Among new services recently introduced on the Internet, the real time broadcasting service that is provided by AfreecaTV and USTREAM is particularly eye catching. This paper introduces a design of a real time broadcasting system that provides Picture by Picture (PBP), Picture in Picture (PIP), caption, synthesis of videos, background music, flexible cue sheet manipulation, saving the video file at a server via FTP, and many other services. The existing real time broadcasting system shows two

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... ed windows: one for background image and the other for caster's video image. With PBP, we can flexibly divide the window into several small windows in order to display multiple images. With PIP and Chroma Key, we can obtain more natural video display from the background image and the real time video. In the existing real time broadcasting system, the number of background images is limited to one. It synthesizes it with the video from the webcam. We can improve this feature so that we can have many background images and choose any one of them during broadcast. We can even use a PowerPoint file for the background images in order to broadcast a real time lecture naturally. Furthermore, even another video can be used as the background image. This paper describes our design of such system in detail.