58 lines
1.6 KiB
Rust
58 lines
1.6 KiB
Rust
/// Very small amount
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const VSA: f32 = 1.0 / 4294967295.0;
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/// Splits the input into three bands
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#[derive(Default)]
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pub struct ThreeBandSplitter {
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// Filter #1 (Low band)
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f1p0: f32, // Poles ...
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f1p1: f32,
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f1p2: f32,
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f1p3: f32,
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// Filter #2 (High band)
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f2p0: f32, // Poles ...
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f2p1: f32,
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f2p2: f32,
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f2p3: f32,
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// Sample history buffer
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sdm1: f32, // Sample data minus 1
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sdm2: f32, // 2
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sdm3: f32, // 3
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}
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impl ThreeBandSplitter {
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/// Returns (low, mid, high) bands
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pub fn process(&mut self, input: f32, lf: f32, hf: f32, sample_rate: f32) -> (f32, f32, f32) {
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let lf = 2.0 * (std::f32::consts::PI * (lf / sample_rate)).sin();
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let hf = 2.0 * (std::f32::consts::PI * (hf / sample_rate)).sin();
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// Filter #1 (low pass)
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self.f1p0 += lf * (input - self.f1p0) + VSA;
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self.f1p1 += lf * (self.f1p0 - self.f1p1);
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self.f1p2 += lf * (self.f1p1 - self.f1p2);
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self.f1p3 += lf * (self.f1p2 - self.f1p3);
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let l = self.f1p3;
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// Filter #2 (high pass)
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self.f2p0 += hf * (input - self.f2p0) + VSA;
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self.f2p1 += hf * (self.f2p0 - self.f2p1);
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self.f2p2 += hf * (self.f2p1 - self.f2p2);
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self.f2p3 += hf * (self.f2p2 - self.f2p3);
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// we subtract from sdm3 because the filter has a three sample delay
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let h = self.sdm3 - self.f2p3;
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// Calculate midrange (signal - (low + high))
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let m = self.sdm3 - (h + l);
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// Shuffle history buffer
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self.sdm3 = self.sdm2;
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self.sdm2 = self.sdm1;
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self.sdm1 = input;
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(l, m, h)
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}
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}
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