An Early CU Partition Mode Decision Algorithm in VVC Based on Variogram for Virtual Reality 360 Degree Videos

360-degree videos have become increasingly popular with the development of virtual reality (VR) technology. These videos are converted to a 2D image plane format before being encoded with standard encoders. To improve coding efficiency, a new generation video coding standard has been launched to be known as Versatile Video Coding (VVC). However, the computational complexity of VVC makes it time-consuming to compress 360-degree videos of high resolution. The diversity of CU partitioning modes of VVC greatly increases the computational complexity. Through statistical experiments on ERP videos, it is found that the probability of using horizontal partitioning for such videos is greater than that of vertical partitioning. The empirical variogram combined with Mahalanobis distance is proposed to measure texture orientation information. The experimental results show that the algorithm saves 32.13% of the coding time with only 0.66% BDBR increasing.