A low complexity MB layer rate control algorithm based on motion similarity for H.264

Abstract

This paper presents a simple but effective macroblock (MB) layer rate control (RC) scheme for H.264/AVC with low complexity. First, to reduce computation cost and inaccuracy of linear mean absolute difference (MAD) prediction at MB layer adopted in JVT-G012, MAD is computed directly according to the difference between current original MB and the reference blocks pointed by estimated MV using intensive motion similarity. Then, MB header bits are predicted based on spatial-temporal correlation because it is not constant due to complicated coding modes and high compression efficiency of H.264. Finally, MB target bit rate is allocated according to its complexity and the parameters of quadratic R-D model are updated using coded MBs with high spatial-temporal correlation and motion similarity not the last coded data points. Simulation results show that the proposed scheme achieves an average PSNR gain of 0.37 dB, meets better with target bit rate, produces more consistent quality for the MBs in a frame and thus improves visual quality compared to classic JVT-H017 RC algorithm, simultaneously has lower computation complexity and suits for real-time application.