A video coding mechanism is disclosed. The mechanism includes encoding a bitstream comprising one or more output layer sets (OLSs). A video parameter set (VPS) specifying the OLS is also encoded into the bitstream. The VPS comprises sequence-level hypothetical reference decoder (HRD) parameters that apply to all OLSs specified by the VPS. A set of bitstream conformance tests are performed based on the sequence-level HRD parameters. The bitstream is stored for communication toward a decoder.