An example method includes encoding, in a video bitstream, a first syntax element specifying whether affine model based motion compensation is enabled; based on affine model based motion compensation being enabled, encoding, in the video bitstream, a second syntax element specifying a maximum number of subblock-based merging motion vector prediction candidates, wherein a value of the second syntax element is constrained based on a value other than a value of the first syntax element; and encoding a picture of the video data based on the maximum number of subblock-based merging motion vector prediction candidates.