The disappearing discnumbers in Matroska files

[confucius]

Matroska mapping

Thanks for finally having Mp3tag support Matroska files. Matroska is quite a powerful and flexible container, thus a fitting addition to Mp3tag. My question is, what "text" should I input into the "Options > Tags > Mapping" for Matroska? This is the place where after a fresh installation, there are 3 items there, which are all of "VorbisComment". I want to map some Matroska tags but I had no luck. I tried inputting "Matroska", "MKV", and "MKA", but no luck, it just constantly reverts to "ID3v2…

I've gone through the above and I'm still at a loss on how to get "Discnumber" back. Leaving "Use recommended mapping for Matroska video" unticked gets it back, but then the "Album" tag gives me two values as does the "Album Artist" tag. Does this mean I need to use some mapping? If so, what do I use in the three columns? This Mapping – Mp3tag Documentation tells me about the second and third column, but not what to put in the first column!

For now I've gone back to V3.27.

On my old laptop that runs V3.05, everything is in the right place.

So I need an idiots guide to get these things back.

Thanks for reading.

[ohrenkino]

I think that the described phenomenon is described in the thread that you linked:

@RobertM

When you enter DISCNUMBER for MKV with this new v3.28e, the field disappears from view in the tag panel, and the entered value pops up in the TVEPISODE field instead.
If you repeat the process (or if TVEPISODE already has a value), then the TVEPISODE field shows multiple occurrences separated by double backslashes (\), creating multiple T=50 PART_NUMBER tags in the MKV file.
I think this is okay though.

So, you would have to add a field for TVEPISODE.

@confucius

Does this mean I need to use some mapping?

The same thread also says that it is not possible to map anything for Matroska.

[RobertM]

The thing to bear in mind with DISCNUMBER is that it's only an Mp3tag field, not an actual Matroska tag.
Mp3tag's DISCNUMBER field used to be the only way to create a target type value 50 entry PART_NUMBER tag on MKV files.
Since target type value 50 corresponds to episode level information for Matroska video, it makes more sense to use Mp3tag's TVEPISODE field for this.