Systems and methods for partitioning video blocks at a boundary of a picture for video coding

1. A method for determining a partitioning of video data for video coding, the method comprising:

determining a coding unit from a picture of the video data, the picture including a boundary:

determining that the coding unit is a fractional boundary coding unit when the coding unit has only a portion within the boundary, wherein a subset of partitioning modes is available for partitioning the fractional boundary coding unit, the subset including quadtree splitting and symmetric binary tree splitting partitioning modes;

determining whether one of a block height and a block width of the coding unit is greater than a corresponding one of a height threshold value and a width threshold value when the coding unit is the fractional boundary coding unit; and

determining a partitioning for the fractional boundary coding unit based on whether the one of the block height and the block width is greater than the corresponding one of the height threshold value and the width threshold value,

wherein determining the partitioning for the fractional boundary coding unit includes:

comparing both the block height and the block width with a parameter indicating a maximum size of a leaf quadtree node allowed to be partitioned by binary splitting,

determining whether at least one of the block height and the block width is greater than the parameter,

determining whether all of the plurality of symmetric binary tree splittings are allowed based on whether the at least one of the block height and the block width is greater than the parameter, and

determining whether one of a plurality of symmetric binary tree splittings is allowed for the fractional boundary coding unit based on whether the one of the block height and the block width is greater than the corresponding one of the height threshold value and the width threshold value.

2. The method of claim 1 , wherein the height threshold value and the width threshold value are distinct from the parameter.

3. The method of claim 1 , wherein a set of available partitioning modes for partitioning coding units in the picture includes quadtree splitting, horizontal symmetric binary tree splitting, vertical symmetric binary tree splitting, horizontal triple tree splitting, and vertical triple tree splitting partitioning modes.

4. A device for coding video data, the device comprising, one or more processors configured to:

determine a coding unit from a picture of the video data, the picture including a boundary;

determine that the coding unit is a fractional boundary coding unit when the coding unit has only a portion within the boundary, wherein a subset of partitioning modes is available for partitioning the fractional boundary coding unit, the subset including quadtree splitting and symmetric binary tree splitting partitioning modes;

determine whether one of a block height and a block width of the coding unit is greater than a corresponding one of a height threshold value and a width threshold value when the coding unit is the fractional boundary coding unit; and

determine a partitioning for the fractional boundary coding unit based on whether the one of the block height and the block width is greater than the corresponding one of the height threshold value and the width threshold value,

wherein determining the partitioning for the fractional boundary coding unit includes:

comparing both the block height and the block width with a parameter indicating a maximum size of a leaf quadtree node allowed to be partitioned by binary splitting,

determining whether at least one of the block height and the block width is greater than the parameter,

determining whether all of the plurality of symmetric binary tree splittings are allowed based on whether the at least one of the block height and the block width is greater than the parameter, and

determining whether one of a plurality of symmetric binary tree splittings is allowed for the fractional boundary coding unit based on whether the one of the block height and the block width is greater than the corresponding one of the height threshold value and the width threshold value.

5. The device of claim 4 , wherein the height threshold value and the width threshold value are distinct from the parameter.

6. The device of claim 4 , wherein a set of available partitioning modes for partitioning coding units in the picture includes quadtree splitting, horizontal symmetric binary tree splitting, vertical symmetric binary tree splitting, horizontal triple tree splitting, and vertical triple tree splitting partitioning modes.

7. A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed, cause one or more processors of a device for coding video data to:

determine a coding unit from a picture of the video data, the picture including a boundary;

determine that the coding unit is a fractional boundary coding unit when the coding unit has only a portion within the boundary, wherein a subset of partitioning modes is available for partitioning the fractional boundary coding unit, the subset including quadtree splitting and symmetric binary tree splitting partitioning modes;

determine whether one of a block height and a block width of the coding unit is greater than a corresponding one of a height threshold value and a width threshold value when the coding unit is the fractional boundary coding unit; and

determine a partitioning for the fractional boundary coding unit based on whether the one of the block height and the block width is greater than the corresponding one of the height threshold value and the width threshold value,

wherein determining the partitioning for the fractional boundary coding unit includes:

comparing both the block height and the block width with a parameter indicating a maximum size of a leaf quadtree node allowed to be partitioned by binary splitting,

determining whether at least one of the block height and the block width is greater than the parameter,

determining whether all of the plurality of symmetric binary tree splittings are allowed based on whether the at least one of the block height and the block width is greater than the parameter, and

determining whether one of a plurality of symmetric binary tree splittings is allowed for the fractional boundary coding unit based on whether the one of the block height and the block width is greater than the corresponding one of the height threshold value and the width threshold value.

8. The non-transitory computer-readable storage medium of claim 7 , wherein the height threshold value and the width threshold value are distinct from the parameter.

9. The non-transitory computer-readable storage medium of claim 7 , wherein a set of available partitioning modes for partitioning coding units in the picture includes quadtree splitting, horizontal symmetric binary tree splitting, vertical symmetric binary tree splitting, horizontal triple tree splitting, and vertical triple tree splitting partitioning modes.

10. The method of claim 1 , wherein:

the parameter is a maximum allowed binary tree root node size.

11. The method of claim 1 , wherein:

the height threshold value is used to determine whether a first one of the plurality of symmetric binary tree splittings is allowed,

the width threshold value is used to determine whether a second one of the plurality of symmetric binary tree splittings is allowed, and

the first one of the plurality of symmetric binary tree splittings is different from the second one of the plurality of symmetric binary tree splittings.