A method for video decoding includes decoding prediction information of a current block, the prediction information being indicative of a symmetric motion vector difference mode for bi-prediction from a pair of forward and backward reference pictures. The method also includes assigning, to a reference picture marked as a long term reference picture (LTRP), a calculated picture order count with a default POC distance to the current picture, and excluding a reference picture from being in the pair of forward and backward reference pictures without a check based on a picture order count (POC) of the reference picture. The method further includes determining a first reference block for the current block in the forward reference picture and a second reference block for the current block in the backward reference picture, and reconstructing at least a sample of the current block according to the first reference block and the second reference block.