update lua scripts

* add proper amplifier (smooth gain change) + text-example
* remove commented no-inplace from High/Low pass
* amend 913609be inline spectrogam re-init

scripts/amp4.lua

@@ -0,0 +1,118 @@
+ardour {
+	["type"]    = "dsp",
+	name        = "Amplifier",
+	category    = "Amplifier",
+	license     = "MIT",
+	author      = "Robin Gareus",
+	email       = "robin@gareus.org",
+	site        = "http://gareus.org",
+	description = [[ Versatile +/- 20dB multichannel amplifier]]
+}
+
+function dsp_ioconfig ()
+	return
+	{
+		{ audio_in = -1, audio_out = -1},
+	}
+end
+
+
+function dsp_params ()
+	return
+	{
+		{ ["type"] = "input", name = "Gain", min = -20, max = 20, default = 0, unit="dB"},
+	}
+end
+
+local lpf = 0.02 -- parameter low-pass filter time-constant
+local cur_gain = 0 -- current gain (dB)
+
+-- called once when plugin is instantiated
+function dsp_init (rate)
+	lpf = 780 / rate -- interpolation time constant
+end
+
+function low_pass_filter_param (old, new, limit)
+	if math.abs (old - new) < limit  then
+		return new
+	else
+		return old + lpf * (new - old)
+	end
+end
+
+-- use ardour's vectorized functions
+--
+-- This is as efficient as Ardour doing it itself in C++
+-- Lua function overhead is negligible
+--
+-- this also exemplifies the /simpler/ way of delegating the
+-- channel-mapping to ardour.
+
+function dsp_run (ins, outs, n_samples)
+	assert (#ins == #outs) -- ensure that we can run in-place (channel count matches)
+	local ctrl = CtrlPorts:array() -- get control port array (read/write)
+	local siz = n_samples
+	local off = 0
+	local changed = false
+
+	-- if the gain parameter was changed, process at most 64 samples at a time
+	-- and interpolate gain until the current settings match the target values
+	if cur_gain ~= ctrl[1] then
+		changed = true
+		siz = 32
+	end
+
+	while n_samples > 0 do
+		if siz > n_samples then siz = n_samples end
+		if changed then
+			cur_gain = low_pass_filter_param (cur_gain, ctrl[1], 0.05)
+		end
+
+		local gain = ARDOUR.DSP.dB_to_coefficient (cur_gain) -- 10 ^ (0.05 * cur_gain)
+		for c = 1,#ins do -- process all channels
+			-- check if output and input buffers for this channel are identical
+			-- http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray
+			if not ins[c]:sameinstance (outs[c]) then
+				-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP
+				ARDOUR.DSP.copy_vector (outs[c]:offset (off), ins[c]:offset (off), siz)
+			end
+			ARDOUR.DSP.apply_gain_to_buffer (outs[c]:offset (off), siz, gain); -- process in-place
+		end
+		n_samples = n_samples - siz
+		off = off + siz
+	end
+
+	if changed then
+		self:queue_draw () -- notify display
+	end
+end
+
+-------------------------------------------------------------------------------
+--- inline display + text example
+
+local txt = nil -- cache globally
+function render_inline (ctx, w, max_h)
+	local ctrl = CtrlPorts:array ()
+
+	if not txt then
+		txt = Cairo.PangoLayout (ctx, "Mono 8px")
+	end
+
+	txt:set_text (string.format ("%+.2f dB", ctrl[1]));
+	tw, th = txt:get_pixel_size ()
+
+	local h = math.ceil (th + 4) -- use text-height with 4px padding
+	if (h > max_h) then h = max_h end -- but at most max-height
+
+	-- clear background
+	ctx:rectangle (0, 0, w, h)
+	ctx:set_source_rgba (.2, .2, .2, 1.0)
+	ctx:fill ()
+
+	-- center text
+	ctx:set_source_rgba (.8, .8, .8, 1.0)
+	ctx:move_to ( .5 * (w - tw), .5 * (h - th))
+	txt:show_in_cairo_context (ctx)
+
+	return {w, h}
+end

scripts/hplp.lua

@@ -150,16 +150,12 @@ function dsp_run (ins, outs, n_samples)
 		for c = 1,#ins do
 			-- check if output and input buffers for this channel are identical
 			-- http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray
-			if false then --- ins[c]:sameinstance (outs[c]) then
+			if not ins[c]:sameinstance (outs[c]) then
-				for k = 1,o do
-					filters[c][k]:run (ins[c]:offset (off), siz) -- in-place processing
-				end
-			else
 				-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP
 				ARDOUR.DSP.copy_vector (outs[c]:offset (off), ins[c]:offset (off), siz)
-				for k = 1,o do
+			end
-					filters[c][k]:run (outs[c]:offset (off), siz)
+			for k = 1,o do
-				end
+				filters[c][k]:run (outs[c]:offset (off), siz) -- in-place processing
 			end
 		end
 

scripts/spectrogram.lua

@@ -215,6 +215,7 @@ function render_inline (ctx, w, max_h)
 	-- re-create image surface
 	if not img or img:get_width() ~= w or img:get_height () ~= h then
 		img = Cairo.ImageSurface (Cairo.Format.ARGB32, w, h)
+		line = 0
 	end
 	local ictx = img:context ()