Indication of one slice per subpicture in subpicture-based video coding
A method of video decoding comprises receiving a bitstream including a picture parameter set (PPS) containing a single slice per subpicture flag; determining whether the single slice per subpicture flag has a first value or a second value, where the first value specifies that each subpicture referring to the PPS includes one and only one rectangular slice, and where the second value specifies that each subpicture referring to the PPS may include one or more rectangular slices; decoding the one and only one rectangular slice when the single slice per subpicture flag has the first value and the one or more rectangular slices when the single slice per subpicture flag has the second value.
1 . A method implemented by a decoder, comprising:
receiving a bitstream including a picture parameter set (PPS) including a single slice per subpicture flag;
determining whether the single slice per subpicture flag has a first value or a second value, wherein the first value specifies that each subpicture referring to the PPS includes one and only one rectangular slice and, when there is only one subpicture per picture, that there is only one slice per picture, and wherein the second value specifies that each subpicture referring to the PPS may include only one rectangular slice and may include more than one rectangular slices; and
decoding the one and only one rectangular slice when the single slice per subpicture flag has the first value and the one or more rectangular slices when the single slice per subpicture flag has the second value to obtain a decoded picture.
2 . The method of claim 1 , wherein the single slice per subpicture flag is designated as pps_single_slice_per_subpic_flag.
3 . The method of claim 1 , wherein the first value is one (1) and the second value is zero (0).
4 . The method of claim 1 , wherein the PPS further comprises a number of slices in picture flag, and wherein a value of the number of slices in picture flag plus one specifies a number of slices in each picture referring to the PPS.
5 . The method of claim 4 , wherein the number of slices in picture flag is designated as pps_num_slices_in_pic_minus1.
6 . The method of claim 1 , wherein each subpicture comprises a rectangular region of one or more slices within a picture.
7 . The method of claim 1 , further comprising generating an image for display based on the one and only one rectangular slice when the single slice per subpicture flag has the first value and the one or more rectangular slices when the single slice per subpicture flag has the second value.
8 . A decoding device, comprising:
a receiver configured to receive a bitstream including a picture parameter set (PPS) containing a single slice per subpicture flag;
a memory coupled to the receiver, the memory storing instructions; and
one or more processors coupled to the memory, the one or more processors configured to execute the instructions to cause the decoding device to:
determine whether the single slice per subpicture flag has a first value or a second value, wherein the first value specifies that each subpicture referring to the PPS includes one and only one rectangular slice and, when there is only one subpicture per picture, that there is only one slice per picture, and wherein the second value specifies that each subpicture referring to the PPS may include only one rectangular slice and may include more than one rectangular slices; and
decode the one and only one rectangular slice when the single slice per subpicture flag has the first value and the one or more rectangular slices when the single slice per subpicture flag has the second value to obtain a decoded picture.
9 . The decoding device of claim 8 , wherein the first value is one (1) and the second value is zero (0).
10 . The decoding device of claim 8 , wherein the PPS further comprises a number of slices in picture flag, and wherein a value of the number of slices in picture flag plus one specifies a number of slices in each picture referring to the PPS.
11 . The decoding device of claim 10 , wherein the number of slices in picture flag is designated as pps_num_slices_in_pic_minus1.
12 . The decoding device of claim 8 , wherein the one or more processors are further configured to generate an image for display based on the one and only one rectangular slice when the single slice per subpicture flag has the first value and the one or more rectangular slices when the single slice per subpicture flag has the second value.