120 lines
3.2 KiB
Lua
120 lines
3.2 KiB
Lua
ardour {
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["type"] = "dsp",
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name = "a-Amplifier",
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category = "Amplifier",
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license = "MIT",
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author = "Ardour Team",
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description = [[Versatile +/- 20dB multichannel amplifier]]
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}
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function dsp_ioconfig ()
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return
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{
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-- -1, -1 = any number of channels as long as input and output count matches
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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 = "Gain", min = -20, max = 20, default = 0, unit="dB"},
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}
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end
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local lpf = 0.02 -- parameter low-pass filter time-constant
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local cur_gain = 0 -- current smoothed gain (dB)
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-- called once when plugin is instantiated
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function dsp_init (rate)
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lpf = 780 / rate -- interpolation time constant
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end
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function low_pass_filter_param (old, new, limit)
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if math.abs (old - new) < limit then
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return new
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else
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return old + lpf * (new - old)
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end
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end
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-- the DSP callback function
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-- "ins" and "outs" are http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray
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function dsp_run (ins, outs, n_samples)
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local ctrl = CtrlPorts:array() -- get control port array (read/write)
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local siz = n_samples -- samples remaining to process
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local off = 0 -- already processed samples
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local changed = false
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-- if the gain parameter was changed, process at most 32 samples at a time
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-- and interpolate gain until the current settings match the target values
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if cur_gain ~= ctrl[1] then
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changed = true
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siz = 32
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end
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while n_samples > 0 do
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if siz > n_samples then siz = n_samples end -- process at most "remaining samples"
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if changed then
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-- smooth gain changes above 0.02 dB difference
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cur_gain = low_pass_filter_param (cur_gain, ctrl[1], 0.02)
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end
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local gain = ARDOUR.DSP.dB_to_coefficient (cur_gain) -- 10 ^ (0.05 * cur_gain)
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for c = 1,#ins do -- process all channels
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-- check if output and input buffers for this channel are identical
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-- http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray
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if ins[c] ~= outs[c] then
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-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP
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ARDOUR.DSP.copy_vector (outs[c]:offset (off), ins[c]:offset (off), siz)
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end
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ARDOUR.DSP.apply_gain_to_buffer (outs[c]:offset (off), siz, gain); -- apply-gain, process in-place
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end
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n_samples = n_samples - siz
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off = off + siz
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end
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--[[
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if changed then
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self:queue_draw () -- notify display
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end
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--]]
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end
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-------------------------------------------------------------------------------
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--- inline display + text example
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--[[
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local txt = nil -- cache pango context globally
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function render_inline (ctx, w, max_h)
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local ctrl = CtrlPorts:array () -- get control ports
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if not txt then
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-- allocate PangoLayout and set font
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--http://manual.ardour.org/lua-scripting/class_reference/#Cairo:PangoLayout
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txt = Cairo.PangoLayout (ctx, "Mono 8px")
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end
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txt:set_text (string.format ("%+.2f dB", ctrl[1]));
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tw, th = txt:get_pixel_size ()
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local h = th + 4 -- use text-height with 4px padding
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if (h > max_h) then h = max_h end -- but at most max-height
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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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-- center text
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ctx:set_source_rgba (.8, .8, .8, 1.0)
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ctx:move_to (.5 * (w - tw), .5 * (h - th))
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txt:show_in_cairo_context (ctx)
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return {w, h}
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end
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--]]
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