I'd like to be able to adjust the frequencies that MIDI uses for notes, rther than depend on the default equal temperament.
Most non-western music is not equal-tempered, and even Western music before 1720 or so did not use equal temperament.
There is some discussion about what Bach meant by "well-tempered". It is likely that he did not mean equal temperament, and there are organs built in his lifetime (whicn he may have played) that use a different temperament.

From what I understand of the specification, it is possible to change the temperament in MIDI, but I can't see how to do it.

Of course MIDI itself is a bit antiquated (like ASCII vs Unicode), since it cannot differentiate between G# and Ab, for example.

Any help would be appreciated, even to the point of writing c code. (I'm on Mac OS X, and have some familiarity with Xcode and c programming.)

Thanks.