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-rw-r--r--share/scripts/HiAndLowPass.lua396
1 files changed, 396 insertions, 0 deletions
diff --git a/share/scripts/HiAndLowPass.lua b/share/scripts/HiAndLowPass.lua
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+ardour {
+ ["type"] = "dsp",
+ name = "a-High/Low Pass Filter",
+ category = "Filter",
+ license = "GPLv2",
+ author = "Ardour Team",
+ description = [[High and Low Pass Filter with de-zipped controls, written in Ardour-Lua]]
+}
+
+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} -- current parameters
+local lpf = 0.03 -- parameter low-pass filter time-constant
+local chn = 0 -- channel/filter count
+local lpf_chunk = 0 -- chunk size for audio processing when interpolating parameters
+local max_freq = 20000
+
+local mem = nil -- memory x-fade buffer
+
+function dsp_init (rate)
+ -- allocate some mix-buffer
+ mem = ARDOUR.DSP.DspShm (8192)
+
+ -- max allowed cut-off frequency
+ max_freq = .499 * rate
+
+ -- create a table of objects to share with the GUI
+ local tbl = {}
+ tbl['samplerate'] = rate
+ tbl['max_freq'] = max_freq
+ self:table ():set (tbl)
+
+
+ -- Parameter smoothing: we want to filter out parameter changes that are
+ -- faster than 15Hz, and interpolate between parameter values.
+ -- For performance reasons, we want to ensure that two consecutive values
+ -- of the interpolated "steepness" are less that 1 apart. By choosing the
+ -- interpolation chunk size to be 64 in most cases, but 32 if the rate is
+ -- strictly less than 22kHz (there's only 8kHz in standard rates), we can
+ -- ensure that steepness interpolation will never change the parameter by
+ -- more than ~0.86.
+ lpf_chunk = 64
+ if rate < 22000 then lpf_chunk = 32 end
+ -- We apply a discrete version of the standard RC low-pass, with a cutoff
+ -- frequency of 15Hz. For more information about the underlying math, see
+ -- https://en.wikipedia.org/wiki/Low-pass_filter#Discrete-time_realization
+ -- (here Δt is lpf_chunk / rate)
+ local R = 2 * math.pi * lpf_chunk * 15 -- Hz
+ lpf = R / (R + 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
+
+ -- A different Biquad is needed for each pass and channel because they
+ -- remember the last two samples seen during the last call of Biquad:run().
+ -- For continuity these have to come from the previous audio chunk of the
+ -- same channel and pass and would be clobbered if the same Biquad was
+ -- called several times by cycle.
+ for k = 1,4 do
+ hp[c][k] = ARDOUR.DSP.Biquad (tbl['samplerate'])
+ lp[c][k] = ARDOUR.DSP.Biquad (tbl['samplerate'])
+ end
+ end
+end
+
+function santize_params (ctrl)
+ -- don't allow manual cross-fades. enforce enums
+ ctrl[1] = math.floor(ctrl[1] + .5)
+ ctrl[4] = math.floor(ctrl[4] + .5)
+
+ -- high pass, clamp range
+ ctrl[2] = math.min (max_freq, math.max (5, ctrl[2]))
+ ctrl[3] = math.min (6, math.max (0.1, ctrl[3]))
+
+ -- low pass, clamp range
+ ctrl[5] = math.min (max_freq, math.max (20, ctrl[5]))
+ ctrl[6] = math.min (6, math.max (0.1, ctrl[6]))
+ return ctrl
+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 ctrl = santize_params (CtrlPorts:array ())
+
+ local changed = false
+ local siz = n_samples
+ local off = 0
+
+ -- if a parameter was changed, process at most lpf_chunk samples
+ -- at a time and interpolate parameters until the current settings
+ -- match the target values
+ if param_changed (ctrl) then
+ changed = true
+ siz = lpf_chunk
+ end
+
+ while n_samples > 0 do
+ if changed then apply_params (ctrl) 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
+
+ -- High Pass
+ local xfade = cur[1] - ho
+
+ -- prepare scratch memory
+ ARDOUR.DSP.copy_vector (mem:to_float (off), ins[c]:offset (off), siz)
+
+ -- run at least |ho| biquads...
+ for k = 1,ho do
+ hp[c][k]:run (mem:to_float (off), siz)
+ end
+ ARDOUR.DSP.copy_vector (outs[c]:offset (off), mem:to_float (off), siz)
+
+ -- mix the output of |ho| biquads (with weight |1-xfade|)
+ -- with the output of |ho+1| biquads (with weight |xfade|)
+ if xfade > 0 then
+ ARDOUR.DSP.apply_gain_to_buffer (outs[c]:offset (off), siz, 1 - xfade)
+ hp[c][ho+1]:run (mem:to_float (off), siz)
+ ARDOUR.DSP.mix_buffers_with_gain (outs[c]:offset (off), mem:to_float (off), siz, xfade)
+ -- also run the next biquad because it needs to have the correct state
+ -- in case it start affecting the next chunck of output. Higher order
+ -- ones are guaranteed not to be needed for the next run because the
+ -- interpolated order won't increase more than 0.86 in one step thanks
+ -- to the choice of the value of |lpf|.
+ if ho + 2 <= 4 then hp[c][ho+2]:run (mem:to_float (off), siz) end
+ elseif ho + 1 <= 4 then
+ -- run the next biquad in case it is used next chunk
+ hp[c][ho+1]:run (mem:to_float (off), siz)
+ end
+
+ -- Low Pass
+ xfade = cur[4] - lo
+
+ -- prepare scratch memory (from high pass output)
+ ARDOUR.DSP.copy_vector (mem:to_float (off), outs[c]:offset (off), siz)
+
+ -- run at least |lo| biquads...
+ for k = 1,lo do
+ lp[c][k]:run (mem:to_float (off), siz)
+ end
+ ARDOUR.DSP.copy_vector (outs[c]:offset (off), mem:to_float (off), siz)
+
+ -- mix the output of |lo| biquads (with weight |1-xfade|)
+ -- with the output of |lo+1| biquads (with weight |xfade|)
+ if xfade > 0 then
+ ARDOUR.DSP.apply_gain_to_buffer (outs[c]:offset (off), siz, 1 - xfade)
+ lp[c][lo+1]:run (mem:to_float (off), siz)
+ ARDOUR.DSP.mix_buffers_with_gain (outs[c]:offset (off), mem:to_float (off), siz, xfade)
+ -- also run the next biquad in case it start affecting the next
+ -- chunck of output.
+ if lo + 2 <= 4 then lp[c][lo+2]:run (mem:to_float (off), siz) end
+ elseif lo + 1 <= 4 then
+ -- run the next biquad in case it is used next chunk
+ lp[c][lo+1]:run (mem:to_float (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)
+ -- 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'])
+ max_freq = tbl['max_freq']
+ end
+
+ local ctrl = santize_params (CtrlPorts:array ())
+ -- set filter coefficients if they have changed
+ if param_changed (ctrl) then
+ 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
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