A method of decoding video data, the video data comprising an access unit, the access unit comprising a plurality of decoding units, the method comprising: for each of the plurality of decoding units within the access unit, decoding from a decoding unit information supplemental enhancement information, SEI, message that is associated with the decoding unit and that further indicates information for a coded picture buffer, CPB, removal time of the decoding unit, a unique identifier for the decoding unit that is different than an identifier for any other decoding unit in the access unit, wherein each of the plurality of decoding units is associated with one or more network abstraction layer, NAL, units, wherein the unique identifier for each decoding unit is an index of the decoding unit in the list of all decoding units in the access unit in decoding order, wherein said decoding for each of the plurality of decoding units within the access unit comprises: i) decoding a first unique identifier from a first decoding unit information SEI message for a first decoding unit of the plurality of decoding units, and ii) decoding a second unique identifier from a second decoding unit information SEI message for a second decoding unit of the plurality of decoding units; determining which NAL units are associated with which decoding units based on the unique identifier for each decoding unit in the access unit, wherein said determining comprises determining that a first SEI NAL unit that includes the first decoding unit information SEI message and all NAL units that follow the first SEI NAL unit up to a second SEI NAL unit that includes the second decoding unit information SEI message are associated with the first decoding unit; and decoding the NAL units of each of the decoding units in the access unit, based on the determination, to reconstruct at least one picture. for each of the plurality of decoding units within the access unit, decoding from a decoding unit information supplemental enhancement information, SEI, message that is associated with the decoding unit and that further indicates information for a coded picture buffer, CPB, removal time of the decoding unit, a unique identifier for the decoding unit that is different than an identifier for any other decoding unit in the access unit, wherein each of the plurality of decoding units is associated with one or more network abstraction layer, NAL, units, wherein the unique identifier for each decoding unit is an index of the decoding unit in the list of all decoding units in the access unit in decoding order, wherein said decoding for each of the plurality of decoding units within the access unit comprises: i) decoding a first unique identifier from a first decoding unit information SEI message for a first decoding unit of the plurality of decoding units, and ii) decoding a second unique identifier from a second decoding unit information SEI message for a second decoding unit of the plurality of decoding units; determining which NAL units are associated with which decoding units based on the unique identifier for each decoding unit in the access unit, wherein said determining comprises determining that a first SEI NAL unit that includes the first decoding unit information SEI message and all NAL units that follow the first SEI NAL unit up to a second SEI NAL unit that includes the second decoding unit information SEI message are associated with the first decoding unit; and decoding the NAL units of each of the decoding units in the access unit, based on the determination, to reconstruct at least one picture.