Signaling of constraint flags using gate flag in coded video stream

1. A method of video encoding in an encoder, comprising:

determining whether a plurality of constraint flags of a constraint information group are to be signaled for a subset of coding blocks;

signaling a gate flag indicating whether the plurality of constraint flags of the constraint information group are signaled, wherein the gate flag is signaled in a general constraint information syntax structure of a coded video bitstream;

in accordance with the signaled gate flag indicating that the plurality of constraint flags of the constraint information group are signaled, signaling the plurality of constraint flags of the constraint information group in the general constraint information syntax structure of the coded video bitstream;

based on the signaled plurality of constraint flags of the constraint information group, signaling one or more offsets and one or more corresponding lengths, wherein each offset indicates a position of a set of contiguous constraint flags in the general constraint information syntax structure and a corresponding length indicates a number of constraint flags in the set of contiguous constraint flags in the general constraint information syntax structure; and

in accordance with the plurality of constraint flags being signaled in the general constraint information syntax structure, encoding the subset of coding blocks based on the plurality of constraint flags.

2. The method of claim 1 , wherein

the plurality of constraint flags of the constraint information group is determined to be signaled in the general constraint information syntax structure; and

the method further includes generating prediction information for the subset of coding blocks based on the plurality of constraint flags in the constraint information group.

3. The method of claim 1 , wherein

the plurality of constraint flags of the constraint information group is determined not to be signaled in the general constraint information syntax structure.

4. The method of claim 1 , wherein the gate flag indicates that the constraint flags of the constraint information group are not signaled, and the constraint flags are not signaled in the general constraint information syntax structure.

5. The method of claim 1 , wherein the general constraint information 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

the plurality of constraint flags of the constraint information group are determined to be signaled,

the plurality of constraint flags of the constraint information group are signaled according to a predetermined order, and

the method further includes

run-encoding the plurality of constraint flags; and

generating 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 of the constraint information group are signaled according to a predetermined order, and

the generating the prediction information further includes run-encoding the plurality of constraint flags.

8. The method of claim 2 , wherein

the general constraint information syntax structure includes plural constraint information groups and plural corresponding gate flags indicating presence of each of the plural constraint information groups, and

an offset and a length are signaled in the general constraint information syntax structure for each of the plural constraint information groups indicating a position of and a number of contiguous constraint flags in the respective one of the plural constraint information groups.

9. The method of claim 8 , wherein

a syntax element indicating a number of offsets included in the general constraint information syntax structure is signaled in the general constraint information syntax structure.

10. The method of claim 1 , wherein

one or more constraint information groups are signaled in the coded video bitstream, and

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

11. An apparatus for video encoding, comprising:

processing circuitry configured to:

determine whether a plurality of constraint flags of a constraint information group is to be signaled for a subset of coding blocks,

signal a gate flag indicating whether the plurality of constraint flags of the constraint information group are signaled, wherein the gate flag is signaled in a general constraint information in a syntax structure of a coded video bitstream;

in accordance with the signaled gate flag indicating that the plurality of constraint flags of the constraint information group are signaled, signal the plurality of constraint flags of the constraint information group in the general constraint information syntax structure of the coded video bitstream;

based on the signaled plurality of constraint flags of the constraint information group, signal one or more offsets and one or more corresponding lengths, wherein each offset indicates a position of a set of contiguous constraint flags in the general constraint information syntax structure and a corresponding length indicates a number of constraint flags in the set of contiguous constraint flags in the general constraint information syntax structure; and

in accordance with the plurality of constraint flags being signaled in the general constraint information syntax structure, encode the subset of coding blocks based on the plurality of constraint flags.

12. The apparatus of claim 11 , wherein

the plurality of constraint flags of the constraint information group is determined to be signaled in the general constraint information syntax structure; and

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

13. The apparatus of claim 11 , wherein

the plurality of constraint flags of the constraint information group is determined not to be signaled in the general constraint information syntax structure.

14. The apparatus of claim 11 , wherein the gate flag indicates that the constraint flags of the constraint information group are not signaled, and the constraint flags are not signaled in the general constraint information syntax structure.

15. The apparatus of claim 11 , wherein the general constraint information 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

the plurality of constraint flags of the constraint information group are determined to be signaled,

the plurality of constraint flags of the constraint information group are signaled according to a predetermined order, and

the processing circuitry is configured to:

run-encode the plurality of constraint flags; and

generate 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 of the constraint information group are signaled according to a predetermined order, and

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

18. The apparatus of claim 12 , wherein

the general constraint information syntax structure includes plural constraint information groups and plural corresponding gate flags indicating presence of each of the plural constraint information groups, and

an offset and a length are signaled in the general constraint information syntax structure for each of the plural constraint information groups indicating a position of and a number of contiguous constraint flags in the respective one of the plural constraint information groups.

19. The apparatus of claim 11 , wherein

one or more constraint information groups are signaled in the coded video bitstream, and

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

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

determining whether a plurality of constraint flags of a constraint information group are to be signaled for a subset of coding blocks;

signaling a gate flag indicating whether the plurality of constraint flags of the constraint information group are signaled, wherein the gate flag is signaled in a general constraint information syntax structure of a coded video bitstream;

in accordance with the signaled gate flag indicating that the plurality of constraint flags of the constraint information group are signaled, signaling the plurality of constraint flags of the constraint information group in the general constraint information syntax structure of the coded video bitstream;

based on the signaled plurality of constraint flags of the constraint information group, signaling one or more offsets and one or more corresponding lengths, wherein each offset indicates a position of a set of contiguous constraint flags in the general constraint information syntax structure and a corresponding length indicates a number of constraint flags in the set of contiguous constraint flags in the general constraint information syntax structure; and

in accordance with the plurality of constraint flags being signaled in the general constraint information syntax structure, encoding the subset of coding blocks based on the plurality of constraint flags.