In the meantime I have installed VirtualDJ and found a solution for exact this situation:
a) You can set the rating in stars in VirtualDJ.
b) You can see the same stars in Mp3tag.
c) You can NOT set unicode stars in Mp3tag, but you can set the numeric value. This will be reflected in VirtualDJ.
-> Please see the Addendum how to enter rating stars
* directly in the File List.
I have not tested MediaMonkey, Windows File Explorer, Tag&Rename, iTunes or other software. If you need support for these, please ask in the MM-/Microsoft-/Tag&Rename/Apple-Forum.
Solution for VirtualDJ and Mp3tag, step-by-step:
(tested with vinstall_virtualdj_2023_b7482_pc and Mp3tag v3.19b)
1.) You have to be aware the following VirtualDJ behaviour:
2.) You have to set the tags settings in VirtualDJ like this:
If you don't set getTagsAuto
you can not interchange the rating between VirtualDJ and Mp3tag.
3.) You can add a new column in Mp3tag with this Value:
This adjusted Value reflects the way VirtualDJ writes it's rating into the tag POPULARIMETER:
It seems, that VirtualDJ only writes
4.) The final result in Mp3tag looks like this:
If you want to change the ratings in Mp3tag, you have to set the POPULARIMETER values as numbers, not as stars. You can enter them directly in the POPULARIMETER column (or in a Tag Panel field %popularimeter% you could also add).
These numbers are 1 for 1 Star, 64 for 2 stars, 128 for 3 stars, 196 for 4 stars and 255 for 5 stars.
5.) The very unusual problem lies inside VirtualDJ:
As you know from point 1.) VirtualDJ will only read the tags ONCE into its database. Every later change outside VirtualDJ will not be re-imported automatically in its database!
If you want to "refresh" the VirtualDJ database, the only way I found is to (slighty) change the filename and reimport this file into VirtualDJ.
You have to ask in the VirtualDJ-Forum, why this current behaviour should be the preferred one.
Corrigendum 13.03.2023, 15.30 Uhr:
I eventually found a workaround to "reload" the tags in VirtualDJ without changing the filename.
It seems that selecting the changed tracks in VirtualDJ and right click on them, selecting the context menu
Batch -> Reload tags
does exactly that: Reloading the externally changed tags.