Playlist Trouble

[Rasmussen]

MinimServer 0.8.4, Win 7 Enterprise

Problem: Player skips over items in M3U playlists, or fails to play an entire playlist, when served by MinimServer. The same playlists have no problems when served by Asset UPnP. (Playlists, files, and locations are the same.) Tested with several different players and controllers.

The log showed no playlist errors when the library was scanned. However, it does show the following kind of error when attempting to play:

Code:

MinimServer: 0$playlists$*p6$*i61802 isn't a valid object

Example (I added the line numbers, they're not in the original file):

Code:

1 F:\FLAC-LB\1\flac-170\classical\Helmut Walcha\Bach - Das Orgelwerk\01 01 BWV565 - 1 Toccata.flac
[...]
66 F:\FLAC-LB\1\flac-170\classical\Helmut Walcha\Bach - Das Orgelwerk\05 13 BWV574 - Fuga C min Legrenzi.flac
67 F:\FLAC-LB\1\flac-170\classical\Helmut Walcha\Bach - Das Orgelwerk\05 14 BWV579 - Fuga B min Corelli.flac
68 F:\FLAC-LB\1\flac-170\classical\Helmut Walcha\Bach - Das Orgelwerk\06 01 BWV535 - 1 Prelude.flac
69 F:\FLAC-LB\1\flac-170\classical\Helmut Walcha\Bach - Das Orgelwerk\06 02 BWV535 - 2 Fuga.flac
70 F:\FLAC-LB\1\flac-170\classical\Helmut Walcha\Bach - Das Orgelwerk\06 03 BWV578 - Little Fuga G min.flac
[...]
126 F:\FLAC-LB\1\flac-170\classical\Helmut Walcha\Bach - Das Orgelwerk\08 08 BWV552 - 1 Prelude.flac

MinimServer definitely finds the files, because items in the playlists are displayed by tags, e.g., item 1 is displayed as "01. Helmut Walcha - BWV 565 - 1 Toccata". Yet it refuses to stream it and skips to line 66. It streams 66 and 67, skips 68 and 69, and jumps to 70.

Initially, I thought maybe there's a problem with paths containing something like "BWV565 - 1" (space-hyphen-space-digit). But it does play line 126, so that can't be it.

Also, the files themselves are OK, because MinimServer skips them only when attempting to stream from the playlist.

Any suggestions? Thanks.

[simoncn]

The "isn't a valid object" message usually means that the control point's view of the library is out of date from the current state of the server. Depending on how your control point caches browsing information retrieved from the server, you might need to do a MinimServer rescan, refresh the control point's cache from the server, or both.

Is your control point playing directly from the M3U playlist viewed as a UPnP container or from a copy of the playlist that was saved on the control point some time previously?

[Rasmussen]

Two issues.

Rescan: The playlists were modified some time ago. I had issued a rescan command afterwards, but didn't pay any further attention. Tried it again today, and I noticed that the rescan took only 1 minute or less. That wasn't right; I changed startupScan from "true" to "full" and rescanned once more. This seems to have solved the playlist issue.

Cache: I use Kodi when working at the computer. Kodi seems to continue to use the playlist version served by MinimServer before the rescan. Presumably it employs some kind of cache, but I don't know how to clear it. Other controllers use the correct playlist version.

[simoncn]

It shouldn't be necessary to do a full rescan to solve the problem you were having.

If Kodi is saving UPnP object IDs for playlist entries and using them later (for example, after MinimServer has been restarted), this would explain the problem you are seeing. MinimServer increments the UPnP SystemUpdateID variable every time there is a change to object IDs and informs the control point of this change. It is an error for the control point to use cached information after there has been a change to SystemUpdateID. For example, the Naim control point implements the SystemUpdateID protocol to clear its cache when necessary.

It is likely that Asset UPnP uses a different scheme for object IDs that makes a change to these less likely and/or less frequent than with MinimServer. This would mask incorrect caching behaviour by the control point.

Many control points that don't support the SystemUpdateID protocol clear their cache of object IDs when the server restarts. For MinimServer, this would include any Restart or Rescan event. I think this would be sufficient to ensure that MinimServer playlist object IDs remain valid.

The situation gets tricky if the control point is storing playlists in an internal form across a server restart (and a change to SystemUpdateID). The Naim control point attempts to handle this by remembering the browsing sequence to locate each item in the playlist but this doesn't work if the browsing menu selection labels change, which can happen with MinimServer.

[Rasmussen]

(14-11-2017 16:39)simoncn Wrote:  It shouldn't be necessary to do a full rescan to solve the problem you were having.

There was a issue, because all DMCs exhibited the same problem. Some time ago I re-wrote some of the playlist, after which I set Asset to rescan the library. I did the same w/ MinimServer, but it looks like that was a "true" rescan, rather than a "full" rescan. The latter did the trick, and now the playlists are OK in most DMCs. The exceptions are Kodi and, on iOS, Marantz Remote, which still show the same errors. I assume they use some kind of cache, which wasn't cleared by MinimServer restarting. I wish I knew how to clear it...

[simoncn]

There is no reason why a "full" rescan should do anything different from a "true" rescan with regard to the problem you reported about incorrect object IDs. Perhaps there was some other issue (not the "incorrect object ID" problem) and this other issue was fixed by the "full" rescan.

On Kodi and Marantz Remote, are you playing directly from the playlist container that is shown by browsing via "n playlists" from the top-level menu? Or are you playing from some internal client-side form of the playlist that was previously saved by the control point?

[Rasmussen]

(15-11-2017 10:19)simoncn Wrote:  On Kodi and Marantz Remote, are you playing directly from the playlist container that is shown by browsing via "n playlists" from the top-level menu?

Yes.

[simoncn]

I think this means that the control point has saved a copy of the playlist (with out-of-date object IDs) internally and does not request it again from the server when you browse to it via "n playlists". I wonder whether this also happens with other containers or just with a playlist container.

Perhaps you could enable debug logging and do some browsing to observe this. If the control point is issuing a UPnP Browse request when you browse to a container, this would show up in the debug log.

[Rasmussen]

(15-11-2017 13:14)simoncn Wrote:  Perhaps you could enable debug logging and do some browsing to observe this. If the control point is issuing a UPnP Browse request when you browse to a container, this would show up in the debug log.

OK, I'll do that. Do I need to restart MinimServer after changing log level to Debug?

[simoncn]

Any change to the logging level takes effect immediately.