alled a clock tick) of a clock tick counter. num_units_in_tick shall be greater than 0. A clock tick is the minimum interval of time that can be represented in the coded data. For example, when the frame rate of a video signal is 30 000 = 1001 Hz, time_scale may be equal to 60 000 and num_units_in_tick may be equal to 1001. See Equation C-1. time_scale is the number of time units that pass in one second. For example, a time coordinate system that measures time using a 27 MHz clock has a time_scale of 27 000 000. time_scale shall be greater than 0. fixed_frame_rate_flag equal to 1 indicates that the temporal distance between the HRD output times of any two consecutive pictures in output order is constrained as follows. fixed_frame_rate_flag equal to 0 indicates that no such constraints apply to the temporal distance between the HRD output times of any two consecutive pictures in output order. When fixed_frame_rate_flag is not present, it shall be inferred to be equal to 0. For each picture n where n indicates the n-th picture (in output order) that is output and picture n is not the last picture in the bitstream (in output order) that is output, the value of n) is specified by = DeltaTfiDivisor (E-34) Rec. ITU-T H.264 (01/2012) where Ato,dpb( n) is specified in Equation C-13 and DeltaTfiDivisor is specified by Table E-6 based on the value of pic c_struct_present_flag, field_pic_flag,and pic struct for the coded video sequence containing picture n. Entries marked "_" in Table E-6 indicate a lack of dependence of DeltaTfiDivisor on the corresponding syntax element. When fixed_frame_rate_flag is equal to 1 for a coded video sequence containing picture n, the value computed for n) shall be equal to tc as specified in Equation C-1 (using the value of tc for the coded video sequence containing picture n) when either or both of the following conditions are true for the following picture nn that is specified for use in Equation C-13: picture nn is in the same coded video sequence as picture n. picture nn is in a different