Example convolution plugin (Lua script, hardcoded IR)

scripts/_convolv.lua

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+ardour { ["type"] = "dsp", name = "Lua Convolver", license = "MIT", author = "Ardour Lua Task Force", description = [[Another simple DSP example]] }
+
+function dsp_ioconfig () return
+	{
+		{ audio_in = 1, audio_out = 1},
+		{ audio_in = 1, audio_out = 2},
+		{ audio_in = 2, audio_out = 2},
+	}
+end
+
+local conv, mode, ir_file
+
+ir_file = "/tmp/reverbs/St Nicolaes Church.wav"
+ir_file = "/tmp/reverbs/Large Wide Echo Hall.wav"
+
+function dsp_configure (ins, outs)
+	if outs:n_audio() == 1 then
+		assert (ins:n_audio() == 1)
+		mode = ARDOUR.DSP.IRChannelConfig.Mono
+	elseif ins:n_audio() == 1 then
+		assert (outs:n_audio() == 2)
+		mode = ARDOUR.DSP.IRChannelConfig.MonoToStereo
+	else
+		assert (ins:n_audio() == 2)
+		assert (outs:n_audio() == 2)
+		mode = ARDOUR.DSP.IRChannelConfig.Stereo
+	end
+
+	conv = ARDOUR.DSP.Convolver (Session, ir_file, mode, 0)
+	collectgarbage ()
+end
+
+function dsp_latency ()
+	if conv then
+		return conv:latency()
+	else
+		return 0
+	end
+end
+
+-- the DSP callback function to process audio audio
+-- "ins" and "outs" are http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray
+function dsp_run (ins, outs, n_samples)
+	assert (#ins <= #outs)
+
+	for c = 1, #ins do
+		if ins[c] ~= outs[c] then -- if processing is not in-place..
+			ARDOUR.DSP.copy_vector (outs[c], ins[c], n_samples) -- ..copy data from input to output.
+		end
+	end
+
+	if #outs == 1 then
+		conv:run (outs[1], n_samples)
+	else
+		conv:run_stereo (outs[1], outs[2], n_samples)
+	end
+end