[John Michaels] “I’m sure disabling this (setting it to full frame active picture) would get rid of the bars, but again, aren’t they supposed to be there for 486 material?”
I think you should get rid of the bars especially if that’s what they want. As to the 6 lines, HD to SD conversion can involve going to 720×480 source and one would need to add the lines (4 on top, 2 bottom as you mention) to get a 486 standard for broadcast. Those lines wouldn’t be visible due to TV overscan.That wouldn’t be VBI though. It its not for broadcast it can be left at 720×480 (DVD for example).
This is why I wonder what the intent is. Might there be a next stage where someone will add pull down frames and interlace? If it’s for DVD use 720×480 would be fine. In fact one might do 720×480 anamorphic for SD 16×9 to keep the aspect ratio.
VBI would be 720×512. This is how I would deliver SD broadcast spots back in the day to DGFastchannel for distribution.