introduce delay

README.md

@@ -5,7 +5,7 @@ Install dependencies:
 
 ```
 # ubuntu
-sudo apt install libgl-dev libxcursor-dev libx11-xcb-dev libxcb-icccm4-dev libxcb-dri2-0-dev libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev
+sudo apt install pkg-config libgl-dev libxcursor-dev libx11-xcb-dev libxcb-icccm4-dev libxcb-dri2-0-dev libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev
 ```
 
 Build:

loudness_limiter/src/lib.rs

@@ -18,6 +18,8 @@ struct LoudnessLimiter {
 
     power_envelope: jimtel::envelope::Envelope,
     loudness_power_envelope: jimtel::envelope::Envelope,
+
+    delay_buffer: jimtel::delay_buffer::DelayBuffer,
 }
 
 impl Plugin for LoudnessLimiter {
@@ -32,6 +34,8 @@ impl Plugin for LoudnessLimiter {
 
             power_envelope: jimtel::envelope::Envelope::new(sample_rate_hz),
             loudness_power_envelope: jimtel::envelope::Envelope::new(sample_rate_hz),
+
+            delay_buffer: jimtel::delay_buffer::DelayBuffer::new(0),
         }
     }
 
@@ -72,6 +76,8 @@ impl Plugin for LoudnessLimiter {
 
         let silence_beyond_power_limit = self.params.silence_beyond_power.get();
 
+        let delay_samples = (self.params.delay.get() / 1000.0 * self.sample_rate_hz) as usize;
+
         self.loudness.set_samples_num_per_windows(
             samples_num_per_loudness_window,
             samples_num_per_power_window,
@@ -81,6 +87,8 @@ impl Plugin for LoudnessLimiter {
         self.loudness_power_envelope
             .set_coefficients(loudness_attack_ms, loudness_release_ms);
 
+        self.delay_buffer.set_delay(delay_samples);
+
         for (in_left, in_right, out_left, out_right) in itertools::izip!(
             in_left_buffer.get(0),
             in_right_buffer.get(0),
@@ -107,8 +115,9 @@ impl Plugin for LoudnessLimiter {
             let gain =
                 input_gain * output_gain * (loudness_coefficient * power_limit_coefficient).sqrt();
 
-            *out_left = in_left * gain;
-            *out_right = in_right * gain;
+            let (delayed_in_left, delayed_in_right) = self.delay_buffer.add(*in_left, *in_right);
+            *out_left = delayed_in_left * gain;
+            *out_right = delayed_in_right * gain;
         }
     }
 
@@ -120,7 +129,7 @@ impl Plugin for LoudnessLimiter {
         Some(Box::new(Editor::new(
             "Jimtel Loudness Limiter".to_string(),
             1280.0,
-            480.0,
+            640.0,
             self.params.clone(),
         )))
     }

loudness_limiter/src/params.rs

@@ -13,7 +13,7 @@ pub struct LoudnessLimiterParams {
     #[param(kind = "LKFS", min = "-80", max = "0")]
     pub loudness: AtomicFloat,
 
-    #[param(kind = "ms", min = "100", max = "10000")]
+    #[param(kind = "ms", min = "1", max = "1000")]
     pub loudness_window: AtomicFloat,
 
     #[param(kind = "ms", min = "0", max = "1000")]
@@ -33,6 +33,9 @@ pub struct LoudnessLimiterParams {
 
     #[param(kind = "checkbox", min = "0", max = "1")]
     pub silence_beyond_power: AtomicFloat,
+
+    #[param(kind = "ms", min = "0", max = "1000")]
+    pub delay: AtomicFloat,
 }
 
 impl LoudnessLimiterParams {
@@ -51,6 +54,7 @@ impl LoudnessLimiterParams {
             power_window: AtomicFloat::new(6.0),
             power_release: AtomicFloat::new(10000.0),
             silence_beyond_power: AtomicFloat::new(0.0),
+            delay: AtomicFloat::new(0.0),
         }
     }
 }

src/delay_buffer.rs

@@ -0,0 +1,62 @@
+pub struct DelayBuffer {
+    delay: usize,
+    buffer: Vec<(f32, f32)>,
+    current_index: usize,
+}
+
+impl DelayBuffer {
+    pub fn new(delay: usize) -> Self {
+        Self {
+            delay,
+            buffer: vec![(0.0, 0.0); delay + 1],
+            current_index: 0,
+        }
+    }
+
+    #[inline(always)]
+    pub fn add(&mut self, current_left_value: f32, current_right_value: f32) -> (f32, f32) {
+        self.buffer[self.current_index] = (current_left_value, current_right_value);
+
+        self.current_index += 1;
+        if self.current_index >= self.buffer.len() {
+            self.current_index = 0;
+        }
+
+        self.buffer[self.current_index]
+    }
+
+    #[inline(always)]
+    pub fn set_delay(&mut self, delay: usize) {
+        if delay != self.delay {
+            self.current_index = 0;
+            self.delay = delay;
+            self.buffer = vec![(0.0, 0.0); delay + 1];
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::DelayBuffer;
+
+    #[test]
+    fn no_delay() {
+        let mut buffer = DelayBuffer::new(0);
+
+        assert_eq!(buffer.add(1.0, 2.0), (1.0, 2.0));
+        assert_eq!(buffer.add(3.0, 4.0), (3.0, 4.0));
+    }
+
+    #[test]
+    fn some_delay() {
+        let mut buffer = DelayBuffer::new(3);
+
+        assert_eq!(buffer.add(1.0, 2.0), (0.0, 0.0));
+        assert_eq!(buffer.add(3.0, 4.0), (0.0, 0.0));
+        assert_eq!(buffer.add(5.0, 6.0), (0.0, 0.0));
+        assert_eq!(buffer.add(7.0, 8.0), (1.0, 2.0));
+        assert_eq!(buffer.add(8.0, 9.0), (3.0, 4.0));
+        assert_eq!(buffer.add(10.0, 11.0), (5.0, 6.0));
+        assert_eq!(buffer.add(12.0, 13.0), (7.0, 8.0));
+    }
+}

src/lib.rs

@@ -1,6 +1,7 @@
+pub mod delay_buffer;
 pub mod editor;
 pub mod envelope;
 pub mod loudness;
 pub mod params;
-pub mod window_handle;
 pub mod sum_buffer;
+pub mod window_handle;