The bit allocation and RDO mode based rate control algorithm

H.264/AVC video encoding standard is a successful video compression standard after the MPEG-2/H.262. It´s received much attention from academic and industrial fields. In this paper, rate control algorithm is discussed. By noticing that the H.264/AVC rate control algorithm has some disadvantages, two frame layer rate control improvement strategies are proposed in this paper, which are based on the bit allocation and the RDO(Rate Distortion Optimization) mode respectively. The proposed rate control algorithm includes GOP layer rate control, frame-layer rate control and basic unit layer rate control. The improvement algorithm has two steps: The first step is the mode selection parameter and the quantification parameter separating; the second step is to adjust λ_MODE, according actual encoding bit rate. The algorithm is performed on the JM86 platform which implants the frame skip scheme. The simulation results show that the improved algorithm do have some advantages over the JM86 rate control algorithm, in the aspects on the buffer controlling, the accuracy of output rate, avoiding frame skip and the smoothness of the decoded sequence.