ardour { ["type"] = "dsp", name = "a-Notch Bank", category = "Filter", license = "MIT", author = "Ardour Lua Task Force", description = [[Notch Filter Bank; useful to remove noise with a harmonic spectum (e.g, mains hum, GSM signals, charge-pump noise, etc). Note: this plugin is not suitable to be automated, it is intended for static noise only.]] } ------------------------------------------------------------------ -- this is a quick/dirty example filter: no de-click, no de-zipper ------------------------------------------------------------------- -- configuration local max_stages = 100 -- plugin i/o ports function dsp_ioconfig () return { -- allow any number of I/O as long as port-count matches { audio_in = -1, audio_out = -1}, } end -- plugin control ports function dsp_params () return { { ["type"] = "input", name = "Base Freq", min = 10, max = 2000, default = 100, unit="Hz", logarithmic = true }, { ["type"] = "input", name = "Quality", min = 1.0, max = 100.0, default = 8.0, logarithmic = true }, { ["type"] = "input", name = "Stages", min = 1.0, max = max_stages, default = 8.0, integer = true }, } end -- plugin instance state local filters = {} -- the biquad filter instances local chn = 0 -- configured channel count local sample_rate = 0 -- configured sample-rate local limit = 0 -- max number of stages (given freq & sample-rate) -- cached control ports (keep track of changed) local freq = 0 local qual = 0 -- dsp_init is called once when instantiating the plugin function dsp_init (rate) -- remember the sample-rate sample_rate = rate end -- dsp_configure is called every time when the channel-count -- changes, and at least once at the beginning. function dsp_configure (ins, outs) assert (ins:n_audio () == outs:n_audio ()) -- explicit cleanup filters = {} collectgarbage () -- remember audio-channels chn = ins:n_audio () -- set up filter instances for all channels for c = 1, chn do filters[c] = {} for i = 1, max_stages do filters[c][i] = ARDOUR.DSP.Biquad (sample_rate) end end end -- the actual process function, called every cycle -- ins, outs are audio-data arrays -- http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray -- n_samples are the number of samples to process function dsp_run (ins, outs, n_samples) -- make sure input and output count matches... assert (#ins == #outs) -- ...and matches the configured number of channels assert (#ins == chn) local ctrl = CtrlPorts:array () -- get control parameters as array -- ctrl[] .. correspond to the parameters given in in dsp_params() -- test if the plugin-parameters have changed if freq ~= ctrl[1] or qual ~= ctrl[2] then -- remember current settings freq = ctrl[1] qual = ctrl[2] -- calc max number of states to configure/process limit = math.floor (sample_rate / (2 * freq)) -- at most up to SR / 2 if limit > max_stages then limit = max_stages end -- re-compute the filter coefficients for all filters for c = 1, chn do -- for each channel for i = 1, limit do -- and for each filter stage -- see http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:Biquad -- and for a list of available types, see -- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR.DSP.Biquad.Type -- the parameters are type, frequency, quality(bandwidth), gain filters[c][i]:compute (ARDOUR.DSP.BiquadType.Notch, freq * i, qual * i, 0) end end end -- limit the number of process stages local stages = math.floor (ctrl['3']) -- current user-set parameter if stages < 1 then stages = 1 end -- at least one stage... if stages > limit then stages = limit end -- process all channels for c = 1, chn do -- when not processing in-place, copy the data from input to output first if ins[c] ~= outs[c] then ARDOUR.DSP.copy_vector (outs[c], ins[c], n_samples) end -- run all stages, in-place on the output buffer for i = 1, stages do filters[c][i]:run (outs[c], n_samples) end end end