1. A method for decoding video data, the method comprising:', 'decoding a duration between coded picture buffer (CPB) removal time of a first decoding unit (DU) in an access unit (AU) and CPB removal time of a second DU, wherein the first DU comprises a non-video coding layer (VCL) network abstraction layer (NAL) unit with nal_unit_type equal to UNSPECO, EOS_NUT, EOB NUT, in the range of RSV NVCL44 to RSV_NVCL47 or in the range of UNSPEC48 to', 'UNSPEC63;', 'determining a removal time of the first DU based at least in part on the decoded duration; and', 'decoding video data of the first DU based at least in part on the removal time.

2. The method of claim 1 , wherein the second DU is subsequent to the first DU in decoding order and in the same AU as the first DU.

3. The method of claim 2, wherein the second DU is immediately subsequent to the first DU in the AU in decoding order.

4. The method of claim 2, wherein the second DU is a last DU in the AU in decoding order.

5. The method of claim 1, further comprising:', 'decoding one or more sub-picture level CPB parameters, wherein determining the removal time of the first DU comprises determining the removal time of the first DU based at least in part on the decoded duration and the sub-picture level CPB parameters.

6. The method of claim 5, wherein decoding one or more sub-picture level CPB parameters comprises:', 'decoding a sub-picture timing supplemental enhancement information (SEI) message that is associated with the first DU.

7. The method of claim 6, wherein the second DU is a last DU in the AU in decoding order, and wherein decoding the sub-picture SEI message comprises:', 'decoding the duration between a removal time of the last DU and the removal time of the first DU in the sub-picture timing SEI message.

8. The method of claim 5, further comprising:', 'decoding a sequence level flag to determine presence of the sub-picture level CPB parameters either in picture timing SEI messages or in sub-picture timing SEI messages.

9. The method of claim 1, wherein the AU has a Temporalld equal to 0, the method further comprising:', 'decoding at least one of a buffering period supplemental enhancement information (SEI) message or a recovery point SEI message associated with the AU

10. The method of claim 1, further comprising:', 'deriving at least one of a CPB arrival time and a CPB nominal removal time for the AU at both an access unit level and a sub-picture level regardless of a value of a syntax element that defines whether the first DU is the AU

11. A video decoding device comprising a video decoder configured to:', 'decode a duration between coded picture buffer (CPB) removal time of a first decoding unit (DU) in an access unit (AU) and CPB removal time of a second DU, wherein the first DU comprises a non-video coding layer (VCL) network abstraction layer (NAL) unit with nal_unit_type equal to UNSPECO, EOS_NUT, EOB NUT, in the range of RSV NVCL44 to RSV_NVCL47 or in the range of UNSPEC48 to', 'UNSPEC63;', 'determine a removal time of the first DU based at least in part on the decoded duration; and', 'decode video data of the first DU based at least in part on the removal time

12. The video decoding device of claim 11, wherein the second DU is subsequent to the first DU in decoding order and in the same AU as the first DU

13. The video decoding device of claim 12, wherein the second DU is immediately subsequent to the first DU in the AU in decoding order

14. The video decoding device of claim 12, wherein the second DU is a last DU in the AU in decoding order

15. The video decoding device of claim 11, wherein the video decoder is further configured to decode one or more sub-picture level CPB parameters, wherein determine the removal time of the first DU comprises determine the removal time of the first DU based at least in part on the decoded duration and the sub-picture level CPB parameters

16. The video decoding device of claim 15, wherein the video decoder is further configured to decode one or more sub-picture level CPB parameters by decoding a sub- picture timing supplemental enhancement information (SEI) message that is associated with the first DU

17. The video decoding device of claim 16, wherein the second DU is a last DU in the AU in decoding order, and wherein decode the sub-picture SEI message comprises decode the duration between a removal time of the last DU and the removal time of the first DU in the sub-picture timing SEI message

18. The video decoding device of claim 15, wherein the video decoder is further configured to decode a sequence level flag to determine presence of the sub-picture level CPB parameters either in picture timing SEI messages or in sub-picture timing SEI messages

19. The video decoding device of claim 11, wherein the AU has a Temporalld equal to 0, wherein the video decoder is further configured to decode at least one of a buffering period supplemental enhancement information (SEI) message or a recovery point SEI message associated with the AU.

20. The video decoding device of claim 11, wherein the video decoder is further configured to derive at least one of a CPB arrival time and a CPB nominal removal time for the AU at both an access unit level and a sub-picture level regardless of a value of a syntax element that defines whether the first DU is the AU.

21. A computer-readable storage medium having stored thereon instructions that, when executed, cause a processor of a device for decoding video data to:', 'decode a duration between coded picture buffer (CPB) removal time of a first decoding unit (DU) in an access unit (AU) and CPB removal time of a second DU, wherein the first DU comprises a non-video coding layer (VCL) network abstraction layer (NAL) unit with nal_unit_type equal to UNSPECO, EOS_NUT, EOB NUT, in the range of RSV NVCL44 to RSV_NVCL47 or in the range of UNSPEC48 to', 'UNSPEC63;', 'determine a removal time of the first DU based at least in part on the decoded duration; and', 'decode video data of the first DU based at least in part on the removal time.

22. The computer-readable storage medium of claim 21, wherein the second DU is in the same AU as the first DU and wherein the second DU is one of immediately subsequent to the first DU in decoding order or a last DU in the AU in decoding order.

23. A video decoding device comprising:', 'means for decoding a duration between coded picture buffer (CPB) removal time of a first decoding unit (DU) in an access unit (AU) and CPB removal time of a second DU, wherein the first DU comprises a non-video coding layer (VCL) network abstraction layer (NAL) unit with nal_unit_type equal to UNSPECO, EOS_NUT, EOB NUT, in the range of RSV NVCL44 to RSV_NVCL47 or in the range of UNSPEC48 to UNSPEC63;', 'means for determining a removal time of the first DU based at least in part on the decoded duration; and', 'means for decoding video data of the first DU based at least in part on the removal time.

24. The video decoding device of claim 23, wherein the second DU is in the same AU as the first DU and wherein the second DU is one of immediately subsequent to the first DU in decoding order or a last DU in the AU in decoding order.

25. A method for encoding video data, the method comprising:', 'determining, for an AU including a first DU, a CPB removal time of a second DU, wherein the second DU is subsequent to the first DU in decoding order and in the same AU as the first DU, and wherein the first DU comprises a non- video coding layer (VCL) network abstraction layer (NAL) unit with nal unit type equal to UNSPECO, EOS_NUT, EOB NUT, in the range of RSV NVCL44 to RSV_NVCL47 or in the range of UNSPEC48 to UNSPEC63;', 'determining a duration between CPB removal time of the first DU and the determined CPB removal time of the second DU; and', 'encoding the determined duration.

26. The method of claim 25, wherein the second DU is subsequent to the first DU in decoding order and in the same AU as the first DU.

27. The method of claim 26, wherein the second DU is immediately subsequent to the first DU in the AU in decoding order.

28. The method of claim 26, wherein the second DU is a last DU in the AU in decoding order.

29. The method of claim 25, wherein encoding video data of the first DU based at least in part on the determined duration further comprises encoding the determined duration in one or more sub-picture level CPB parameters.

30. The method of claim 29, wherein encoding one or more sub-picture level CPB parameters comprises:', 'encoding a sub-picture timing supplemental enhancement information (SEI) message that is associated with the first DU.

31. The method of claim 30, wherein the second DU is a last DU in the AU in decoding order, and wherein encoding the sub-picture SEl message comprises:', 'encoding the duration between a removal time of the last DU and the removal time of the first DU in the sub-picture timing SEl message.

32. The method of claim 29, further comprising:', 'encoding a sequence level flag to indicate presence of the sub-picture level CPB parameters either in picture timing SEl messages or in sub-picture timing SEl messages.

33. The method of claim of claim 25, wherein the AU has a Temporalld equal to 0, the method further comprising:', 'encoding at least one of a buffering period supplemental enhancement information (SEl) message or a recovery point SEl message associated with the AU.

34. The method of claim 25, further comprising:', 'deriving at least one of a CPB arrival time and a CPB nominal removal time for the AU at both an access unit level and a sub-picture level regardless of a value of a syntax element that defines whether the first DU is the AU.

35. A video encoding device comprising a video encoder configured to:', 'determine, for an AU including a first DU, a CPB removal time of a second DU, wherein the second DU is subsequent to the first DU in decoding order and in the same AU as the first DU, and wherein the first DU comprises a non- video coding layer (VCL) network abstraction layer (NAL) unit with nal unit type equal to UNSPECO,', 'EOS_NUT, EOB NUT, in the range of RSV NVCL44 to RSV_NVCL47 or in the range of UNSPEC48 to UNSPEC63;', 'determine a duration between CPB removal time of the first DU and the determined CPB removal time of the second DU; and', 'encode video data of the first DU based at least in part on the determined duration.

36. The video encoding device of claim 35, wherein the second DU is subsequent to the first DU in decoding order and in the same AU as the first DU.

37. The video encoding device of claim 36, wherein the second DU is immediately subsequent to the first DU in the AU in decoding order.

38. The video encoding device of claim 36, wherein the second DU is a last DU in the AU in decoding order.

39. The video encoding device of claim 35, wherein encode video data of the first DU based at least in part on the determined duration further comprises encode the determined duration in one or more sub-picture level CPB parameters.

40. The video encoding device of claim 39, wherein the video encoder is further configured to encode one or more sub-picture level CPB parameters by decoding a sub- picture timing supplemental enhancement information (SEI) message that is associated with the first DU.

41. The video encoding device of claim 40, wherein the second DU is a last DU in the AU in decoding order, and wherein encode the sub-picture SEI message comprises encode the duration between a removal time of the last DU and the removal time of the first DU in the sub-picture timing SEI message.

42. The video encoding device of claim 39, the video encoder is further configured to encode a sequence level flag to indicate presence of the sub-picture level CPB parameters either in picture timing SEI messages or in sub-picture timing SEI messages.

43. The video encoding device of claim 35, wherein the AU has a Temporalld equal to 0, the video encoder further configured to encode at least one of a buffering period supplemental enhancement information (SEI) message or a recovery point SEI message associated with the AU.

44. The video encoding device of claim 35, the video encoder is further configured to derive at least one of a CPB arrival time and a CPB nominal removal time for the AU at both an access unit level and a sub-picture level regardless of a value of a syntax element that defines whether the first DU is the AU.

45. A computer-readable storage medium having stored thereon instructions that, when executed, cause a processor of a device for encoding video data to:', 'determine, for an AU including a first DU, a CPB removal time of a second DU, wherein the second DU is subsequent to the first DU in decoding order and in the same AU as the first DU, and wherein the first DU comprises a non- video coding layer (VCL) network abstraction layer (NAL) unit with nal unit type equal to UNSPECO,', 'EOS_NUT, EOB NUT, in the range of RSV NVCL44 to RSV_NVCL47 or in the range of UNSPEC48 to UNSPEC63;', 'determine a duration between CPB removal time of the first DU and the determined CPB removal time of the second DU; and', 'encode video data of the first DU based at least in part on the determined duration.

46. The computer-readable storage medium of claim 45, wherein the second DU is in the same AU as the first DU and wherein the second DU is one of immediately subsequent to the first DU in decoding order or a last DU in the AU in decoding order.']