US Patent 7245660 Method and an apparatus for mixing compressed video

A system for controlling a conference that takes input streams from a variety of sources, at least some of the streams having a relatively low-resolution, and composes the input streams into a single output stream of a relatively high-resolution. In doing the conversion the system takes intra Macro Blocks (MBs) of the input stream and produces inter output frames. As part of the conversion process, the system converts the Groups Of Blocks (GOBs) that have GOB headers into slices.