prefix no-inst script with an underscore and skip install

scripts/_amp3.lua

@@ -0,0 +1,44 @@
+ardour {
+	["type"]    = "dsp",
+	name        = "Simple Amp III",
+	category    = "Example",
+	license     = "MIT",
+	author      = "Ardour Lua Task Force",
+	description = [[
+	An Example DSP Plugin for processing audio, to
+	be used with Ardour's Lua scripting facility.]]
+}
+
+function dsp_ioconfig ()
+	return
+	{
+		{ audio_in = -1, audio_out = -1},
+	}
+end
+
+
+function dsp_params ()
+	return
+	{
+		{ ["type"] = "input", name = "Gain", min = -20, max = 20, default = 6, unit="dB", scalepoints = { ["0"] = 0, ["twice as loud"] = 6 , ["half as loud"] = -6 } },
+	}
+end
+
+
+-- use ardour's vectorized functions
+--
+-- This is as efficient as Ardour doing it itself in C++
+-- Lua function overhead is negligible
+--
+-- this also exemplifies the /simpler/ way of delegating the
+-- channel-mapping to ardour.
+
+function dsp_run (ins, outs, n_samples)
+	local ctrl = CtrlPorts:array() -- get control port array (read/write)
+	local gain = ARDOUR.DSP.dB_to_coefficient (ctrl[1])
+	assert (#ins == #outs) -- ensure that we can run in-place (channel count matches)
+	for c = 1,#ins do
+		assert (ins[c]:sameinstance(outs[c])) -- check in-place
+		ARDOUR.DSP.apply_gain_to_buffer (ins[c], n_samples, gain); -- process in-place
+	end
+end