An overview of rate control techniques in HEVC and SHVC video encoding

Video standards are crucial for exchanging video content, enabling a myriad of services and supporting a wide variety of devices ranging from personal devices to clouds and IoT. One of the core requirements in video standards is the rate control that regulates the bit allocation and picture quality. This paper presents an overview of rate control techniques in the HEVC video coding standard. While providing an insight into the rate control mechanism specific to HEVC, it describes the basic operating principle of rate control algorithms, including their essential parameter, outputs, and performance measures. We review rate control in past coding standards and bring out the basic features of HEVC that drive the need for new rate control algorithms. Alongside, we delineate the Rate-Distortion model-based taxonomy of various algorithms, including their classification criteria. The paper gives out another classification of the rate control algorithms based on their basic principle and mechanisms. The article also explains the scalable extension of HEVC, namely SHVC, while highlighting some of the possible SHVC rate control design challenges. Finally, we present some of the unresolved research issues in HEVC rate control and outline possible future research directions.