ardour { ["type"] = "dsp", name = "a-High/Low Pass Filter", category = "Filter", license = "GPLv2", author = "Ardour Team", 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 = "High Pass Steepness", min = 0, max = 4, default = 1, enum = true, scalepoints = { ["Off"] = 0, ["12dB/oct"] = 1, ["24dB/oct"] = 2, ["36dB/oct"] = 3, ["48dB/oct"] = 4, } }, { ["type"] = "input", name = "High Pass Cut off frequency", min = 5, max = 20000, default = 100, unit="Hz", logarithmic = true }, { ["type"] = "input", name = "High Pass Resonance", min = 0.1, max = 6, default = .707, logarithmic = true }, { ["type"] = "input", name = "Low Pass Steepness", min = 0, max = 4, default = 1, enum = true, scalepoints = { ["Off"] = 0, ["12dB/oct"] = 1, ["24dB/oct"] = 2, ["36dB/oct"] = 3, ["48dB/oct"] = 4, } }, { ["type"] = "input", name = "Low Pass Cut off frequency", min = 20, max = 20000, default = 18000, unit="Hz", logarithmic = true }, { ["type"] = "input", name = "Low Pass Resonance", min = 0.1, max = 6, default = .707, logarithmic = true }, } end -- these globals are *not* shared between DSP and UI local hp = {} -- the biquad high-pass filter instances (DSP) local lp = {} -- the biquad high-pass filter instances (DSP) local filt = nil -- the biquad filter instance (GUI, response) local cur = {0, 0, 0, 0, 0, 0, 0} -- current parameters local lpf = 0.03 -- parameter low-pass filter time-constant local chn = 0 -- channel/filter count local mem = nil -- memory x-fade buffer function dsp_init (rate) -- allocate some mix-buffer mem = ARDOUR.DSP.DspShm (8192) -- create a table of objects to share with the GUI local tbl = {} tbl['samplerate'] = rate self:table ():set (tbl) -- interpolation time constant, 64fpp lpf = 5000 / rate end function dsp_configure (ins, outs) assert (ins:n_audio () == outs:n_audio ()) local tbl = self:table ():get () -- get shared memory table chn = ins:n_audio () cur = {0, 0, 0, 0, 0, 0} hp = {} lp = {} collectgarbage () for c = 1, chn do hp[c] = {} lp[c] = {} -- initialize filters -- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:Biquad for k = 1,4 do hp[c][k] = ARDOUR.DSP.Biquad (tbl['samplerate']) lp[c][k] = ARDOUR.DSP.Biquad (tbl['samplerate']) end end end -- helper functions for parameter interpolation function param_changed (ctrl) for p = 1,6 do if ctrl[p] ~= cur[p] then return true end end return false 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 -- low-pass filter ctrl parameter values, smooth transition cur[1] = low_pass_filter_param (cur[1], ctrl[1], 0.05) -- HP order x-fade cur[2] = low_pass_filter_param (cur[2], ctrl[2], 1.0) -- HP freq/Hz cur[3] = low_pass_filter_param (cur[3], ctrl[3], 0.01) -- HP quality cur[4] = low_pass_filter_param (cur[4], ctrl[4], 0.05) -- LP order x-fade cur[5] = low_pass_filter_param (cur[5], ctrl[5], 1.0) -- LP freq/Hz cur[6] = low_pass_filter_param (cur[6], ctrl[6], 0.01) -- LP quality for c = 1, chn do for k = 1,4 do hp[c][k]:compute (ARDOUR.DSP.BiquadType.HighPass, cur[2], cur[3], 0) lp[c][k]:compute (ARDOUR.DSP.BiquadType.LowPass, cur[5], cur[6], 0) end end end -- the actual DSP callback function dsp_run (ins, outs, n_samples) assert (n_samples < 8192) assert (#ins == chn) 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 while n_samples > 0 do if changed then apply_params (CtrlPorts:array ()) end if siz > n_samples then siz = n_samples end local ho = math.floor(cur[1]) local lo = math.floor(cur[4]) -- process all channels for c = 1, #ins do local xfade = cur[1] - ho assert (xfade >= 0 and xfade < 1) ARDOUR.DSP.copy_vector (mem:to_float (off), ins[c]:offset (off), siz) -- initialize output if cur[1] == 0 then -- high pass is disabled, just copy data. ARDOUR.DSP.copy_vector (outs[c]:offset (off), mem:to_float (off), siz) else -- clear output, The filter mixes into the output buffer ARDOUR.DSP.memset (outs[c]:offset (off), 0, siz) end -- high pass -- allways run all filters so that we can interplate as needed. for k = 1,4 do if xfade > 0 and k == ho + 1 then ARDOUR.DSP.mix_buffers_with_gain (outs[c]:offset (off), mem:to_float (off), siz, 1 - xfade) end hp[c][k]:run (mem:to_float (off), siz) if k == ho and xfade == 0 then ARDOUR.DSP.copy_vector (outs[c]:offset (off), mem:to_float (off), siz) elseif k == ho + 1 then ARDOUR.DSP.mix_buffers_with_gain (outs[c]:offset (off), mem:to_float (off), siz, xfade) end end -- low pass xfade = cur[4] - lo assert (xfade >= 0 and xfade < 1) -- copy output of high-pass into "processing memory" ARDOUR.DSP.copy_vector (mem:to_float (off), outs[c]:offset (off), siz) if cur[4] > 0 then -- clear output, Low-pass mixes interpolated data into output, -- in which case we just keep the output ARDOUR.DSP.memset (outs[c]:offset (off), 0, siz) end for k = 1,4 do if xfade > 0 and k > lo and k <= lo + 1 then ARDOUR.DSP.mix_buffers_with_gain (outs[c]:offset (off), mem:to_float (off), siz, 1 - xfade) end lp[c][k]:run (mem:to_float (off), siz) if k == lo and xfade == 0 then ARDOUR.DSP.copy_vector (outs[c]:offset (off), mem:to_float (off), siz) elseif k > lo and k <= lo + 1 then ARDOUR.DSP.mix_buffers_with_gain (outs[c]:offset (off), mem:to_float (off), siz, xfade) 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) -- frequency in Hz at given x-axis pixel return 20 * 1000 ^ (x / w) end function x_at_freq (f, w) -- x-axis pixel for given frequency, power-scale return w * math.log (f / 20.0) / math.log (1000.0) end function db_to_y (db, h) -- y-axis gain mapping if db < -60 then db = -60 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 -- note that a cairo pixel at Y spans [Y - 0.5 to Y + 0.5] 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 response (ho, lo, f) -- calculate transfer function response for given -- hi/po pass order at given frequency [Hz] local db = ho * filt['hp']:dB_at_freq (f) return db + lo * filt['lp']:dB_at_freq (f) end function render_inline (ctx, w, max_h) if not filt then local tbl = self:table ():get () -- get shared memory table -- instantiate filter (to calculate the transfer function's response) filt = {} filt['hp'] = ARDOUR.DSP.Biquad (tbl['samplerate']) filt['lp'] = ARDOUR.DSP.Biquad (tbl['samplerate']) end -- set filter coefficients if they have changed if param_changed (CtrlPorts:array ()) then local ctrl = CtrlPorts:array () for k = 1,6 do cur[k] = ctrl[k] end filt['hp']:compute (ARDOUR.DSP.BiquadType.HighPass, cur[2], cur[3], 0) filt['lp']:compute (ARDOUR.DSP.BiquadType.LowPass, cur[5], cur[6], 0) end -- calc height of inline display local h = 1 | math.ceil (w * 9 / 16) -- use 16:9 aspect, odd number of y pixels 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 () ctx:rectangle (0, 0, w, h) ctx:clip () -- set line width: 1px 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: 1 pixel 2 space ctx:set_source_rgba (.5, .5, .5, .8) grid_db (ctx, w, h, 0) ctx:set_dash (dash3, 2) -- dashed line: 1 pixel 3 space 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 () -- draw transfer function line local ho = math.floor(cur[1]) local lo = math.floor(cur[4]) ctx:set_source_rgba (.8, .8, .8, 1.0) ctx:move_to (-.5, db_to_y (response(ho, lo, freq_at_x (0, w)), h)) for x = 1,w do local db = response(ho, lo, freq_at_x (x, w)) ctx:line_to (-.5 + x, db_to_y (db, h)) end -- stoke a line, keep the path 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