Rate Control for 360° Versatile Video Coding Based on Visual Gaze Mechanism

In the past few years, 360° video has started to infiltrate various aspects of daily life. Although there have been significant developments in 360° video coding technology, understanding of the human visual gaze mechanism has been somewhat overlooked. In this paper, we propose a rate control scheme for 360° Versatile Video Coding (VVC) based on a human visual gaze mechanism, targeting at improving the coding performance and bitrate accuracy. More specifically, based on the Equi-rectangular Projection (ERP) format, latitude information is systematically analyzed and a stripe-level bit allocation scheme is established, to better mitigate the projection distortion. Subsequently, the Lagrange parameter λ is further optimized with distortion dependency and identification of the visual gaze guided key Coding Tree Units (CTUs). The proposed rate control scheme is implemented on the VVC Test Model for 360° video. Experimental results show that the proposed rate control scheme can achieve BD-rate savings in terms of Weighted to Spherically uniform-Peak Signal-to-Noise Ratio (WS-PSNR) and Sphere-Peak Signal-to-Noise Ratio (S-PSNR) under the various configurations, respectively. Meanwhile, a healthier buffer status and better visual quality can be observed, further demonstrating the advantages of the proposed scheme.