add an lua DSP example filter w/inline display
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scripts/filt.lua
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190
scripts/filt.lua
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ardour {
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["type"] = "dsp",
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name = "Biquad Filter",
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category = "Filter",
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license = "MIT",
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author = "Robin Gareus",
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email = "robin@gareus.org",
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site = "http://gareus.org",
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description = [[
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An Example DSP Plugin for processing audio, to
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be used with Ardour's Lua scripting facility.]]
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}
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function dsp_ioconfig ()
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return
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{
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{ audio_in = -1, audio_out = -1},
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}
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end
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function dsp_params ()
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return
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{
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{ ["type"] = "input", name = "Type", min = 0, max = 4, default = 0, enum = true, scalepoints =
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{
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["Peaking"] = 0,
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["Low Shelf"] = 1,
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["High Shelf"] = 2,
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["Low Pass"] = 3,
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["High Pass"] = 4,
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}
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},
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{ ["type"] = "input", name = "Gain", min = -20, max = 20, default = 0, unit="dB" },
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{ ["type"] = "input", name = "Freq", min = 20, max = 20000, default = 1000, unit="Hz", logarithmic = true },
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{ ["type"] = "input", name = "Q", min = 0.1, max = 8, default = .707, logarithmic = true },
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}
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end
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-- these globals are *not* shared between DSP and UI
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local filt -- the filter instance
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local cur = {0, 0, 0, 0} -- current settings
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function dsp_init (rate)
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self:shmem ():allocate (1) -- shared mem to tell UI about samplerate
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local cfg = self:shmem ():to_int (0):array ()
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cfg[1] = rate
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filt = ARDOUR.DSP.Biquad (rate) -- initialize filter
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end
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-- apply parameters, re-compute filter coefficients if needed
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function apply_params (ctrl)
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if ctrl[1] == cur[1] and ctrl[2] == cur[2] and ctrl[3] == cur[3] and ctrl[4] == cur[4] then
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return false
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end
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local ft
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if ctrl[1] == 1 then
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ft = ARDOUR.DSP.BiQuadType.LowShelf
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elseif ctrl[1] == 2 then
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ft = ARDOUR.DSP.BiQuadType.HighShelf
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elseif ctrl[1] == 3 then
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ft = ARDOUR.DSP.BiQuadType.LowPass
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elseif ctrl[1] == 4 then
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ft = ARDOUR.DSP.BiQuadType.HighPass
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else
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ft = ARDOUR.DSP.BiQuadType.Peaking
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end
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-- TODO low-pass filter ctrl values, smooth transition
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filt:compute (ft, ctrl[3], ctrl[4], ctrl[2])
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cur[1] = ctrl[1]
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cur[2] = ctrl[2]
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cur[3] = ctrl[3]
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cur[4] = ctrl[4]
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return true
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end
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-- the actual DSP callback
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function dsp_run (ins, outs, n_samples)
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if apply_params (CtrlPorts:array ()) then
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self:queue_draw ()
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end
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for c = 1,#ins do
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if ins[c]:sameinstance (outs[c]) then
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filt:run (ins[c], n_samples) -- in-place
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else
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ARDOUR.DSP.copy_vector (outs[c], ins[c], n_samples)
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filt:run (outs[c], n_samples)
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end
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end
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end
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-------------------------------------------------------------------------------
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--- inline display
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function round (n)
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return math.floor (n + .5)
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end
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function freq_at_x (x, w)
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return 20 * 1000 ^ (x / w)
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end
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function x_at_freq (f, w)
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return w * math.log (f / 20.0) / math.log (1000.0)
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end
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function db_to_y (db, h)
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if db < -20 then db = -20 end
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if db > 20 then db = 20 end
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return -.5 + 0.5 * h * (1 - db / 20)
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end
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function grid_db (ctx, w, h, db)
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local y = -.5 + round (db_to_y (db, h))
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ctx:move_to (0, y)
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ctx:line_to (w, y)
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ctx:stroke ()
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end
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function grid_freq (ctx, w, h, f)
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local x = -.5 + round (x_at_freq (f, w))
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ctx:move_to (x, 0)
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ctx:line_to (x, h)
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ctx:stroke ()
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end
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function render_inline (ctx, w, max_h)
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if not filt then
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-- instantiate filter (to calculate the transfer function)
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local shmem = self:shmem () -- get shared memory region
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local cfg = shmem:to_int (0):array () -- "cast" into lua-table
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filt = ARDOUR.DSP.Biquad (cfg[1])
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end
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apply_params (CtrlPorts:array ())
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-- calc height of inline display
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local h = math.ceil (w * 10 / 16) -- 16:10 aspect
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h = 2 * round (h / 2) -- even number of vertical px
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if (h > max_h) then
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h = max_h
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end
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-- clear background
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ctx:rectangle (0, 0, w, h)
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ctx:set_source_rgba (.2, .2, .2, 1.0)
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ctx:fill ()
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ctx:set_line_width (1.0)
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-- draw grid
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local dash3 = C.DoubleVector ()
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dash3:add ({1, 3})
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ctx:set_dash (dash3, 2)
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ctx:set_source_rgba (.5, .5, .5, .5)
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grid_db (ctx, w, h, 0)
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grid_db (ctx, w, h, 6)
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grid_db (ctx, w, h, 12)
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grid_db (ctx, w, h, 18)
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grid_db (ctx, w, h, -6)
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grid_db (ctx, w, h, -12)
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grid_db (ctx, w, h, -18)
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grid_freq (ctx, w, h, 100)
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grid_freq (ctx, w, h, 1000)
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grid_freq (ctx, w, h, 10000)
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ctx:unset_dash ()
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-- draw transfer function
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ctx:set_source_rgba (.8, .8, .8, 1.0)
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ctx:move_to (-.5, db_to_y (filt:dB_at_freq (freq_at_x (0, w)), h))
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for x = 1,w do
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local db = filt:dB_at_freq (freq_at_x (x, w))
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ctx:line_to (-.5 + x, db_to_y (db, h))
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end
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ctx:stroke_preserve ()
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-- fill area to zero under the curve
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ctx:line_to (w, -.5 + h * .5)
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ctx:line_to (0, -.5 + h * .5)
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ctx:close_path ()
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ctx:set_source_rgba (.5, .5, .5, .5)
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ctx:fill ()
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return {w, h}
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end
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@ -20,7 +20,7 @@ function dsp_params ()
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{
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{ ["type"] = "input", name = "Timescale", min = .1, max = 5, default = 2, unit="sec", logarithmic = true },
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{ ["type"] = "input", name = "Logscale", min = 0, max = 1, default = 0, toggled = true },
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{ ["type"] = "input", name = "Height", min = 0, max = 3, default = 1, unit="dB", enum = true, scalepoints =
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{ ["type"] = "input", name = "Height", min = 0, max = 3, default = 1, enum = true, scalepoints =
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{
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["Min"] = 0,
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["16:10"] = 1,
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