Region-of-interest based rate control algorithm for H.264/AVC video coding

Abstract

Conventional rate control algorithms allocate bits for every macroblock (MB) without consider whether it needs encoding, and they choose encoding mode only from the set provided by H.264/AVC standard. While, according to the human visual system (HVS) research, human eyes can only focus on one area in a frame, which is called region-of-interest (ROI). This phenomenon gives a chance to code all MBs unequally, especially for NROI MB, we may do not need encoded. In this paper, a ROI-based rate control algorithm for H.264/AVC video coding is proposed to improve the coding efficiency. After the ROI segmentation, the target bits are unequally allocated for each MB. For non-region-of-interest (NROI) MB coding, we proposed the Active MB Concealment (AMC) Mode in rate-distortion optimization (RDO). The AMC gives a tradeoff between the rate and distortion and improve the quality of the ROI MBs at the cost of the quality decreasing of the NROI MBs. Compared with the conventional rate control algorithms, the experimental results demonstrate that the proposed algorithm gives the better performance in terms of the average peak signal-to-noise ratio (PSNR) and the subjective evaluations, and maintains the smoothness of video quality.