Lua Amplifier plugin with gain-coeff ratio controls

share/scripts/_amp_coefficient_ratio.lua

@@ -0,0 +1,48 @@
+ardour {
+	["type"]    = "dsp",
+	name        = "a-Gain Ratio",
+	category    = "Amplifier",
+	license     = "MIT",
+	author      = "Ardour Team",
+	description = [[Multichannel amplifier with gain coefficient ratio (not dezippered). Beware this plugin allows for significant gain ratios, it's intended to academic purposes.]]
+}
+
+function dsp_ioconfig ()
+	return
+	{
+		-- -1, -1 = any number of channels as long as input and output count matches
+		{ audio_in = -1, audio_out = -1},
+	}
+end
+
+function dsp_params ()
+	return
+	{
+		{ ["type"] = "input", name = "Gain Coefficient numerator", min = 0, max = 1048576, default = 1, unit="", logarithmic = true},
+		{ ["type"] = "input", name = "Gain coefficient denominator", min = 1, max = 1048576, default = 1, unit="", logarithmic = true},
+	}
+end
+
+local sr = 48000
+local cur_gain = 0.0
+
+function dsp_init (rate)
+	sr = rate
+end
+
+function dsp_configure (ins, outs)
+	n_out   = outs
+	n_audio = outs:n_audio ()
+end
+
+function dsp_runmap (bufs, in_map, out_map, n_samples, offset)
+	local ctrl = CtrlPorts:array()
+	local gain = ctrl[1] / ctrl[2]
+	ARDOUR.DSP.process_map (bufs, n_out, in_map, out_map, n_samples, offset)
+	for c = 1, n_audio do
+		local ob = out_map:get (ARDOUR.DataType ("audio"), c - 1); -- get id of mapped output buffer for given cannel
+		if (ob ~= ARDOUR.ChanMapping.Invalid) then
+			bufs:get_audio (ob):apply_gain (gain, n_samples);
+		end
+	end
+end