Lua example script: fix some typos and add some comments

1 files changed, 16 insertions, 9 deletions

diff --git a/scripts/voice_activate.lua b/scripts/voice_activate.lua
index eb9ef962f0..bf21071075 100644
--- a/scripts/voice_activate.lua
+++ b/scripts/voice_activate.lua
@@ -7,12 +7,13 @@ ardour {
 	site        = "http://gareus.org",
 	description = [[
 	An Example Audio Plugin that rolls the transport
-	when the signal level on the plugin's input a given threshold.]]
+	when the signal level on the plugin's input exceeds a given threshold.]]
 }
 
 function dsp_ioconfig ()
 	return
 	{
+		-- support all in/out as long as input port count equals output port count
 		{ audio_in = -1, audio_out = -1},
 	}
 end
@@ -26,24 +27,30 @@ function dsp_params ()
 end
 
 function dsp_configure (ins, outs)
-	n_channels = ins:n_audio();
+	n_channels = ins:n_audio()
 end
 
--- use ardour's vectorized functions
 function dsp_runmap (bufs, in_map, out_map, n_samples, offset)
 	local ctrl = CtrlPorts:array() -- get control port array (read/write)
-	if Session:transport_rolling() then ctrl[2] = -math.huge return end
+
+	if Session:transport_rolling() then
+		-- don't do anything if the transport is already rolling
+		ctrl[2] = -math.huge -- set control output port value
+		return
+	end
+
 	local threshold = 10 ^ (.05 * ctrl[1]) -- dBFS to coefficient
 	local level = -math.huge
+
 	for c = 1,n_channels do
-		local b = in_map:get(ARDOUR.DataType("audio"), c - 1); -- get id of buffer for given cannel
-		if b ~= ARDOUR.ChanMapping.Invalid then
-			local a = ARDOUR.DSP.compute_peak(bufs:get_audio(b):data(offset), n_samples, 0)
+		local b = in_map:get(ARDOUR.DataType("audio"), c - 1) -- get id of audio-buffer for the given channel
+		if b ~= ARDOUR.ChanMapping.Invalid then -- check if channel is mapped
+			local a = ARDOUR.DSP.compute_peak(bufs:get_audio(b):data(offset), n_samples, 0) -- compute digital peak
 			if a > threshold then
 					Session:request_transport_speed(1.0, true)
 			end
-			if a > level then level = a end
+			if a > level then level = a end -- max level of all channels
 		end
 	end
-	ctrl[2] = ARDOUR.DSP.accurate_coefficient_to_dB (level)
+	ctrl[2] = ARDOUR.DSP.accurate_coefficient_to_dB (level) -- set control output port value
 end