Something that has received little notice in the transition to all-digital broadcasting is what happens to differing aspect ratios on cable, satellite, and telephone-company redistribution of broadcast signals.
When stations had separate digital and analog transmissions, they could carry HDTV on the digital and whatever seemed best on the analog, generally letterbox or center cut. Active format description (AFD) is supposed to carry aspect-ratio choices from program producer straight through to home viewer. But it’s not here yet, and more and more analog stations are going off the air.
Cable, satellite, and telco retransmitters can’t afford to have someone watching each program segment and adjusting aspect ratio control on the fly, so they’re basically just setting ATSC receivers for one setting and leaving them that way. The choice seems to be center cut, even if a station requests letterbox.
If letterbox were chosen, there would be issues with black bars on screens. Old 4:3 analog TV sets connected to set-top boxes without aspect ratio controls would see top and bottom bars on 16:9 programming, but they’d see those as well as side bars for 4:3 programming, an effect sometimes called picture frame and sometimes “postage stamp” for the size of the shrunken image.
Widescreen TVs would get even 16:9 programming in a picture-frame mode, surrounded by black, but those TVs have a zoom function allowing it to be restored to fill the screen, if at somewhat lowered resolution. Four-by-three programming that gets zoomed will probably still have black bars at the sides of widescreen sets, even after zooming. So there would be shrunken pictures and reduced resolution if letterbox is chosen.
Center cut, unfortunately, is a lot worse. It seems perfect for 4:3 programming sent to 4:3 TVs. But both of those are on the way out. Widescreen programming loses its sides on any TV, no matter what kind of zoom function it has. But consider what happens to even 4:3 programming on widescreen TVs. It has those black bars on the sides. If a viewer zooms to get rid of them, the tops and bottoms get cut off (for 16:9 programming, the tops, bottoms and sides all get cut off).
It’s a mess no matter what choice is made, but I, for one, would much rather have shrunken pictures than pictures that have their artistic framing chopped up. Let’s go letterbox.
Get the TV Tech Newsletter
The professional video industry's #1 source for news, trends and product and tech information. Sign up below.