Switch Mode Based Deep Fractional Interpolation in Video Coding

Fractional interpolation is a significant technology in motion compensation of video coding. It generates sub-pixel level reference samples in inter prediction to facilitate temporal redundancy removal between video frames. Recently, some methods explore to introduce the deep learning technique for fractional interpolation and have obtained better compression results. However, existing deep learning based methods still treat fractional interpolation as a traditional interpolation problem but fail to adjust it to the motion compensation scenario. In this paper, we design a switch mode based deep fractional interpolation method to introduce integer pixels of different positions to the interpolation of sub-pixel position samples. By switching between integer pixels of different positions, our method can infer the sub-pixels with smaller variations and achieve better fractional interpolation results. Consequently the motion compensation performance can be further improved. Experimental results have also verified the efficiency of the switch mode based deep fractional interpolation. Compared with High Efficiency Video Coding, our method achieves 2.8% bit saving on average and up to 6.2% bit saving under low-delay P configuration.