Comment 2 for bug 618300

Musical key detection is a feature i would really like to see in Mixxx. Just throwing in some additional resources which may help.

* The Queen Mary plugin we use in lp:~mixxxcontributors/mixxx/features_vamp do include a key estimator as well. Cant say how accurate it is though. There was already some discussion going about using the QM plugin in another bug , see lp:804700
* KeyFinder(GPL) is a promising new open source key detection tool. It supports standard as well as custom notations , e.g. Camelot ® or OK-Notation. Keyfinder seems pretty accurate compared to other products.
* Chromaprint (LGPL) does link to the Musicbrainz DB and may not work offline. Cant say how accurate it is though.

Resources:
The Queen Mary plugin
http://www.vamp-plugins.org/download.html

Keyfinder
http://www.ibrahimshaath.co.uk/keyfinder/
http://www.ibrahimshaath.co.uk/keyfinder/KeyFinder.pdf

Chromaprint
http://acoustid.org/chromaprint

Detection comparisons
http://www.djtechtools.com/2012/01/26/key-detection-software-showdown-2012-edition/
http://ibrahimshaath.co.uk/keyfinder/comparison.pdf