Abstract: In modern video codecs,bi-prediction technique plays a significant role for removing temporal redundancy by exploiting temporal correlations between pictures.The bi-prediction signal is formed simply by averaging two uni-prediction signals using a fixed weight value 0.5.However,it will produce serious distortion in some condition that illumination changes rapidly from one reference picture to another or the prediction quality of one motion-compensated prediction block may differ from the other due to the factors such as quantization.To solve the above problems,an adaptive weighted bi-prediction method based on reference quality was proposed in this paper.In this scheme,the greater weight value will be assigned to the reference block if the quality of the reference block is better,and vice versa.The simulation results show that compared with JEM5.0.1,the proposed weighted bi-prediction can achieve about 0.25% and 0.3% Bjntegaard delta (BD) bitrate savings on average under random access main (RA) and low-delay B main(LDB) confi-gurations,respectively,while the increased encoding and decoding complexities are moderate.

Key words: Illumination changes rapidly, Motion-compensated block, Reference quality, Weighted prediction