Hi. Im not sure if there exist an activator into vmix for outputs feedback and before vmix 28 the info we need for this,is not externally readable.
From Vmix 28 and up,exist in the API the info that reads the Fullscreen/outputs.
Personally I'm doing this by using bitfocus companion vmix module and I have buttons that say which output has either output or any input by using the proper variables.
With bitfocus is very easy to do it to send to any button this info. Directly in streamdeck with activators I don't know if possible.
Maybe you can do a script that will read this info and then in a gt text input write something when output has this or that in order to inform you
Also you can do an external app like this to see/lock the outputs and Fullscreen. This is my amateur app for this purpose
https://forums.vmix.com/...arty-program-for-Vmix-28
and companion variables for fullscreen 1 and pgm. We can do also for fullscreen 2 and output 2/3/4 to inform us
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