Adaptive motion vector resolution prediction in block-based video coding

In the classical block-based video coding, motion vector is derived for each coding block to remove the inter-frame redundancy. However, the motion vector resolution is usually restricted to be identical, typically 1/4-pixel resolution, regardless of the different video contents. In this paper, we propose an algorithm that can adaptively select the optimal motion vector resolution at frame level according to the characteristics of the video contents. We first derived a residual energy model, and the major factors that may impact the motion vector resolution are considered, including the texture complexity, motion scale, inter-frame noise and quantization parameter. Experimental results have shown that the proposed scheme can achieve 1.8% BD-rate gain on average without complexity increment.