Techniques for implementing a decoding order within a coded picture

An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:

• perform a conversion between a video comprising one or more pictures comprising one or more subpictures comprising one or more slices and a bitstream of the video according to a rule,
• wherein the bitstream includes a number of coded units, and
• wherein the rule specifies that a decoding order of coded units within a subpicture is in an increasing order of values of slice_address syntax elements in slice headers that specify slice addresses of slices corresponding to the coded units,
• wherein when a slice mode is a rectangular slice mode, a value of a slice_address syntax element in a slice header is equal to a subpicture-level slice index, and
• wherein the subpicture-level slice index specifies an index of a slice to a list of slices in a subpicture in an order as they are signaled in a picture parameter set.

A non-transitory computer-readable storage medium storing instructions that cause a processor to:

• perform a conversion between a video comprising one or more pictures comprising one or more subpictures comprising one or more slices and a bitstream of the video according to a rule,
• wherein the bitstream includes a number of coded units, and
• wherein the rule specifies that a decoding order of coded units within a subpicture is in an increasing order of values of slice_address syntax elements in slice headers that specify slice addresses of slices corresponding to the coded units,
• wherein when a slice mode is a rectangular slice mode, a value of a slice_address syntax element in a slice header is equal to a subpicture-level slice index, and
• wherein the subpicture-level slice index specifies an index of a slice to a list of slices in a subpicture in an order as they are signaled in a picture parameter set.

A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:

• generating the bitstream of the video comprising one or more pictures comprising one or more subpictures comprising one or more slices according to a rule,
• wherein the bitstream includes a number of coded units, and
• wherein the rule specifies that a decoding order of coded units within a subpicture is in an increasing order of values of slice_address syntax elements in slice headers that specify slice addresses of slices corresponding to the coded units,
• wherein when a slice mode is a rectangular slice mode, a value of a slice_address syntax element in a slice header is equal to a subpicture-level slice index, and
• wherein the subpicture-level slice index specifies an index of a slice to a list of slices in a subpicture in an order as they are signaled in a picture parameter set.