such as remote desktop, distance conferencing, and video streaming, etc.
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