Different DVD's = Different Position of Black bars (1 Viewer)

[Jon_Gregory]

Ok on my Panasonic Pt53wx53 RPTV, I have noticed that some DVDs will have a thicker black bar on the top sometimes and other times the black bar will be thicker on the bottom. And then there are times when a movie will be dead center from top to bottom. This varries between movie titles and can be repeated with the same DVD title, but another physical DVD. So it seems that this is specific to a movie title and not a physical disk.

I posted this in the DVD forum, because I think this is an aspect of the DVD and not my TV. My question is, what causes this to happen with different DVD titles.

 

[MarcusUdeh]

listen to Chris

 

[ChristopherDAC]

The letterbox bars are encoded on the DVD as data structures, specifying "so-and-so many lines blanked out in 4:3 play mode, so-and-so many in 16:9 mode" at the top of the frame and again at the bottom. In the authoring process, it is possible to allocate more lines to one bar than the other, or even to have only one extra-wide bar which would appear either at top or bottom. When this is done, it may reflect a preference on the part of the authoring staff, or an attempt to provide a background for viewing of subtitles, or nothing at all beyond somebody's random decision. I suspect, though, that you would get very similar results on the same disc from a wide selection of players.