MIDI LFO generator plugin

diff --git a/scripts/_midi_lfo.lua b/scripts/_midi_lfo.lua
new file mode 100644 (file)
index 0000000..fd8b2b0
--- /dev/null
+++ b/scripts/_midi_lfo.lua
@@ -0,0 +1,74 @@
+ardour {
+       ["type"]    = "dsp",
+       name        = "MIDI LFO",
+       category    = "Example", -- Utility
+       license     = "MIT",
+       author      = "Ardour Lua Task Force",
+       description = [[MIDI CC LFO Example -- Triangle full scale CC Parameter automation]]
+}
+
+function dsp_ioconfig ()
+       return { { midi_in = 1, midi_out = 1, audio_in = 0, audio_out = 0}, }
+end
+
+function dsp_params ()
+       return
+       {
+               { ["type"] = "input", name = "BPM", min = 40, max = 200, default = 60, unit="BPM"},
+               { ["type"] = "input", name = "CC",  min = 0, max = 127,  default = 1, integer = true },
+       }
+end
+
+local samplerate
+local time = 0
+local step = 0
+
+function dsp_init (rate)
+       samplerate = rate
+       local bpm = 120
+       spb = rate * 60 / bpm
+end
+
+function dsp_run (_, _, n_samples)
+       assert (type(midiin) == "table")
+       assert (type(midiout) == "table")
+
+       local ctrl = CtrlPorts:array ()
+       local bpm = ctrl[1]
+       local cc  = ctrl[2]
+
+       local spb = samplerate * 60 / bpm -- samples per beat
+       local sps = spb / 254 -- samples per step (0..127..1 = 254 steps)
+
+       assert (sps > 1)
+       local i = 1
+       local m = 1
+
+       for ts = 1, n_samples do
+               time = time + 1
+
+               -- forward incoming midi
+               if i <= #midiin then
+                       while midiin[i]["time"] == ts do
+                               midiout[m] = midiin[i]
+                               i = i + 1
+                               m = m + 1
+                               if i > #midiin then break end
+                       end
+               end
+
+               -- inject LFO events
+               if time >= spb then
+                       local val
+                       if step > 127 then val = 254 - step else val = step end
+
+                       midiout[m] = {}
+                       midiout[m]["time"] = ts
+                       midiout[m]["data"] = { 0xb0, cc, val }
+
+                       m = m + 1
+                       time = time - sps
+                       if step == 253 then step = 0 else step = step + 1 end
+               end
+       end
+end