Computing flow from a given frame range

[AntonioMarsella]

Hi Will,

thank you for the awesome work!

I have to create optical flow from specific clips in a video. It would be great if it was possible to add the initial and final frames/times of the video we want to generate OF from.

Is it something already possible? I tried to dig into the code but I got a bit lost. In flowty/src/flowty/cv/videoio.pyx in the class VideoSource there is pos_frames(self) that I think it's what I need to use, but I don't know how to make it accessible with a command line.

Thank you very much!