ardour { ["type"] = "dsp", name = "ACE Slow-Mute", category = "Amplifier", license = "MIT", author = "Ardour Community", description = [[Mute button with slow fade in/out (approx. 1sec exponential)]] } function dsp_ioconfig () -- -1, -1 = any number of channels as long as input and output count matches return { { audio_in = -1, audio_out = -1} } end function dsp_params () return { { ["type"] = "input", name = "Mute", min = 0, max = 1, default = 0, toggled = true } } end local cur_gain = 1 local lpf = 0.002 -- parameter low-pass filter time-constant function dsp_init (rate) lpf = 100 / rate -- interpolation time constant 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 -- the DSP callback function -- "ins" and "outs" are http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray function dsp_run (ins, outs, n_samples) local ctrl = CtrlPorts:array() -- get control port array local target_gain = ctrl[1] > 0 and 0.0 or 1.0; -- when muted, target_gain = 0.0; otherwise use 1.0 local siz = n_samples -- samples remaining to process local off = 0 -- already processed samples local changed = false -- if the target gain changes, process at most 32 samples at a time, -- and interpolate gain until the current settings match the target values if cur_gain ~= target_gain then changed = true siz = 32 end while n_samples > 0 do if siz > n_samples then siz = n_samples end if changed then cur_gain = low_pass_filter_param (cur_gain, target_gain, 0.001) end for c = 1,#ins do -- process all channels if ins[c] ~= outs[c] then ARDOUR.DSP.copy_vector (outs[c]:offset (off), ins[c]:offset (off), siz) end ARDOUR.DSP.apply_gain_to_buffer (outs[c]:offset (off), siz, cur_gain); end n_samples = n_samples - siz off = off + siz end end