Methods and apparatuses for block partitioning at picture boundary

1. A video processing method implemented in a decoder, comprising:

determining whether a coding block comprises samples outside a picture boundary;

in response to the coding block being determined to comprise samples outside a picture boundary, performing quad tree splitting of the coding block comprising:

determining a value of a first flag of the coding block, the first flag indicating whether the coding block is split into a plurality of subblocks;

determining values of a first, a second, a third, a fourth, and a fifth parameter of the coding block, the parameters respectively indicating whether quad tree, binary horizontal tree, binary vertical tree, ternary horizontal tree, and ternary vertical tree are allowed to be used to split the coding block; and

in response to the value of the first flag being equal to 1 and the values of the first, the second, the third, the fourth, and the fifth parameters being equal to 0, determining a value of a second flag of the coding block to be equal to 1, the second flag indicating whether to perform quad tree splitting of the coding block.

2. The method of claim 1 , further comprising:

in response to the value of the first parameter being equal to 1, determining the value of the second flag of the coding block to be equal to 1.

3. The method of claim 1 , further comprising:

setting the value of the first flag to be 1, when the coding block is determined to comprise samples outside of a picture boundary.

4. The method of claim 1 , further comprising:

determining the value of the first parameter based on one or more of:

a size of the coding block,

a multi-type tree depth,

a sixth parameter indicating whether a single tree or a dual tree is used to split the coding block, or

a seventh parameter indicating whether one or more of an intra mode, an inter mode, and an intra block copy (IBC) mode are allowed to code the coding block.

5. The method of claim 1 , wherein in response to the coding block being determined to comprise samples outside a picture boundary, performing quad tree splitting of the coding block comprises:

performing quad tree splitting of the coding block, regardless of a bitstream conformance associated with the coding block.

6. The method of claim 5 , wherein the bitstream conformance sets a minimum block size to which the quad tree splitting is allowed to be applied.

7. The method of claim 6 , wherein the minimum block size is set to be smaller than or equal to 64.

8. The method of claim 5 , wherein the bitstream conformance sets a maximum binary tree depth or a maximum ternary tree depth.

9. A video processing apparatus implemented in an encoder, comprising:

at least one memory for storing instructions; and

at least one processor configured to execute the instructions to cause the apparatus to perform:

determining whether a coding block comprises samples outside a picture boundary;

in response to the coding block being determined to comprise samples outside a picture boundary, performing quad tree splitting of the coding block comprising:

determining a value of a first flag of the coding block, the first flag indicating whether the coding block is split into a plurality of subblocks;

determining values of a first, a second, a third, a fourth, and a fifth parameter of the coding block, the parameters respectively indicating whether quad tree, binary horizontal tree, binary vertical tree, ternary horizontal tree, and ternary vertical tree are allowed to be used to split the coding block; and

in response to the value of the first flag being equal to 1 and the values of the first, the second, the third, the fourth, and the fifth parameters being equal to 0, determining a value of a second flag of the coding block to be equal to 1, the second flag indicating whether to perform quad tree splitting of the coding block.

10. The apparatus of claim 9 , wherein the at least one processor is configured to execute the instructions to cause the apparatus to perform:

in response to the value of the first parameter being equal to 1, determining the value of the second flag of the coding block to be equal to 1.

11. The apparatus of claim 9 , wherein the at least one processor is configured to execute the instructions to cause the apparatus to perform:

setting the value of the first flag to be 1, when the coding block is determined to comprise samples outside of a picture boundary.

12. A non-transitory computer readable storage medium storing a bitstream of a video for processing according to a method comprising:

determining whether a coding block of the bitstream comprises samples outside a picture boundary;

in response to the coding block being determined to comprise samples outside a picture boundary, performing quad tree splitting of the coding block comprising:

determining a value of a first flag of the coding block, the first flag indicating whether the coding block is split into a plurality of subblocks;

determining values of a first, a second, a third, a fourth, and a fifth parameter of the coding block, the parameters respectively indicating whether quad tree, binary horizontal tree, binary vertical tree, ternary horizontal tree, and ternary vertical tree are allowed to be used to split the coding block; and

in response to the value of the first flag being equal to 1 and the values of the first, the second, the third, the fourth, and the fifth parameters being equal to 0, determining a value of a second flag of the coding block to be equal to 1, the second flag indicating whether to perform quad tree splitting of the coding block.

13. The non-transitory computer readable storage medium of claim 12 , wherein the set of instructions are executable by the one or more processing devices to cause the video processing apparatus to perform:

in response to the value of the first parameter being equal to 1, determining the value of the second flag of the coding block to be equal to 1.

14. The non-transitory computer readable storage medium of claim 12 , wherein the set of instructions that are executable by the one or more processing devices to cause the video processing apparatus to further perform:

setting the value of the first flag to be 1, when the coding block is determined to comprise samples outside of a picture boundary.