Method and apparatus for video coding

1. A method of video decoding in a decoder, comprising:

obtaining a gate flag for each of at least one constraint information group in constraint information in a syntax structure signaled in a coded video bitstream, each gate flag indicating whether a constraint information group of the at least one constraint information group corresponding to the respective gate flag is present in the constraint information, the constraint information being for a subset of coding blocks in the coded video bitstream, and the constraint information group of the gate flag including a plurality of constraint flags for the subset of coding blocks, wherein the gate flag for each of the at least one constraint information group is signaled in the constraint information in the syntax structure and each gate flag indicates whether the plurality of constraint flags for the subset of coding blocks corresponding to the respective gate flag is signaled in the constraint information in the same syntax structure;

determining, based on the gate flag of the constraint information group of the at least one constraint information group, whether the constraint information group of the gate flag is present in the constraint information;

determining prediction information for the subset of coding blocks based on whether the constraint information group of the gate flag is present in the constraint information; and

reconstructing the subset of coding blocks based on the prediction information.

2. The method of claim 1 , wherein

the constraint information group of the gate flag is determined to be present in the constraint information; and

the determining the prediction information includes determining the prediction information for the subset of coding blocks based on the plurality of constraint flags in the constraint information group of the gate flag.

3. The method of claim 1 , wherein the constraint information group of the gate flag is determined not to be present in the constraint information.

4. The method of claim 1 , wherein each gate flag indicates that the constraint information group corresponding to the respective gate flag is not present in the constraint information, and no constraint flags are present in the constraint information.

5. The method of claim 1 , wherein the syntax structure is a high level syntax structure for at least one picture, and the subset of coding blocks includes coding blocks in the at least one picture.

6. The method of claim 1 , wherein

one or more of the at least one constraint information group are present in the coded video bitstream,

a plurality of constraint flags in the one or more of the at least one constraint information group is signaled according to a predetermined order, and

the determining the prediction information further includes

run-decoding the plurality of constraint flags; and

determining the prediction information for the subset of coding blocks based on the plurality of constraint flags.

7. The method of claim 2 , wherein

the plurality of constraint flags in the constraint information group of the gate flag is signaled according to a predetermined order, and

the determining the prediction information further includes run-decoding the plurality of constraint flags.

8. The method of claim 2 , wherein an offset and a length are present in the constraint information indicating that the plurality of constraint flags in the constraint information group of the gate flag is present in the constraint information.

9. The method of claim 1 , wherein

one or more of the at least one constraint information group are present in the coded video bitstream;

for each of the one or more of the at least one constraint information group, an offset and a length are present in the constraint information indicating that at least one constraint flag in the respective one of the one or more of the at least one constraint information group is present in the constraint information; and

a number of the offsets is signaled in the coded video bitstream.

10. The method of claim 1 , wherein

one or more of the at least one constraint information group are present in the coded video bitstream, and

one or more syntax elements in the constraint information are byte aligned, the one or more syntax elements including the gate flag for each of the at least constraint information group and a plurality of constraint flags in the one or more of the at least one constraint information group.

11. An apparatus for video decoding, comprising processing circuitry configured to:

obtain a gate flag for each of at least one constraint information group in constraint information in a syntax structure signaled in a coded video bitstream, each gate flag indicating whether a constraint information group of the at least one constraint information group corresponding to the respective gate flag is present in the constraint information, the constraint information being for a subset of coding blocks in the coded video bitstream, and the constraint information group of the gate flag including a plurality of constraint flags for the subset of coding blocks, wherein the gate flag for each of the at least one constraint information group is signaled in the constraint information in the syntax structure and each gate flag indicates whether the plurality of constraint flags for the subset of coding blocks corresponding to the respective gate flag is signaled in the constraint information in the same syntax structure;

determine, based on the gate flag of the constraint information group of the at least one constraint information group, whether the constraint information group of the gate flag is present in the constraint information;

determine prediction information for the subset of coding blocks based on whether the constraint information group of the gate flag is present in the constraint information; and

reconstruct the subset of coding blocks based on the prediction information.

12. The apparatus of claim 11 , wherein

the constraint information group of the gate flag is determined to be present in the constraint information; and

the processing circuitry is configured to determine the prediction information for the subset of coding blocks based on the plurality of constraint flags in the constraint information group of the gate flag.

13. The apparatus of claim 11 , wherein the constraint information group of the gate flag is determined not to be present in the constraint information.

14. The apparatus of claim 11 , wherein each gate flag indicates that the constraint information group corresponding to the respective gate flag is not present in the constraint information, and no constraint flags are present in the constraint information.

15. The apparatus of claim 11 , wherein the syntax structure is a high level syntax structure for at least one picture, and the subset of coding blocks includes coding blocks in the at least one picture.

16. The apparatus of claim 11 , wherein

one or more of the at least one constraint information group are present in the coded video bitstream,

a plurality of constraint flags in the one or more of the at least one constraint information group is signaled according to a predetermined order, and

the processing circuitry is configured to:

run-decode the plurality of constraint flags; and

determine the prediction information for the subset of coding blocks based on the plurality of constraint flags.

17. The apparatus of claim 12 , wherein

the plurality of constraint flags in the constraint information group of the gate flag is signaled according to a predetermined order, and

the processing circuitry is configured to run-decode the plurality of constraint flags.

18. The apparatus of claim 12 , wherein

an offset and a length are present in the constraint information indicating that the plurality of constraint flags in the constraint information group of the gate flag is present in the constraint information.

19. The apparatus of claim 11 , wherein

one or more of the at least one constraint information group are present in the coded video bitstream, and

one or more syntax elements in the constraint information are byte aligned, the one or more syntax elements including the gate flag for each of the at least constraint information group and a plurality of constraint flags in the one or more of the at least one constraint information group.

20. A non-transitory computer-readable storage medium storing instructions executable by at least one processor to perform:

obtaining a gate flag for each of at least one constraint information group in constraint information in a syntax structure signaled in a coded video bitstream, each gate flag indicating whether a constraint information group of the at least one constraint information group corresponding to the respective gate flag is present in the constraint information, the constraint information being for a subset of coding blocks in the coded video bitstream, and the constraint information group of the gate flag including a plurality of constraint flags for the subset of coding blocks, wherein the gate flag for each of the at least one constraint information group is signaled in the constraint information in the syntax structure and each gate flag indicates whether the plurality of constraint flags for the subset of coding blocks corresponding to the respective gate flag is signaled in the constraint information in the same syntax structure;

determining, based on the gate flag of the constraint information group of the at least one constraint information group, whether the constraint information group of the gate flag is present in the constraint information;

determining prediction information for the subset of coding blocks based on whether the constraint information group of the gate flag is present in the constraint information; and

reconstructing the subset of coding blocks based on the prediction information.