Spatial Coupling Strategy and Improved BFGS-Based Advanced Rate Control for VVC

This paper presents an advanced rate control (ARC) algorithm for Versatile Video Coding (VVC). The proposed method is based on spatial coupling strategy and improved Broyden Fletcher Goldfarb Shanno (BFGS) algorithm to achieve a high performance rate control (RC). In this paper, we address the problem that the current coding block does not fully utilise the spatial information during the encoding process. Firstly, a parameter updating strategy at the coding tree unit (CTU) level is constructed based on spatial coupling strategy. The spatial coupling strategy established the relationship between video parameters and video texture, which enables the video parameters at the CTU level to be more closely aligned with the video content. Furthermore, in order to enhance the precision of RC, we have proposed an improved BFGS algorithm to update video parameters, which utilizes the optimal search direction of the different partial differentials and sets an adaptive speed control factor. The experimental results indicate that the proposed method offers better performance compared to the default RC in VVC Test Moder (VTM) 19.0, with Bjøntegaard Delta Rate (BD-Rate) savings of 6.35%, 5.09% and 5.43% under Low Delay P, Low Delay B and Random Access configurations, respectively. Moreover, the proposed method demonstrates superior performance compared to other state-of-the-art algorithms.