id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
790	Log2 issue in subpicture signaling	zhangkai		"With the signaling of subpictures, we have
subpic_ctu_top_left_x[ i ] specifies horizontal position of top left CTU of i-th subpicture in unit of CtbSizeY. The length of the syntax element is Ceil( Log2( pic_width_max_in_luma_samples / CtbSizeY ) ) bits. When not present, the value of subpic_ctu_top_left_x[ i ] is inferred to be equal to 0.
subpic_ctu_top_left_y[ i ] specifies vertical position of top left CTU of i-th subpicture in unit of CtbSizeY. The length of the syntax element is Ceil( Log2( pic_height_max_in_luma_samples / CtbSizeY ) ) bits. When not present, the value of subpic_ctu_top_left_y[ i ] is inferred to be equal to 0.
subpic_width_minus1[ i ] plus 1 specifies the width of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil( Log2( pic_width_max_in_luma_samples / CtbSizeY ) ) bits. When not present, the value of subpic_width_minus1[ i ] is inferred to be equal to Ceil( pic_width_max_in_luma_samples / CtbSizeY ) − 1.
subpic_height_minus1[ i ] plus 1 specifies the height of the i-th subpicture in units of CtbSizeY. The length of the syntax element is Ceil( Log2( pic_height_max_in_luma_samples / CtbSizeY ) ) bits. When not present, the value of subpic_height_minus1[ i ] is inferred to be equal to Ceil( pic_height_max_in_luma_samples / CtbSizeY ) − 1.



pic_width_max_in_luma_samples / CtbSizeY is equal to zero if pic_width_max_in_luma_samples < CtbSizeY, which makes Log2() meaningless.

Log2( pic_width_max_in_luma_samples / CtbSizeY ) should be changed to '''Log2( (pic_width_max_in_luma_samples + CtbSizeY - 1)/ CtbSizeY )'''
Log2( pic_height_max_in_luma_samples / CtbSizeY ) should be changed to '''Log2( (pic_height_max_in_luma_samples + CtbSizeY - 1)/ CtbSizeY )'''"	defect	closed	minor		spec	VVC D7 vE	fixed		ksuehring bbross XiangLi fbossen jvet@…