Is there a way of editing the MPD database direct?

[JST1963]

.... the library numbers 18,000 tracks, and I already have comprehensive metadata stored elsewhere.  So to avoid repeating all the work I've put in over the years I'd like to simply import this existing metadata into MPD's database directly via the usual methods, either direct writing, csv import or whatever.  

The issue here is the lack of information about MPD's database, what format it is, how to see and edit the database direct.  I

You are missing the mpd's format on how it stores the metadata. But we also miss the way your metadata is stored. How is that done? I'm sure you can find some software that converts your metadata into some other format....
J