Is this a good idea?
Would it be useful to have the option of specifying a key signature to be used in chord recognition?
Currently, chord recognition on all arranger keyboards (AFAIK) is ignorant of key. Thus, if you play a base line c-d-e-f-g you get a progression of major chords. But wouldn't Cmaj-Dm-Em-Fmaj-Gmaj be more useful sometimes.
Sheet music provides for a key signature at the beginning of a piece. Why not let us specify a key signature for a piece that affects chord recognition? Thus, if I specify C-major key, the base line c-d-e-f-g would result in Cmaj-Dm-Em-Fmaj-Gmaj.
Currently, it is easy to force a minor chord using two fingers. But it is a lot easier playing a one finger base line than a two finger base line. Also, you might prefer the sound of the one-finger base line.
Also, if you play a wind controller, you can only input a melody. It would be nice to play a melody into an arranger and have it generate a harmonically correct accompaniment. This not easily achieved with the keyless chord recognition schemes. But if you could specify a key (e.g., Eb), you could get a useful harmony. This would apply to other sources of melodic input such as pitch-to-MIDI conversion of voice or wind instruments. (Note that vocal harmonizers do allow key to be specified.)
Also, many of the chord recognitions that seem to come up with the wrong chord recognition might be fixed by adding the option of specifying a key signature.