Video encoding/decoding method and apparatus

1 . A video decoding method, comprising:

generating an inter-prediction block of a current block based on a reference block corresponding to the current block and present in a reference picture;

generating an intra-prediction block of the current block based on at least one of at least one reference block adjacent to the current block, an intra-prediction mode list, a first region adjacent to the current block, a most probable mode (MPM) list of the current block, or reconstructed reference pixels adjacent to the current block; and

generating a combined inter-intra prediction (CIIP) block of the current block by weighted averaging the inter-prediction block and the intra-prediction block,

wherein generating the intra-prediction block of the current block comprises:

determining at least one intra-prediction mode based on mode occurrence frequency of intra-prediction modes of reference blocks adjacent to the current block; and

generating intra-prediction block of the current block based on the at least one intra-prediction mode.

2 . The video decoding method of claim 1 ,

wherein weighted values assigned to the intra prediction block decrease from a top-left region toward a bottom-right region of the current block, and

wherein weighted values assigned to the inter prediction block decrease from the bottom-right region toward the top-left region of the current block.

3 . The video decoding method of claim 1 ,

wherein weighted values assigned to the intra prediction block increase from a center region toward edge regions of the current block, and

wherein weighted values assigned to the inter prediction block increase from the edge regions toward the center region of the current block.

4 . The video decoding method of claim 1 , wherein generating the intra-prediction block of the current block comprises:

generating prediction pixels by applying intra-prediction modes of the at least one reference block adjacent to the current block, to reference pixels of a first region adjacent to the current block;

calculating sum of absolute transformed differences between the prediction pixels and reconstructed pixels in the first region;

deriving an intra-prediction mode of the current block based on the sum of absolute transformed differences; and

generating the intra-prediction block based on the intra-prediction mode of the current block, and

wherein the intra-prediction mode of the current block is an intra-prediction mode of a reference block utilized to generate a prediction pixel that causes a least sum of absolute transformed differences.

5 . The video decoding method of claim 1 , wherein generating the intra-prediction block of the current block comprises:

generating an intra-prediction mode list based on intra-prediction modes of the at least one reference block adjacent to the current block;

deriving an intra-prediction mode of the current block from the intra-prediction mode list based on sum of absolute transformed differences and a mode occurrence frequency; and

generating the intra-prediction block based on the intra-prediction mode of the current block.

6 . The video decoding method of claim 1 , wherein generating the intra-prediction block of the current block comprises:

applying a Sobel filter to a reference pixel that is reconstructed and adjacent to the current block to calculate a gradient of the reference pixel;

generating a gradient list based on the gradient of the reference pixel;

selecting one gradient from the gradient list;

deriving an intra-prediction mode of the current block based on the one gradient; and

generating the intra-prediction block based on the intra-prediction mode of the current block, and

wherein the one gradient is selected based on size of gradients.

7 . The video decoding method of claim 1 , wherein generating the intra-prediction block of the current block comprises:

generating prediction pixels by applying candidate modes in the MPM list of the current block to reference pixels of a first region adjacent to the current block;

calculating sum of absolute transformed differences between the prediction pixels and reconstructed pixels in the first region;

deriving an intra-prediction mode of the current block based on the sum of absolute transformed differences; and

generating the intra-prediction block based on the intra-prediction mode of the current block,

wherein the intra-prediction mode of the current block is a candidate mode utilized to generate a prediction pixel that causes a least sum of absolute transformed differences.

8 . The video decoding method of claim 1 , wherein weighted values utilized in the weighted averaging are derived based on at least one of an error distribution of intra prediction or an error distribution of inter prediction.

9 . The video decoding method of claim 4 , wherein generating the CIIP block of the current block comprises:

partitioning the current block into four subblocks based on directionality of the intra-prediction mode of the current block; and

generating the CIIP block of the current block by weighted averaging the inter-prediction block and the intra-prediction block for each of the four subblocks.

10 . The video decoding method of claim 9 , wherein the current block is partitioned vertically or horizontally based on directionality of the intra-prediction mode of the current block, and

wherein the four subblocks each have a different weighted value utilized in the weighted averaging.

11 . A video encoding method, comprising:

generating an inter-prediction block of a current block based on a reference block corresponding to the current block and present in a reference picture;

generating an intra-prediction block of the current block based on at least one of at least one reference block adjacent to the current block, an intra-prediction mode list, a first region adjacent to the current block, a most probable mode (MPM) list of the current block, or reconstructed reference pixels adjacent to the current block; and

generating a combined inter-intra prediction (CIIP) block of the current block by weighted averaging the inter-prediction block and the intra-prediction block,

wherein generating the intra-prediction block of the current block comprises:

determining at least one intra-prediction mode based on mode occurrence frequency of intra-prediction modes of reference blocks adjacent to the current block; and

generating intra-prediction block of the current block based on the at least one intra-prediction mode.

12 . The video encoding method of claim 11 ,

wherein weighted values assigned to the intra prediction block decrease from a top-left region toward a bottom-right region of the current block, and

wherein weighted values assigned to the inter prediction block decrease from the bottom-right region toward the top-left region of the current block.

13 . The video encoding method of claim 11 ,

wherein weighted values assigned to the intra prediction block increase from a center region toward edge regions of the current block, and

wherein weighted values assigned to the inter prediction block increase from the edge regions toward the center region of the current block.

14 . The video encoding method of claim 11 , wherein generating the intra-prediction block of the current block comprises:

generating prediction pixels by applying intra-prediction modes of the at least one reference block adjacent to the current block, to reference pixels of a first region adjacent to the current block;

calculating sum of absolute transformed differences between the prediction pixels and reconstructed pixels in the first region;

determining an intra-prediction mode of the current block based on the sum of absolute transformed differences; and

generating the intra-prediction block based on the intra-prediction mode of the current block, and

wherein the intra-prediction mode of the current block is an intra-prediction mode of a reference block utilized to generate a prediction pixel that causes a least sum of absolute transformed differences.

15 . The video encoding method of claim 11 , wherein generating the intra-prediction block of the current block comprises:

generating an intra-prediction mode list based on intra-prediction modes of the at least one reference block adjacent to the current block;

determining an intra-prediction mode of the current block from the intra-prediction mode list based on sum of absolute transformed differences and a mode occurrence frequency; and

generating the intra-prediction block based on the intra-prediction mode of the current block.

16 . The video encoding method of claim 11 , wherein generating the intra-prediction block of the current block comprises:

calculating a gradient of the reference pixel by applying a Sobel filter to a reference pixel that is reconstructed and adjacent to the current block;

generating a gradient list based on the gradient of the reference pixel;

selecting one gradient from the gradient list;

determining an intra-prediction mode of the current block based on the one gradient; and

generating the intra-prediction block based on the intra-prediction mode of the current block, and

wherein the one gradient is selected based on size of gradients.

17 . The video encoding method of claim 11 , wherein generating the intra-prediction block of the current block comprises:

generating prediction pixels by applying candidate modes in the MPM list of the current block, to reference pixels of a first region adjacent to the current block;

calculating sum of absolute transformed differences between the prediction pixels and reconstructed pixels in the first region;

determining an intra-prediction mode of the current block based on the sum of absolute transformed differences; and

generating the intra-prediction block based on the intra-prediction mode of the current block, and

wherein the intra-prediction mode of the current block is a candidate mode utilized to generate a prediction pixel that causes a least sum of absolute transformed differences.

18 . The video encoding method of claim 14 , wherein generating the CIIP block of the current block comprises:

partitioning the current block into four subblocks based on directionality of the intra-prediction mode of the current block; and

generating the CIIP block of the current block by weighted averaging the inter-prediction block and the intra-prediction block for each of the four subblocks.

19 . The video encoding method of claim 18 ,

wherein the current block is partitioned vertically or horizontally based on directionality of the intra-prediction mode of the current block, and

wherein the four subblocks each have a different weighted value utilized in the weighted averaging.

20 . A method for providing a video decoding apparatus with video data, the method comprising:

encoding the video data into a bitstream; and

transmitting the bitstream to the video decoding apparatus,

wherein encoding the video data comprises:

generating an inter-prediction block of a current block based on a reference block corresponding to the current block and present in a reference picture;

generating an intra-prediction block of the current block based on at least one of at least one reference block adjacent to the current block, an intra-prediction mode list, a first region adjacent to the current block, a most probable mode (MPM) list of the current block, or reconstructed reference pixels adjacent to the current block; and

generating a combined inter-intra prediction (CIIP) block of the current block by weighted averaging the inter-prediction block and the intra-prediction block, wherein generating the intra-prediction block of the current block comprises:

determining at least one intra-prediction mode based on mode occurrence frequency of intra-prediction modes of reference blocks adjacent to the current block; and

generating intra-prediction block of the current block based on the at least one intra-prediction mode.