Bar data should be included in video user data
whenever the rectangular picture area containing useful information
does not extend to the full height or width of the coded frame
and AFD alone is insufficient to describe the extent of the image.
Note: either vertical or horizontal bars are specified, but not both.
Bar data should be included in video user data whenever the rectangular picture area containing useful information does not extend to the full height or width of the coded frame and AFD alone is insufficient to describe the extent of the image.
Note: either vertical or horizontal bars are specified, but not both.
For more details, see:
https://www.atsc.org/wp-content/uploads/2015/03/a_53-Part-4-2009.pdf
and SMPTE ST2016-1