Methods, devices and systems for intra-block coding based decoding or encoding of video while using block vector signaling and/or merge candidates are disclosed. An example method for video processing includes performing a conversion between a video region of a video and a bitstream representation of the video, wherein the bitstream representation selectively includes motion vector difference (MVD) related syntax elements for an intra block copy (IBC) advanced motion vector prediction (AMVP) mode based on a maximum number of a first type of IBC candidates used during the conversion of the video region, wherein, when an IBC mode is applied, samples of the video region are predicted from other samples in a video picture corresponding to the video region.