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|
use crate::window_size::WindowSize;
use std::{collections::VecDeque, f32::consts::PI};
pub trait WindowFunction: Send {
/// Apply the window in-place
fn apply(&mut self, data: &mut VecDeque<f32>);
/// Reverse the window in-place
fn reverse(&mut self, data: &mut [f32]);
/// Yields the amount of samples still required to apply the window
fn needed(&self) -> usize;
/// Updates the window size
fn window_size(&mut self, window_size: WindowSize);
}
pub struct RectangularWindow {
window_size: usize,
}
impl RectangularWindow {
pub fn new(window_size: &WindowSize) -> Self {
Self {
window_size: window_size.inner(),
}
}
}
impl WindowFunction for RectangularWindow {
fn apply(&mut self, _data: &mut VecDeque<f32>) {}
fn reverse(&mut self, _data: &mut [f32]) {}
fn needed(&self) -> usize {
self.window_size
}
fn window_size(&mut self, _window_size: WindowSize) {}
}
pub struct HannWindow {
window_size: usize,
function: Vec<f32>,
normalize: Vec<f32>,
previous: Vec<f32>,
overlap_add: Vec<f32>,
}
impl HannWindow {
pub fn new(window_size: &WindowSize) -> Self {
let window_size = window_size.inner();
let half_window_size = window_size / 2;
let window_size_f32 = window_size as f32;
// 50% overlap
let overlap_add = vec![0.0; window_size];
// with capacity is important for the first needed samples
let previous = Vec::with_capacity(window_size);
let function = (0..window_size)
.map(|i| {
let i = i as f32;
0.5 * (1.0 - f32::cos((2.0 * PI * i) / (window_size_f32 - 1.0)))
})
.collect::<Vec<f32>>();
let normalize = (0..half_window_size)
.map(|i| {
(function[i] * function[i])
+ (function[i + half_window_size] * function[i + half_window_size])
})
.collect::<Vec<f32>>();
Self {
window_size,
function,
normalize,
previous,
overlap_add,
}
}
}
impl WindowFunction for HannWindow {
fn apply(&mut self, data: &mut VecDeque<f32>) {
let half_window_size = self.window_size / 2;
// the full window size is needed to window over the samples the first time
if self.previous.is_empty() {
// store the latter half for when only half the size is needed
for sample in data.iter().skip(half_window_size).copied() {
self.previous.push(sample);
}
// apply the function
for (i, sample) in data.iter_mut().enumerate() {
*sample *= self.function[i];
}
return;
}
// In a real time "sliding window" it's necessary to add in the previous samples
// to get the full resolution
for sample in self.previous.iter().rev().copied() {
data.push_front(sample);
}
self.previous.clear();
// keep this iteration's samples for the next window
for sample in data.iter().skip(half_window_size).copied() {
self.previous.push(sample);
}
// apply the function
for (i, sample) in data.iter_mut().enumerate() {
*sample *= self.function[i];
}
}
fn reverse(&mut self, data: &mut [f32]) {
let half_window_size = self.window_size / 2;
for i in 0..self.window_size {
self.overlap_add[i] += data[i] * self.function[i];
}
for i in 0..half_window_size {
if self.normalize[i] > 1e-6 {
data[i] = self.overlap_add[i] / self.normalize[i];
} else {
data[i] = 0.0;
}
}
self.overlap_add.rotate_left(half_window_size);
for sample in &mut self.overlap_add[half_window_size..] {
*sample = 0.0;
}
}
fn needed(&self) -> usize {
if self.previous.is_empty() {
self.window_size
} else {
self.window_size / 2
}
}
fn window_size(&mut self, window_size: WindowSize) {
let window_size = window_size.inner();
let half_window_size = window_size / 2;
let window_size_f32 = window_size as f32;
self.overlap_add.resize(window_size, 0.0);
self.previous.clear();
self.previous.reserve_exact(window_size);
self.function = (0..window_size)
.map(|i| {
let i = i as f32;
0.5 * (1.0 - f32::cos((2.0 * PI * i) / (window_size_f32 - 1.0)))
})
.collect::<Vec<f32>>();
self.normalize = (0..half_window_size)
.map(|i| {
(self.function[i] * self.function[i])
+ (self.function[i + half_window_size] * self.function[i + half_window_size])
})
.collect::<Vec<f32>>();
}
}
pub struct BlackmanHarrisWindow {
window_size: usize,
function: Vec<f32>,
normalize: Vec<f32>,
previous: Vec<f32>,
overlap_add: Vec<f32>,
}
impl BlackmanHarrisWindow {
const A_0: f32 = 0.35875;
const A_1: f32 = 0.48829;
const A_2: f32 = 0.14128;
const A_3: f32 = 0.01168;
pub fn new(window_size: &WindowSize) -> Self {
let window_size = window_size.inner();
let quarter_window_size = window_size / 4;
let three_quarters_window_size = 3 * quarter_window_size;
let window_size_f32 = window_size as f32;
let overlap_add = vec![0.0; window_size];
let previous = Vec::with_capacity(three_quarters_window_size);
let function = (0..window_size)
.map(|i| {
let i = i as f32;
let two = f32::cos((2.0 * PI * i) / (window_size_f32 - 1.0));
let four = f32::cos((4.0 * PI * i) / (window_size_f32 - 1.0));
let six = f32::cos((6.0 * PI * i) / (window_size_f32 - 1.0));
Self::A_0 - (Self::A_1 * two) + (Self::A_2 * four) - (Self::A_3 * six)
})
.collect::<Vec<f32>>();
#[rustfmt::skip]
let normalize = (0..quarter_window_size)
.map(|i| {
(function[i] * function[i])
+ (function[i + quarter_window_size] * function[i + quarter_window_size])
+ (function[i + 2 * quarter_window_size] * function[i + 2 * quarter_window_size])
+ (function[i + 3 * quarter_window_size] * function[i + 3 * quarter_window_size])
})
.collect::<Vec<f32>>();
Self {
window_size,
function,
normalize,
previous,
overlap_add,
}
}
}
impl WindowFunction for BlackmanHarrisWindow {
fn apply(&mut self, data: &mut VecDeque<f32>) {
let quarter_window_size = self.window_size / 4;
if self.previous.is_empty() {
for sample in data.iter().skip(quarter_window_size).copied() {
self.previous.push(sample);
}
for (i, sample) in data.iter_mut().enumerate() {
*sample *= self.function[i];
}
return;
}
for sample in self.previous.iter().rev().copied() {
data.push_front(sample);
}
self.previous.clear();
for sample in data.iter().skip(quarter_window_size).copied() {
self.previous.push(sample);
}
for (i, sample) in data.iter_mut().enumerate() {
*sample *= self.function[i];
}
}
fn reverse(&mut self, data: &mut [f32]) {
let quarter_window_size = self.window_size / 4;
let three_quarters_window_size = 3 * quarter_window_size;
for i in 0..self.window_size {
self.overlap_add[i] += data[i] * self.function[i];
}
for i in 0..quarter_window_size {
if self.normalize[i] > 1e-6 {
data[i] = self.overlap_add[i] / self.normalize[i];
} else {
data[i] = 0.0;
}
}
self.overlap_add.rotate_left(quarter_window_size);
for sample in &mut self.overlap_add[three_quarters_window_size..] {
*sample = 0.0;
}
}
fn needed(&self) -> usize {
if self.previous.is_empty() {
self.window_size
} else {
self.window_size / 4
}
}
fn window_size(&mut self, window_size: WindowSize) {
let window_size = window_size.inner();
let quarter_window_size = window_size / 4;
let three_quarters_window_size = 3 * quarter_window_size;
let window_size_f32 = window_size as f32;
self.overlap_add.resize(window_size, 0.0);
self.previous.clear();
self.previous.reserve_exact(window_size);
self.function = (0..window_size)
.map(|i| {
let i = i as f32;
let two = f32::cos((2.0 * PI * i) / (window_size_f32 - 1.0));
let four = f32::cos((4.0 * PI * i) / (window_size_f32 - 1.0));
let six = f32::cos((6.0 * PI * i) / (window_size_f32 - 1.0));
Self::A_0 - (Self::A_1 * two) + (Self::A_2 * four) - (Self::A_3 * six)
})
.collect::<Vec<f32>>();
self.normalize = (0..quarter_window_size)
.map(|i| {
(self.function[i] * self.function[i])
+ (self.function[i + quarter_window_size]
* self.function[i + quarter_window_size])
+ (self.function[i + 2 * quarter_window_size]
* self.function[i + 2 * quarter_window_size])
+ (self.function[i + 3 * quarter_window_size]
* self.function[i + 3 * quarter_window_size])
})
.collect::<Vec<f32>>();
}
}
|
