Handling of multiple picture size and conformance windows for reference picture resampling in video coding

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

receiving, by the video decoder, a first picture parameter set and a second picture parameter set each referring to same sequence parameter set, the first picture parameter set and the second picture parameter set having same values of a conformance window when the first picture parameter set and the second picture parameter set have same values of picture width and picture height; and

applying, by the video decoder, the conformance window to a current picture corresponding to the first picture parameter set or the second picture parameter set.

2. The method of claim 1 , wherein the conformance window comprises a conformance window left offset, a conformance window right offset, a conformance window top offset, and a conformance window bottom offset.

3. The method of claim 1 , further comprising decoding the current picture corresponding to the first picture parameter set or the second picture parameter set using inter prediction after the conformance window has been applied, wherein the inter prediction is based on a resampled reference picture.

4. The method of claim 1 , further comprising resampling a reference picture associated with the current picture corresponding to the first picture parameter set or the second picture parameter set using reference picture resampling (RPS).

5. The method of claim 4 , wherein the resampling of the reference picture changes a resolution of the reference picture used to inter predict the current picture corresponding to the first picture parameter set or the second picture parameter set.

6. The method of claim 1 , wherein the picture width and the picture height are measured in luma samples.

7. The method of claim 1 , further comprising determining whether bi-direction optical flow (BDOF) is enabled for decoding the current picture based on the picture width, the picture height, and the conformance window of the current picture and a reference picture for the current picture.

8. The method of claim 1 , further comprising determining whether decoder-side motion vector refinement (DMVR) is enabled for decoding the current picture based on the picture width, the picture height, and the conformance window of the current picture and a reference picture for the current picture.

9. The method of claim 1 , further comprising displaying on a display of an electronic device an image generated using the current picture.

10. A method of encoding implemented by a video encoder, the method comprising:

generating, by the video encoder, a first picture parameter set and a second picture parameter set each referring to same sequence parameter set, the first picture parameter set and the second picture parameter set having same values of a conformance window when the first picture parameter set and the second picture parameter set have same values of picture width and picture height;

encoding, by the video encoder, the first picture parameter set and the second picture parameter set into a video bitstream; and

storing, by the video encoder, the video bitstream for transmission toward a video decoder.

11. The method of claim 10 , wherein the conformance window comprises a conformance window left offset, a conformance window right offset, a conformance window top offset, and a conformance window bottom offset.

12. The method of claim 10 , wherein the picture width and the picture height are measured in luma samples.

13. The method of claim 10 , further comprising transmitting the video bitstream containing the first picture parameter set and the second picture parameter set toward the video decoder.

14. A decoding device, comprising:

a receiver configured to receive a coded video bitstream;

a memory coupled to the receiver, the memory storing instructions; and

a processor coupled to the memory, the processor configured to execute the instructions to cause the decoding device to:

receive a first picture parameter set and a second picture parameter set each referring to same sequence parameter set, the first picture parameter set and the second picture parameter set having same values of a conformance window when the first picture parameter set and the second picture parameter set have same values of picture width and picture height; and

apply the conformance window to a current picture corresponding to the first picture parameter set or the second picture parameter set.

15. The decoding device of claim 14 , wherein the conformance window comprises a conformance window left offset, a conformance window right offset, a conformance window top offset, and a conformance window bottom offset.

16. The decoding device of claim 15 , further comprising a display configured to display an image generated based on the current picture.

17. The decoding device of claim 14 , further comprising decoding the current picture corresponding to the first picture parameter set or the second picture parameter set using inter prediction after the conformance window has been applied, wherein the inter prediction is based on a resampled reference picture.

18. An encoding device, comprising:

a memory containing instructions;

a processor coupled to the memory, the processor configured to implement the instructions to cause the encoding device to:

generate a first picture parameter set and a second picture parameter set each referring to same sequence parameter set, the first picture parameter set and the second picture parameter set having same values of a conformance window when the first picture parameter set and the second picture parameter set have same values of picture width and picture height; and

encode the first picture parameter set and the second picture parameter set into a video bitstream; and

a transmitter coupled to the processor, the transmitter configured to transmit the video bitstream containing the first picture parameter set and the second picture parameter set toward a video decoder.

19. The encoding device of claim 18 , wherein the conformance window comprises a conformance window left offset, a conformance window right offset, a conformance window top offset, and a conformance window bottom offset.

20. The encoding device of claim 18 , wherein the picture width and the picture height are measured in luma samples.