Support key detection analyzers

[Jeremy Salwen]

I'm not sure how to report this as a wishlist bug, because obviously it's not a defect, but it would be very nice if mixxx implemented chord/ key detection to allow harmonic mixing (mixxxing). The tools provided by CLAM/ Chordata (http://clam-project.org/ http://clam-project.org/wiki/Chordata_tutorial ) would be perfect and seem to be very effective at their job. I'm not sure how much effort it would take to integrate it into mixxx, but it seems that at least a basic "key" field could be added in the database if you pass the song through CLAM

[RJ Skerry-Ryan (rryan)]

Definitely agree, actually some people already worked on building a CLAM-based key analyzer, you can find it in the source code under mixxx/src/tonal. It's basically a wholesale copy of some of the key-related stuff from the CLAM codebase.

I think you can build that experimental code with the scons build flag 'tonal=1'.

Once the analyzer is done, the library integration would be, as you said, adding a key column to the database (see the SQL manifest mixxx/res/schema.xml) and the various library code would need to be updated to show it, etc.

Another useful thing would be being able to recognize some key metadata tags from other popular harmonic software like Mixed in Key, etc.

[jus (jus)]

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

[RJ Skerry-Ryan (rryan)]

Support for VAMP key detectors is now in master. We need to add keyfinder. QM KeyDetect is already in.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/5481