High Efficiency Rate Control for Versatile Video Coding Based on Composite Cauchy Distribution

Yunhao MAO, Meng WANG, Shiqi WANG, Sam KWONG

Research output: Journal PublicationsJournal Article (refereed)peer-review

21 Citations (Scopus)


In this work, we propose a novel rate control algorithm for Versatile Video Coding (VVC) standard based on its distinct rate-distortion characteristics. By modelling the transform coefficients with the composite Cauchy distribution, higher accuracy compared with traditional distributions has been achieved. Based on the transform coefficient modelling, the theoretically derived R-Q and D-Q models which have been shown to deliver higher accuracy in characterizing RD characteristics for sequences with different content are incorporated into the rate control process. Furthermore, to establish an adaptive bit allocation scheme, the dependency between different levels of frames is modelled by a dependency factor to describe relationship between the reference and to-be-coded frames. Given the derived R-Q and D-Q relationships, as well as the dependency factor, an adaptive bit allocation scheme is developed for optimal bits allocation. We implement the proposed algorithm on VVC Test Model (VTM) 3.0. Experiments show that due to proper bit allocation, for low delay configuration the proposed algorithm can achieve 1.03% BD-Rate saving compared with the default rate control algorithm and 2.96% BD-Rate saving compared with fixed-QP scheme. Moreover, 1.29% BD-Rate saving and higher control accuracy have also been observed under the random access configuration.
Original languageEnglish
Pages (from-to)2371-2384
JournalIEEE Transactions on Circuits and Systems for Video Technology
Issue number4
Early online date29 Jun 2021
Publication statusPublished - Apr 2022
Externally publishedYes

Bibliographical note

This work was supported in part by the General Research Fund-Research Grants Council (GRF-RGC) under Grant 9042816 (CityU 11209819) and Grant 9042958 (CityU 11203820), in part by the Hong Kong Research Grants Council, Early Career Scheme (RGC ECS) under Grant 21211018, and in part by the General Research Fund (GRF) under Grant 11203220.


  • distortion model
  • rate control
  • rate model
  • Versatile video coding


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