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. A method of decoding a 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 into a selective one of a plurality of partitioning structures including quaternary tree partitioning, symmetric binary tree partitioning, and/or asymmetric tree partitioning;
parsing said bitstream to determine if at least one of asymmetric tree partitioning and/or symmetric binary tree partitioning splits a parent node into child nodes, wherein symmetric binary tree partitioning splits a parent node into a plurality of child nodes of equal size, and asymmetric tree partitioning splits a parent node into a plurality of child nodes of unequal size;
identifying each of the child nodes within each respective parent unit, wherein a node can be recursively partitioned into smaller nodes;
wherein the partitioning structure allows both asymmetric tree partitioning and symmetric binary tree partitioning to occur in either order during recursive partitioning of a parent node;
wherein the partitioning structure allows further partitioning of child nodes that are produced from asymmetric tree partitioning of at least one parent node; and
decoding the identified coding units using an intra decoding process.
2. The method of claim 1 , wherein said asymmetric tree partitioning produces child nodes having a size ratio that is anything other than 1.
3. The method of claim 2 , wherein at least one parent node is asymmetrically 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 method of claim 3 , wherein the larger child node is a restricted node and the smaller child node is a binary node.
5. The method of claim 4 , wherein the restricted node is further asymmetrically 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 partitioning has the same dimensions as the complimentary smaller node of its parent restricted node.
6. The method of claim 2 , wherein at least one parent node is asymmetrically 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 method of claim 2 , wherein if the parent node uses 3:1 asymmetric partitioning, further partitioning using binary partition or 3:1 asymmetric partitioning is allowed for the smaller child node and the larger child node is restricted to further partitioning by only 2:1 asymmetric partitioning.
8. The method 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.