Replacing phone screen - output aspect ratio changing

I'm learning on the job here...

I have successfully tracked and keyed out an iPhone green screen and can add in footage that was shot landscape. However, some of the footage to be dropped in is portrait. Whenever I add this portrait footage it makes the output aspect ratio change (to that of the source clip) and crops the entire image.

What simple trick am I missing to maintain the aspect ratio (4k UHD in this case) in the final output.

Many thanks in advance for any advice.

Is this in Fusion standalone or in the Fusion page of Resolve?
Can you show us how you set up your nodes?

Usually in cases like this, it's some sort of order of operations issue. i.e. Fusion takes it resolution of its bottom most 'layer' so if you import the footage in the wrong way or connect it up in the wrong way, it could result in what you're describing, but we're going to need a little more info than this to help you further.

Thanks.

This is Fusion inside Resolve.

This is my node layout. The PhoneGreenScreen is 4k UHD and the PhoneFootage is HD in a portrait format.

Yup. Your insert footage is determining the output aspect ratio, since in the merge it's the yellow input (meaning the background) You should definitely change this around. Just use the corner positioner in the planar tracker directly (it's in the operations section I think it's called) to merge your footage on top of the phone. Since you're replacing the screen anyway there's no need to key out the green. Just put it on top of the original footage.

Thank you.

I'll take a look at this. Unfortunately I do have to key because of the shape of the screen and the notch etc. But this gives me some good clues to the issue.

Maybe I should just resize my content for the screen first?

Any chance you can share your shot? You can reach me throuh PM if you can't share it publicly.
The notch shouldn't be a problem. Keying a phone screen is something you really don't want to do if you can avoid it.It's a rectangle, even with the notch. You can cut it out with masks in your original footage when you overlay it on top of the phone. If you track a black screen you can use all the original reflections of the phone, which results in much more realistic composits.

I hear you about using a black screen only - I wasn't on the shoot so it was done with a green screen. I resized my footage to the same as the composition and it seems to wok for now.

I can't share because of NDAs etc.

Thanks for your help!

You'll want to place your phone screen on top of the 4K plate, not under it like you may think. You can pipe your Delta Keyer into the Mask input of the merge and still cut things out the way you want to preserve things like fingers or the notch.

Another way to think of it, you don't want to cut a hole in the background plate, you want to cut your foreground to fit.