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        MIDI-OX >> Scripting Questions >> Midiox script to map expression pedal to kick drum
        
(Message started by: PenguiN42 on Jan 23^rd, 2011, 4:53am)

Title: Midiox script to map expression pedal to kick drum
Post by PenguiN42 on Jan 23^rd, 2011, 4:53am

So I've found a few utilities out there that map the sustain pedal to a kick drum hit, but the problem with that is you don't have any velocity control.

So I thought -- wouldn't it be cool to use a volume or expression pedal and deduce the velocity from that, and make a MIDI kick drum out of it?

Below is a VBscript for midi-ox that does just this. Feel free to use and abuse it! I tested it with a Roland EV-5 through an m-audio Axiom 61 into Cakewalk's Session Drummer 3 and it felt pretty good (other than the lack of spring action in the pedal). Here's a test track I recorded with it http://soundcloud.com/ken-taylor/drum-gtr-test-012211

And here's the code:

(Edit: I should probably mention that the code in its current form is very dependent on the rate at which your midi device sends controller updates. I originally tried to make it independent by using timestamps, but that wasn't consistent enough in my tests, so I just put in a fudge factor instead that assumes the device is sending at a constant rate. You can see the commented out timestamp-lasttime and lasttime-lasttime2 in the code below)

' For use with MIDI-OX ' Translates expression pedal hits into bass drum hits with velocity info option explicit dim thresh, in_ctrl, out_note dim v_in_min, v_in_max dim v_out_min, v_out_max dim nonlin thresh = &H50 in_ctrl = 11 out_note = 36 v_in_min = 0 v_in_max = 3.5 v_out_min = 0 v_out_max = &H7F nonlin = 0.7 dim lasttime, lastpos, lasttime2, lastpos2 dim mox lasttime = 0 lastpos = 0 lasttime2 = 0 lastpos2 = 0 ' Create object Set mox = WScript.CreateObject("MIDIOX.MOXScript.1", "OnTrigger_") mox.DivertMidiInput = 1 ' when set, routes all data mox.FireMidiInput = 1 ' begins input Do While mox.ShouldExitScript = 0 WScript.sleep(1) Loop mox.FireMidiInput = 0 ' stops MIDI input mox.DivertMidiInput = 0 ' ----------------------------------------------------------- ' This is the function that gets called by MIDI-OX Sub OnTrigger_MidiInput( timestamp, port, status, dat1, dat2) dim vel_in1, vel_in2, vel_in, vel_out if status = &HB0 and dat1 = in_ctrl then if (lastpos < thresh) and (dat2 >= thresh) then vel_in1 = (dat2-lastpos)/20 '(timestamp-lasttime) vel_in2 = (lastpos-lastpos2)/20 '/(lasttime-lasttime2) if (vel_in1 > vel_in2) then vel_in = vel_in1 else vel_in = vel_in2 end if 'vel_in = (vel_in1+vel_in2)/2 vel_in = ((vel_in-v_in_min)^nonlin)/((v_in_max-v_in_min)^nonlin) _ *(v_in_max-v_in_min) + v_in_min 'MsgBox("threshold crossed, vel = " & vel_in) vel_out = ((vel_in-v_in_min)/(v_in_max-v_in_min))*(v_out_max-v_out_min)+v_out_min 'MsgBox("out vel = " & Int(vel_out)) 'MsgBox("status = " & status) if(vel_out > v_out_max) then vel_out = v_out_max end if if(vel_out < v_out_min) then vel_out = v_out_min end if mox.OutputMidiMsg -1, &H90, out_note, Int(vel_out) mox.OutputMidiMsg -1, &H90, out_note, 0 end if lastpos2 = lastpos lasttime2 = lasttime lastpos = dat2 lasttime = timestamp else ' ship it right back mox.OutputMidiMsg -1, status, dat1, dat2 end if End Sub