Chain-based motion vector and chain-based motion vector predictor derivation

Abstract

A method for video decoding includes receiving coded information of a current block indicating inter prediction for the current block. Whether a current intermediate vector pointing to a first block in a first reference picture from a second block in a second reference picture is valid for deriving one of a chain-based MV and a chain-based MVP for the current block is determined based on one or more of reference picture information of the first reference picture, reference picture information of the current block, a position of the first block, and history information associated with at least one previously derived intermediate vector that is associated with the current block and the second block. When the current intermediate vector is valid, the one of the chain-based MV and the chain-based MVP is determined based on the current intermediate vector and the at least one previously derived intermediate vector.