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ardour {
["type"] = "dsp",
name = "a-b Switch",
category = "Amplifier",
license = "MIT",
author = "Ardour Team",
description = [[Auotomatable A/B Input Select. Channels are mapped in pairs: In 1/2 -> Out 1, In 3/4 -> Out 2, etc.]]
}
function dsp_ioconfig ()
return {
-- in theory any combination with N_in = 2 * N_out is possible
-- (and we should inform the host to override strict-i/o
-- connect_all_audio_outputs = true)
{ audio_in = 2, audio_out = 1},
{ audio_in = 4, audio_out = 2},
{ audio_in = 8, audio_out = 4},
}
end
function dsp_params ()
return { { ["type"] = "input", name = "A/B", min = 0, max = 1, default = 0, toggled = true } }
end
local sr = 48000
local cur_a = 0.0
local cur_b = 0.0
function dsp_init (rate)
sr = rate
end
function dsp_configure (ins, outs)
n_ainp = ins:n_audio ()
n_aout = outs:n_audio ()
assert (n_aout * 2 == n_ainp)
end
-- the DSP callback function
function dsp_runmap (bufs, in_map, out_map, n_samples, offset)
local ctrl = CtrlPorts:array() -- get control port array
local target_A = ctrl[1] > 0 and 0.0 or 1.0
local target_B = 1 - target_A
local gA = cur_a
local gB = cur_b
for c = 1, n_aout do
local o = out_map:get (ARDOUR.DataType ("audio"), c - 1)
if o == ARDOUR.ChanMapping.Invalid then
goto next
end
local in_a = c * 2 - 1
local in_b = c * 2
local ia = in_map:get (ARDOUR.DataType ("audio"), in_a - 1)
local ib = in_map:get (ARDOUR.DataType ("audio"), in_b - 1)
local buf_aout = bufs:get_audio(o)
-- optimize fixed gain case
if cur_a == target_A and cur_b == target_B then
if target_A == 1.0 then
-- the first (and only first) channel may be in-place
if buf_aout ~= bufs:get_audio(ia) then
buf_aout:read_from (bufs:get_audio(ia):data (0), n_samples, offset, offset)
end
else
assert (buf_aout ~= bufs:get_audio(ib))
buf_aout:read_from (bufs:get_audio(ib):data (0), n_samples, offset, offset)
end
goto next
end
-- apply gain to each input channel
if ia ~= ARDOUR.ChanMapping.Invalid and ia ~= ib then
cur_a = ARDOUR.Amp.apply_gain (bufs:get_audio(ia), sr, n_samples, gA, target_A, offset)
end
if ib ~= ARDOUR.ChanMapping.Invalid and ia ~= ib then
cur_b = ARDOUR.Amp.apply_gain (bufs:get_audio(ib), sr, n_samples, gB, target_B, offset)
end
-- channels are supposed to be in linear order
assert (buf_aout ~= bufs:get_audio(ib))
-- copy input to output if needed (first channel may be in-place)
if buf_aout ~= bufs:get_audio(ia) then
buf_aout:read_from (bufs:get_audio(ia):data (0), n_samples, offset, offset)
end
-- add the second buffer
ARDOUR.DSP.mix_buffers_no_gain (buf_aout:data (offset), bufs:get_audio(ib):data (offset), n_samples)
::next::
end
end
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