Video encoding or decoding methods and apparatuses related to high-level information signaling

1. A video processing method in a video encoding or decoding system, comprising:

receiving input video data of video pictures referring to a high-level syntax set;

determining a first syntax element signaled or to be signaled in the high-level syntax set indicating whether reference picture resampling is disabled or constrained for the video pictures associated with the high-level syntax set;

determining a second syntax element indicating whether subpicture partitioning is disabled or constrained for the video pictures associated with the high-level syntax set, wherein the first syntax element and the second syntax element are restricted to disable or constrain subpicture partitioning when reference picture resampling is enabled; and

encoding or decoding the video pictures by allowing pictures with different resolutions to be referenced in inter prediction when reference picture resampling is enabled or allowing pictures only with a same resolution to be referenced in inter prediction when reference picture resampling is disabled, and encoding or decoding the video pictures by dividing each picture into one or more subpictures when subpicture partitioning is enabled or by processing each picture without dividing into subpictures when subpicture partitioning is disabled.

2. The method of claim 1 , wherein the high-level syntax set is a Sequence Parameter Set (SPS).

3. The method of claim 1 , wherein the second syntax element is conditionally signaled in the high-level syntax set and the second syntax element is only signaled when reference picture resampling is disabled.

4. The method of claim 1 , wherein all the video pictures referring to the high-level syntax set have a same derived value of a scaling window width and a same derived value of a scaling window height when subpicture partitioning is enabled.

5. The method of claim 4 , wherein the scaling window width for a picture is derived from a picture width, a left scaling window offset, and a right scaling window offset signaled in a Picture Parameter Set (PPS) referred to by the picture, and the scaling window height for the picture is derived from a picture height, a top scaling window offset, and a bottom scaling window offset.

6. The method of claim 1 , wherein the first and second syntax elements are restricted to disable or constrain subpicture partitioning when reference picture resampling is enabled or the first and second syntax elements are restricted to disable or constrain reference picture resampling when subpicture partitioning is enabled.

7. The method of claim 6 , wherein the first syntax element is conditionally signaled in the high-level syntax set and the first syntax element is only signaled when subpicture partitioning is disabled.

8. The method of claim 6 , wherein the first syntax element is a reference picture resampling enabling flag specifying whether reference picture resampling is enabled, and the second syntax element is a subpicture partitioning present flag specifying whether subpicture parameters are present in the high-level syntax set.

9. The method of claim 8 , wherein the reference picture resampling enabling flag is inferred to be equal to 0 or is not signaled when the subpicture partitioning present flag is equal to 1, and the reference picture resampling enabling flag is only signaled in the high-level syntax set when the subpicture partitioning present flag is equal to 0, wherein the reference picture resampling enabling flag is inferred to be equal to 0 when the reference picture resampling enabling flag is not signaled.

10. The method of claim 8 , wherein the subpicture partitioning present flag is inferred to be equal to 0 or is not signaled when the reference picture resampling enabling flag is equal to 1, and the subpicture partitioning present flag is only signaled in the high-level syntax set when the reference picture resampling enabling flag is equal to 0, wherein the subpicture partitioning present flag is inferred to be equal to 0 when the subpicture partitioning present flag is not signaled.

11. The method of claim 1 , wherein the first syntax element is a resolution change flag specifying whether a picture spatial resolution is changeable within a Coded Layer Video Sequence (CLVS), and the second syntax element is a subpicture partitioning present flag specifying whether subpicture information is present for the CLVS in the high-level syntax set.

12. The method of claim 11 , wherein the subpicture information is not present for the CLVS in the high-level syntax set when the picture spatial resolution is changeable within the CLVS referring to the high-level syntax set by inferring subpicture partitioning present flag to be equal to 0 when the resolution change flag is equal to 1.

13. The method of claim 1 , further comprising determining a third syntax element according to the second syntax element, wherein the second syntax element is a subpicture partitioning present flag specifying whether subpicture information is present for a CLVS in the high-level syntax set, and the third syntax element is a subpicture Identification (ID) flag specifying whether subpicture ID mapping is present in the high-level syntax set.

14. The method of claim 13 , further comprising determining a related subpicture layout when the subpicture partitioning present flag is equal to 1.

15. The method of claim 13 , wherein the subpicture ID flag is not coded and is inferred to be equal to 0 when the subpicture partitioning present flag is equal to 0, and the subpicture ID flag is only signaled in the high-level syntax set when the subpicture partitioning present flag is equal to 1.

16. An apparatus of processing video data in a video encoding or decoding system, the apparatus comprising one or more electronic circuits configured for:

receiving input video data of video pictures referring to a high-level syntax set;

determining a first syntax element signaled or to be signaled in the high-level syntax set indicating whether reference picture resampling is disabled or constrained for the video pictures associated with the high-level syntax set;

determining a second syntax element indicating whether subpicture partitioning is disabled or constrained for the video pictures associated with the high-level syntax set, wherein the first syntax element and the second syntax element are restricted to disable or constrain subpicture partitioning when reference picture resampling is enabled; and

encoding or decoding the video pictures by allowing pictures with different resolutions to be referenced in inter prediction when reference picture resampling is enabled or allowing pictures only with a same resolution to be referenced in inter prediction when reference picture resampling is disabled, and encoding or decoding the video pictures by dividing each picture into one or more subpictures when subpicture partitioning is enabled or by processing each picture without dividing into subpictures when subpicture partitioning is disabled.

17. A non-transitory computer readable medium storing program instruction causing a processing circuit of an apparatus to perform a video processing method for video data, and the method comprising:

receiving input video data of video pictures referring to a high-level syntax set;

determining a first syntax element signaled or to be signaled in the high-level syntax set indicating whether reference picture resampling is disabled or constrained for the video pictures associated with the high-level syntax set;

determining a second syntax element indicating whether subpicture partitioning is disabled or constrained for the video pictures associated with the high-level syntax set, wherein the first syntax element and the second syntax element are restricted to disable or constrain subpicture partitioning when reference picture resampling is enabled; and

encoding or decoding the video pictures by allowing pictures with different resolutions to be referenced in inter prediction when reference picture resampling is enabled or allowing pictures only with a same resolution to be referenced in inter prediction when reference picture resampling is disabled, and encoding or decoding the video pictures by dividing each picture into one or more subpictures when subpicture partitioning is enabled or by processing each picture without dividing into subpictures when subpicture partitioning is disabled.