refine lua-script documentation

1 files changed, 13 insertions, 7 deletions

diff --git a/scripts/rawmidi.lua b/scripts/rawmidi.lua
index 73e62ef243..3b1dfb1d68 100644
--- a/scripts/rawmidi.lua
+++ b/scripts/rawmidi.lua
@@ -16,18 +16,24 @@ end
 function dsp_has_midi_input () return true end
 function dsp_has_midi_output () return true end
 
+-- "dsp_runmap" uses Ardour's internal processor API, eqivalent to
+-- 'connect_and_run()". There is no overhead (mapping, translating buffers).
+-- The lua implementation is responsible to map all the buffers directly.
 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
+	-- see http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:ChanMapping
+	local ib = in_map:get (ARDOUR.DataType ("midi"), 0); -- get index of the 1st mapped midi input buffer
+	local ob = in_map:get (ARDOUR.DataType ("midi"), 0); -- get index of the 1st mapped midi output buffer
 	assert (ib ~= ARDOUR.ChanMapping.Invalid);
-	assert (ib == ob);  -- inplace, buffers are identical
+	assert (ib == ob);  -- require inplace, buffers are identical
 
-	local mb = bufs:get_midi (ib)
-	events = mb:table() -- copy event list into lua table
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:MidiBuffer
+	local mb = bufs:get_midi (ib) -- get the mapped buffer
+	events = mb:table () -- copy event list into a lua table
 
+	-- iterate over all midi events
 	for _,e in pairs (events) do
-		-- e is an http://ardourman/lua-scripting/class_reference/#Evoral:MidiEvent
-		--
+		-- e is-a http://manual.ardour.org/lua-scripting/class_reference/#Evoral:MidiEvent
+
 		--print (e:channel())
 	end
 end