add hamming window

3 files changed, 78 insertions, 146 deletions

diff --git a/src/window_function.rs b/src/window_function.rs
index b0ed54d..09c5d31 100644
--- a/src/window_function.rs
+++ b/src/window_function.rs
@@ -11,11 +11,9 @@ pub trait WindowFunction: Send {
     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);
 }
 
-/// Effectively a chunking function rather than a sliding window
+/// Effectively a chunking function
 pub struct RectangularWindow {
     window_size: usize,
 }
@@ -36,102 +34,114 @@ impl WindowFunction for RectangularWindow {
     fn needed(&self) -> usize {
         self.window_size
     }
-
-    fn window_size(&mut self, _window_size: WindowSize) {
-        todo!()
-    }
 }
 
-/// A window designed specifically to reduce clicking and leave all other artifacts
-/// Results vary
-pub struct HaemolacriaaWindow {
+/// Hann function
+pub struct HannWindow {
     window_size: usize,
-    function_start: Vec<f32>,
-    function_end: Vec<f32>,
+    function: Vec<f32>,
+    normalize: Vec<f32>,
     previous: Vec<f32>,
     overlap_add: Vec<f32>,
 }
 
-impl HaemolacriaaWindow {
-    /// Ensure this value isn't greater than or equal to any default window size
-    const SAMPLE_COUNT: usize = 16;
-
+impl HannWindow {
     pub fn new(window_size: &WindowSize) -> Self {
         let window_size = window_size.inner();
-        let sample_count_f32 = Self::SAMPLE_COUNT as f32;
+        let half_window_size = window_size / 2;
+        let window_size_f32 = window_size as f32;
 
-        let overlap_add = vec![0.0; Self::SAMPLE_COUNT];
+        // 50% overlap
+        let overlap_add = vec![0.0; window_size];
+
+        // with capacity is important for the first needed samples
+        let previous = Vec::with_capacity(half_window_size);
 
-        let function_start = (0..Self::SAMPLE_COUNT)
+        let function = (0..window_size)
             .map(|i| {
-                let x = i as f32 / (sample_count_f32 - 1.0);
+                let i = i as f32;
 
-                f32::sin(PI * 0.5 * x)
+                0.5 * (1.0 - f32::cos((2.0 * PI * i) / (window_size_f32)))
             })
             .collect::<Vec<f32>>();
 
-        let function_end = (0..Self::SAMPLE_COUNT)
+        let normalize = (0..half_window_size)
             .map(|i| {
-                let x = i as f32 / (sample_count_f32 - 1.0);
-
-                f32::cos(PI * 0.5 * x)
+                (function[i] * function[i])
+                    + (function[i + half_window_size] * function[i + half_window_size])
             })
             .collect::<Vec<f32>>();
 
-        let previous = Vec::with_capacity(Self::SAMPLE_COUNT);
-
         Self {
             window_size,
-            function_start,
-            function_end,
+            function,
+            normalize,
             previous,
             overlap_add,
         }
     }
 }
 
-impl WindowFunction for HaemolacriaaWindow {
+impl WindowFunction for HannWindow {
     fn apply(&mut self, data: &mut VecDeque<f32>) {
-        let last_few = self.window_size - Self::SAMPLE_COUNT;
+        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() {
-            for sample in data.iter().skip(last_few).copied() {
+            // 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);
             }
 
-            for i in 0..Self::SAMPLE_COUNT {
-                data[i] *= self.function_start[i];
-                data[last_few + i] *= self.function_end[i];
+            // 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
         for sample in self.previous.iter().rev().copied() {
             data.push_front(sample);
         }
 
         self.previous.clear();
 
-        for sample in data.iter().skip(last_few).copied() {
+        // keep this iteration's samples for the next window
+        for sample in data.iter().skip(half_window_size).copied() {
             self.previous.push(sample);
         }
 
-        for i in 0..Self::SAMPLE_COUNT {
-            data[i] *= self.function_start[i];
-            data[last_few + i] *= self.function_end[i];
+        // apply the function
+        for (i, sample) in data.iter_mut().enumerate() {
+            *sample *= self.function[i];
         }
     }
 
     fn reverse(&mut self, data: &mut [f32]) {
-        let last_few = self.window_size - Self::SAMPLE_COUNT;
+        let half_window_size = self.window_size / 2;
 
-        for (i, sample) in data.iter_mut().take(Self::SAMPLE_COUNT).enumerate() {
-            *sample += self.overlap_add[i];
+        // overlap add data and save the next overlap (latter half of this buffer)
+        for (i, sample) in data.iter().copied().enumerate() {
+            self.overlap_add[i] += sample * self.function[i];
         }
 
-        for (i, sample) in data.iter().skip(last_few).copied().enumerate() {
-            self.overlap_add[i] = sample;
+        // normalize the output
+        for (i, sample) in data.iter_mut().enumerate().take(half_window_size) {
+            if self.normalize[i] > 1e-6 {
+                *sample = self.overlap_add[i] / self.normalize[i];
+            } else {
+                *sample = 0.0;
+            }
+        }
+
+        // shift the saved overlap to become the next overlap
+        self.overlap_add.rotate_left(half_window_size);
+
+        // clear a spot for the overlap next time
+        for sample in &mut self.overlap_add[half_window_size..] {
+            *sample = 0.0;
         }
     }
 
@@ -139,17 +149,13 @@ impl WindowFunction for HaemolacriaaWindow {
         if self.previous.is_empty() {
             self.window_size
         } else {
-            self.window_size - Self::SAMPLE_COUNT
+            self.window_size / 2
         }
     }
-
-    fn window_size(&mut self, _window_size: WindowSize) {
-        todo!()
-    }
 }
 
-/// Hann function
-pub struct HannWindow {
+/// Hamming function
+pub struct HammingWindow {
     window_size: usize,
     function: Vec<f32>,
     normalize: Vec<f32>,
@@ -157,27 +163,25 @@ pub struct HannWindow {
     overlap_add: Vec<f32>,
 }
 
-impl HannWindow {
+impl HammingWindow {
     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 previous = Vec::with_capacity(half_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)))
+                0.53836 - (0.46164 * f32::cos((2.0 * PI * i) / (window_size_f32)))
             })
             .collect::<Vec<f32>>();
-
-        let normalize = (0..half_window_size)
+			
+		let normalize = (0..half_window_size)
             .map(|i| {
                 (function[i] * function[i])
                     + (function[i + half_window_size] * function[i + half_window_size])
@@ -194,18 +198,15 @@ impl HannWindow {
     }
 }
 
-impl WindowFunction for HannWindow {
+impl WindowFunction for HammingWindow {
     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];
             }
@@ -213,19 +214,16 @@ impl WindowFunction for HannWindow {
             return;
         }
 
-        // In a real time "sliding window" it's necessary to add in the previous samples
         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];
         }
@@ -260,32 +258,6 @@ impl WindowFunction for HannWindow {
             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>>();
-    }
 }
 
 /// 4-term Blackman-Harris window function
@@ -317,9 +289,9 @@ impl BlackmanHarrisWindow {
             .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));
+                let two = f32::cos((2.0 * PI * i) / (window_size_f32));
+                let four = f32::cos((4.0 * PI * i) / (window_size_f32));
+                let six = f32::cos((6.0 * PI * i) / (window_size_f32));
 
                 Self::A_0 - (Self::A_1 * two) + (Self::A_2 * four) - (Self::A_3 * six)
             })
@@ -406,45 +378,9 @@ impl WindowFunction for BlackmanHarrisWindow {
             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>>();
-    }
 }
 
-/// 4th order power of sine window function
+/// 4th power of sine window function
 pub struct Sine4Window {
     window_size: usize,
     function: Vec<f32>,
@@ -472,8 +408,8 @@ impl Sine4Window {
             .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 two = f32::cos((2.0 * PI * i) / (window_size_f32));
+                let four = f32::cos((4.0 * PI * i) / (window_size_f32));
 
                 Self::A_0 - (Self::A_1 * two) + (Self::A_2 * four)
             })
@@ -560,8 +496,4 @@ impl WindowFunction for Sine4Window {
             self.window_size / 4
         }
     }
-
-    fn window_size(&mut self, window_size: WindowSize) {
-        todo!()
-    }
 }
diff --git a/src/window_type.rs b/src/window_type.rs
index 06c87be..acbf727 100644
--- a/src/window_type.rs
+++ b/src/window_type.rs
@@ -3,16 +3,16 @@
 
 use crate::{
     window_function::{
-        BlackmanHarrisWindow, HaemolacriaaWindow, HannWindow, RectangularWindow, Sine4Window,
-        WindowFunction,
+        BlackmanHarrisWindow, HammingWindow, HannWindow, RectangularWindow,
+        Sine4Window, WindowFunction,
     },
     window_size::WindowSize,
 };
 
 pub enum WindowType {
     Rectangular,
-    Haemolacriaa,
     Hann,
+    Hamming,
     BlackmanHarris,
     Sine4,
 }
@@ -21,8 +21,8 @@ impl WindowType {
     fn into_function(self, window_size: &WindowSize) -> Box<dyn WindowFunction> {
         match self {
             Self::Rectangular => Box::new(RectangularWindow::new(window_size)),
-            Self::Haemolacriaa => Box::new(HaemolacriaaWindow::new(window_size)),
             Self::Hann => Box::new(HannWindow::new(window_size)),
+            Self::Hamming => Box::new(HammingWindow::new(window_size)),
             Self::BlackmanHarris => Box::new(BlackmanHarrisWindow::new(window_size)),
             Self::Sine4 => Box::new(Sine4Window::new(window_size)),
         }
@@ -31,8 +31,8 @@ impl WindowType {
     pub fn as_str(&self) -> &'static str {
         match self {
             Self::Rectangular => "Rectangular",
-            Self::Haemolacriaa => "haemolacriaa",
             Self::Hann => "Hann",
+            Self::Hamming => "Hamming",
             Self::BlackmanHarris => "Blackman-Harris",
             Self::Sine4 => "Sin^4",
         }
@@ -41,8 +41,8 @@ impl WindowType {
     pub fn iter() -> impl Iterator<Item = Self> {
         [
             Self::Rectangular,
-            Self::Haemolacriaa,
             Self::Hann,
+            Self::Hamming,
             Self::BlackmanHarris,
             Self::Sine4,
         ]
diff --git a/src/windowed_fft.rs b/src/windowed_fft.rs
index 19bf566..3e4e648 100644
--- a/src/windowed_fft.rs
+++ b/src/windowed_fft.rs
@@ -5,7 +5,7 @@
 
 use crate::{
     window_function::{
-        BlackmanHarrisWindow, HaemolacriaaWindow, HannWindow, RectangularWindow, Sine4Window,
+        BlackmanHarrisWindow, HannWindow, RectangularWindow, Sine4Window, HammingWindow,
         WindowFunction,
     },
     window_size::WindowSize,
@@ -28,7 +28,7 @@ pub struct WindowedRealFft {
 
 impl WindowedRealFft {
     pub fn new(window_size: WindowSize) -> Self {
-        let window_function = Box::new(HaemolacriaaWindow::new(&window_size));
+        let window_function = Box::new(HannWindow::new(&window_size));
         let window_size = window_size.inner();
 
         let mut planner = RealFftPlanner::new();
@@ -63,7 +63,7 @@ impl WindowedRealFft {
             return;
         }
 
-        self.window_function = Box::new(HaemolacriaaWindow::new(&window_size));
+        self.window_function = Box::new(HannWindow::new(&window_size));
         self.window_size = window_size.inner();
 
         self.forward = self.planner.plan_fft_forward(self.window_size);