Ideal canvas res for a 2d game

[Lunardixx]

I'm playing a game that does not get picked up by game capture in obs so everyone who streams/records it uses window capture.
I use a custom res on the monitor I'm recording, it is not a full screen game so I have windows tool bar at the bottom.
It's not use to me to capture windows tool bar. I took a screenshot of the active game window and used those for the canvas.
Just wondering if this is recommended in this exact situation or if there is a better idea.
The reason I ask is everyone instantly replies with "always put your monitor's current resolution" but for obvious reasons that may not apply.

 

[koala]

It makes no sense to use the monitor resolution, if your game runs with a slightly smaller resolution, so you probably did the right thing.
I would do it this way:

As first step, use the Windows Desktop resolution as canvas resolution in OBS.
Then add the capture source for your game. It should be on the top left corner of your OBS preview. If you already added your game, do right-click the source->Transform->Reset transform to revert any scaling you might have done previously.
Since your game is windowed, the will now be smaller than the canvas, so you get black regions to the right and to the bottom. Then right-click your source and choose "Resize Output (source size)". This will reduce your canvas and output size to exactly the source of your game. This way your recordings will get no distortion, no stretching, just 1:1 the game size.

However, if you intend to stream your games, keep in mind all streaming services will force your video into their 16:9 aspect ratio players. So if your actual game resolution isn't 16:9 aspect ratio, and windowed games usually are some odd aspect ratio and not exactly 16:9, you will get small letterboxes to the left+light or top+bottom. To make these letterboxes as small as possible, resize the window of your game to get closer to 16:9 aspect ratio. For example, if you get letterboxes at top+bottom, your video is too wide, so make the game window a little bit narrower (move the right or left border of your game window a little bit in) and use the resizing option again. If you get letterboxes at left+right, your video is too narrow, so do move the top or bottom border of your game window a little bit in. You will be wasting some space, but the aspect ratio will be better.