+++ /dev/null
-ardour {
- ["type"] = "dsp",
- name = "a-High/Low Pass Filter",
- category = "Filter",
- license = "MIT",
- 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 = "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
-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
- 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] = {}
- -- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:Biquad
- for k = 1,4 do
- filters[c][k] = ARDOUR.DSP.Biquad (rate) -- initialize filters
- end
- end
- cur = {0, 0, 0, 0}
-end
-
--- helper functions for parameter interpolation
-function param_changed (ctrl)
- if math.floor(ctrl[1]) == math.floor(cur[1]) and math.floor(ctrl[2]) == math.floor(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 c = 1, chn do
- for k = 1,4 do
- filters[c][k]:reset ()
- end
- 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 c = 1, chn do
- for k = 1,4 do
- filters[c][k]:compute (map_type (cur[1]), cur[3], cur[4], 0)
- end
- 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 = math.floor(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 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
- for k = 1,o do
- filters[c][k]:run (outs[c]:offset (off), siz) -- in-place processing
- 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 < -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
- 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 = 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
- -- 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 = math.floor(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
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