1. A method of inter-view or inter-layer video decoding, the method comprising: receiving a bitstream that includes information for deriving a motion vector for a current block from a motion vector predictor, wherein the motion vector refers to an inter-view or an inter-layer reference picture, wherein the bitstream is constrained such that the information ensures that the derived motion vector is compliant with a motion vector restriction, and wherein the motion vector restriction restricts a range of the motion vector to refer to a sub-portion of the inter-view or inter-layer reference picture; deriving the motion vector for the current block based on the information in the bitstream; and inter-view or inter-layer prediction decoding the current block based on the derived motion vector.