Add script to normalize all tracks

scripts/normalize_all_tracks.lua

@@ -0,0 +1,58 @@
+ardour { ["type"] = "EditorAction",
+	name = "Normalize All Tracks",
+	license     = "MIT",
+	author      = "Ardour Team",
+	description = [[Normalize all regions using a common gain-factor per track.]]
+}
+
+function factory () return function ()
+	-- target values -- TODO: use a LuaDialog.Dialog and ask..
+	local target_peak = -1 --dBFS
+	local target_rms = -18 --dBFS/RMS
+
+	-- prepare undo operation
+	Session:begin_reversible_command ("Normalize Tracks")
+	local add_undo = false -- keep track if something has changed
+
+	-- loop over all tracks in the session
+	for track in Session:get_tracks():iter() do
+		local norm = 0 -- per track gain
+		-- loop over all regions on track
+		for r in track:to_track():playlist():region_list():iter() do
+			-- test if it's an audio region
+			local ar = r:to_audioregion ()
+			if ar:isnil () then goto next end
+
+			local peak = ar:maximum_amplitude (nil)
+			local rms  = ar:rms (nil)
+			-- check if region is silent
+			if (peak > 0) then
+				local f_rms = rms / 10 ^ (.05 * target_rms)
+				local f_peak = peak / 10 ^ (.05 * target_peak)
+				local tg = (f_peak > f_rms) and f_peak or f_rms  -- max (f_peak, f_rms)
+				norm = (tg > norm) and tg or norm -- max (tg, norm)
+			end
+			::next::
+		end
+
+		-- apply same gain to all regions on track
+		if norm > 0 then
+			for r in track:to_track():playlist():region_list():iter() do
+				local ar = r:to_audioregion ()
+				if ar:isnil () then goto skip end
+				ar:to_stateful ():clear_changes ()
+				ar:set_scale_amplitude (1 / norm)
+				add_undo = true
+				::skip::
+			end
+		end
+	end
+
+	-- all done. now commit the combined undo operation
+	if add_undo then
+		-- the 'nil' command here means to use all collected diffs
+		Session:commit_reversible_command (nil)
+	else
+		Session:abort_reversible_command ()
+	end
+end end