LCU-based adaptive interpolation filter

Interpolation filter that supports motion estimation with fractional-pel accuracy is one of important coding tools for improving efficiency of inter frame coding. A lot of interpolation filters were proposed to standardization activity of Joint Collaborative Team on Video Coding (JCT-VC) to establish a next video coding standard called High Efficiency Video Coding (HEVC). DCT-based interpolation filter (DCT-IF) is currently employed in the HEVC test model (HM) software. However, the values of the filter coefficients are constant regardless of the characteristic of the input video. The authors proposed a region-based adaptive interpolation filter (RBAIF) that optimizes the filter coefficients on a region-by-region basis. In this paper, some modifications are added to the conventional RBAIF. Simulation results showed that, compared to the HM software, the proposed filter offers about 0.5% and 0.4% average coding gains for luminance and chrominance, respectively. Runtime of the encoder and the decoder were 101.4% and 102.5% on average, respectively.