Video encoding method and apparatus, and video decoding method and apparatus

A video encoding method, comprising:

• generating reference sample information indicating reference samples among a plurality of adjacent samples including first adjacent samples and second adjacent samples;
• when the reference sample information does not indicate the first adjacent samples, determining a intra prediction mode candidate list, for a current block, including a plurality of candidate intra prediction modes excluding a planar mode;
• generating an index indicating an intra prediction mode for the current block among the plurality of candidate intra prediction modes;
• and
• generating predicted samples of the current block using the intra prediction mode for the current block and the second adjacent samples,
• wherein:
• the first adjacent samples include an adjacent sample directly adjacent to the current block,
• the second adjacent samples include an adjacent sample being above the adjacent sample directly adjacent to the current block,
• the adjacent sample being above the adjacent sample directly adjacent to the current block is one line away from the current block, and
• the reference sample information is for the current block.

A non-transitory computer-readable medium for recording a bitstream, the bitstream comprising:

• reference sample information indicating reference samples among a plurality of adjacent samples including first adjacent samples and second adjacent samples;
• and
• an index indicating an intra prediction mode for a current block among a plurality of candidate intra prediction modes,
• wherein the reference sample information and the index are obtained by:
• generating the reference sample information;
• when the reference sample information does not indicate the first adjacent samples, determining a intra prediction mode candidate list, for the current block, including the plurality of candidate intra prediction modes excluding a planar mode;
• generating the index;
• and
• generating predicted samples of the current block using the intra prediction mode for the current block and the second adjacent samples,
• wherein:
• the first adjacent samples include an adjacent sample directly adjacent to the current block,
• the second adjacent samples include an adjacent sample being above the adjacent sample directly adjacent to the current block,
• the adjacent sample being above the adjacent sample directly adjacent to the current block is one line away from the current block, and
• the reference sample information is for the current block.