My Networkbridge is connected to my iMac via UPnP and I can see my whole iTunes library on my Android Mosaic app. (I prefer “folder View”). However at least 75% of the albums are missing their artwork, yet the artwork is there in iTunes on my iMac. e.g. if I select “Get Info.” on an album track (in iTunes) and then scroll through each track, I can see the artwork. However there is none when I view on Mosaic. I have added new artwork to some albums on iTunes, done “Rescan” on MinimServer and the artwork then appears on Mosaic. But it’s going to take a very long and frustrating time if I have to find and reload all my iTunes artwork! I’ve Googled various topics on “refreshing iTunes album artwork” but these all seem to relate to iTunes itself not showing the artwork; not that a receiving app. doesn’t see it. Thanks in advance for any help.
Hi Simon,
UPnP servers will either pull the cover art image data from the track tags (if the track tags include cover art image data) or if they don’t then they’ll usually look for a cover.jpg, folder.jpg or other . file in the album directory and use that.
iTunes however is a bit of a law unto itself as to how it holds its data and it doesn’t generally add cover art images to tracks that don’t have cover art images and it doesn’t put cover art images into the album folders.
What you really need to do is use a Tag Editor to check to see what information is actually contained in the track tags and add cover art images to the tagging if necessary - unfortunately Macs are REALLY poorly served with tag editor software. My goto app is a program called MP3Tag but unfortunately that’s Windows only.
Phil
Hi Phil,
MP3Tag is available for Macs now, it’s in the Mac App Store.
By the way, thanks for all your great contributions here.
David
Ahhhhh is it now … that’s excellent news and good to know! (I’m mainly a Windows person - I do have a Mac somewhere though…)
It’s not the easiest program in the world to get into but once you get the hang of it it is such a powerful tagging tool. Basically it just gives you a big table of everything you pointed it at (whether that’s 15 files from a single album or thousands of files from a complete collection of music) and you can simply edit and fill in the blanks to your hearts content and then shove all those edits back in to the files in one hit. It’s definitely well worth the effort of getting into.
Well, thank you so very much for the thank you… 
I’ve not been here long (well, this time at least, but this is my second time at dCS, I was here very briefly in 2019) and I really hope that I can maintain the dCS reputation, you can have no idea just how wonderful these guys are here and how much of a pleasure it is to work with them…!
Phil
Phil thanks so much for your detailed reply, and David for the news on MP3Tag. It certainly gives me something to investigate further (Tag editing is a whole new experience!). I’m still not 100% sure what I need to do (using an editor may make it clearer) but in very basic terms it seems to me that iTunes is putting the cover art somewhere in the song (.m4a) file (because I can see it in iTunes and on my iPod). iTunes is obviously(?) inconsistent in that it may not put the artwork in the same place for each song, or even not putting it in some songs - there seems to be no such thing as an album artwork as there is no file that is an album; may be one issue with Mosaic is that if it doesn’t see the (same) artwork in all song files that constitute the album, then it doesn’t show anything. I have certainly found albums on Mosaic where no artwork is shown for the album or songs, and when delving into iTunes I see that 8 out of 10 tracks have the same artwork and 2 either have no, or different artwork, for example (only Apple knows how this can happen!).
When I re-add artwork to an album on iTunes, and check to see it is there for all songs, Mosaic does then show this artwork. I hope this is then a permanent fix for that album and the artwork won’t go walkies! So back to the original matter of editing the Tag data - I assume the aim is to have the same artwork in the same place for all songs in an album (which is effectively what I’m doing when I re-add the artwork via iTunes)?
If Tag editing means I still have to drag a .jpg file into a place-holder in the song file, then it’s not going to be a lot quicker (or any less frustrating) than doing it the iTunes “add artwork” way. However I can see that having an editor would be great reassurance to view the tags/file to prove it is 100% correct.
I’ll certainly take a look at available editors and any other info on this subject matter (I did see that MP3Tag was £18 in the App Store so I’d like to be sure it will do exactly what I need.).
Thanks again.
Yes, you will end up needing to highlight all the songs of an album, select the cover art image that you want to add to those files and then hit “save” and it will insert the cover art directly into the file tags…
One thing that is really handy is pointing it at a block of files and then just browsing the table that it produces to look for any unpopulated fields that might be batter filled in.
For what it does, even though I only use MP3Tag a few times a year (and assuming that it is the same program) I’d pay £18 for it…
Phil
Thanks again Phil. I downloaded a free Tag Editor app that reads the files and puts them in a spread-sheet so you can see/edit the tags. It’s probably pretty basic but it did prove the problem; with a problem song/album, the Artwork tag field was empty. But surprisingly when you do “preview” the app will show the album artwork, so it’s obviously hidden in the file somewhere, but not in the correct tag field. As you say, it’s relatively easy to load a block of files and drag the artwork file into the correct tag field, and re-save. In that the effort is mainly in retrieving the artwork from the web (as the app doesn’t find it for you), then doing it the iTunes way is just as easy. I did this and re-opened the app. to verify the artwork was now in the correct tag field, and it was. I guess over time with all the OS upgrades, etc. iTunes has misplaced the artwork, and since my iMac is end of life so far as OS upgrades are concerned, hopefully sorting this out will be the last time I need to do it.
Thanks again for your help.
Simon
Hi Simon,
Basically iTunes holds data in its own databases rather than inserting it into the files (as obviously that would make the files more usable to programs other than iTunes) but of course MinimServer cannot / does not access that data so that’s why it is important to get the tagging right … 
Phil
As a Mac user, I’ve tried mp3tag but the interface is too hierarchic and Windows-y for me. I struggle to navigate in that app. I’m a fervent user of another well-known and much more Mac-like ID tag editor, Yate…
Heartily recommended. And, it can do Internet searches for you in multiple databases such as Discogs, MusicBrainz and more.
Great to know about Yate … thank you!
Phil
Another vote for Yate. Both the software and the support from its developer are first rate.
Thanks to you all for these valuable contributions. I certainly have lots to get stuck into now! By the way,I’d be glad to hear any other (i)Mac experiences you have had or problems you’ve overcome. I’ve ripped all my CDs using my iMac drive, into iTunes in ALAC format, and am running MinimServer on the iMac to present these files to my Network Bridge. It all seems to work fine and sounds pretty good to me (beats by CD playing). I started using XLD to rip the CDs into FLAC but gave up when I couldn’t hear any difference 
and like the Apple/iTunes interface (or am just too familiar with it to change!).