Novel flexible size scheme for basic unit-level rate control

Abstract

Rate control algorithm is very important for controlling video to achieve a target bitrate with high visual quality. In this paper, a basic unit (BU)-level rate control with flexible BU size for achieving a higher coding performance. The novel scheme harnesses a criterion derived from rate–quantisation scale (R–Q) model for partitioning pictures into BUs with flexible sizes. The target bits are adaptively allocated for each BUs according to the complexity of BU’s content. The rate control algorithm of the H.264/AVC is applied to each of BUs for achieving the target bitrate. The proposed scheme is implemented in H.264/AVC reference software JM76 for performance evaluation. The experimental results show that the proposed method effectively improves the performance of rate control in respect to the rate control method in H.264/AVC reference software in low bit rate.