In reading the 10/20/04 GPO Update docs I ran across the following:
Solo wind instruments now have "hidden" vibrato control...
Aftertouch = Vibrato Intensity
cc17 = Vibrato Speed Those who do not have aftertouch-sensitive keyboard can assign cc131 to a hardware slider.
I'm confused about this... AFAIA, MIDI cc numbers only go up to 127 (7-bit). Is there a need to assign a 14-bit controller to achieve that cc value? Wait, no, even as I wrote that it doesn't make sense... which cc's would be needed to get the proper equivalent of cc 131 in this case? Nope, something doesn't compute...
Yes. This has been discussed on many threads in the past couple of years. The missing piece of information is "on many popular M-Audio keyboards." These M-Audio keyboards do not have aftertouch so they allow the aftertouch function to be assigned to a hardware slider or knob by using a controller outside of the MIDI spec (cc131.) This is internal to the particular keyboard. The assignment is cc131 but the keyboard actually outputs aftertouch. To the best of my knowledge, this is a practice confined to M-Audio.
(This was a case of "ya think ya know something (like MIDI) like the back of your hand, and then something like this pops up in a manual and...)
OK. Great. This now leads me to two feature requests...
1) an update of that documentation! (I may be a latecomer to GPO, and the doc I read was from Oct. 2004, but AFAIK this is still the latest documentation being offered as an addendeum to the GPO booklet that's enclosed with the DVD's).
2) Of course, aftertouch is a natural way to introduce vibrato, but then again, so is the modwheel, but by now we all know that modwheel has a specific, dedicated function in GPO. So looking to the standard definition for MIDI CC's #76 & 77, they are, respectively, Vibrato Rate and Vibrato Depth! So what's the possibility of adding these standard MIDI CC's to enable vibrato control in GPO? NFN, but I like the occasional bit of vibrato on clarinet and bassoon, to name two. That's what I was going for today when I ran into the CC#131 thing.