There are a few these days, but the only one I have
ever used is
aubionotes, from the aubio package.
http://aubio.org/aubionotes.html
Thanks. I didn't know about aubio, though apparently it has been
around for ages.
Setting up aubionotes is very easy. Unfortunately, it doesn't work
quite well enough for me (pitch detection is error-prone). But it is
probably possible to fine-tune the detection parameters by going to
libaubio directly (aubionotes doesn't have too many options to tweak,
and the ones available aren't documented).
How did you use aubionotes? Any special tips?
-- Dan