Signaling of non-picture-level syntax elements at the picture level

1. A method implemented by a video decoder and comprising:

receiving a video bitstream comprising a reference picture list (RPL) flag, wherein the RPL flag equal to a first value specifies that RPL signaling is present in a picture header (PH) and is not present in slice headers, wherein the RPL flag equal to a second value specifies that the RPL signaling is not present in the PH and may be present in the slice headers, wherein the RPL signaling is RPL information comprised in the video bitstream, wherein the RPL information comprises an RPL index or ref_pic_list_struct(listIdx, rplsIdx) syntax structure, wherein the RPL index specifics an index, into a list of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i included in a sequence parameter set (SPS), of the ref pic list struct(listIdx, rplsIdx) syntax structure with listIdx equal to i that is used for derivation of RPL i of a current picture, wherein the video bitstream further comprises an adaptive loop filter (ALF) flag, wherein the ALF flag equal to the first value specifies that ALF signaling is present in the PH and not present in the slice headers, wherein the ALF flag equal to the second value specifies that the ALF signaling is not present in the PH and may be present in the slice headers, and wherein the ALF signaling comprises an ALF enable flag; and

decoding, based on the RPL flag and the ALF flag, a coded picture to obtain a decoded picture.

2. The method of claim 1 , wherein the first value is 1.

3. The method of claim 1 , wherein the second value is 0.

4. The method claim 1 , wherein the video bitstream further comprises an RPL SPS flag.

5. The method of claim 4 , wherein the RPL SPS flag specifies that RPL i is derived based on one of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i in an SPS or specifies that RPL i is derived based on one of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i that is directly included.

6. The method of claim 1 , further comprising displaying the decoded picture on a display of an electronic device.

7. A video decoder comprising:

a memory configured to store instructions; and

one or more processors coupled to the memory and configured to execute the instructions to cause the video decoder to:

receive a video bitstream comprising a reference picture list (RPL) flag, wherein the RPL flag equal to a first value specifies that RPL signaling is present in a picture header (PH) and is not present in slice headers, wherein the RPL flag equal to a second value specifies that the RPL signaling is not present in the PH and may be present in the slice headers, wherein the RPL signaling is RPL information comprised in the video bitstream, wherein the RPL information comprises an RPL index or ref_pic_list_struct(listIdx, rplsIdx) syntax structure, wherein the RPL index specifics an index, into a list of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i included in a sequence parameter set (SPS), of the ref_pic_list_struct(listIdx, rplsIdx) syntax structure with listIdx equal to i that is used for derivation of RPL i of a current picture, wherein the video bitstream further comprises an adaptive loop filter (ALF) flag, wherein the ALF flag equal to the first value specifies that ALF signaling is present in the PH and not present in the slice headers, wherein the ALF flag equal to the second value specifies that the ALF signaling is not present in the PH and may be present in the slice headers, and wherein the ALF signaling comprises an ALF enable flag; and

decode, based on the RPL flag and the ALF flag, a coded picture to obtain a decoded picture.

8. The video decoder of claim 7 , wherein the video bitstream further comprises an RPL SPS flag.

9. The video decoder of claim 7 , wherein the first value is 1.

10. The video decoder of claim 7 , wherein the second value is 0.

11. The video decoder of claim 8 , wherein the RPL SPS flag specifies that RPL i is derived based on one of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i in an SPS or specifies that RPL i is derived based on one of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i that is directly included.

12. The video decoder of claim 7 , wherein the one ore more processors are further configured to execute the instructions to cause the video decoder to display the decoded picture on a display of an electronic device.

13. A method implemented by a video encoder and comprising:

generating a reference picture list (RPL) flag, wherein the RPL flag equal to a first value specifies that RPL signaling is present in a picture header (PH) and is not present in slice headers, and wherein the RPL flag equal to a second value specifies that the RPL signaling is not present in the PH and may be present in the slice headers, wherein the RPL signaling is RPL information, wherein the RPL information comprises an RPL index or ref_pic_list_struct(listIdx, rplsIdx) syntax structure, and wherein the RPL index specifics an index, into a list of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i included in a sequence parameter set (SPS), of the ref_pic_list_struct(listIdx, rplsIdx) syntax structure with listIdx equal to i that is used for derivation of RPL i of a current picture;

encoding the RPL flag into a video bitstream;

generating an adaptive loop filter (ALF) flag, wherein the ALF flag equal to the first value specifies that ALF signaling is present in the PH and not present in the slice headers, wherein the ALF flag equal to the second value specifies that the ALF signaling is not present in the PH and may be present in the slice headers, and wherein the ALF signaling comprises an ALF enable flag;

encoding the ALF flag into the video bitstream; and

storing the video bitstream for communication toward a video decoder.

14. The method of claim 13 , wherein the first value is 1.

15. The method of claim 13 , wherein the second value is 0.

16. The method claim 13 , further comprising:

generating an RPL SPS flag; and

encoding the RPL SPS flag into the video bitstream.

17. The method of claim 16 , wherein the RPL SPS flag specifies that RPL i is derived based on one of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i in an SPS or specifies that RPL i is derived based on one of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i that is directly included.

18. The method of claim 13 , further comprising communicating the video bitstream to the video decoder.

19. A video encoder comprising:

a memory configured to store instructions; and

one or more processors coupled to the memory and configured to execute the instructions to cause the video encoder to:

generate a reference picture list (RPL) flag, wherein the RPL flag equal to a first value specifies that RPL signaling is present in a picture header (PH) and is not present in slice headers, and wherein the RPL flag equal to a second value specifies that the RPL signaling is not present in the PH and may be present in the slice headers, wherein the RPL signaling is RPL information, wherein the RPL information comprises an RPL index or ref_pic_list_struct(listIdx, rplsIdx) syntax structure, and wherein the RPL index specifics an index, into a list of the ref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdx equal to i included in a sequence parameter set (SPS), of the ref_pic_list_struct(listIdx, rplsIdx) syntax structure with listIdx equal to i that is used for derivation of RPL i of a current picture;

encode the RPL flag into a video bitstream;

generate an adaptive loop filter (ALF) flag, wherein the ALF flag equal to the first value specifies that ALF signaling is present in the PH and not present in the slice headers, wherein the ALF flag equal to the second value specifies that the ALF signaling is not present in the PH and may be present in the slice headers, and wherein the ALF signaling comprises an ALF enable flag;

encode the ALF flag into the video bitstream; and

store the video bitstream for communication toward a video decoder.

20. The video encoder of claim 19 , wherein the first value is 1, and wherein the second value is 0.