1 files changed, 74 insertions, 0 deletions
diff --git a/share/scripts/_find_nonzero_sample.lua b/share/scripts/_find_nonzero_sample.lua
new file mode 100644
index 0000000000..c23d2b0b4d
--- /dev/null
+++ b/share/scripts/_find_nonzero_sample.lua
@@ -0,0 +1,74 @@
+ardour {
+	["type"] = "EditorAction",
+	name = "Find non zero audio sample",
+	author = "Ardour Team",
+	description = [[Find the position of first non-zero audio sample in selected regions.]]
+}
+
+function factory () return function ()
+	-- get Editor GUI Selection
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:Selection
+	local sel = Editor:get_selection ()
+
+	-- allocate a buffer (float* in C)
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:DspShm
+	local cmem = ARDOUR.DSP.DspShm (8192)
+	local msg = ""
+
+	-- iterate over selected regions
+	-- http://manual.ardour.org/lua-scripting/class_reference/#ArdourUI:RegionSelection
+	for r in sel.regions:regionlist ():iter () do
+		-- test if it's an audio region
+		if r:to_audioregion ():isnil () then
+			goto next
+		end
+
+		-- to read the Region data, we use the Readable interface of the Region
+		-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:Readable
+		local rd = r:to_readable ()
+
+		local n_samples = rd:readable_length ()
+		local n_channels = rd:n_channels ()
+
+		local nonzeropos = -1
+
+		-- iterate over all channels in Audio Region
+		for c = 0, n_channels -1 do
+			local pos = 0
+			repeat
+				-- read at most 8K samples of channel 'c' starting at 'pos'
+				local s = rd:read (cmem:to_float (0), pos, 8192, c)
+				-- access the raw audio data
+				-- http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray
+				local d = cmem:to_float (0):array()
+				-- iterate over the audio sample data
+				for i = 0, s do
+					if math.abs (d[i]) > 0 then
+						if (nonzeropos < 0 or pos + i < nonzeropos) then
+							nonzeropos = pos + i
+						end
+						break
+					end
+				end
+				pos = pos + s
+				if (nonzeropos >= 0 and pos > nonzeropos) then
+					break
+				end
+			until s < 8192
+		end
+
+		if (nonzeropos >= 0) then
+			msg = msg .. string.format("%s: %d\n", r:name (), nonzeropos + r:position())
+		else
+			msg = msg .. "Region: '%s' is silent\n"
+		end
+
+		::next::
+	end
+
+	if (msg ~= "") then
+		local md = LuaDialog.Message ("First Non Zero Sample", msg, LuaDialog.MessageType.Info, LuaDialog.ButtonType.Close)
+		md:run()
+	end
+
+end end