I've noticed that fingerprint calculation seems to be failing (or at least not used) fairly often due to an fpcalc problem that doesn't seem to be a real problem.

I'm often getting the following error (with rc = 3) from fpcalc (so far mainly noticed on mp3 files):

ERROR: Error decoding audio frame (End of file)

There seems to be no problem at all with the mp3 encoding of these files, as mp3val doesn't see any problems with them.

I think this might be a bug in the underlying ffmpeg libraries that fpcalc seems to be using?

In any case, fingerprinting is often failing even though there is nothing wrong with the source files, and a fingerprint is actually being generated.  Picard is just ignoring the fingerprint (presumably) because fpcalc is returning an error when there isn't actually anything wrong with the source file.