Alternative Half-Sample Interpolation Filters for Versatile Video Coding

To reduce the residual energy of a video signal, motion compensated prediction with fractional-sample accuracy has been successfully employed in modern video coding technology. In contrast to the fixed quarter-sample motion vector resolution for the luma component in High Efficiency Video Coding standard, the current draft of a new Versatile Video Coding standard introduces a block-level adaptive motion vector resolution (AMVR) scheme. The AMVR allows coding of motion vector difference at different precisions. Nevertheless, the interpolation filters for each fractional sample position are fixed. In this paper, alternative half-luma-sample interpolation filters are proposed. Enabling the interpolation filter selection at a fine granularity allows to better adapt to the local image characteristics. Experimental results show that the proposed method can improve the average BD-rate of VTM 5.0 reference software by -0.40% for Random Access configuration and by -0.76% for Low Delay P configuration.