Greenscreen video shot in portrait mode being fitted in landscape has black sections left and right, will not let background video go through during chroma key

I hope someone can help me here. I have a greenscreen project for my kid’s school assignment. Video of my child with a disco background. Openshoot is not working out for me so i am trying out Shotcut. here is my problem:

When using openshot and prior to running its chromakey i get this look


My kids video was taken via portrait mode. And my target output is landscape. But openshot’s chroma key doesnt get the job done properly. So im hoping that shotcut’s chroma key would do a much better job. But its initial setup shows that there are now black bars at the left and right instead of the discoball background.

Can anyone please tell me how to make shotcut make those black sections transparent? So then i can start tinkering around the chromakey functions to remove the actual greenscreen.
I have considered rendering the orignal video in the proper aspect ratio but replacing the black bars with green bars. But im hoping for a more elegant solution.


Hello. On the video with the child, you need to apply the “size and position” filter. Easy to apply, no need to change anything there. Black stripes should disappear.

Hi @raymerium

In this particular case, the resolution of your project should fit the resolution of the disco ball file (landscape orientation). I suspect that your Video Mode (File > Video Mode) is set to Automatic
If you imported the vertical (portrait) video of your daughter first, the project was automatically set to the resolution and frame rate of that file

Go to File > Video Mode and choose a mode that fits the resolution of the background clip.
Like 1920 x 1080 maybe?

Put the background video on video track V1. Put the portrait video on video track V2. This is what you get:

If that is not what you get then, yeah, it could be a Video Mode problem or your portrait video has black bars baked into it. If the black bars are baked in, then you can either use the Crop: Source or Crop: Rectangle filter with Padding color = Transparent on the portrait video.

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