Sorry, my bad. I'm new to macos.
They are created during the Collection Creation, but this is normal behaviour by mac os itself.
For all other newbies: https://apple.stackexchange.com/questions/14980/why-are-dot-underscore-files-created-and-how-can-i-avoid-them

Hi,
I just installed SBM Player on my mac.
During the initial Collection of mp3 Files from the give folders, there are files added with the pattern ._<name_of_mp3file.mp3>.
All of them are 4k big.

Is this really generated by the SBM Player App?
What is the reason for this? Is this the Database of the Collection in flat files?

BR Günther