When watching SD content in particular, it would be nice to have the video that comes up in a small 4x3 box in the middle of the screen at least be able to be zoomed out to 4x3 maxing out height-wise. I did see a settings in the preferences for “Stretch Video to fit”, but that actually made things worse. 
So, something like a typical web video player to take the video full-screen would be great.
seconding this, but on tvOS. we have stations in the bay area that broadcast downrez 16:9 HD on 4:3 channels, leading to a letterboxed and pillarboxed display on a 16:9 TV. it would be nice to have the option to zoom the central 16:9 image to the larger 16:9 display.
Your best bet there is to just use the zoom setting on your TV.
As an American expat, I’ve never understood why American TV channels do this. In the UK, SD channels broadcast 16:9 content in 16:9, and 4:3 content in 4:3. DVB has flags so the TV will switch automatically. It works not only when switching channels, but even when the content changes whilst watching a channel. For example, CBS Action airs a lot of old programmes from the 80s and 90s that are 4:3. When it goes to an ad break, the TV automatically switches to 16:9. When it returns to the programme, it automatically switches back to 4:3.
I’m pretty sure ATSC has those flags and capabilities as well, but they hardly ever get used correctly (or at all).
i agree, it is silly. my guess is that most stations don’t know how to use their encoders to the fullest. the opening months of ATSC were very rough, and probably once they got something working they did not want to mess with it.
i tried the zoom on the TV. it’s not the best solution. on the samsung TVs there’s no preset for this so i had to set the custom zoom to do what i want. then i have to remember to unzoom after exiting channels. if for instance i just powered everything down without exiting channels, the next user (wife or one of the kids) is going to be very confused about the zoom. it’s not family-friendly.
my feeling is that eventually channels DVR is going to have to have per-channel database entries for comskip yes/no and even comskip.ini differences. this would be a convenient place to stash whether or not the channel needs custom zoom. in the end the TV has zero information about what the program is and channels potentially has a lot of info, so that heuristic decisions can be made about zoom. where i’m coming from is that ETV has this zoom functionality, ETV is kind of a pile, and channels is and can be so much more. from my POV it’s a loss of functionality in a product that’s way ahead of the competition.
BTW i noticed that the ATV client can now stretch the image to fill the screen width-wise (or maybe this was always there?). this only applies to SD channels, so Channels seems to know not to stretch an HD channel.
one of the default zoom setting on my samsung TV can then stretch the vertical dimension. that’s a lot easier than having to make a custom stretch, but it’s still no good for the family unless i can set up a macro on my logitech harmony that can toggle the stretch.
but i wanted to ask, since it seems you added this 1-d stretch functionality, if it would be possible to add a stretch for both dimensions in the ATV client.
VLC on iOS has the ability to change the aspect ratio on the fly. This is a feature that I love VLC for! For instance, if a video is 21:9 then I can change it to 16:9 and it takes up the full screen and (to me) looks much better on the smaller iOS Screens.
Could it not be implemented the same way Live Channels on Android works? They have zoom/stretch options, once enabled it auto detects the source and only applies it to SD channels that aren’t screen fit.