Sequence-level HRD parameters

1. A method implemented by a decoder, the method comprising:

receiving a bitstream comprising one or more output layer sets (OLSs) and a video parameter set (VPS), wherein the VPS specifies the OLSs and comprises sequence-level hypothetical reference decoder (HRD) parameters that apply to all OLSs specified by the VPS, wherein the sequence-level HRD parameters include a decoding unit HRD parameters present flag, wherein the decoding unit HRD parameters present flag is set to one when the HRD operates at an access unit (AU) level or a decoding unit (DU) level, and wherein the decoding unit HRD parameters present flag is set to zero when the HRD operates at the AU level; and

decoding a picture from the OLSs.

2. The method of claim 1 , wherein the sequence-level HRD parameters are included in a general HRD parameters syntax structure, and wherein the general HRD parameters syntax structure provides parameters used in HRD operations.

3. The method of claim 2 , wherein the HRD operations include a set of bitstream conformance tests that are performed by an HRD.

4. The method of claim 1 , wherein the sequence-level HRD parameters include a HRD coded picture buffer count (hrd_cpb_cnt_minus1), wherein the hrd_cpb_cnt_minus1 plus one specifies a number of alternative coded picture buffer (CPB) delivery schedules, and wherein a value of hrd_cpb_cnt_minus1 is constrained to a range from zero to thirty one, inclusive.

5. The method of claim 1 , wherein the VPS further comprises a sublayer coded picture buffer (CPB) parameters present flag (sublayer_cpb_params_present_flag), wherein the sublayer_cpb_params_present_flag is set to one when an ith layer HRD parameter syntax structure contains HRD parameters for sublayer representations with a temporal identifier (ID) in a range of zero to a maximum HRD temporal ID (hrd_max_tid[i]), inclusive, and wherein the sublayer_cpb_params_present_flag is set to zero when the ith layer HRD parameter syntax structure contains HRD parameters for a sublayer representation with a temporal ID equal to hrd_max_tid[i] only.

6. The method of claim 1 , wherein a presence of the sequence-level HRD parameters indicates the decoder is capable of decoding the bitstream according to a delivery schedule.

7. A method implemented by an encoder, the method comprising:

encoding a bitstream comprising one or more output layer sets (OLSs);

encoding into the bitstream a video parameter set (VPS) specifying the OLSs, the VPS comprising sequence-level hypothetical reference decoder (HRD) parameters that apply to all OLSs specified by the VPS, wherein the sequence-level HRD parameters include a decoding unit HRD parameters present flag, wherein the decoding unit HRD parameters present flag is set to one when the HRD operates at an access unit (AU) level or a decoding unit (DU) level, and wherein the decoding unit HRD parameters present flag is set to zero when the HRD operates at the AU level; and

performing a set of bitstream conformance tests based on the sequence-level HRD parameters.

8. The method of claim 7 , wherein the sequence-level HRD parameters are included in a general HRD parameters syntax structure, and wherein the general HRD parameters syntax structure provides parameters used in HRD operations.

9. The method of claim 8 , wherein the HRD operations include the set of bitstream conformance tests, and wherein the bitstream conformance tests are performed by an HRD.

10. The method of claim 7 , wherein the sequence-level HRD parameters include a HRD coded picture buffer count (hrd_cpb_cnt_minus1), wherein the hrd_cpb_cnt_minus1 plus one specifies a number of alternative coded picture buffer (CPB) delivery schedules, and wherein a value of hrd_cpb_cnt_minus1 is constrained to a range from zero to thirty one, inclusive.

11. The method of claim 7 , wherein the VPS further comprises a sublayer coded picture buffer (CPB) parameters present flag (sublayer_cpb_params_present_flag), wherein the sublayer_cpb_params_present_flag is set to one when an ith layer HRD parameter syntax structure contains HRD parameters for sublayer representations with a temporal identifier (ID) in a range of zero to a maximum HRD temporal ID (hrd_max_tid[i]), inclusive, and wherein the sublayer_cpb_params_present_flag is set to zero when the ith layer HRD parameter syntax structure contains HRD parameters for a sublayer representation with a temporal ID equal to hrd_max_tid[i] only.

12. The method of claim 7 , wherein a presence of the sequence-level HRD parameters indicates a decoder is capable of decoding the bitstream according to a delivery schedule.

13. A video coding device comprising:

a receiver configured to receive a bitstream comprising one or more output layer sets (OLSs) and a video parameter set (VPS), wherein the VPS specifies the OLSs and comprises sequence-level hypothetical reference decoder (HRD) parameters that apply to all OLSs specified by the VPS, wherein the sequence-level HRD parameters include a decoding unit HRD parameters present flag, wherein the decoding unit HRD parameters present flag is set to one when the HRD operates at an access unit (AU) level or a decoding unit (DU) level, and wherein the decoding unit HRD parameters present flag is set to zero when the HRD operates at the AU level; and

a processor coupled to the receiver and configured to decode a picture from the OLSs.

14. The video coding device of claim 13 , wherein the sequence-level HRD parameters are included in a general HRD parameters syntax structure, and wherein the general HRD parameters syntax structure provides parameters used in HRD operations.

15. The video coding device of claim 14 , wherein the HRD operations include a set of bitstream conformance tests that are performed by an HRD.

16. The video coding device of claim 13 , wherein the sequence-level HRD parameters include a HRD coded picture buffer count (hrd_cpb_cnt_minus1), wherein the hrd_cpb_cnt_minus1 plus one specifies a number of alternative coded picture buffer (CPB) delivery schedules, and wherein a value of hrd_cpb_cnt_minus1 is constrained to a range from zero to thirty one, inclusive.

17. The video coding device of claim 13 , wherein the VPS further comprises a sublayer coded picture buffer (CPB) parameters present flag (sublayer_cpb_params_present_flag), wherein the sublayer_cpb_params_present_flag is set to one when an ith layer HRD parameter syntax structure contains HRD parameters for sublayer representations with a temporal identifier (ID) in a range of zero to a maximum HRD temporal ID (hrd_max_tid[i]), inclusive, and wherein the sublayer_cpb_params_present_flag is set to zero when the ith layer HRD parameter syntax structure contains HRD parameters for a sublayer representation with a temporal ID equal to hrd_max_tid[i] only.