Capturing frames of a specific window

[arncore]

I've been trying to figure out how to capture a frame of a specific window and I'm stuck so I would appreciate some guidance. I cant seem to understand how the ffmpeg-rs supports that use case. In ffmpeg cmdline the "title" input option instructs ffmpeg to look for a window with a certain title and consider that as input. However, the ffmpeg-rs API requires a specific input path which, from my experiments, seems to override that input option and just record the whole display or displays instead.

I tried to open a discussion but the link is dead. Sorry if this is not the right place. Any help is appreciated. Thanks.