Add test synth to debug capture alignment

1 files changed, 37 insertions, 0 deletions

diff --git a/scripts/_spike_synth.lua b/scripts/_spike_synth.lua
new file mode 100644
index 0000000000..167e0e27d2
--- /dev/null
+++ b/scripts/_spike_synth.lua
@@ -0,0 +1,37 @@
+ardour {
+	["type"]    = "dsp",
+	name        = "Spike Synth",
+	category    = "Instrument",
+	license     = "MIT",
+	author      = "Ardour Lua Task Force",
+	description = [[A debug and test-instrumentation synth. This plugin is useful with Ardour's "Dummy" backend "Engine-Pulse" mode to verify capture alignment. This plugin generate the exact same audio-signal from MIDI data that the backend also generates: Note-on: +1, Note-off: -1.]]
+}
+
+function dsp_ioconfig ()
+	return { { midi_in = 1, audio_in = 0, audio_out =  1} }
+end
+
+function dsp_run (ins, outs, n_samples)
+	local a = {}
+	for s = 1, n_samples do a[s] = 0 end
+
+	for c = 1,#outs do
+		ARDOUR.DSP.memset (outs[c], 0, n_samples)
+	end
+
+	assert (type(midiin) == "table")
+	for _,b in pairs (midiin) do
+		local t = b["time"] -- t = [ 1 .. n_samples ]
+		local d = b["data"] -- get midi-event
+		if (#d == 3 and (d[1] & 240) == 144) then -- note on
+			for c = 1,#outs do
+				outs[c]:array()[t] = 1.0
+			end
+		end
+		if (#d == 3 and (d[1] & 240) == 128) then -- note off
+			for c = 1,#outs do
+				outs[c]:array()[t] = -1.0
+			end
+		end
+	end
+end