NG
I have overscan switched off on my TV, but it only seems to apply to native HD resolution, SD channels (from both the internal tuner, and PVR), are overscanned regardless. That will be a feature of the TV's internal upscaler.
That's for two reasons: firstly disabling overscan is so you can get a 1:1 correspondence between video pixels and TV pixels, which gives a slightly sharper image, which won't happen with an SD source anyway so there's not much point in it. Secondly SD sources should be treated as if they have nominal analogue blanking to get the aspect ratio right, which necessarily means cropping the left and right (and top and bottom sometimes have partial lines which are never meant to be displayed either).
That interpretation does vary from TV to TV (or manufacturer to manufacturer). Some have 1:1 pixel options (which only work at panel resolution - or 2:1 multiples thereof - so 1920x1080 is 2:1 matched on a 3840x2160 display along with 1:1 matched 3840x2160, but 1280x720, 702x576 are cropped and zoomed) others have zero overscan options which work in all modes.
if you have a Sky, Freesat or Freeview HD box you can often get your set top box to output 576i stuff at 1080i/p so then 1:1 match this and avoid overscan too (though a Sky HD box will not aspect switch as it would if it was in AUTO mode and output 576i as 576p with aspect flags)
noggin
Founding member
I have overscan switched off on my TV, but it only seems to apply to native HD resolution, SD channels (from both the internal tuner, and PVR), are overscanned regardless. That will be a feature of the TV's internal upscaler.
That's for two reasons: firstly disabling overscan is so you can get a 1:1 correspondence between video pixels and TV pixels, which gives a slightly sharper image, which won't happen with an SD source anyway so there's not much point in it. Secondly SD sources should be treated as if they have nominal analogue blanking to get the aspect ratio right, which necessarily means cropping the left and right (and top and bottom sometimes have partial lines which are never meant to be displayed either).
That interpretation does vary from TV to TV (or manufacturer to manufacturer). Some have 1:1 pixel options (which only work at panel resolution - or 2:1 multiples thereof - so 1920x1080 is 2:1 matched on a 3840x2160 display along with 1:1 matched 3840x2160, but 1280x720, 702x576 are cropped and zoomed) others have zero overscan options which work in all modes.
if you have a Sky, Freesat or Freeview HD box you can often get your set top box to output 576i stuff at 1080i/p so then 1:1 match this and avoid overscan too (though a Sky HD box will not aspect switch as it would if it was in AUTO mode and output 576i as 576p with aspect flags)