JVET quadtree plus binary tree (QTBT) structure with multiple asymmetrical partitioning
A method of partitioning in video coding for JVET, comprising representing a JVET coding tree unit as a root node in a quadtree plus binary tree (QTBT) structure that can have quadtree or binary partitioning of the root node and quadtree or binary trees branching from each of the leaf nodes. The partitioning at any depth can use asymmetric binary partitioning to split a node represented by a leaf node into two child nodes of unequal size, representing the two child nodes as leaf nodes in a binary tree branching from the parent leaf node and coding the child nodes represented by final leaf nodes of the binary tree with JVET, wherein further partitioning of child nodes split from leaf nodes via asymmetric binary partitioning is allowed recursively along the same branch in any order with symmetric partitioning.
1. An apparatus for coding video data comprising one or more processors configured to:
receive a bitstream indicating how a coding tree unit was partitioned into coding units according to a partitioning structure that allows root nodes to be split with at least one of quadtree partitioning, symmetric binary partitioning, and/or asymmetric binary partitioning;
parse said bitstream to determine if at least one of asymmetric binary partitioning and/or symmetric binary partitioning splits a parent node into child nodes, wherein symmetric binary partitioning splits a parent node in to child nodes of equal size, and asymmetric binary partitioning splits a parent node in to child nodes of unequal size;
identify each of the child nodes within each respective parent unit, wherein a node can be recursively partitioned in to smaller nodes,
wherein the partitioning structure allows both asymmetric binary partitioning and symmetric binary partitioning to occur in either order during recursive partitioning of a parent node, and
wherein the partitioning structure allows further partitioning of child nodes that are produced from asymmetric binary partitioning of at least one parent node;
decode the identified coding units using JVET.
2. The apparatus of claim 1 , wherein asymmetric binary partitioning produces child nodes having a size ratio that is anything other than 1.
3. The apparatus of claim 2 , wherein at least one parent node is asymmetrically binary partitioned into two child nodes of unequal sizes, where a larger child node is three times as large as a smaller child node for a size ratio of 3:1.
4. The apparatus of claim 3 , wherein the larger child node is a restricted node and the smaller child node is a binary node.
5. The apparatus of claim 4 , wherein the restricted node is further asymmetrically binary partitioned so the larger child node lies next to the complimentary smaller node of its parent restricted node from a prior partitioning and the smaller node produced from said further asymmetrical binary partitioning has the same dimensions as the complimentary smaller node of its parent restricted node.
6. The apparatus of claim 2 , wherein at least one parent node is asymmetrically binary partitioned into two child nodes of unequal sizes, where a larger child node is two times as large as a smaller child node for a size ratio of 2:1.
7. The apparatus of claim 2 , wherein if the parent node uses 3:1 asymmetric binary partitioning, further partitioning using binary partition or 3:1 asymmetric binary partitioning is allowed for the smaller child node and the larger child node is restricted to further partitioning by only 2:1 asymmetric binary partitioning.
8. The apparatus of claim 1 , wherein if a parent node is partitioned using quadtree, the child nodes can use at least one of quadtree partitioning, binary partitioning, or 3:1 asymmetric binary partitioning.
9. The apparatus of claim 1 , wherein a size discrepancy limit (SDL) parameter is employed to limit a smallest size of a binary node or restricted node produced by the partitioning.
10. The apparatus of claim 1 , wherein a syntax element included in the bitstream indicates at least one of:
a type of partitioning method;
whether quadtree or a non-quadtree partitioning method is used;
whether to use horizontal or vertical partitioning;
whether symmetric or asymmetric binary partition is used;
whether a first child node is larger than a second child node;
whether a child node is a restricted node, a quadtree node, and/or a binary node;
whether a node is restricted and can be further partitioned; and/or
whether further partition occurs on a child node.
11. A method of decoding a JVET bitstream, the method comprising:
receiving a bitstream indicating how a coding tree unit was partitioned into coding units according to a partitioning structure that allows root nodes to be split with at least one of quadtree partitioning, symmetric binary partitioning, and/or asymmetric binary partitioning;
parsing said bitstream to determine if at least one of asymmetric binary partitioning and/or symmetric binary partitioning splits a parent node into child nodes, wherein symmetric binary partitioning splits a parent node in to child nodes of equal size, and asymmetric binary partitioning splits a parent node in to child nodes of unequal size;
identifying each of the child nodes within each respective parent unit, wherein a node can be recursively partitioned in to smaller nodes,
wherein the partitioning structure allows both asymmetric binary partitioning and symmetric binary partitioning to occur in either order during recursive partitioning of a parent node, and
wherein the partitioning structure allows further partitioning of child nodes that are produced from asymmetric binary partitioning of at least one parent node; and
decoding the identified coding units using JVET.