· I would add the url and mimetype in the cto, plugins should not be able to change it anyway. · Documentation needs improvement, specially ExtractionResult (making it clear that you should inherit it in order to use the lib). · ExtratorPlugin::mimetypes is pure virtual yet it has an implementation · Add context to i18n in typeinfo Also you might want to use Qt translation libs so kfilemetadata becomes a Qt only lib, that might help other desktops/apps to use it (in kf5 you can use k18n if you want).
Once this is fix, yo get +1 from me !