Systems and methods for decoding based on inferred video parameter sets

1. A method performed by at least one processor, the method comprising:

receiving a bitstream including at least one coded picture;

inferring a value of a first identifier of a video parameter set, based on the first identifier of the video parameter set not being in the bitstream;

inferring a value of a syntax element, that indicates an output layer set mode, based on a first flag indicating that all layers specified by the video parameter set are independently coded without using inter-layer prediction, and based on a second flag indicating that each layer in a coded video sequence (CVS), referring to the video parameter set, is an output layer set (OLS) containing only one layer; and

decoding the at least one coded picture based on the inferring the value of the first identifier and the inferring the value of the syntax element.

2. The method of claim 1 , wherein the inferring the value of the first identifier comprises inferring the value of the first identifier as 0 based on the first identifier of the video parameter set not being in the bitstream.

3. The method of claim 1 , wherein the value of the first identifier indicates that the video parameter set is not present in the bitstream.

4. The method of claim 1 , further comprises:

inferring a value of a second identifier of a layer of the video parameter set based on the first identifier of the video parameter set not being in the bitstream.

5. The method of claim 4 , wherein the inferring the value of the second identifier comprises inferring the value of the second identifier as 0 based on the first identifier of the video parameter set not being in the bitstream.

6. The method of claim 1 , further comprises:

inferring a value of a third flag based on the third flag not being in the bitstream, wherein the third flag indicates whether another syntax element is present that indicates whether pictures of a layer, specified by the video parameter set, are used as interlayer reference pictures (ILRPs).

7. The method of claim 6 , wherein the inferring the value of the third flag comprises inferring the value of the third flag as 0 based on the third flag not being in the bitstream.

8. The method of claim 1 , wherein the inferring the value of the syntax element comprises inferring the value of the syntax element as 0 based on the first flag having a value of 1 and the second flag having a value of 1.

9. The method of claim 1 , wherein

the inferring the value of the syntax element comprises inferring the value of the syntax element as a value that indicates the output layer set mode is a mode in which:

a total number of OLSs specified by the video parameter set is equal to a total number of the layers specified by the video parameter set,

an i-th OLS from among the OLSs includes layers with layer indices from 0 to i, inclusive, and

for each OLS from among the OLSs, only a highest layer in the OLS is an output layer.

10. The method of claim 1 , wherein

the first identifier provides an identification (ID) of the video parameter set, based on the value of the first identifier being greater than 0, and

the first identifier indicates that the video parameter set is not present in the bitstream, based on the value of the first identifier being equal to 0.

11. A system comprising:

at least one memory storing computer code; and

at least one processor configured to receive a bitstream comprising at least one coded picture, the at least one processor further configured to access the computer code and operate as instructed by the computer code, the computer code including:

inferring code configured to cause the at least one processor to:

infer a value of a first identifier of a video parameter set, based on the first identifier of the video parameter set not being in the bitstream, and

infer a value of a syntax element, that indicates an output layer set mode, based on a first flag indicating that all layers specified by the video parameter set are independently coded without using inter-layer prediction, and based on a second flag indicating that each layer in a coded video sequence (CVS), referring to the video parameter set, is an output layer set (OLS) containing only one layer; and

decoding code configured to cause the at least one processor to decode the at least one coded picture based on the inferring the value of the first identifier and the inferring the value of the syntax element.

12. The system of claim 11 , wherein the inferring code is configured to cause the at least one processor to infer the value of the first identifier as 0 based on the first identifier of the video parameter set not being in the bitstream.

13. The system of claim 11 , wherein the value of the first identifier indicates that the video parameter set is not present in the bitstream.

14. The system of claim 11 , wherein the inferring code is further configured to cause the at least one processor to infer a value of a second identifier of a layer of the video parameter set based on the first identifier of the video parameter set not being in the bitstream.

15. The system of claim 14 , wherein the inferring code is configured to cause the at least one processor to infer the value of the second identifier as 0 based on the first identifier of the video parameter set not being in the bitstream.

16. The system of claim 11 , wherein

the inferring code is further configured to cause the at least one processor to infer a value of a third flag based on the third flag not being in the bitstream, and

the third flag indicates whether another syntax element is present that indicates whether pictures of a layer, specified by the video parameter set, are used as interlayer reference pictures (ILRPs).

17. The system of claim 16 , wherein the inferring code is configured to cause the at least one processor to infer the value of the third flag as 0 based on the third flag not being in the bitstream.

18. The system of claim 11 , wherein the inferring code is configured to cause the at least one processor to infer the value of the syntax element as 0 based on the first flag having a value of 1 and the second flag having a value of 1 .

19. A non-transitory computer-readable medium storing computer code that is configured to, when executed by at least one processor, cause the at least one processor to:

infer a value of a first identifier of a video parameter set, based on the first identifier of the video parameter set not being in a received bitstream that includes at least one coded picture;

infer a value of a syntax element, that indicates an output layer set mode, based on a first flag indicating that all layers specified by the video parameter set are independently coded without using inter-layer prediction, and based on a second flag indicating that each layer in a coded video sequence (CVS), referring to the video parameter set, is an output layer set (OLS) containing only one layer; and

decode the at least one coded picture based on inferring the value of the first identifier and inferring the value of the syntax element.

20. The system of claim 11 , wherein

the first identifier provides an identification (ID) of the video parameter set, based on the value of the first identifier being greater than 0, and

the first identifier indicates that the video parameter set is not present in the bitstream, based on the value of the first identifier being equal to 0.