]> git.nihav.org Git - nihav.git/blame - nihav-core/src/dsp/window.rs
realmedia: fix some clippy warnings
[nihav.git] / nihav-core / src / dsp / window.rs
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e35062e7
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1use std::f32::consts;
2
3#[derive(Debug,Clone,Copy,PartialEq)]
4pub enum WindowType {
5 Square,
6 Sine,
9669f269 7 KaiserBessel(f32),
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8}
9
10pub fn generate_window(mode: WindowType, scale: f32, size: usize, half: bool, dst: &mut [f32]) {
11 match mode {
12 WindowType::Square => {
13 for n in 0..size { dst[n] = scale; }
14 },
15 WindowType::Sine => {
16 let param;
17 if half {
18 param = consts::PI / ((2 * size) as f32);
19 } else {
20 param = consts::PI / (size as f32);
21 }
22 for n in 0..size {
23 dst[n] = (((n as f32) + 0.5) * param).sin() * scale;
24 }
25 },
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26 WindowType::KaiserBessel(alpha) => {
27 let dlen = if half { size as f32 } else { (size as f32) * 0.5 };
28 let alpha2 = ((alpha * consts::PI / dlen) * (alpha * consts::PI / dlen)) as f64;
29
30 let mut kb: Vec<f64> = Vec::with_capacity(size);
31 let mut sum = 0.0;
32 for n in 0..size {
33 let b = bessel_i0(((n * (size - n)) as f64) * alpha2);
34 sum += b;
35 kb.push(sum);
36 }
37 sum += 1.0;
38 for n in 0..size {
39 dst[n] = (kb[n] / sum).sqrt() as f32;
40 }
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41 },
42 };
43}
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44
45fn bessel_i0(inval: f64) -> f64 {
46 let mut val: f64 = 1.0;
47 for n in (1..64).rev() {
48 val *= inval / ((n * n) as f64);
49 val += 1.0;
50 }
51 val
52}