Is this something that can be added in the next version?

As far as I know this is a fairly unusual use-case - I don't remember it being requested in the GUI, for example. Most people are quite averse to cropping a picture just to make it fit a "standard" container, as far as I know.

Would --crop-left, --crop-right etc. CLI options be enough for you, or is the calculation of the required crops also valuable for your use-case?

Can you say a bit more about what you will use this for?

I actually do create quite a bit of DCPs where the file is 3840x2160 with DCI Scope black bars that are baked in. Then I would want to output a DCI scope DCP that crops accordingly. The auto-crop I'm not sure how accurate that is to do that? Where as it is really easy to set the container size to scope and then say fill the container. That is what I would do in DaVinci Resolve is set image to fill frame with crop. This also is the case if I have a 3840x2160 video that I want to create a DCI flat DCP. I would want to create a crop of the video on top and bottom and fill to frame rather than having pillars on the left and right. Just depends from a creative perspective what I want the output to be. The only solution I can think of right now would be to re-encode the video before running through the CLI for dcp-o-matic, but I feel like that is a bit excessive for a small crop.

The way the DCP-o-matic GUI approaches this is that if you crop the black parts off your source image, everything else should be taken care of. Auto-crop should work for this, or I could also add --crop-left, --crop-right etc. so with a 3840x2160 (1.78:1) source has black top and bottom you could say

--container-ratio 239 --crop-top 276 --crop-bottom 276

Or maybe better would be something "automatic" like --crop-for-source-ratio 185 --container-ratio 239.

Any thoughts?