Abstract: Synthesizing of video frames that have been dropped by a video encoder is achieved by interpolating between decoded frames at a decoder. The method consists of successive refinement stages that increase in computational complexity. Starting with a spatio-temporal median filtering approach, each stage uses information that improves the quality of the interpolated frames, such as bit stream motion information, decoder-based motion estimation and motion-based state segmentation of regions. By using more computational resources, each of these stages results in an improved quality of interpolated video. The motion compensation techniques are based on block-based motion estimation of the kind used by block-transform based video encoders. More accurate motion estimates are obtained by using a combination of forward and backward block motion estimation.

Abstract: A method and apparatus for displaying a user selected region-of-interest clearly on a video display terminal in an audiovisual conferencing system is disclosed. The method comprising the steps of having a user select his or her region-of-interest on a display terminal with an input device, having the video decoder translate the user's selection to corresponding horizontal and vertical coordinates recognizable both by the video decoder and the video encoder, having the video decoder transmit the coordinates to the video encoder through a back transmission channel, and having the video encoder allocate bits originally for representing compressed video information outside the region-of-interest to represent compressed video information within the interested region of images and transmit the compressed video information to the video decoder through a forward transmission channel.