Convert selectively (e.g only FLAC files)

Given a selection of files, it should be possible to only convert FLAC files from that selection, simply based on the suffix. This can be worked around on the user side by manually moving all FLAC files into a specific folder but this is an unintuitive, time-consuming process.

Generally, a feature that allows users to specify which filetypes they want converted

EDIT: Actually scratch this, I've just realised you can select FLAC files from the file manager dialog (Nautilus / GNOME Files)