I have two clients drawing files from my PC via UPnP --- a Kindle Fire HDX and a Grace Digital Primo network player. I also have three server packages running on that machine --- WMP, UMS, and fb2k.
The Primo and Fire HDX see all three servers and can connect with all of them. But for some reason the Primo will not display cover art for songs retrieved via fb2k's UPnP plugin. For any song played, it reports "Artwork not provided." When connected via WMP or UMS, the Primo displays the cover art. All three servers are sending the same files, of course.
The Primo will only display cover art embedded in the files (these are all FLAC or WAV files, not mp3s). The cover art IS embedded in those files, which I've confirmed with a hex editor. The checkbox in the UPnP plugin setup screen for "Allow album art streaming" is checked.
The Fire HDX, on the other hand, does display art for files sent by fb2k. So the plugin is sending the artwork. But somehow it is handling it differently from the other two servers --- a difference that makes it invisible to the Primo.
Each album folder also contains a cover image for the album named "cover.jpg." I know that if a file has no art embedded, foobar will search the folder for an image. I thought perhaps foobar was sending that image to the clients, and confusing the Primo (which will not display external art). So I renamed those "cover.jpg" files for a couple of albums --- one with embedded art, one without, so that fb2k cannot recognize them as image files. The files with no embedded art now show no cover art on the Fire HDX, the files with embedded art do. So fb2k is streaming the embedded art. But it is streaming it in some way that the Primo cannot recognize.
Anyone have any idea what might be the difference between the way that the fb2k plugin streams artwork and the way other players do it?
PS: That Grace Digital Primo is a very cool little streamer. It's wifi connection is rock-solid and the interface and color display make it easy to navigate a large music library. And it's cheap --- about $120 at Amazon.