Lua example script: fix some typos and add some comments

diff --git a/scripts/voice_activate.lua b/scripts/voice_activate.lua
index eb9ef962f068b44e1b7120b98e4b5190cda2c830..bf2107107563e7188e572c758c99f911833a9a71 100644 (file)
--- 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