Originally Posted by Jeremy W
I don't believe any HD newscasts broadcast in letterbox on their SD channels. They should, though. Forget center cutting, all HD material should be letterboxed in SD.
Problem with that is what happens with 4:3 SD material upconverted. If you pillarbox this as 12P16 when you upconvert (which is the best solution for resolution/quality), and then letterbox the output, you end up with window box / postage stamp, which viewers absolutely hate, especially when you consider many 4:3 SD viewers are 4:3 SD viewers because they are watching on smaller sets, where postage stamping can be incredibly annoying.
If you upconvert 4:3 SD using 14P16 (as we do in the UK for News - though this is SD 4:3 to SD 16:9 conversion) or 16F16 then you end up with a major resolution loss - which will cause the SD material to look dreadful in HD.
Annoying as it is - there is a very valid argument for retaining 12F12 (i.e. 4:3 centre cut) conversion for SD outlets whilst SD 4:3 archive / agency / live shot material still needs to be upconverted.
Another argument is graphics. If you are designing your HD graphics to be legible in SD - then 12F12 conversion (i.e. centre cutting) ensures they stay as large as possible on SD outlets, whereas if you broadcast as 16L12 (i.e. 16:9 letterbox) on SD, your HD graphics need to be bigger in HD to be legible on SD...
(For 12F12 your 1080/720 lines are scaled to 480, for 16L12 your 1080/720 lines are scaled to just 360 lines. Therefore graphics need to be much bigger in HD if you 16L12 transfer)