I'm using OBS v25.0.8 for Mac and I'm trying to capture a two screen video, one from my laptop camera (Facetime camera 1280x720) and one presentation (Window share PowerPoint).

I set up my video config as follows:

  • Canvas 3840x1080
  • Output 1280x720 (OBS set this automatically)

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As you can see from the screenshot above, the PowerPoint presentation is not taking the full width, leaving an empty space between the two screens.

I tried changing the output ratio, but nothing seems to happen. My laptop is a Macbook Pro with the following display 15.4-inch (2880 × 1800)

What is the correct calculation to get the two screens to fit proportionally?

1 Answer 1


You could eliminate the gap by reducing the width of the Base Resolution from 3840 to what fits: 1280 + the width of the powerpoint presentation. You may need to drag the righthand frame over, but it should fit.

But you've got another issue: your Base and Output are very different aspect ratios, so your output will be distorted as it smushes 50% horizontally (to use a technical term :-).

If you're going to output (capture) 16:9, I believe your canvas needs to be at that ratio too. If you keep the base height 1080, the base width should be 1280 / 720 * 1080 = 1920.

To handle that, you can start by cropping your Facetime camera on the sides, although it won't be enough. You'll need a different aspect ratio in your PowerPoint itself, which will likely require changing the layout of all your slides. Alternately, you could shrink down the presentation in OBS, leaving a gap above and below it and have a nice background color behind the whole frame (or some cool looping animation).

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