Methods and apparatus are provided for implicit adaptive motion vector predictor selection for video encoding and decoding. The method encodes an image block using implicit adaptive motion vector predictor selection. The motion vector for encoding the block is predicted by defining a set of motion vector predictor candidates for the block based on a plurality of spatio-temporal neighboring motion vectors; and then selecting from the set a particular motion vector predictor candidate as the motion vector for encoding the bloc. The selection is made responsive to respective values for a fidelity of the spatio-temporal neighboring motion vectors.