Reference line for directional intra prediction

An apparatus, comprising processing circuitry configured to:

• decode prediction information of a current block in a current picture that is a part of a coded video sequence, the prediction information indicating one of a plurality of intra prediction directions for the current block;
• determine a subset of a plurality of reference lines based on (i) a reference line index of each of the subset of the plurality of reference lines and (ii) a tangent value of a prediction angle associated with the one of the plurality of intra prediction directions indicated in the prediction information;
• perform an intra prediction of the current block based on the determined subset of the plurality of reference lines;
• and
• reconstruct the current block based on the intra prediction of the current block.

A non-transitory computer-readable storage medium storing instructions which when executed by at least one processor cause the at least one processor to perform:

• decoding prediction information of a current block in a current picture that is a part of a coded video sequence, the prediction information indicating one of a plurality of intra prediction directions for the current block;
• determining a subset of a plurality of reference lines based on (i) a reference line index of each of the subset of the plurality of reference lines and (ii) a tangent value of a prediction angle associated with the one of the plurality of intra prediction directions indicated in the prediction information;
• performing an intra prediction of the current block based on the determined subset of the plurality of reference lines;
• and
• reconstructing the current block based on the intra prediction of the current block.