I'm in the same boat as Jack and Gianni. I have the following filesystem folder structure on my DNS-323:
/media
/video - contains only video files (500 files currently)
/pictures - contains only image filese (16,000 files currently)
/music - contains only audio files (15,000 files currently)
If I set my UPnP base folder to /media, I see the following when browsing via my Xbox 360. I'm noting in brackets which device I believe is generating each item:
Video Library (Xbox 360)
-> All_Folders (DNS-323 UPnP AV Server)
-> This option takes a very long time to produce any results, and most of the time never produces any results.
-> Folders (DNS-323 UPnP AV Server)
-> video (filesystem)
-> This now contains all of the real sub-directories under /media/video on my DNS-323
-> pictures (filesystem)
-> This now contains all of the real sub-directories under /media/pictures on my DNS-323, which of course doesn't produce any files since there are no real video files stored under here.
-> music (filesystem)
-> This now contains all of the real sub-directories under /media/music on my DNS-323, which of course doesn't produce any files since there are no real video files stored under here.
If I want to look at pictures, I do the following on my Xbox:
Picture Library (Xbox 360)
-> All_Folders (DNS-323 UPnP AV Server)
-> Again, this takes a very long time to produce any files, if ever. On several occasions I have left it searching for over an hour with no luck.
-> Folders (DNS-323 UPnP AV Server)
-> This shows the same filesystem folders as above, but rarely displays any files. It just spins the little hourglass icon thing, apparently searching for files.
I get the same behaviour for Music Library (Xbox 360) as I do for the Picture Library.
Basically, I think I have too many files for the DNS-323's UPnP AV Server to handle. It takes around an hour to refresh the UPnP index via the admin website, which is ridiculous. And once the index is built, the DNS-323 doesn't seem to be able to search it and return results to the Xbox 360 in any reasonable amount of time. I've tried to find logs for the UPnP AV Server, but they're severely lacking - all I can get is console output if I run the UPnP AV Server manually from a shell.
What I think Jack, Gianni, and I are looking for is a UPnP AV Server that acts exactly like Samba/CIFS. It serves up the underlying filesystem, and maybe filters out files whose media type/filename don't match the current media category being browsed. No indexing, no searching. Our media files are already organized and we know exactly where everything is - we don't need a (poorly designed/implemented?) layer between our renderers/clients and our media files. Maybe the UPnP AV Server is implemented just fine and it's the DNS-323 that is merely underpowered - perhaps it simply cannot handle more than a few hundred files. That would be unfortunate, since the whole point of the box is to store your ever expanding media collection.
Maybe this is a feature we'll see in the v1.10 firmware (if that ever sees the light of day), or maybe it is something the community can add to Alt-F. Until then, I basically cannot use the DNS-323's UPnP AV feature to look at any of my pictures or listen to my music. The videos work pretty well, but only when I set the UPnP base to /media/video (which drastically shrinks the index size).
Frown.
Of course, maybe my problems are all or mostly related to the Xbox 360's UPnP client implementation. I've tried setting up Fuppes in the past, and I never managed to get it configured to speak/understand the Xbox's particular (broken AFAIK) flavour of UPnP AV.
If anyone out there as an Xbox 360 and a DNS-323 behaving nicely together with tens-of-thousands of media files being indexed, _please_ let me know how you managed it

-Paul