Bongo should be able to extract metadata from tags embedded in files (ID3 tags, Ogg tags, etc.).

EMMS does this asynchronuously, to avoid taking forever to load tags from files as they are inserted.  Bongo already takes forever to extract metadata from file names as files are inserted, but I expect that extracting tags is going to take a lot more forever, so we will want to consider doing it asynchronously as well.

What are some good tools that we can use for extracting metadata from tags?  Romain suggested ‘ogginfo’ and ‘mpginfo’ (from the ‘mpgtx’ package in Debian).  It would be nice if we could use a tool for some library that aims to be able to read all kinds of tags.  I think the greatest common divisor of tags will be enough for our purposes: artist name, album year, album title, track index, track title.  At least I hope those are part of the GCD.