I would like to export all ID3 tags (both ID3v1 and ID3v2) in a group of MP3 files as a CSV file or something similar. I currently use Mp3tag for tagging, but its export feature requires that I specify which tags I want to export; I'd simply like to export all tags that exist (and ideally only those that exist) in any of the MP3 files (including user-defined "TXXX" tags). For "APIC" tags storing embedded images, it would be enough to output that the tag exists (or even better, a count of the number of embedded images).
I'm using Microsoft Windows and I'm looking for a freeware solution. I'm happy to use command-line tools (indeed I often prefer them).