From 1cf6661196cb388d09114f263cafcff5f3139f87 Mon Sep 17 00:00:00 2001 From: Robin Gareus Date: Mon, 23 May 2016 00:43:55 +0200 Subject: [PATCH] add a lua high/low pass filter with configurable slope --- scripts/hplp.lua | 273 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 273 insertions(+) create mode 100644 scripts/hplp.lua diff --git a/scripts/hplp.lua b/scripts/hplp.lua new file mode 100644 index 0000000000..3b6a34c0fd --- /dev/null +++ b/scripts/hplp.lua @@ -0,0 +1,273 @@ +ardour { + ["type"] = "dsp", + name = "High/Low Pass Filter", + category = "Filter", + license = "MIT", + author = "Robin Gareus", + email = "robin@gareus.org", + site = "http://gareus.org", + description = [[Example Ardour Lua DSP Plugin]] +} + +function dsp_ioconfig () + return + { + -- allow any number of I/O as long as port-count matches + { audio_in = -1, audio_out = -1}, + } +end + + +function dsp_params () + return + { + { ["type"] = "input", name = "Type", min = 0, max = 1, default = 0, enum = true, scalepoints = + { + ["High Pass"] = 0, + ["Low Pass"] = 1, + } + }, + { ["type"] = "input", name = "Steepness", min = 1, max = 4, default = 1, enum = true, scalepoints = + { + ["12dB/oct"] = 1, + ["24dB/oct"] = 2, + ["36dB/oct"] = 3, + ["48dB/oct"] = 4, + } + }, + { ["type"] = "input", name = "Cut off frequency", min = 5, max = 20000, default = 1000, unit="Hz", logarithmic = true }, + { ["type"] = "input", name = "Resonance", min = 0.1, max = 8, default = .707, logarithmic = true }, + } +end + +-- translate type parameter to DSP enum +-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR.DSP.Biquad.Type +function map_type (t) + if t == 1 then + return ARDOUR.DSP.BiquadType.LowPass + else + return ARDOUR.DSP.BiquadType.HighPass + end +end + +-- these globals are *not* shared between DSP and UI +local filters = {} -- the biquad filter instances (DSP) +local filt -- the biquad filter instance (GUI, response) +local cur = {0, 0, 0, 0} -- current parameters +local lpf = 0.03 -- parameter low-pass filter time-constant + +function dsp_init (rate) + self:shmem ():allocate (1) -- shared mem to tell the GUI the samplerate + local cfg = self:shmem ():to_int (0):array () + cfg[1] = rate + -- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:Biquad + for k = 1,4 do + filters[k] = ARDOUR.DSP.Biquad (rate) -- initialize filters + end + lpf = 13000 / rate -- interpolation time constant +end + +-- helper functions for parameter interpolation +function param_changed (ctrl) + if ctrl[1] == cur[1] and ctrl[2] == cur[2] and ctrl[3] == cur[3] and ctrl[4] == cur[4] then + return false + end + return true +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 + +-- apply parameters, re-compute filter coefficients if needed +function apply_params (ctrl) + if not param_changed (ctrl) then + return + end + + if cur[1] ~= ctrl[1] or cur[2] ~= ctrl[2] then + -- reset filter state when type or order changes + for k = 1,4 do + filters[k]:reset () + end + for k = 1,4 do cur[k] = ctrl[k] end + else + -- low-pass filter ctrl parameter values, smooth transition + cur[3] = low_pass_filter_param (cur[3], ctrl[3], 1.0) -- freq/Hz + cur[4] = low_pass_filter_param (cur[4], ctrl[4], 0.01) -- quality + end + + if cur[2] < 1 then cur[2] = 1 end + if cur[2] > 4 then cur[2] = 4 end + + for k = 1,4 do + filters[k]:compute (map_type (cur[1]), cur[3], cur[4], 0) + end +end + + +-- the actual DSP callback +function dsp_run (ins, outs, n_samples) + local changed = false + local siz = n_samples + local off = 0 + + -- if a parameter was changed, process at most 64 samples at a time + -- and interpolate parameters until the current settings match + -- the target values + if param_changed (CtrlPorts:array ()) then + changed = true + siz = 64 + end + + local o = cur[2] + + while n_samples > 0 do + if changed then apply_params (CtrlPorts:array ()) end + if siz > n_samples then siz = n_samples end + + -- process all channels + 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 ins[c]:sameinstance (outs[c]) then + for k = 1,o do + filters[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 + filters[o]:run (outs[c]:offset (off), siz) + end + end + end + + n_samples = n_samples - siz + off = off + siz + end + + if changed then + -- notify display + self:queue_draw () + end +end + + +------------------------------------------------------------------------------- +--- inline display + +function round (n) + return math.floor (n + .5) +end + +function freq_at_x (x, w) + -- x-axis pixel for given freq, power-scale + return 20 * 1000 ^ (x / w) +end + +function x_at_freq (f, w) + -- frequency at given x-axis pixel + return w * math.log (f / 20.0) / math.log (1000.0) +end + +function db_to_y (db, h) + -- y-axis gain mapping + if db < -48 then db = -48 end + if db > 12 then db = 12 end + return -.5 + round (0.2 * h) - h * db / 60 +end + +function grid_db (ctx, w, h, db) + -- draw horizontal grid line + local y = -.5 + round (db_to_y (db, h)) + ctx:move_to (0, y) + ctx:line_to (w, y) + ctx:stroke () +end + +function grid_freq (ctx, w, h, f) + -- draw vertical grid line + local x = -.5 + round (x_at_freq (f, w)) + ctx:move_to (x, 0) + ctx:line_to (x, h) + ctx:stroke () +end + +function render_inline (ctx, w, max_h) + if not filt then + -- the GUI is separate from the DSP, but the GUI needs to know + -- the sample-rate that the DSP is using. + local shmem = self:shmem () -- get shared memory region + local cfg = shmem:to_int (0):array () -- "cast" into lua-table + -- instantiate filter (to calculate the transfer function's response) + filt = ARDOUR.DSP.Biquad (cfg[1]) + end + + -- set filter coefficients if they have changed + if param_changed (CtrlPorts:array ()) then + local ctrl = CtrlPorts:array () + for k = 1,4 do cur[k] = ctrl[k] end + if cur[2] < 1 then cur[2] = 1 end + if cur[2] > 4 then cur[2] = 4 end + filt:compute (map_type (cur[1]), cur[3], cur[4], 0) + end + + -- calc height of inline display + local h = math.ceil (w * 10 / 16) -- use 16:10 aspect + if (h > max_h) then h = max_h end -- but at most max-height + + -- ctx is a http://cairographics.org/ context + -- http://manual.ardour.org/lua-scripting/class_reference/#Cairo:Context + + -- clear background + ctx:rectangle (0, 0, w, h) + ctx:set_source_rgba (.2, .2, .2, 1.0) + ctx:fill () + + -- set line width: 1px + -- Note: a cairo pixel at [1,1] spans [0.5->1.5 , 0.5->1.5] + -- hence the offset -0.5 in various move_to(), line_to() calls + ctx:set_line_width (1.0) + + -- draw grid + local dash3 = C.DoubleVector () + local dash2 = C.DoubleVector () + dash2:add ({1, 2}) + dash3:add ({1, 3}) + ctx:set_dash (dash2, 2) -- dotted line + ctx:set_source_rgba (.5, .5, .5, .8) + grid_db (ctx, w, h, 0) + ctx:set_dash (dash3, 2) -- dotted line + ctx:set_source_rgba (.5, .5, .5, .5) + grid_db (ctx, w, h, -12) + grid_db (ctx, w, h, -24) + grid_db (ctx, w, h, -36) + grid_freq (ctx, w, h, 100) + grid_freq (ctx, w, h, 1000) + grid_freq (ctx, w, h, 10000) + ctx:unset_dash () + + local o = cur[2] + -- draw transfer function line + ctx:set_source_rgba (.8, .8, .8, 1.0) + ctx:move_to (-.5, db_to_y (o * filt:dB_at_freq (freq_at_x (0, w)), h)) + for x = 1,w do + local db = o * filt:dB_at_freq (freq_at_x (x, w)) + ctx:line_to (-.5 + x, db_to_y (db, h)) + end + ctx:stroke_preserve () + + -- fill area to zero under the curve + ctx:line_to (w, -.5 + round (db_to_y (0, h))) + ctx:line_to (0, -.5 + round (db_to_y (0, h))) + ctx:close_path () + ctx:set_source_rgba (.5, .5, .5, .5) + ctx:fill () + + return {w, h} +end -- 2.30.2