Motion Hint Field with Content Adaptive Motion Model for High Efficiency Video Coding (HEVC)

Traditional video coding standards employ block-based translational motion modelwhere all the pixels inside the current block are assigned a single motion vector. Thisuniformity of motion within a block assumption does not hold if the block containsa motion discontinuity. To improve the coding gain, modern video codecs partitionblocks around object boundaries into smaller square or rectangular sub-blocks. The prediction residual energy of the current frame is minimized at the expense of increasing the bit rate to code motion data. The inspiration behind motion hints is to move away from this redundant approach of using the motion model to describe object boundaries, since the spatial structure of previously-decoded frames can be exploited to infer appropriate boundaries for the future ones.A motion hint provides a global description of motion over a specific domain and is related to the foreground-background segmentation where the foreground and background motions are the hints. A bi-directional motion hints based coding paradigm was proposed in [1, 2] that carries out segmentation in the reference frames. The segmented foreground and background regions are then mapped (motion compensated) and fused together to generate a prediction for the current frame. In this paper, the motion hint model is tuned according to the motion hint field's complexity for superior motion compensation, where the candidate motion model set is affine, elastic[3].