Question / Help Video preview not filling up the entire window

[InvictusGuy]

When OBS is open and I can see my video feed onscreen, it't not filling up the entire viewing area within OBS...why is that?
I'm not trying to simply go in "fullscreen mode"...talking about with the editor open, etc. in working mode. Why is it black around the video feed?

 

[Narcogen]

That would appear to indicate a difference between the dimensions of the source you're looking at and the size of the canvas resolution as specified in Settings > Video.