Question / Help Capture only part of window (Change canvas size)


New Member
I have not been able to solve this silly issue. I am sure there must be a way to capture (record) only a specific region of the screen. I am aware of cropping (alt) the visible region. This records both the cropped visible region and the region outside the visible region (entire desktop using the display source), which is black video. I do not want to include that black region. I can, of course, use some NLE system to crop, but there must be a way to record just the visible region.

Also "fit to screen" only works if the canvas is identical to your always changing visible cropped region.

Sorry for the long post, but in my research I have seen others post the identical question and the respondents always tell them about the alt-crop feature, or the "fit to screen" option. Neither of which resolves this issue.

How about adding a source called "Region", that would be cool.


Active Member
After cropping, you can get the size of the cropped region by right-clicking the source->Transform->Edit transform. Note the size and close the dialog. Then move the cropped region to the top left corner of the canvas. Then to to Settings->Video and set canvas size and output size to the just noted size of the source. Now you should have exactly the cropped region in your video and nothing black around it.


New Member
Thank you for quick and clear explanation. Unfortunately, this does not work. My canvas size is not changing even though it shows my edited canvas size. I tried restarting OBC, but no luck. I am using "Display Capture" as my source. Perhaps I should use some other source?
I attached three screengrabs for each step. You can see on the last grab (OBS_sg3.png) that there is plenty of black left on the sides and it records that way.
I am using v 22.0.2 (64-bit).


  • OBS_sg1.png
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  • OBS_sg2.png
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  • OBS_sg3.png
    79.4 KB · Views: 1,656


Active Member
Works for me, although my description is only accurate if you use the crop filter.
If you crop by alt-dragging the borders, the size of the source doesn't change, so you get the wrong canvas size. You have to substract the crop left/right/top/bottom values at the bottom of the "edit transform" dialog manually from the source size to get the cropped size.


You don't need to crop at all. Just set your canvas size to the size of your desired rectangle (a bit of guesswork required). You can now drag the source around as if the canvas is a small window that gives view to only part of the bigger source. Just move it so that the canvas gives view to exactly your desired rectangle.