add a raw midi buffer plugin example

scripts/rawmidi.lua

@@ -0,0 +1,33 @@
+ardour {
+	["type"]    = "dsp",
+	name        = "Midi Passthru",
+	category    = "Example",
+	license     = "MIT",
+	author      = "Robin Gareus",
+	email       = "robin@gareus.org",
+	site        = "http://gareus.org",
+	description = [[An Example Midi Passthrough Plugin using raw buffers.]]
+}
+
+function dsp_ioconfig ()
+	return { { audio_in = 0, audio_out = 0}, }
+end
+
+function dsp_has_midi_input () return true end
+function dsp_has_midi_output () return true end
+
+function dsp_runmap (bufs, in_map, out_map, n_samples, offset)
+	local ib = in_map:get(ARDOUR.DataType("midi"), 0); -- get id of input buffer
+	local ob = in_map:get(ARDOUR.DataType("midi"), 0); -- get id of output buffer
+	assert (ib ~= ARDOUR.ChanMapping.Invalid);
+	assert (ib == ob);  -- inplace, buffers are identical
+
+	local mb = bufs:get_midi (ib)
+	events = mb:table() -- copy event list into lua table
+
+	for _,e in pairs (events) do
+		-- e is an http://ardourman/lua-scripting/class_reference/#Evoral:MidiEvent
+		--
+		--print (e:channel())
+	end
+end