A game theory based CTU-level bit allocation scheme for HEVC region of interest coding

In this article, a new CTU-level bit allocation scheme aimed at subjectively optimized video coding for video conferencing applications is presented, in which the non-cooperative Stackelberg game is used for formulating and solving the bit allocation problem during the encoding process. Videos are divided into the Region of interests (ROI) which attracts people more and the non-ROI. The two regions are defined as the players in the game, where the ROI is the leader who takes the priority in strategy making and the non-ROI follows the leader's strategy. Based on the formulated game, the bit allocation problem can be expressed as a utility optimization problem. By solving the corresponding utility optimization problem, the bit allocation strategy between the ROI and the non-ROI will be established. Then the bits will be allocated to each CTU by a Newton-method-based algorithm for encoding, in which a trade-off between the ROI's quality and the overall quality can be achieved. Both the objective and subjective experimental results show that our proposed bit allocation method can improve the quality of ROI significantly with an acceptable overall quality degradation, leading to a better visual experience.