(note: throughout this post, MIDI-related numbers start from 1, eg. 1-128 patches, 1-16 channels)
GM (and, IIRC, GS and XG) MIDI defines percussion as channel 10 and defines about six of the 128 possible patches as fully defined kits. If you have a MIDI sequence that isn't using channel 10 for percussion but the note events map one-to-one to a GM percussion kit, depending on your editor it should be trivial to hand edit the track in question by switching the track's channel to 10, selecting all the events matching the original drum note (eg, if your MIDI mapper has note 60/C4 as an acoustic snare, select all the C4 notes of the track), and transposing to the appropriate MIDI pitch (in the case of the above acoustic snare, 38/C#2 on patch 1).
I unfortunately don't know off the top of my head an app that automatically does this for you, but it sounds like a good programming exercise for me in the future! Please let us know what MIDIs you have that don't conform to GM standard and what standard they instead use, thanks!
|