Window-based rate control for video quality optimization with a novel INTER-dependent rate-distortion model

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Most model-based rate control schemes use independent rate-distortion (R–D) models at macroblock (MB) level to represent the relationship among bit rate, distortion and encoding complexity. However the correlations between frames (INTER-dependency) are not well considered for distortion, bit allocation and quantization parameter (QP) decision. In this paper, a novel INTER-dependent R–D model is proposed based on the theoretical analysis of the relationship between the predicted residual of one frame and the distortion of its reference frame. To achieve both bit rate accuracy and consistent video quality, a window-based rate control scheme with two sliding windows is introduced. One window is to group certain previously encoded frames and current frame to control the bit rate and buffer delay; the other is to group certain future encoding frames to optimize the fluctuation of video quality. Furthermore, the optimization of Lagrange multiplier is also discussed under the INTER-dependent situation. Experimental results demonstrate that the proposed window-based rate control scheme with INTER-dependent R–D model can achieve accurate target bit rate and improve PSNR performance, meanwhile the variation of PSNR is the smallest compared with other three benchmark algorithms. This one-pass rate control scheme is highly practical for the real-time video coding applications.