Originally Posted by Mark12547
And I hate that all the SD sub-channels around here seem to all be 4:3! Other than for content originally at 4:3 (1.33:1) or the old "Academy Ratio" (1.375:1), there are two poor choices: either send widescreen stuff in butcher-and-slice, otherwise known as "pan and scan"; or letterbox into the 4:3 display area so on the 16:9 TVs the resulting image is windowboxed or postage stamp, and zooming windowboxed to fill the screen makes the poor resolution painfully obvious.
Why don't SD sub-channels broadcast in 16:9? At least then more of the screen can be used for the image and would be a better fit for modern shows and require less chopping or letterboxing for both 1.85:1 and 2.35:1 content.
There are a number of reasons. Unless a station has installed a 5th generation HD encoder, putting more than one HD channel on the air is problematic. With the newest HD encoders, a station can do two HD channels and two SD channels without compromising quality or motion (sports action) on any of the channels. However, the channels mentioned in the previous post come down on the satellite from the supplier in SD 4x3 format only. A station simply receives the video and sends it on to an SD encoder to be multiplexed onto the OTA feed.
Another reason is that there is no ATSC standard for SD 16x9 video. Yes, there is a squeezed method called Anamorphic but not all TV's and cable boxes will accommodate it. Further, your standard MK-I consumer would get frustrated changing their setup to watch a SD 16x9 channel and then having to change it back for regular viewing. By the way, this method gives you more vertical resolution but the horizontal resolution remains the same as in a postage stamp.
And there is the cable carriage issue. With 256 QAM, a cable company will typically limit the number of HD programs on a RF channel to two and probably slip in two to three SD channels before they run out of bits. If GetTV, Bounce, and their like were true HD program streams, then their chance of cable carriage would be significantly reduced due to space allocation.