An ROI/xROI based rate control algorithm in H.264|AVC for video telephony applications

Abstract

Channel bandwidth in 3G communication networks is very much limited for video telephony services. Therefore, it is worthwhile to enhance a subjective quality of video contents via ROI based coding. In this paper, An ROI/xROI based rate-control method is proposed, which considers the coding of both the ROI and the extended ROIs (xROI's) in non-ROI to meet given target bitrates. In the proposed method, the QP values are increasingly assigned in MB wide inside the non-ROI away from ROI. This reduces the abrupt change in visual quality and the amounts of residual signals along the border between ROI and non-ROI. In this regard, the subjective visual quality is enhanced as well as the proposed rate control has flexibility to control the amounts of the output bitstreams. Experimental results show that the proposed scheme can more effectively achieve the average target bitrates with the better subjective quality than the existing rate control algorithm in H.264|AVC by reducing the variation of the output bitstream amounts. © 2009 Springer Berlin Heidelberg.