This subject is very interesting to me because despite I use it,
I think I don't understand all with advanced output way of life.
I did understood that stage values are bananas so let's see how it seems to work :
1/ by setting the preview panel in 'Preferences' at 4/3 or 16/10 or any custom value (!), you get an advanced output stage with 640x480 bananas
2/ by setting the preview panel in 'Preferences' at 8/3, you get an advanced output stage with 1280x480 bananas
3/ by setting the preview panel in 'Preferences' at 4/1, you get an advanced output stage with 1920x480 bananas
4/ by setting the preview panel in 'Preferences' at 16/9, you get an advanced output stage with 854x480.3 bananas
It's not so logical, not so easy to handle, especially when you got more than one projector and more than one output clip or a soft-edge to set.
I dream for a virtual stage, where I could precisely indicate the total output pixels number, and set my clips, one by one, with their real values.
I do not know if it is very clear, my english is so …, but the idea would be swapping bananas to pixels, somewhat !
PS : To be totally honest, I got to add something : in every live production I make, I thanks the Big God of Video Bananas (He does exist !) because I'm sending video with bananas values and it works !