Multi-Objective Optimization of Quality in VVC Rate Control for Low-Delay Video Coding

In this paper, a multi-objective optimization of quality based coding tree unit (CTU) level rate control method, named MORC, for low-delay video coding of Versatile Video Coding (VVC) is proposed. Unlike the traditional rate control algorithms, objectives of minimizing average distortion and minimizing quality fluctuation are introduced and considered simultaneously to obtain the optimal solution. Weighting method is then used to convert the multi-objective optimization problem into a simplistic single-objective problem. Accordingly, given the target rate constraint, rate allocation is formulated as a convex optimization problem to achieve better trade-off among three multiple objectives: minimizing average video distortion, meeting rate constraint and minimizing video quality fluctuation. Based on the D- λ model, a two-stage method is further proposed to solve the optimization problem. Experiments have been conducted on the test model of VVC, which is VTM 3.0. Compared with the state-of-the-art rate control algorithms, the proposed method can obtain the Pareto optimal solution, which dominates the solution of other methods and is able to achieve better trade-off among multiple objectives.