Method for signaling subpicture identifier in tiled video stream

1. A method of decoding an encoded video bitstream using at least one processor, the method comprising:

obtaining a first flag indicating that a subpicture identifier for a subpicture of a current picture is explicitly signaled;

based on the first flag, obtaining a second flag indicating whether the subpicture identifier is signaled in a picture parameter set (PPS) or a sequence parameter set (SPS);

based on the second flag indicating that the subpicture identifier is signaled in the PPS, determining the subpicture identifier based on a first syntax element included in the PPS;

based on the second flag indicating that the subpicture identifier is signaled in the SPS, determining the subpicture identifier based on a second syntax element included in the SPS; and

decoding the current picture based on the determined subpicture identifier,

wherein based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture, a third flag indicates that subpictures of the current picture are independent.

2. The method of claim 1 , wherein the second flag is signaled in the PPS.

3. The method of claim 1 , wherein a length of the first syntax element is signaled in the PPS.

4. The method of claim 1 , wherein the second flag indicates that the subpicture identifier is signaled in the PPS based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture.

5. The method of claim 1 , wherein based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture, a fourth flag indicates that subpictures of the current picture are treated as pictures.

6. The method of claim 1 , wherein based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture, a fifth flag indicates that loop filtering is disabled across subpicture boundaries in the current picture.

7. A device for decoding an encoded video bitstream, the device comprising:

at least one memory configured to store program code; and

at least one processor configured to read the program code and operate as instructed by the program code, the program code including:

first obtaining code configured to cause the at least one processor to obtain a first flag indicating that a subpicture identifier for a subpicture of a current picture is explicitly signaled;

second obtaining code configured to cause the at least one processor to, based on the first flag, obtain a second flag indicating whether the subpicture identifier is signaled in a picture parameter set (PPS) or a sequence parameter set (SPS);

first determining code configured to cause the at least one processor to, based on the second flag indicating that the subpicture identifier is signaled in the PPS, determine the subpicture identifier based on a first syntax element included in the PPS;

second determining code configured to cause the at least one processor to, based on the second flag indicating that the subpicture identifier is signaled in the SPS, determine the subpicture identifier based on a second syntax element included in the SPS; and

decoding code configured to cause the at least one processor to decode the current picture based on the determined subpicture identifier,

wherein based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture, a third flag indicates that subpictures of the current picture are independent.

8. The device of claim 7 , wherein the second flag is signaled in the PPS.

9. The device of claim 7 , wherein a length of the first syntax element is signaled in the PPS.

10. The device of claim 7 , wherein the second flag indicates that the subpicture identifier is signaled in the PPS based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture.

11. The device of claim 7 , wherein based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture, a fourth flag indicates that subpictures of the current picture are treated as pictures.

12. The device of claim 7 , wherein based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture, a fifth flag indicates that loop filtering is disabled across subpicture boundaries in the current picture.

13. A non-transitory computer-readable medium storing instructions, the instructions comprising: one or more instructions that, when executed by one or more processors of a device for decoding an encoded video bitstream, cause the one or more processors to:

obtain a first flag indicating that a subpicture identifier for a subpicture of a current picture is explicitly signaled;

based on the first flag, obtain a second flag indicating whether the subpicture identifier is signaled in a picture parameter set (PPS) or a sequence parameter set (SPS);

based on the second flag indicating that the subpicture identifier is signaled in the PPS, determine the subpicture identifier based on a first syntax element included in the PPS;

based on the second flag indicating that the subpicture identifier is signaled in the SPS, determine the subpicture identifier based on a second syntax element included in the SPS; and

decode the current picture based on the determined subpicture identifier

wherein based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture, a third flag indicates that subpictures of the current picture are independent.

14. The non-transitory computer-readable medium of claim 13 , wherein the second flag is signaled in the PPS.

15. The non-transitory computer-readable medium of claim 13 , wherein the second flag indicates that the subpicture identifier is signaled in the PPS based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture.

16. The non-transitory computer-readable medium of claim 13 , wherein based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture, a fourth flag indicates that subpictures of the current picture are treated as pictures.

17. The non-transitory computer-readable medium of claim 13 , wherein based on the subpicture identifier being different from a previous subpicture identifier of a corresponding previous subpicture of a previous picture, a fifth flag indicates that loop filtering is disabled across subpicture boundaries in the current picture.