Encoder, a decoder and corresponding methods of deblocking filter adaptation

1. A coding method, comprising:

determining whether a current coding unit is predicted by an application of combined inter-intra prediction (CIIP);

in response to determining that the current coding unit is predicted by the application of CIIP, setting a boundary strength of a boundary of the current coding unit to a first value, wherein coding includes decoding or encoding;

upon determination that the current coding unit is not predicted by the application of CIIP, determining whether the boundary of the current coding unit is an edge of a transform block and the transform block contains one or more non-zero transform coefficient levels; and

upon determination that the boundary of the current coding unit is an edge of a transform block and the transform block contains one or more non-zero transform coefficient levels, setting the boundary strength of the boundary of the current coding unit to a second value.

2. The method of claim 1 , wherein the first value is within a range from 1 to 2.

3. The method of claim 1 , wherein the first value is 2.

4. The method of claim 1 , wherein the first value is 1.

5. The method of claim 4 , further comprising:

incrementing the first value by 1 in response to determining that one of the following conditions is satisfied:

at least one of the current coding unit and an adjacent coding unit that is adjacent to the boundary of the current coding unit has non-zero transform coefficients, or

an absolute difference between motion vectors used to predict the current coding unit and the adjacent coding unit is greater than or equal to one integer sample.

6. The method of claim 1 ,

wherein the current coding unit comprises at least two sub-coding units, and a boundary of a sub-coding unit is a boundary between the at least two sub-coding units.

7. The method of claim 6 , wherein the second value is 1.

8. The method of claim 6 , wherein when the boundary of the sub-coding unit is an edge of a transform unit, the second value is equal to the first value.

9. The method of claim 6 , wherein when the boundary of the sub-coding unit is not an edge of a transform unit, the second value is different from the first value.

10. The method of claim 1 , further comprising:

determining whether the boundary of the current coding unit is aligned with an 8×8 grid; and

in response to determining that the boundary of the current coding unit is not aligned with the 8×8 grid, setting the boundary strength of the boundary of the current coding unit to zero.

11. The method of claim 6 , further comprising:

determining whether the boundary of the sub-coding unit is aligned with a sub-grid, the sub-grid being a 4×4 grid or an 8×8 grid, and

in response to determining that the boundary of the sub-coding unit is not aligned with the sub-grid, setting a boundary strength of the boundary of the sub-coding unit to zero.

12. A computer program product comprising instructions which, when the program is executed by a computer, cause the computer to perform processes of

determining whether a current coding unit is predicted by an application of combined inter-intra prediction (CIIP);

in response to determining that the current coding unit is predicted by the application of CIIP, setting a boundary strength of a boundary of the current coding unit to a first value;

upon determination that the current coding unit is not predicted by the application of CIIP, determining whether the boundary of the current coding unit is an edge of a transform block and the transform block contains one or more non-zero transform coefficient levels; and

upon determination that the boundary of the current coding unit is an edge of a transform block and the transform block contains one or more non-zero transform coefficient levels, setting the boundary strength of the boundary of the current coding unit to a second value.

13. A decoder, comprising:

one or more processors; and

a non-transitory computer-readable storage medium coupled to the one or more processors and storing instructions for execution by the one or more processors, wherein the instructions, when executed by the one or more processors, configure the decoder to perform processes of:

determining whether a current coding unit is predicted by an application of combined inter-intra prediction (CIIP);

in response to determining that the current coding unit is predicted by the application of CIIP, setting a boundary strength of a boundary of the current coding unit to a first value;

upon determination that the current coding unit is not predicted by the application of CIIP, determining whether the boundary of the current coding unit is an edge of a transform block and the transform block contains one or more non-zero transform coefficient levels; and

upon determination that the boundary of the current coding unit is an edge of a transform block and the transform block contains one or more non-zero transform coefficient levels, setting the boundary strength of the boundary of the current coding unit to a second value.

14. The decoder of claim 13 , wherein the first value is 2.

15. The decoder of claim 13 , wherein the first value is 1.

16. The decoder of claim 15 , wherein the instructions, when executed by the one or more processors, configure the decoder to perform processes of:

incrementing the first value by 1 in response to determining that one of the following conditions is satisfied:

at least one of the current coding unit and an adjacent coding unit that is adjacent to the boundary of the current coding unit has non-zero transform coefficients,

an absolute difference between motion vectors used to predict the current coding unit and the adjacent coding unit is greater than or equal to one integer sample,

the current coding unit and the adjacent coding unit are predicted on the basis of different reference pictures, or

a number of motion vectors used to predict the current coding unit and the adjacent coding unit differs.

17. An encoder, comprising:

one or more processors; and

a non-transitory computer-readable storage medium coupled to the one or more processors and storing instructions for execution by the one or more processors, wherein the instructions, when executed by the one or more processors, configure the encoder to perform processes of:

determining whether a current coding unit is predicted by an application of combined inter-intra prediction (CLIP);

in response to determining that the current coding unit is predicted by the application of CIIP, setting a boundary strength of a boundary of the current coding unit to a first value;

upon determination that the current coding unit is not predicted by the application of CIIP, determining whether the boundary of the current coding unit is an edge of a transform block and the transform block contains one or more non-zero transform coefficient levels; and

upon determination that the boundary of the current coding unit is an edge of a transform block and the transform block contains one or more non-zero transform coefficient levels, setting the boundary strength of the boundary of the current coding unit to a second value.

18. The encoder of claim 17 , wherein the first value is 2.

19. The encoder of claim 17 , wherein the first value is 1.

20. A video data decoding device, comprising:

a non-transitory memory storage, configured to store video data in a form of a bitstream; and

a video decoder, configured to perform the method according to claim 1 .

21. The method of claim 4 , further comprising:

incrementing the first value by 1 in response to determining that one of the following conditions is satisfied:

the current coding unit and an adjacent coding unit are predicted on the basis of different reference pictures, or

a number of motion vectors used to predict the current coding unit and the adjacent coding unit differs.