Apparatus and method for video encoding or decoding supporting various block sizes
Disclosed herein is video encoding or decoding for efficiently encoding video. The techniques of the present disclosure are related to various split shapes of a block, syntaxes representing various split types of blocks, and syntax elements represented at a high level therefor.
1. A method for decoding video data, comprising:
receiving a bitstream containing encoded data for a block of video data;
parsing first syntax elements for block partitioning defined at header information of a high level from the bitstream, wherein the block partitioning is based on a partitioning structure in which a multi-type tree is rooted from a leaf node of a quad tree (QT), and the multi-type tree includes a binary tree (BT) in which a block corresponding to a parent node is allowed to be divided into two subblocks corresponding to two child nodes and a triple tree in which a parent node is allowed to be divided into three subblocks corresponding to three child nodes;
parsing second syntax elements for modification for some of the first syntax elements defined at header information of a low level belonging to the high level;
calculating parameters for block partitioning from the first syntax elements and the second syntax elements, wherein the parameters for block partitioning comprise a first parameter indicating a minimum block size of a leaf node allowed in the BT, a second parameter indicating a minimum block size of a leaf node allowed in the QT, a third parameter indicating a maximum block size of a root node allowed in the BT, and a fourth parameter indicating a size of the block of the video data;
parsing third syntax elements which specify the partitioning structure for the block of the video data from the bitstream under restrictions imposed based on the calculated parameters to derive the partitioning structure for the block of the video data, the block of the video data belonging to the low level; and
decoding subblocks corresponding to leaf nodes of the partitioning structure for the block of the video data based on the video bitstream,
wherein some of the first syntax elements explicitly indicates some of the parameters for block partitioning, and wherein the others of the first syntax elements indicate a difference between some of the parameters for block partitioning.
2. The method of claim 1 , wherein the first syntax elements include elements for specifying:
the size of the block of the video data;
the minimum block size of the leaf node allowed in the BT;
a difference between the minimum block size of the leaf node allowed in the BT and the minimum block size of the leaf node allowed in the QT; and
a difference between the maximum block size of the root node allowed in the BT and the minimum block size of the leaf node allowed in the QT.
3. The method of claim 1 , wherein the third syntax elements include elements for indicating:
whether a block corresponding to a parent node in the QT is divided into four subblocks corresponding to four child nodes;
whether a block corresponding to a parent node in the multi-type tree is divided into two subblocks corresponding to two child nodes or into three subblocks corresponding to three child nodes; and
a direction in which a block corresponding to a parent node in the multi-type tree is divided into subblocks.
4. The method of claim 1 , wherein the deriving of the partitioning structure comprises:
when a height of a given subblock is equal to the size indicated by the first parameter and the given subblock is BT-split, inferring that the given subblock is split in a vertical direction.
5. The method of claim 1 , wherein the deriving of the partitioning structure comprises:
when a width of a given subblock is equal to the size indicated by the first parameter and the given subblock is BT-split, inferring that the given subblock is split in a horizontal direction.
6. The method of claim 1 , wherein the deriving of the partitioning structure comprises:
when a size of the leaf node of the QT is greater than the size indicated by the third parameter, inferring that the leaf node of the QT is a leaf node of the partitioning structure.
7. The method of claim 1 , wherein the deriving of the partitioning structure comprises:
when the size indicated by the fourth parameter is greater than a predefined or predetermined maximum transform size, inferring that the block of the video data is recursively QT-split into the maximum transform size.
8. A method for encoding video data, comprising:
determining parameters for block partitioning at a high level, wherein the block partitioning is based on a partitioning structure in which a multi-type tree is rooted from a leaf node of a quad tree (QT), and the multi-type tree includes a binary tree (BT) in which a block corresponding to a parent node is allowed to be divided into two subblocks corresponding to two child nodes and a triple tree in which a parent node is allowed to be divided into three subblocks corresponding to three child nodes;
encoding first syntax elements for block partitioning in header information of the high level;
determining the parameters for the block partitioning at a low level belonging to the high level;
encoding second syntax elements for modification for some of the first syntax elements in header information of the low level;
encoding third syntax elements which specify the partitioning structure for the block of the video data belonging to the low level under restrictions imposed by the parameters; and
encoding subblocks corresponding to leaf nodes of the partitioning structure for the block of the video data,
wherein the first parameters for block partitioning comprise a first parameter indicating a minimum block size of a leaf node allowed in the BT, a second parameter indicating a minimum block size of a leaf node allowed in the QT, a third parameter indicating a maximum block size of a root node allowed in the BT, and a fourth parameter indicating a size of the block of the video data;
wherein some of the first syntax elements explicitly indicates some of the parameters for block partitioning, and wherein the others of the first syntax elements indicate a difference between some of the parameters for block partitioning.
9. The method of claim 8 , wherein the first syntax elements include elements for specifying:
the size of the block of the video data;
the minimum block size of the leaf node allowed in the BT;
a difference between the minimum block size of the leaf node allowed in the BT and the minimum block size of the leaf node allowed in the QT; and
a difference between the maximum block size of the root node allowed in the BT and the minimum block size of the leaf node allowed in the QT.
10. The method of claim 8 , wherein the third syntax elements include elements for indicating:
whether a block corresponding to a parent node in the QT is divided into four subblocks corresponding to four child nodes;
whether a block corresponding to a parent node in the multi-type tree is divided into two subblocks corresponding to two child nodes or into three subblocks corresponding to three child nodes; and
a direction in which a block corresponding to a parent node in the multi-type tree is divided into subblocks.
11. A non-transitory computer readable medium storing a bitstream containing encoded data for a block of video data, the bitstream being decoded by processes of:
receiving a bitstream containing encoded data for a block of video data;
parsing first syntax elements for block partitioning defined at header information of a high level from the bitstream, wherein the block partitioning is based on a partitioning structure in which a multi-type tree is rooted from a leaf node of a quad tree (QT), and the multi-type tree includes a binary tree (BT) in which a block corresponding to a parent node is allowed to be divided into two subblocks corresponding to two child nodes and a triple tree in which a parent node is allowed to be divided into three subblocks corresponding to three child nodes;
parsing second syntax elements for modification for some of the first syntax elements defined at header information of a low level belonging to the high level;
calculating parameters for block partitioning from the first syntax elements and the second syntax elements, wherein the parameters for block partitioning comprise a first parameter indicating a minimum block size of a leaf node allowed in the BT, a second parameter indicating a minimum block size of a leaf node allowed in the QT, a third parameter indicating a maximum block size of a root node allowed in the BT, and a fourth parameter indicating a size of the block of the video data;
parsing third syntax elements which specify the partitioning structure for the block of the video data from the bitstream under restrictions imposed based on the calculated parameters to derive the partitioning structure for the block of the video data, the block of the video data belonging to the low level; and
decoding subblocks corresponding to leaf nodes of the partitioning structure for the block of the video data based on the video bitstream,
wherein some of the first syntax elements explicitly indicates some of the parameters for block partitioning, and wherein the others of the first syntax elements indicate a difference between some of the parameters for block partitioning.
12. The non-transitory computer readable medium of claim 11 , wherein the first syntax elements include elements for specifying:
the size of the block of the video data;
the minimum block size of the leaf node allowed in the BT;
a difference between the minimum block size of the leaf node allowed in the BT and the minimum block size of the leaf node allowed in the QT; and
a difference between the maximum block size of the root node allowed in the BT and the minimum block size of the leaf node allowed in the QT.
13. The non-transitory computer readable medium of claim 11 , wherein the third syntax elements include elements for indicating:
whether a block corresponding to a parent node in the QT is divided into four subblocks corresponding to four child nodes;
whether a block corresponding to a parent node in the multi-type tree is divided into two subblocks corresponding to two child nodes or into three subblocks corresponding to three child nodes; and
a direction in which a block corresponding to a parent node in the multi-type tree is divided into subblocks..