Can I sync "stars" for my music between devices without a server?
Maybe using Syncthing or MPD? I'm searching something to keep/share my votes or even maybe listen counts for desktop and mobile. Also it would be nice to create a backup for these data.
Stars in what? In a specific app, or in file metadata? If it's metadata, syncthing will be fine.
I'm already a Syncthing fan but I haven't found an Android app capable to rate tracks editing the tag.
Depending on which format your music is in you can store a star rating in the metadata of the file.
I'm using flacs and MusicBrainz to manage my collection. So should I edit my tags with Picard?
Yes, Picard should be able to add the tag, flac support is great
The problem with this solution is to find an Android player capable to read/rate the tag
Resilio sync works really well for my music collection to sync all the ratings. Using musicbee can also make autoplaylists to create playlist files for any app which might not support the ratings fully. You technically don't need servers but it's best to have some device always online. I haven't preferred syncthing, just doesn't work as cleanly I find.
I haven't found a completely cross platform listen counting method, but there're some plugins on musicbee to do CSV play recodlrding!
Thanks for your tips. The smartphone is a good "always on device" for my Syncthing serverless setup. Edit: wait, resilio looks like syncthing but worse.