Block vector difference signaling based on validity determination

Abstract

An apparatus receives, in a bitstream for a block, an indication of a block vector predictor (BVP) and a first and a second component magnitude of a block vector difference (BVD). The apparatus determines each of a plurality of block vector (BV) candidates based on a sum of the BVP and a different one of a plurality of BVD candidates. Each of the plurality of BVD candidates includes: the first and second component magnitudes of the BVD, and a different combination of signs for the first and second component magnitudes. Validities of the plurality of BV candidates are determined based on values of samples, stored in a reference memory, of reference blocks indicated by the plurality of BV candidates. The apparatus determines a sign for at least one of the first and second component magnitudes of the BVD based on the validities of the plurality of BV candidates.