diff options
author | Robin Gareus <robin@gareus.org> | 2016-08-10 03:12:11 +0200 |
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committer | Robin Gareus <robin@gareus.org> | 2016-08-10 03:12:11 +0200 |
commit | a8143ea44e83a87fb6a9500d59409a14a94ad655 (patch) | |
tree | 3aac8610dc26fb63abd4cc1c7afe864714a2f408 /scripts/_biquad_filter.lua | |
parent | 2b7a89ecffa92a616cd61774d42bea1e99db6f79 (diff) |
prefix no-inst script with an underscore and skip install
Diffstat (limited to 'scripts/_biquad_filter.lua')
-rw-r--r-- | scripts/_biquad_filter.lua | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/scripts/_biquad_filter.lua b/scripts/_biquad_filter.lua new file mode 100644 index 0000000000..c0dec8bd1f --- /dev/null +++ b/scripts/_biquad_filter.lua @@ -0,0 +1,280 @@ +ardour { + ["type"] = "dsp", + name = "Biquad Filter", + category = "Filter", + license = "MIT", + author = "Ardour Lua Task Force", + description = [[A Versatile Filter 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 = "Enable", min = 0, max = 1, default = 1, bypass = true, toggled = true }, + { ["type"] = "input", name = "Type", min = 0, max = 4, default = 0, enum = true, scalepoints = + { + ["Peaking"] = 0, + ["Low Shelf"] = 1, + ["High Shelf"] = 2, + ["Low Pass"] = 3, + ["High Pass"] = 4, + } + }, + { ["type"] = "input", name = "Gain", min = -20, max = 20, default = 0, unit="dB" }, + { ["type"] = "input", name = "Freq", min = 20, max = 20000, default = 1000, unit="Hz", logarithmic = true }, + { ["type"] = "input", name = "Q", 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.LowShelf + elseif t == 2 then + return ARDOUR.DSP.BiquadType.HighShelf + elseif t == 3 then + return ARDOUR.DSP.BiquadType.LowPass + elseif t == 4 then + return ARDOUR.DSP.BiquadType.HighPass + else + return ARDOUR.DSP.BiquadType.Peaking + end +end + +function ctrl_data () + local ctrl = CtrlPorts:array () + if ctrl[1] <= 0 then -- when disabled + ctrl[3] = 0; -- force gain to 0dB + end + return ctrl +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, 0} -- current parameters +local lpf = 0.03 -- parameter low-pass filter time-constant +local chn = 0 -- channel/filter count + +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 + filt = ARDOUR.DSP.Biquad (rate) -- initialize filter + lpf = 13000 / rate -- interpolation time constant +end + +function dsp_configure (ins, outs) + assert (ins:n_audio () == outs:n_audio ()) + local cfg = self:shmem ():to_int (0):array () + local rate = cfg[1] + chn = ins:n_audio () + for c = 1, chn do + filters[c] = ARDOUR.DSP.Biquad (rate) -- initialize filters + end + cur = {0, 0, 0, 0, 0} +end + +-- helper functions for parameter interpolation +function param_changed (ctrl) + if ctrl[2] == cur[2] and ctrl[3] == cur[3] and ctrl[4] == cur[4] and ctrl[5] == cur[5] 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[2] ~= ctrl[2] then + -- reset filter state when type changes + filt:reset () + for k = 2,5 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], 0.1) -- gain/dB + cur[4] = low_pass_filter_param (cur[4], ctrl[4], 1.0) -- freq/Hz + cur[5] = low_pass_filter_param (cur[5], ctrl[5], 0.01) -- quality + end + + for c = 1, chn do + filters[c]:compute (map_type (cur[2]), cur[4], cur[5], cur[3]) + end +end + + +-- the actual DSP callback +function dsp_run (ins, outs, n_samples) + local changed = false + local siz = n_samples + local off = 0 + local ctrl = ctrl_data () + + -- 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 (ctrl) then + changed = true + siz = 64 + end + + while n_samples > 0 do + if changed then apply_params (ctrl) 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 + filters[c]:run (ins[c]:offset (off), siz) -- in-place processing + else + -- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP + ARDOUR.DSP.copy_vector (outs[c]:offset (off), ins[c]:offset (off), siz) + filters[c]:run (outs[c]:offset (off), siz) + 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 < -20 then db = -20 end + if db > 20 then db = 20 end + return -.5 + 0.5 * h * (1 - db / 20) +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 = ctrl_data () + for k = 2,5 do cur[k] = ctrl[k] end + filt:compute (map_type (cur[2]), cur[4], cur[5], cur[3]) + end + + -- calc height of inline display + local h = math.ceil (w * 10 / 16) -- use 16:10 aspect + h = 2 * round (h / 2) -- with an even number of vertical 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 () + + -- 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 () + dash3:add ({1, 3}) + ctx:set_dash (dash3, 2) -- dotted line + ctx:set_source_rgba (.5, .5, .5, .5) + grid_db (ctx, w, h, 0) + grid_db (ctx, w, h, 6) + grid_db (ctx, w, h, 12) + grid_db (ctx, w, h, 18) + grid_db (ctx, w, h, -6) + grid_db (ctx, w, h, -12) + grid_db (ctx, w, h, -18) + 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 + ctx:set_source_rgba (.8, .8, .8, 1.0) + ctx:move_to (-.5, db_to_y (filt:dB_at_freq (freq_at_x (0, w)), h)) + for x = 1,w do + local db = 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 + h * .5) + ctx:line_to (0, -.5 + h * .5) + ctx:close_path () + ctx:set_source_rgba (.5, .5, .5, .5) + ctx:fill () + + return {w, h} +end |