Exportation webp

Good morning,

For a fair trade association, I produce a newsletter. To prevent the Internet user from leaving the newsletter too quickly, I would like to incorporate a few small animations in webp format. To try, I transformed a small video for mobile into 450x800 9/16 format, therefore 5 images second, without difficulty with Handbreak em mp4, but I have the following problem when exporting from Shotcut to the webp.

By default the webp export offers 1080p, so I modify the export to the format of the video which is in the timeline, but this is not respected! It reduces the original to me because it seems that the software remains on the 16/9 1080p format…

What to do ?
THANKS :slight_smile:

I found, I have to create the video mode that corresponds to my constraints…