Album covers for songs without albums are not displayed in the MPRIS notification
Submitted by Piotr Drąg
Covers are embedded in the ID3 tags. Rhythmbox itself displays these fine, but the shell shows a stock image.
Quoting Florian from gnome-shell#81 (comment 77326) :
“The MPRIS specification for the mpris:artUrl metadata documents it as
The location of an image representing the track or album
If Rhythmbox fails to set it for album-less tracks, then it's a Rhythmbox bug. Working around that by poking at the ID3 tags of the file pointed to by xesam:url ourselves sounds like a bad idea ...”