Pick coverart from video (nth second dump) while playing back the audio

[zDEFz]

It would be nice to know, how I do that without generating coverart priorly - with tons of files, this would be cool.
Because if we assume second 3 for coverart, if not present, or any other arbitrary value, the UI still shows with UI and the UI is not blank, it shows the video. Unlike --vf=fps=1, here you are meant to only get the audio stream, and one static coverart, to reduce cpu and gpu load.

IS this doable?

[zDEFz]

Just to add, theres a script that helps this by providing at least something going on in the UI when something plays.
https://github.com/mfcc64/mpv-scripts/blob/master/visualizer.lua