Content adaptive interpolation filters based on HEVC framework

Motion compensation is the key technique to reduce temporal redundancy in video coding. Interpolation filters are adopted to generate the inter frame prediction for motion compensation with fractional pixel accuracy. In existing video coding standards such as H.264/AVC and HEVC, a set of predefined interpolation filters is adopted in motion compensation. However, predefined interpolation filters cannot adapt to the video content, which may compromise the coding efficiency. In this paper, a content adaptive interpolation scheme is proposed for motion compensation. In the proposed scheme, a set of adaptive interpolation filters is derived for each frame as additional interpolation filters to minimize the inter prediction difference. Rate-distortion optimization is employed to choose between the predefined interpolation filters and the derived adaptive interpolation filters to achieve the best coding performance at the low bit rates. The proposed scheme is implemented into the HM 12.1 software. Experimental results show that the proposed scheme achieves 5.13 percent, 3.42 percent and 4.07 percent bit rate saving on average compared with HEVC under the “low delay P”, the “low delay B” and the “random access” configurations respectively.