1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
|
ardour {
["type"] = "dsp",
name = "a-High/Low Pass Filter",
category = "Filter",
license = "MIT",
author = "Ardour Team",
description = [[Example Ardour Lua DSP Plugin]]
}
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 = "Type", min = 0, max = 1, default = 0, enum = true, scalepoints =
{
["High Pass"] = 0,
["Low Pass"] = 1,
}
},
{ ["type"] = "input", name = "Steepness", min = 1, max = 4, default = 1, enum = true, scalepoints =
{
["12dB/oct"] = 1,
["24dB/oct"] = 2,
["36dB/oct"] = 3,
["48dB/oct"] = 4,
}
},
{ ["type"] = "input", name = "Cut off frequency", min = 5, max = 20000, default = 1000, unit="Hz", logarithmic = true },
{ ["type"] = "input", name = "Resonance", min = 0.1, max = 8, default = .707, logarithmic = true },
}
end
-- translate type parameter to DSP enum
-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR.DSP.Biquad.Type
function map_type (t)
if t == 1 then
return ARDOUR.DSP.BiquadType.LowPass
else
return ARDOUR.DSP.BiquadType.HighPass
end
end
-- these globals are *not* shared between DSP and UI
local filters = {} -- the biquad filter instances (DSP)
local filt -- the biquad filter instance (GUI, response)
local cur = {0, 0, 0, 0} -- current parameters
local lpf = 0.03 -- parameter low-pass filter time-constant
local chn = 0 -- channel/filter count
function dsp_init (rate)
self:shmem ():allocate (1) -- shared mem to tell the GUI the samplerate
local cfg = self:shmem ():to_int (0):array ()
cfg[1] = rate
lpf = 13000 / rate -- interpolation time constant
end
function dsp_configure (ins, outs)
assert (ins:n_audio () == outs:n_audio ())
local cfg = self:shmem ():to_int (0):array ()
local rate = cfg[1]
chn = ins:n_audio ()
for c = 1, chn do
filters[c] = {}
-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP:Biquad
for k = 1,4 do
filters[c][k] = ARDOUR.DSP.Biquad (rate) -- initialize filters
end
end
cur = {0, 0, 0, 0}
end
-- helper functions for parameter interpolation
function param_changed (ctrl)
if math.floor(ctrl[1]) == math.floor(cur[1]) and math.floor(ctrl[2]) == math.floor(cur[2]) and ctrl[3] == cur[3] and ctrl[4] == cur[4] then
return false
end
return true
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
if cur[1] ~= ctrl[1] or cur[2] ~= ctrl[2] then
-- reset filter state when type or order changes
for c = 1, chn do
for k = 1,4 do
filters[c][k]:reset ()
end
end
for k = 1,4 do cur[k] = ctrl[k] end
else
-- low-pass filter ctrl parameter values, smooth transition
cur[3] = low_pass_filter_param (cur[3], ctrl[3], 1.0) -- freq/Hz
cur[4] = low_pass_filter_param (cur[4], ctrl[4], 0.01) -- quality
end
if cur[2] < 1 then cur[2] = 1 end
if cur[2] > 4 then cur[2] = 4 end
for c = 1, chn do
for k = 1,4 do
filters[c][k]:compute (map_type (cur[1]), cur[3], cur[4], 0)
end
end
end
-- the actual DSP callback
function dsp_run (ins, outs, n_samples)
local changed = false
local siz = n_samples
local off = 0
-- if a parameter was changed, process at most 64 samples at a time
-- and interpolate parameters until the current settings match
-- the target values
if param_changed (CtrlPorts:array ()) then
changed = true
siz = 64
end
local o = math.floor(cur[2])
while n_samples > 0 do
if changed then apply_params (CtrlPorts:array ()) end
if siz > n_samples then siz = n_samples end
-- process all channels
for c = 1,#ins do
-- check if output and input buffers for this channel are identical
-- http://manual.ardour.org/lua-scripting/class_reference/#C:FloatArray
if not ins[c]:sameinstance (outs[c]) then
-- http://manual.ardour.org/lua-scripting/class_reference/#ARDOUR:DSP
ARDOUR.DSP.copy_vector (outs[c]:offset (off), ins[c]:offset (off), siz)
end
for k = 1,o do
filters[c][k]:run (outs[c]:offset (off), siz) -- in-place processing
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)
-- x-axis pixel for given freq, power-scale
return 20 * 1000 ^ (x / w)
end
function x_at_freq (f, w)
-- frequency at given x-axis pixel
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
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 render_inline (ctx, w, max_h)
if not filt then
-- the GUI is separate from the DSP, but the GUI needs to know
-- the sample-rate that the DSP is using.
local shmem = self:shmem () -- get shared memory region
local cfg = shmem:to_int (0):array () -- "cast" into lua-table
-- instantiate filter (to calculate the transfer function's response)
filt = ARDOUR.DSP.Biquad (cfg[1])
end
-- set filter coefficients if they have changed
if param_changed (CtrlPorts:array ()) then
local ctrl = CtrlPorts:array ()
for k = 1,4 do cur[k] = ctrl[k] end
if cur[2] < 1 then cur[2] = 1 end
if cur[2] > 4 then cur[2] = 4 end
filt:compute (map_type (cur[1]), cur[3], cur[4], 0)
end
-- calc height of inline display
local h = math.ceil (w * 10 / 16) -- use 16:10 aspect
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
-- Note: a cairo pixel at [1,1] spans [0.5->1.5 , 0.5->1.5]
-- hence the offset -0.5 in various move_to(), line_to() calls
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
ctx:set_source_rgba (.5, .5, .5, .8)
grid_db (ctx, w, h, 0)
ctx:set_dash (dash3, 2) -- dotted line
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 ()
local o = math.floor(cur[2])
-- draw transfer function line
ctx:set_source_rgba (.8, .8, .8, 1.0)
ctx:move_to (-.5, db_to_y (o * filt:dB_at_freq (freq_at_x (0, w)), h))
for x = 1,w do
local db = o * filt:dB_at_freq (freq_at_x (x, w))
ctx:line_to (-.5 + x, db_to_y (db, h))
end
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
|