A Convex Optimization-Based Frame-Level Rate Control Algorithm for Motion Compensated Hybrid DCT/DPCM Video Coding

This paper presents a convex optimization-based frame-level rate control algorithm for motion compensated hybrid DCT/DPCM video coding. By modifying the existing rate-distortion models, an improved empirical rate-distortion model with more flexibility is proposed to explain the experimental observations. The convexity and monotonicity of the proposed model are exploited to formulate the frame-level bit allocation problem as a convex programming problem. Thus the bit allocation among the frames with different picture types can be solved using convex programming methods such as the interior-point methods, if the optimal solution exists. Different importance weights for various picture types (I-, P-, etc) can also be incorporated into the scheme in order to account for the relative importance of different picture types due to their inter-dependency. The relevant model parameters are determined using previously encoded frames by means of linear regression. Simulation results show that the proposed algorithm achieves a considerably better picture quality in terms of PSNR than the conventional approaches for the tested video sequences. Therefore, it is a good alternative to these conventional approaches.