Improved higher order motion compensation in HEVC with block-to-block translational shift compensation

Conventionally, complex motion in video sequences is approximated by smaller block units in order to be representable by a translational motion model. This approximation results in a fine block partitioning and a high prediction error, both at cost of more data rate than potentially necessary. A worthwhile data reduction has been shown to be achievable by adding a higher order motion model to the most recent video coding standard, High Efficiency Video Coding (HEVC). The benefit of this additional option of inter-frame prediction is due to the more accurate motion compensation as well as the usage of larger block sizes. This paper deals with more efficient encoding of higher order motion parameters in this context. The geometrically accurate prediction of higher order motion parameters from a neighbored block needs to consider the dependency of the block-to-block parameter difference based on the spatial relation between two block centers. An algorithm is introduced for correcting the translational component and reducing the difference between the actual and the predicted motion when determining higher order parameters from neighbored blocks. Additionally, a further increase of the maximum block size up to 512×512 pixels is investigated.