METHOD FOR OUTPUT LAYER SET FOR MULTILAYERED VIDEO STREAM

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

obtaining video data that is partitioned into a plurality of layers;

generating a video parameter set (VPS) for the video data, including:

generating a first flag that specifies whether layers specified by the VPS may use inter-layer prediction or that the layers are independently coded without using inter-layer prediction;

generating a second flag that specifies whether each OLS contains only one layer or at least one OLS contains more than one layer; and

determining an ols_mode_idc parameter specifying whether, for each output layer set (OLS), all layers or only a highest layer in the OLS is an output layer, wherein when the first flag is equal to 1 and the second flag is equal to 0, a value of the ols_mode_idc parameter is inferred to be equal to 2; and

encoding, based on the ols_mode_idc parameter, a portion of the video data into a coded video stream.

2 . The method of claim 1 , further comprising:

deriving (i) at least one first syntax element that specifies at least one first layer, from among the plurality of layers, to be outputted in an output layer set, and (ii) at least one second syntax element that indicates profile-tier-level information of the output layer set; and

wherein the VPS includes a third syntax element that indicates a number of the profile-tier-level information of the output layer set in a coded video sequence of the coded video stream referring to the VPS.

3 . The method of claim 2 , wherein the third syntax element is signaled within the VPS, based on a maximum allowed number of layers in each coded video sequence of the coded video stream referring to the VPS being greater than 1.

4 . The method of claim 2 , wherein the at least one second syntax element includes a set of syntax elements indicating the profile-tier-level information or includes an index indicating at least one entry in a profile-tier-level information set.

5 . The method of claim 2 , wherein the VPS includes a fourth syntax element that indicates a mode of output layer signaling for the output layer set.

6 . The method of claim 5 , wherein the at least one first syntax element is signaled within the VPS based on the mode indicated by the fourth syntax element.

7 . The method of claim 6 , wherein the at least one first syntax element includes a flag indicating whether one of the plurality of layers is to be output.

8 . The method of claim 2 , wherein:

the VPS includes a fourth syntax element that indicates a mode of output layer set signaling for a plurality of output layer sets, including the output layer set; and

decoding the coded video stream based on the VPS further comprises inferring whether to output a second layer, from among the plurality of layers, based on a mode indicated by the fourth syntax element.

9 . The method of claim 2 , further comprising determining a mode of output layer set signaling for a plurality of output layer sets, including the output layer set.

10 . A system for encoding a coded video stream, the system comprising:

memory configured to store computer program code; and

at least one processor configured to access the computer program code and operate as instructed by the computer program code, the computer program code comprising instructions for:

obtaining video data that is partitioned into a plurality of layers;

generating a video parameter set (VPS) for the video data, including:

generating a first flag that specifies whether layers specified by the VPS may use inter-layer prediction or that the layers are independently coded without using inter-layer prediction;

generating a second flag that specifies whether each OLS contains only one layer or at least one OLS contains more than one layer; and

determining an ols_mode_idc parameter specifying whether, for each output layer set (OLS), all layers or only a highest layer in the OLS is an output layer, wherein when the first flag is equal to 1 and the second flag is equal to 0, a value of the ols_mode_idc parameter is inferred to be equal to 2; and

encoding, based on the ols_mode_idc parameter, a portion of the video data into a coded video stream

11 . The system of claim 10 , wherein the computer program code further comprises instructions for deriving (i) at least one first syntax element that specifies at least one first layer, from among the plurality of layers, to be outputted in an output layer set, and (ii) at least one second syntax element that indicates profile-tier-level information of the output layer set; and

wherein the VPS includes a third syntax element that indicates a number of the profile-tier-level information of the output layer set in a coded video sequence of the coded video stream referring to the VPS.

12 . The system of claim 11 , wherein the third syntax element is signaled within the VPS, based on a maximum allowed number of layers in each coded video sequence of the coded video stream referring to the VPS being greater than 1.

13 . The system of claim 11 , wherein the at least one second syntax element includes a set of syntax elements indicating the profile-tier-level information or includes an index indicating at least one entry in a profile-tier-level information set.

14 . A non-transitory computer-readable storage medium storing a video bitstream that is generated by a video encoding method, the video encoding method comprising:

obtaining video data that is partitioned into a plurality of layers;

generating a video parameter set (VPS) for the video data, including:

generating a first flag that specifies whether layers specified by the VPS may use inter-layer prediction or that the layers are independently coded without using inter-layer prediction;

generating a second flag that specifies whether each OLS contains only one layer or at least one OLS contains more than one layer; and

determining an ols_mode_idc parameter specifying whether, for each output layer set (OLS), all layers or only a highest layer in the OLS is an output layer, wherein when the first flag is equal to 1 and the second flag is equal to 0, a value of the ols_mode_idc parameter is inferred to be equal to 2; and

encoding, based on the ols_mode_idc parameter, a portion of the video data;

wherein the video bitstream comprises the VPS and the encoded portion of the video data.

15 . The non-transitory computer-readable storage medium of claim 14 , wherein the VPS includes a third syntax element that indicates a number of profile-tier-level information of the output layer set referring to the VPS.

16 . The non-transitory computer-readable storage medium of claim 15 , wherein the third syntax element is signaled within the VPS, based on a maximum allowed number of layers in each coded video sequence referring to the VPS being greater than 1.

17 . The non-transitory computer-readable storage medium of claim 14 , wherein the VPS further includes a set of syntax elements indicating profile-tier-level information of the output layer set or includes an index indicating at least one entry in a profile-tier-level information set.

18 . The non-transitory computer-readable storage medium of claim 14 , wherein the VPS includes a fourth syntax element that indicates a mode of output layer signaling for the output layer set.

19 . The non-transitory computer-readable storage medium of claim 18 , wherein at least one first syntax element is signaled within the VPS based on the mode indicated by the fourth syntax element, wherein the at least one first syntax element specifies at least one first layer, from among the plurality of layers, to be outputted in an output layer set.

20 . The non-transitory computer-readable storage medium of claim 19 , wherein the at least one first syntax element includes a flag indicating whether one of the plurality of layers is to be output.