Hello,
My movies are organized in separate folders with movie name.
In every folder, there is a subfolder ".actors" wich contains the images of the actors.
This information is -together with the *.nfo file and other artwork- created by MediaElch
http://www.kvibes.de/mediaelch/download/
This tools creates all the necessary information on disk, and can be read by KODI, PLEX, etc...
I succeeded to configure EMBY to read the local *.nfo file, but the artwork for cast & crew r