Profile, tier and layer indication 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 plurality of video layers and a bitstream of the video,
• wherein the bitstream comprises a plurality of output layer sets (OLSs), each comprising one or more of the plurality of video layers, and the bitstream conforms to a format rule,
• wherein the format rule specifies that, for an OLS having a single layer, a profile-tier-level (PTL) syntax structure that indicates a profile, a tier and a level for the OLS is included in a video parameter set for the bitstream, and the PTL syntax structure for the OLS is also included in a sequence parameter set coded in the bitstream,
• wherein the format rule specifies that a number syntax element is included in the video parameter set indicative of a number of the PTL syntax structures coded in the video parameter set, and
• wherein the number of PTL syntax structures is equal to a value of the number syntax element plus one.

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

• perform a conversion between a video comprising a plurality of video layers and a bitstream of the video,
• wherein the bitstream comprises a plurality of output layer sets (OLSs), each comprising one or more of the plurality of video layers, and the bitstream conforms to a format rule,
• wherein the format rule specifies that, for an OLS having a single layer, a profile-tier-level (PTL) syntax structure that indicates a profile, a tier and a level for the OLS is included in a video parameter set for the bitstream, and the PTL syntax structure for the OLS is also included in a sequence parameter set coded in the bitstream,
• wherein the format rule specifies that a number syntax element is included in the video parameter set indicative of a number of the PTL syntax structures coded in the video parameter set, and
• wherein the number of PTL syntax structures is equal to a value of the number syntax element plus one.

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 plurality of video layers,
• wherein the bitstream comprises a plurality of output layer sets (OLSs), each comprising one or more of the plurality of video layers, and the bitstream conforms to a format rule,
• wherein the format rule specifies that, for an OLS having a single layer, a profile-tier-level (PTL) syntax structure that indicates a profile, a tier and a level for the OLS is included in a video parameter set for the bitstream, and the PTL syntax structure for the OLS is also included in a sequence parameter set coded in the bitstream,
• wherein the format rule specifies that a number syntax element is included in the video parameter set indicative of a number of the PTL syntax structures coded in the video parameter set, and
• wherein the number of PTL syntax structures is equal to a value of the number syntax element plus one.