SGA: A Sporadic GDI Adapter for Smooth Motion Recording on Computer Screen

Users need to record whole motions on their computer screens in many applications, such as distance learning, video/audio conference, share desktop and remote control etc. Capturing from VGA output interfaces to form a video and capturing from desktops to become a proprietary file are two technologies to record computer screen. (1) Using VGA capture to form a video, images of computer screen in the video are usually blurred and recorded output file is usually large. (2) Using a daemon to capture screen from desktop utilizes too much system resource. Therefore, recording quality cannot be guaranteed and user´s operations on their computers are definitely affected. This paper focuses on improving performance of capturing computer screen directly from desktop. A dynamic control mechanism, called Sporadic GDI Adapter (SGA) mechanism, is proposed in the smooth motion recording on computer screen. In order to verify the effect of the SGA mechanism, this paper tests SGA mechanism in four different applications, web browsing, text editing, slide presentation, and video playback. The SGA mechanism dramatically reduces system workload in handling screen recording. In addition to reduce system workload, this SGA mechanism also guarantee the screen recording quality (smooth presentation of full motions on a computer screen). Experimental results show that the SGA mechanism reduces system workload, CPU utilization, by more than 50%.