Method and device for processing video signal for intra prediction

1. A method for decoding a video signal, the method comprising:

obtaining reference sample line information of a current block from the video signal, wherein reference sample line information represents an index indicating reference sample line being used for the intra prediction;

obtaining an intra sub-partition(ISP) flag representing whether the current block is partitioned into sub-partitions based on the reference sample line information;

obtaining intra prediction information of the current block to which the intra prediction is applied based on the reference sample line information, wherein the intra prediction information includes a first flag representing whether an intra prediction mode is not a planar mode;

determining the intra prediction mode of the current block based on the intra prediction information, wherein based on the first flag corresponds to 0, the planar mode is determined as the intra prediction mode and based on the first flag corresponds to 1, one of a plurality of candidate modes is determined as the intra prediction mode;

deriving prediction samples of the current block based on the intra prediction mode and reference samples;

obtaining residual information of the current block from the video signal;

deriving residual samples of the current block based on the residual information; and

reconstructing the current block based on the prediction samples and residual samples.

2. The method of claim 1 , further comprising

obtaining an ISP type flag representing whether an ISP type is horizontal or vertical based on the current block is partitioned into sub-partitions.

3. The method of claim 1 , wherein the first flag is obtained based on the reference sample line information corresponds to reference samples positioned on a line adjacent to the current block.

4. The method of claim 1 , further comprising

determining whether to use most probable mode (MPM) candidate modes based on a MPM flag;

obtaining a MPM index if the MPM candidate modes are used; and

obtaining a remaining index if the MPM candidate modes are not used.

5. The method of claim 4 , wherein the MPM index is obtained based on reference samples positioned spaced apart from the current block by a 2-sample distance or more are used.

6. The method of claim 1 , wherein the determining of the intra prediction mode includes

configuring an MPM candidate list including the MPM candidate modes when the first flag corresponds to 1, and

wherein the MPM candidate list is configured based on intra prediction modes other than the planar mode among the all modes.

7. A method for encoding a video signal, the method comprising:

determining reference sample line being used for the intra prediction;

generating reference sample line information of a current block, wherein reference sample line information represents an index indicating reference sample line being used for the intra prediction;

determining an intra prediction mode of the current block;

generating intra prediction information based on the intra prediction mode;

generating an intra sub-partition(ISP) flag representing whether the current block is partitioned into sub-partitions based on the reference sample line information;

generating prediction samples of the current block based on the intra prediction mode and reference samples;

generating residual samples of the current block based on the prediction samples; and

performing a transform, quantization and entropy-encoding the residual samples,

wherein the intra prediction information includes a first flag representing whether the intra prediction mode is not a planar mode, and

wherein the first flag is coded with 0 based on the intra prediction mode corresponds to the planar mode and coded with 1 based on the intra prediction mode corresponds to one of modes other than the planar mode.

8. A non-transitory computer-readable storage medium storing video information generated by performing the steps of:

determining reference sample line being used for the intra prediction;

generating reference sample line information of a current block, wherein reference sample line information represents an index indicating reference sample line being used for the intra prediction;

determining an intra prediction mode of the current block;

generating intra prediction information based on the intra prediction mode;

generating an intra sub-partition(ISP) flag representing whether the current block is partitioned into sub-partitions based on the reference sample line information;

generating prediction samples of the current block based on the intra prediction mode and reference samples;

generating residual samples of the current block based on the prediction samples; and

performing a transform, quantization and entropy-encoding the residual samples,

wherein the intra prediction information includes a first flag representing whether the intra prediction mode is not a planar mode, and

wherein the first flag is coded with 0 based on the intra prediction mode corresponds to the planar mode and coded with 1 based on the intra prediction mode corresponds to one of modes other than the planar mode.