According to some embodiments, a method performed by at least one processor is provided. The method includes: receiving a coded video stream including a picture partitioned into first sub-picture units, the first sub-picture units including: one first sub-picture unit, and an additional first sub-picture unit including a first ordered second sub-picture unit, from among second sub-picture units of the additional first sub-picture unit, and a last ordered second sub-picture unit, from among the second sub-picture units of the additional first sub-picture unit. The method further includes decoding the picture, the decoding including: obtaining index values of the first ordered second sub-picture unit and the last ordered second sub-picture unit of the additional first sub-picture unit, without the coded video stream explicitly signaling any of the index values and a difference value between the index values of the first ordered second sub-picture unit and the last ordered second sub-picture unit to the at least one processor, and wherein the additional first sub-picture unit has an order value that is subsequent to an order value of the one first sub-picture unit.

According an embodiment, the one first sub-picture unit includes a last ordered second sub-picture unit, from among second sub-picture units of the one first sub-picture unit, and the obtaining the index value of the first ordered second sub-picture unit of the additional first sub-picture unit includes obtaining the index value of the first ordered second sub-picture unit of the additional first sub-picture unit based on an index value of the last ordered second sub-picture unit of the one first sub-picture unit.