The multimedia interactive conferencing application (MICA), a personal-workstation application for multipoint visual teleconferencing, is described. MICA allows people at two or more locations to share visual material such as documents, photographs, and computer screens in a highly interactive way. It supports the distribution, storage, retrieval, and high-quality display of visuals, real-time interaction by pointing and annotation, and meeting services facilities. The context of multimedia teleconferencing and computer-supported cooperative work is established, relating earlier research to the design of MICA. The services MICA offers are outlined. The handling, compression, and display of multiple media, and the design of a suitable user interface for MICA are discussed.>

In this paper several video conferencing systems are discussed. These include single person-camera, voice-switched, split-screen, continuous presence, and virtual space systems. Special emphasis is placed on the more recent video conferencing systems, i.e., the continuous presence and the virtual space systems. The role of digital signal processing in the video conferencing environment is discussed. The interaction between service definition, the video conferencing system, and the digital signal processing requirements is highlighted.

Noise in television signals degrades both the image quality and the performance of image coding algorithms. This paper describes a nonlinear temporal filtering algorithm using motion compensation for reducing noise in image sequences. A specific implementation for NTSC composite television signals is described, and simulation results on several video sequences are presented. This approach is shown to be successful in improving image quality and also improving the efficiency of subsequent image coding operations.

This paper presents techniques for interframe prediction of color NTSC signals using motion estimation and compensation techniques. A key element in movement-compensated prediction is the displacement estimation algorithm. A number of techniques for performing this estimation have been presented in the literature [1]-[13]. Some new techniques giving improved performance are presented in this paper. Also, a movement-compensated composite prediction approach for coding of the NTSC color signals is presented. The performance of different displacement estimation algorithms is evaluated and compared for both component and composite approaches. A database of several color NTSC video sequences is used in the evaluation.

This paper presents the coding algorithms and simulation results of multimode movement-compensated interframe video coders operating at 15 and 20 mbits/s for broadcast applications. The coding algorithms are based on a motion-compensated predictive coding approach. Simulation results using samples of broadcast video sequence indicate that excellent picture quality is obtained at the 20 Mbit/s transmission bit rate. Results of informal subjective evaluation of picture quality are also presented.