For multipoint video conferencing over a wide-area network, a video bridge is often used to combine the coded video signals from multiple participants into a single video for display. The video combining can be done in the coded-domain by concatenating coded video bitstreams, or in the pixel-domain by transcoding. In this paper we compare the video quality using the two approaches for a multipoint video conference over a symmetrical wide-area network such as Integrated Service Digital Network (ISDN). We observe that in most multipoint video conferences usually only one or two persons are active at one time, while other participants are just listening with little motion. To achieve similar video quality for all the conference participants, the active persons require higher bit rates than the inactive persons. By doing video combining using the transcoding approach and dynamically allocating more bits to the active persons, we show that the achieved video quality can be much better than that can be achieved using the coded-domain video combining approach.Index Terms-Dynamic bit allocation, multipoint control unit, video combining, video conferencing.
In this study, we propose a Content-based Learning Content Management System (CBLCMS). Through this system, video content can be segmented by an automatic shot/scene retrieval technology and stored in the Learning Asset Database (LADB). Using the MPEG-7 visual descriptor to define the metadata of the multimedia assets, users (teachers) is easier to construct their learning material, for example, SCO. By integration of MPEG-7 and SCORM standards, the learning material can be used in any LMS (Learning Management System), as long as it also conforms to SCORM standard. Since the mental illness prevails to bring about many social problems over the years, understanding the symptoms of mental illness and treatment is important for the care giver. For this reason, a home care teaching materials will be treated as an example to elucidate the operation of the system.
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