By default OBS maintains the source's aspect ratio on all resizes, unless you hold a certain modifier key while performing the resize.Hi Tomasz. Thanks for your reply. By filling the source to the screen do you mean to physically drag the red field of view outline outward so there is no black space above, below, left, or right of the video feed? I experimented with that, but doing so zooms the image in rather than proportionally adjusting the size. I assume I'm doing something wrong? Thanks for your help! Log file for my last video is attached.