Constraints on collocated pictures in video coding

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 a current picture and a bitstream of the video,
• wherein the bitstream conforms to a format rule, and
• wherein the format rule specifies that a slice header associated with a slice of the current picture comprises one or more constraints on a collocated picture of the current picture, and
• wherein the one or more constraints specifies that a variable indicating that a reference picture resampling process is disabled for the collocated picture.

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

• perform a conversion between a video comprising a current picture and a bitstream of the video,
• wherein the bitstream conforms to a format rule, and
• wherein the format rule specifies that a slice header associated with a slice of the current picture comprises one or more constraints on a collocated picture of the current picture, and
• wherein the one or more constraints specifies that a variable indicating that a reference picture resampling process is disabled for the collocated picture.

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 a current picture,
• wherein the bitstream conforms to a format rule, and
• wherein the format rule specifies that a slice header associated with a slice of the current picture comprises one or more constraints on a collocated picture of the current picture, and
• wherein the one or more constraints specifies that a variable indicating that a reference picture resampling process is disabled for the collocated picture.