Hierarchical inter mode decision for HEVC

The newest video coding standard-high efficiency video coding (HEVC) can achieve higher coding efficiency, but at the expense of tremendous computational complexity. To address this problem, a fast inter mode decision algorithm, called the hierarchical inter mode decision (HIMD), is proposed in this paper. For each coding tree unit (CTU), the proposed HIMD algorithm determines the optimal mode in time by checking the early termination condition, which is developed based on the observation that the relationship between the rate-distortion (RD) cost and the size of prediction mode is a uni-modal function (only one minimum value). Experimental results have shown that compared with the exhaustive mode decision in HEVC, the proposed HIMD algorithm is able to achieve a reduction of computational complexity by 45.81% on average, while incurring only 0.07dB loss in Bjontegaard delta peak signal-to-noise ratio (BDPSNR) and 2.04% increment on the Bjontegaard delta bit rate (BDBR).