add Lua script example for vamp onset analysis

1 files changed, 82 insertions, 0 deletions

diff --git a/scripts/_vamp_onset_example.lua b/scripts/_vamp_onset_example.lua
new file mode 100644
index 0000000000..56e5903a53
--- /dev/null
+++ b/scripts/_vamp_onset_example.lua
@@ -0,0 +1,82 @@
+ardour { ["type"] = "Snippet", name = "Vamp Onset Detection Example" }
+
+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 a Vamp Plugin
+	-- see http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:LuaAPI:Vamp
+	--
+	-- here: the "Queen Mary Note Onset Detector" Vamp plugin (which comes with Ardour)
+	-- http://vamp-plugins.org/plugin-doc/qm-vamp-plugins.html#qm-onsetdetector
+	local vamp = ARDOUR.LuaAPI.Vamp("libardourvampplugins:qm-onsetdetector", Session:nominal_frame_rate())
+
+	-- prepare table to hold results
+	local onsets = {}
+
+	-- 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)
+		onsets[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: Detected note onset times
+			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)
+						--print ("-", f.timestamp:toString(), fn)
+						table.insert (onsets[r:name ()],  fn)
+					end
+				end
+			end
+		end
+
+		-- Configure Vamp plugin
+		--
+		-- One could query the Parameter and Program List:
+		--   http://manual.ardour.org/lua-scripting/class_reference/#Vamp:Plugin
+		-- but since the Plugin is known, we can directly refer to the plugin doc:
+		-- http://vamp-plugins.org/plugin-doc/qm-vamp-plugins.html#qm-onsetdetector
+		vamp:plugin ():setParameter ("dftype", 3);
+		vamp:plugin ():setParameter ("sensitivity", 50);
+		vamp:plugin ():setParameter ("whiten", 0);
+		-- in this case the above (3, 50, 0) is equivalent to
+		--vamp:plugin ():selectProgram ("General purpose");
+
+		-- run the plugin, analyze the first channel of the audio-region
+		--
+		-- This uses a "high-level" convenience wrapper provided by Ardour
+		-- which reads raw audio-data from the region and and calls
+		--     f = vamp:plugin ():process (); callback (f)
+		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 n,o in pairs(onsets) do
+		print ("Onset analysis for region:", n)
+		for _,t in ipairs(o) do
+			print ("-", t)
+		end
+	end
+
+end end