Prediction method and device using reference block
Disclosed herein are a video decoding method and apparatus and a video encoding method and apparatus. In the encoding and decoding of a video, a prediction mode may be selected from among multiple prediction modes using prediction mode information for a target block, and prediction may be performed on the target block based on the selected prediction mode, wherein the prediction mode information includes information related to a reference block, and wherein the reference block comprises one or more of a spatially neighboring block that is spatially adjacent to the target block and a temporally neighboring block that is temporally adjacent to the target block. When the selected prediction mode includes a plurality of prediction modes, a prediction mode to be used for prediction of the target block may be decided on among the plurality of selected prediction modes through signaling of the prediction mode decision information.
1. A video decoding method, comprising:
generating a merge list for a target block; and
performing inter prediction for the target block using the merge list,
wherein the merge list is generated based on information of a plurality of adjacent blocks spatially adjacent to the target block,
wherein the target block is composed of a plurality of sub-blocks corresponding to spatially partitioned regions of the target block, respectively,
wherein a size of the target block is greater than a size of each of the plurality of sub-blocks,
wherein the merge list is commonly used to derive initial motion vectors of the plurality of sub-blocks,
wherein a motion vector of a sub-block of the plurality of sub-blocks is derived based on an initial motion vector of the sub-block using a block matching between two blocks determined based on the initial motion vector,
wherein whether bi-directional inter prediction is used for the target block or not is checked to determine a type of prediction for the target block,
wherein the inter prediction derives the initial motion vectors of the plurality of sub-blocks using the merge list is performed in a case that the bi-directional inter prediction is used for the target block, and
wherein whether the inter prediction derives the initial motion vectors of the plurality of sub-blocks using the merge list is performed or not is determined using a difference between a Picture Order Count (POC) of a target picture comprising the target block and a POC of a reference picture for the target block.
2. A video encoding method, comprising:
generating a merge list for a target block; and
generating an index for the merge list,
wherein the merge list is generated based on information of a plurality of adjacent blocks spatially adjacent to the target block,
wherein the target block is composed of a plurality of sub-blocks corresponding to spatially partitioned regions of the target block, respectively,
wherein a size of the target block is greater than a size of each of the plurality of sub-blocks,
wherein the index indicates a candidate of the merge list which is commonly used to derive initial motion vectors of the plurality of sub-blocks in decoding of the target block,
wherein a motion vector of a sub-block of the plurality of sub-blocks is derived based on an initial motion vector of the sub-block using a block matching between two blocks determined based on the initial motion vector in the decoding of the target block,
wherein whether bi-directional inter prediction is used for the target block or not is checked to determine a type of prediction for the target block,
wherein the inter prediction derives the initial motion vectors of the plurality of sub-blocks using the merge list is performed in a case that the bi-directional inter prediction is used for the target block, and
wherein whether the inter prediction derives the initial motion vectors of the plurality of sub-blocks using the merge list is performed or not is determined using a difference between a Picture Order Count (POC) of a target picture comprising the target block and a POC of a reference picture for the target block.
3. A non-transitory computer-readable medium storing a bitstream configured by a video encoding apparatus performing a video encoding method, the video encoding method comprising:
generating a merge list for a target block;
generating an index for the merge list; and
storing the bitstream comprising index information indicating the index in the non-transitory computer-readable medium,
wherein the merge list is generated based on information of a plurality of adjacent blocks spatially adjacent to the target block,
wherein the target block is composed of a plurality of sub-blocks corresponding spatially partitioned regions of the target block, respectively,
wherein a size of the target block is greater than a size of each of the plurality of sub-blocks,
wherein the index indicates a candidate of the merge list which is commonly used to derive initial motion vectors of the plurality of sub-blocks in decoding of the target block,
wherein a motion vector of a sub-block of the plurality of sub-blocks is derived based on an initial motion vector of the sub-block using a block matching between two blocks determined based on the initial motion vector,
wherein whether bi-directional inter prediction is used for the target block or not is checked to determine a type of prediction for the target block,
the inter prediction to derive the initial motion vectors of the plurality of sub-blocks using the merge list is performed in a case that the bi-directional inter prediction is used for the target block, and
wherein whether the inter prediction to derive the initial motion vectors of the plurality of sub-blocks using the merge list is performed or not is determined using a difference between a Picture Order Count (POC) of a target picture comprising the target block and a POC of a reference picture for the target block.
4. A method for sending a bitstream, the method comprising:
sending the bitstream comprising an index for a merge list;
wherein the index indicates a candidate of the merge list,
wherein the merge list is generated based on information of a plurality of adjacent blocks spatially adjacent to the target block,
wherein the target block is composed of a plurality of sub-blocks corresponding to spatially partitioned regions of the target block, respectively,
wherein a size of the target block is greater than a size of each of the plurality of sub-blocks,
wherein the candidate of the merge list is commonly used to derive initial motion vectors of the plurality of sub-blocks,
wherein a motion vector of a sub-block of the plurality of sub-blocks is derived based on an initial motion vector of the sub-block using a block matching between two blocks determined based on the initial motion vector,
wherein whether bi-directional inter prediction is used for the target block or not is checked to determine a type of prediction for the target block,
wherein the inter prediction derives the initial motion vectors of the plurality of sub-blocks using the merge list is performed in a case that the bi-directional inter prediction is used for the target block, and
wherein whether the inter prediction derives the initial motion vectors of the plurality of sub-blocks using the merge list is performed or not is determined using a difference between a Picture Order Count (POC) of a target picture comprising the target block and a POC of a reference picture for the target block.
5. The video decoding method of claim 1 ,
wherein the plurality of adjacent blocks comprise a first block, a second block, a third block, a fourth block, a fifth block, a sixth block and a seventh block,
wherein the first block is a left-most block among a plurality of blocks adjacent to an upper side of the target block,
wherein the second block is a right-most block among a plurality of blocks adjacent to an upper side of the target block,
wherein the third block is an upper-most block among a plurality of blocks adjacent to a left side of the target block,
wherein the fourth block is a bottom-most block among a plurality of blocks adjacent to a left side of the target block,
wherein the fifth block is diagonally adjacent to an upper-left corner of the target block,
wherein the sixth block is diagonally adjacent to an upper-right corner of the target block, and
wherein the seventh block is diagonally adjacent to a bottom-left corner of the target block.
6. The video decoding method of claim 1 ,
wherein a motion vector for the inter prediction for the target block is derived based on information for four reference blocks, and
wherein x-coordinates of rightmost pixels of the four reference blocks are smaller than x-coordinates of leftmost pixels of the target block.
7. The video decoding method of claim 1 ,
wherein a motion vector for the inter prediction for the target block is derived based on information for seven different blocks spatially adjacent to the target block.
8. The video encoding method of claim 2 ,
wherein a motion vector for the inter prediction for the target block is derived based on information for four reference blocks, and
wherein x-coordinates of rightmost pixels of the four reference blocks are smaller than x-coordinates of leftmost pixels of the target block.
9. The video encoding method of claim 2 ,
wherein a motion vector for the inter prediction for the target block is derived based on information for seven different blocks spatially adjacent to the target block.
10. The method of claim 4 ,
wherein the plurality of adjacent blocks comprise a first block, a second block, a third block, a fourth block, a fifth block, a sixth block and a seventh block,
wherein the first block is a left-most block among a plurality of blocks adjacent to an upper side of the target block,
wherein the second block is a right-most block among a plurality of blocks adjacent to an upper side of the target block,
wherein the third block is an upper-most block among a plurality of blocks adjacent to a left side of the target block,
wherein the fourth block is a bottom-most block among a plurality of blocks adjacent to a left side of the target block,
wherein the fifth block is diagonally adjacent to an upper-left corner of the target block,
wherein the sixth block is diagonally adjacent to an upper-right corner of the target block, and
wherein the seventh block is diagonally adjacent to a bottom-left corner of the target block.
11. The method of claim 4 ,
wherein a motion vector for the inter prediction for the target block is derived based on information for four reference blocks, and
wherein x-coordinates of rightmost pixels of the four reference blocks are smaller than x-coordinates of leftmost pixels of the target block.
12. The method of claim 4 ,
wherein a motion vector for the inter prediction for the target block is derived based on information for seven different blocks spatially adjacent to the target block.
13. The video decoding method of claim 1 ,
wherein the number of rows of the plurality of sub-blocks in the target block is 4, and
wherein the number of columns of the plurality of sub-blocks in the target block is 4.
14. The video encoding method of claim 2 ,
wherein the number of rows of the plurality of sub-blocks in the target block is 4, and
wherein the number of columns of the plurality of sub-blocks in the target block is 4.
15. The method of claim 4 ,
wherein the number of rows of the plurality of sub-blocks in the target block is 4, and
wherein the number of columns of the plurality of sub-blocks in the target block is 4.
16. The video decoding method of claim 1 ,
wherein the block matching is performed using a Sum of Absolute Differences (SAD) between the two blocks.
17. The video encoding method of claim 2 ,
wherein the block matching is performed using a Sum of Absolute Differences (SAD) between the two blocks.
18. The method of claim 4 ,
wherein the block matching is performed using a Sum of Absolute Differences (SAD) between the two blocks.