A method of decoding a video bitstream is disclosed. The method includes: using a set of previously decoded pictures for decoding a subsequent picture; receiving a delta_poc_msb_present_flag indicating whether a delta_poc_msb_cycle_lt is present or not present, wherein the delta_poc_msb_cycle_lt being present indicates that more than one reference picture in the set of previously decoded pictures having same value, wherein the first previously decoded picture has a temporal ID being equal to zero, is not a RASL picture, not a RADL picture, not a sub-layer non-reference picture.