56 lines
1.3 KiB
Text
56 lines
1.3 KiB
Text
// A dense stereo reverb: four blocks in one loop, each block two allpasses
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// then a delay, a damping low-pass and the decay gain; the input enters at
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// every block head and the blocks' outputs alternate left and right.
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let AP_LEN = [263, 863, 1319, 1433, 439, 359, 887, 1399]
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let DL_LEN = [233, 1367, 4253, 2903]
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let decay = param(0.6, 0, 0.95)
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let damp = param(0.3, 0, 0.9)
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let mix = param(0.3, 0, 1)
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struct Allpass {
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buf: [0.0; 2048]
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w: int(0)
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}
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struct Delay {
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buf: [0.0; 8192]
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w: int(0)
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}
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var aps = [Allpass{}; 8]
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var dls = [Delay{}; 4]
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var lp = [0.0; 4]
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var fb = 0.0
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fn allpass(ap, x, len, g) {
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let d = ap.buf[ap.w - len]
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let v = x + g * d
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ap.buf[ap.w] = v
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ap.w = ap.w + 1
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d - g * v
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}
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fn effect(l, r) {
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let input = (l + r) * 0.5
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let x = fb
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let wl = 0.0
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let wr = 0.0
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for b in 0..4 {
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x = x + input
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x = allpass(aps[2 * b], x, int(AP_LEN[2 * b]), 0.5)
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x = allpass(aps[2 * b + 1], x, int(AP_LEN[2 * b + 1]), 0.5)
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let dl = dls[b]
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let y = dl.buf[dl.w - int(DL_LEN[b])]
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dl.buf[dl.w] = x
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dl.w = dl.w + 1
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lp[b] = lp[b] + (y - lp[b]) * (1.0 - damp)
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x = lp[b] * decay
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if b % 2 == 0 {
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wl = wl + y
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} else {
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wr = wr + y
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}
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}
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fb = x
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vec2(l + (wl * 0.5 - l) * mix, r + (wr * 0.5 - r) * mix)
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}
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