Simplification of BCW in Versatile Video Coding (VVC)

The emerging Versatile Video Coding (VVC) standard introduces Bi-prediction with CU-level Weights (BCW) to enhance the bi-predictive prediction. The syntax element of BCW index is adaptively coded according to the value of NoBackwardPredFlag which indicates if there is no future picture in the display order among the reference pictures, and it can violate the flexibility of codec and cause the dependency issue. This paper proposes BCW clean-up design that allows all weights can be parsed without any condition. The experimental results show negligible BD-rate losses while resolving the issues.