Conformance window parameters 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 picture in a video unit and a bitstream of the video according to a format rule,
• wherein the format rule specifies that, responsive to a width of the picture being equal to a maximum allowed picture width in the video unit and a height of the picture being equal to a maximum allowed picture height in the video unit, a conformance window flag in a picture parameter set corresponding to the picture is set to a zero value, and
• wherein the format rule specifies either that:
• responsive to (a) the conformance window flag having the zero value and (b) the width of the picture being equal to the maximum allowed picture width in the video unit and the height of the picture being equal to the maximum allowed picture height in the video unit, conformance window syntax elements indicating conformance cropping window offset parameters are excluded from the picture parameter set and are inferred to have same values as indicated in a sequence parameter set referred to by the video unit;
• or
• responsive to (c) the conformance window flag having the zero value and (d) the width of the picture being not equal to the maximum allowed picture width in the video unit or the height of the picture being not equal to the maximum allowed picture height in the video unit, conformance window syntax elements indicating the conformance cropping window offset parameters are inferred to have zero values.

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

• perform a conversion between a video comprising a picture in a video unit and a bitstream of the video according to a format rule,
• wherein the format rule specifies that, responsive to a width of the picture being equal to a maximum allowed picture width in the video unit and a height of the picture being equal to a maximum allowed picture height in the video unit, a conformance window flag in a picture parameter set corresponding to the picture is set to a zero value, and
• wherein the format rule specifies either that:
• responsive to (a) the conformance window flag having the zero value and (b) the width of the picture being equal to the maximum allowed picture width in the video unit and the height of the picture being equal to the maximum allowed picture height in the video unit, conformance window syntax elements indicating conformance cropping window offset parameters are excluded from the picture parameter set and are inferred to have same values as indicated in a sequence parameter set referred to by the video unit;
• or
• responsive to (c) the conformance window flag having the zero value and (d) the width of the picture being not equal to the maximum allowed picture width in the video unit or the height of the picture being not equal to the maximum allowed picture height in the video unit, conformance window syntax elements indicating the conformance cropping window offset parameters are inferred to have zero values.

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 for the video comprising a picture in a video unit according to a format rule,
• wherein the format rule specifies that, responsive to a width of the picture being equal to a maximum allowed picture width in the video unit and a height of the picture being equal to a maximum allowed picture height in the video unit, a conformance window flag in a picture parameter set corresponding to the picture is set to a zero value, and
• wherein the format rule specifies either that:
• responsive to (a) the conformance window flag having the zero value and (b) the width of the picture being equal to the maximum allowed picture width in the video unit and the height of the picture being equal to the maximum allowed picture height in the video unit, conformance window syntax elements indicating conformance cropping window offset parameters are excluded from the picture parameter set and are inferred to have same values as indicated in a sequence parameter set referred to by the video unit;
• or
• responsive to (c) the conformance window flag having the zero value and (d) the width of the picture being not equal to the maximum allowed picture width in the video unit or the height of the picture being not equal to the maximum allowed picture height in the video unit, conformance window syntax elements indicating the conformance cropping window offset parameters are inferred to have zero values.