af(n)tai(n)+b(n):BitRate[SchedSelldx) (C-6) where b( (n) is the size in bits of access unit n, counting the bits of the VCL NAL units and the filler data NAL units for the Type I conformance point or all bits of the Type II bitstream for the Type II conformance point, where the Type I and Type II conformance points are as shown in Figure C-1. The values of SchedSelIdx, BitRate[ SchedSelIdx ], and CpbSize[ SchedSelIdx ] are constrained as follows: If the content of the active sequence parameter sets for access unit n and access unit n - 1 differ, the HSS selects a value SchedSelIdx1 of SchedSelIdx from among the values of SchedSelIdx provided in the active sequence parameter set for access unit n that results in a BitRate[ SchedSelIdx1 or CpbSize[ SchedSelIdx1 ] for access unit n. The value of BitRate[ SchedSelIdx1 ] or CpbSize[ SchedSelIdx1 may differ from the value of BitRate[ SchedSelIdx0 ] or CpbSize[ SchedSelIdx0 ] for the value SchedSelIdx0 of SchedSelldx that was in use for access unit n - 1. Otherwise, the HSS continues to operate with the previous values of SchedSelIdx, BitRate[ SchedSelIdx ] and CpbSize[ SchedSelldx ]. When the HSS selects values of BitRate[ SchedSelIdx ] or CpbSize[ SchedSelIdx ] that differ from those of the previous access unit, the following applies: the variable BitRate[ SchedSelIdx ] comes into effect at time tai( (n) the variable CpbSize[ SchedSelIdx ] comes into effect as follows: If the new value of CpbSize[ SchedSelIdx ] exceeds the old CPB size, it comes into effect at time tai(n), Otherwise, the new value of CpbSize[ SchedSelIdx ] comes into effect at the time t,(n). C.1.2 Timing of coded picture removal When an access unit n is the access unit with n equal to 0 (the access unit that initialises the HRD), the nominal removal time of the access unit from the CPB is specified by tr,n( 0) = initial_cpb_removal_delay[SchedSelldx ] 90000 (C-7) Rec. ITU-T H.264 (01/2012) When an access unit n is the first access unit of a buffering period that does not initialise the HRD, the nomin