Sub-picture track level indicator

1. A method for processing video data, comprising:

determining one or more level indicators for a set of subpictures included in one or more subpicture tracks, wherein the subpicture tracks are included in a subpicture entity group, wherein the level indicators are included in at least one of: a sample group entry of one or more sample groups carrying information for the set of subpictures, or in a data structure specifying the subpicture entity group, and wherein whether the level indicators are included in the sample group entry of the one or more sample groups carrying information for the set of subpictures or in the data structure specifying the subpicture entity group is based on whether a level is constant for all samples in the subpicture tracks; and

performing a conversion between a visual media data and a media data file based on the level indicator.

2. The method of claim 1 , wherein the level indicators are included in the data structure specifying the subpicture entity group when a level is constant for all samples in the subpicture tracks.

3. The method of claim 2 , wherein the level indicators are included in the sample groups when more than one level is applied to the samples in the subpicture tracks.

4. The method of claim 3 , wherein each of the level indicators indicates a level applied to a corresponding set of subpictures.

5. The method of claim 1 , wherein the data structure specifying the subpicture entity group is an entity to group box.

6. The method of claim 5 , wherein the entity to group box includes a flag with a first value indicating that a level is constant for all samples in the subpicture tracks.

7. The method of claim 5 , wherein the entity to group box includes a flag with a second value indicating that more than one level is applied to samples in the subpicture tracks.

8. An apparatus for processing video data comprising:

a processor; and

a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:

determine one or more level indicators for a set of subpictures included in one or more subpicture tracks, wherein the subpicture tracks are included in a subpicture entity group, wherein the level indicators are included in at least one of: a sample group entry of one or more sample groups carrying information for the set of subpictures, or in a data structure specifying the subpicture entity group, and wherein whether the level indicators are included in the sample group entry of the one or more sample groups carrying information for the set of subpictures or in the data structure specifying the subpicture entity group is based on whether a level is constant for all samples in the subpicture tracks; and

perform a conversion between a visual media data and a media data file based on the level indicator.

9. The apparatus of claim 8 , wherein the level indicators are included in the data structure specifying the subpicture entity group when a level is constant for all samples in the subpicture tracks.

10. The apparatus of claim 9 , wherein the level indicators are included in the sample groups when more than one level is applied to the samples in the subpicture tracks.

11. The apparatus of claim 10 , wherein each of the level indicators indicates a level applied to a corresponding set of subpictures.

12. The apparatus of claim 8 , wherein the data structure specifying the subpicture entity group is an entity to group box.

13. The apparatus of claim 12 , wherein the entity to group box includes a flag with a first value indicating that a level is constant for all samples in the subpicture tracks.

14. The apparatus of claim 12 , wherein the entity to group box includes a flag with a second value indicating that more than one level is applied to samples in the subpicture tracks.

15. A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to:

determine one or more level indicators for a set of subpictures included in one or more subpicture tracks, wherein the subpicture tracks are included in a subpicture entity group, wherein the level indicators are included in at least one of: a sample group entry of one or more sample groups carrying information for the set of subpictures, or in a data structure specifying the subpicture entity group, and wherein whether the level indicators are included in the sample group entry of the one or more sample groups carrying information for the set of subpictures or in the data structure specifying the subpicture entity group is based on whether a level is constant for all samples in the subpicture tracks; and

perform a conversion between a visual media data and a media data file based on the level indicator.

16. The non-transitory computer readable medium of claim 15 , wherein the level indicators are included in the data structure specifying the subpicture entity group when a level is constant for all samples in the subpicture tracks.

17. The non-transitory computer readable medium of claim 16 , wherein the level indicators are included in the sample groups when more than one level is applied to the samples in the subpicture tracks.

18. The non-transitory computer readable medium of claim 17 , wherein each of the level indicators indicates a level applied to a corresponding set of subpictures.

19. The method of claim 1 , wherein the conversion includes encoding the visual media data into the media data file.

20. The method of claim 1 , wherein the conversion includes decoding the visual media data from the media data file.