Low bit rate video coding using an adaptive partially connected motion model

Current video coding standards use simple translational motion models in predefined blocks to reduce temporal redundancy. Although this approach is quite effective, artifacts are produced by the simplistic motion model used and the fixed motion boundaries. The motion compensation algorithm presented in this paper uses a new partially connected motion model that removes the constraint of fixed block sizes and translational motion. The resulting motion field is guaranteed to be smooth and generally provides a good approximation to the true motion in the scene. The parameters of this motion model are optimized using a previously described algorithm that provides an efficient method for updating several motion vectors simultaneously. The complete motion estimation/compensation algorithm is incorporated into a transform based coder and compared to an existing H.263 codec. Since the transmitted motion field provides a good approximation to the true motion in the scene, an additional advantage of the partially connected motion model is demonstrated by using the transmitted motion parameters to interpolate skipped frames at the receiver.