present in the bitstream and is equal to 1, for the i-th subset of coded video sequences, the need for presence of buffering periods for NAL HRD operation to be present in the bitstream in buffering period SEI messages is determined by the application, by some means not specified in this Recommendation | International Standard. - Otherwise, the value of VuiExtNalHrdBpPresentFlag| i ] shall be set equal to 0. vui_ext_vcl_hrd_parameters_present_flag[i]specifies the value ofvcl_hrd_parameters_present_flag,as specified in clause E.2.1, for the i-th subset of coded video sequences. When vui_ext_vcl_hrd_parameters_present_flag[i] is equal to 1, VCL HRD parameters (clauses E.1.2 and E.2.2) for the i-th subset of coded video sequences immediately follow the flag. The variable VuiExtVclHrdBpPresentFlag[ i ] is derived as follows: If any of the following is true, the value of VuiExtVclHrdBpPresentFlag[ shall be set equal to 1: Rec. ITU-T H.264 (01/2012) ui_ext_vcl_hrd_parameters_present_flag| i ] is present in the bitstream and is equal to 1, for the i-th subset of coded video sequences, the need for presence of buffering periods for VCL HRD operation to be present in the bitstream in buffering period SEI messages is determined by the application, by some means not specified in this Recommendation | International Standard. Otherwise, the value of VuiExtVclHrdBpPresentFlag[ i ] shall be set equal to 0. The variable VuiExtCpbDpbDelaysPresentFlag[ i ] is derived as follows: If any of the following is true, the value of VuiExtCpbDpbDelaysPresentFlag| i ] shall be set equal to 1: - vui_ext_nal_hrd_parameters_present_flag i ] is present in the bitstream and is equal to 1, vui_ext_vcl_hrd_parameters_present_flag| i ] is present in the bitstream and is equal to for the i-th subset of coded video sequences, the need for presence of CPB and DPB output delays to be present in the bitstream in picture timing SEI messages is determined by the application, by some means not specified in this Recommendation International Standard. Otherw