Rough-in an qm-barbeattracker Lua example

scripts/_vamp_tempomap_example.lua

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+ardour { ["type"] = "Snippet", name = "Vamp TempoMap Test" }
+
+function factory () return function ()
+
+	-- get Editor selection
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:Editor
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:Selection
+	local sel = Editor:get_selection ()
+
+	-- Instantiate the QM BarBeat Tracker
+	-- see http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:LuaAPI:Vamp
+	-- http://vamp-plugins.org/plugin-doc/qm-vamp-plugins.html#qm-barbeattracker
+	local vamp = ARDOUR.LuaAPI.Vamp("libardourvampplugins:qm-barbeattracker", Session:nominal_frame_rate())
+
+	-- prepare table to hold results
+	local beats = {}
+	local bars = {}
+
+	-- for each selected region
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:RegionSelection
+	for r in sel.regions:regionlist ():iter () do
+		-- "r" is-a http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:Region
+
+		-- prepare lua table to hold results for the given region (by name)
+		beats[r:name ()] = {}
+		bars[r:name ()] = {}
+
+		-- callback to handle Vamp-Plugin analysis results
+		function callback (feats)
+			-- "feats" is-a http://manual.ardour.org/lua-scripting/class_reference/#Vamp:Plugin:FeatureSet
+
+			-- get the first output. here: Beats, estimated beat locations & beat-number
+			local fl = feats:table()[0]
+			-- "fl" is-a http://manual.ardour.org/lua-scripting/class_reference/#Vamp:Plugin:FeatureList
+			-- which may be empty or not nil
+			if fl then
+				-- iterate over returned features
+				for f in fl:iter () do
+					-- "f" is-a  http://manual.ardour.org/lua-scripting/class_reference/#Vamp:Plugin:Feature
+					if f.hasTimestamp then
+						local fn = Vamp.RealTime.realTime2Frame (f.timestamp, 48000)
+						table.insert (beats[r:name ()], {pos = fn, beat = f.label})
+					end
+				end
+			end
+
+			-- get the 2nd output. here: estimated bar locations
+			local fl = feats:table()[1]
+			if fl then
+				for f in fl:iter () do
+					if f.hasTimestamp then
+						local fn = Vamp.RealTime.realTime2Frame (f.timestamp, 48000)
+						table.insert (bars[r:name ()],  fn)
+					end
+				end
+			end
+		end
+
+		vamp:plugin ():setParameter ("Beats Per Bar", 4); -- TODO ask
+
+		-- run the plugin, analyze the first channel of the audio-region
+		vamp:analyze (r:to_readable (), 0, callback)
+		-- get remaining features (end of analyis)
+		callback (vamp:plugin ():getRemainingFeatures ())
+		-- reset the plugin (prepare for next iteration)
+		vamp:reset ()
+	end
+
+	-- print results (for now)
+	-- TODO: calculate and set tempo-map
+	for n,o in pairs(bars) do
+		print ("Bar analysis for region:", n)
+		for _,t in ipairs(o) do
+			print ("-", t)
+		end
+	end
+	for n,o in pairs(beats) do
+		print ("Beat analysis for region:", n)
+		for _,t in ipairs(o) do
+			print ("-", t['pos'], t['beat'])
+		end
+	end
+
+end end