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livetrax/scripts/_midi_lfo.lua

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2016-11-21 15:24:11 -05:00
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