From dbcc5373fab41d876f4495463d76c1ab28c9d670 Mon Sep 17 00:00:00 2001
From: Eskil Q <eskilq@kth.se>
Date: Sun, 27 Dec 2020 15:43:58 +0100
Subject: create noise-gate struct

---
 Cargo.lock        |  3 +++
 mumd/Cargo.toml   |  3 +++
 mumd/src/audio.rs | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index 945a736..e8e5cd5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1161,7 +1161,10 @@ dependencies = [
  "argparse",
  "bytes 0.5.6",
  "cpal",
+ "dasp_frame",
  "dasp_interpolate",
+ "dasp_ring_buffer",
+ "dasp_sample",
  "dasp_signal",
  "futures",
  "futures-util",
diff --git a/mumd/Cargo.toml b/mumd/Cargo.toml
index 7f014bd..e548559 100644
--- a/mumd/Cargo.toml
+++ b/mumd/Cargo.toml
@@ -23,6 +23,9 @@ bytes = "0.5"
 cpal = "0.13"
 dasp_interpolate = { version = "0.11", features = ["linear"] }
 dasp_signal = "0.11"
+dasp_frame = "0.11"
+dasp_sample = "0.11"
+dasp_ring_buffer = "0.11"
 futures = "0.3"
 futures-util = "0.3"
 hound = "3.4"
diff --git a/mumd/src/audio.rs b/mumd/src/audio.rs
index 8f9e2ab..bed9ceb 100644
--- a/mumd/src/audio.rs
+++ b/mumd/src/audio.rs
@@ -14,6 +14,9 @@ use std::collections::hash_map::Entry;
 use std::collections::{HashMap, VecDeque};
 use std::sync::{Arc, Mutex};
 use tokio::sync::{mpsc, watch};
+use dasp_frame::Frame;
+use dasp_sample::{Sample, SignedSample};
+use dasp_ring_buffer::Fixed;
 
 //TODO? move to mumlib
 pub const EVENT_SOUNDS: &[(&'static [u8], NotificationEvents)] = &[
@@ -354,3 +357,65 @@ impl Audio {
         play_sounds.extend(samples.iter().skip(l));
     }
 }
+
+struct NoiseGate<S: Signal> {
+    open: bool,
+    signal: S,
+    buffer: dasp_ring_buffer::Fixed<Vec<S::Frame>>,
+    activate_threshold: <<S::Frame as Frame>::Sample as Sample>::Float,
+    deactivate_threshold: <<S::Frame as Frame>::Sample as Sample>::Float,
+}
+
+impl<S: Signal> NoiseGate<S> {
+    pub fn new(signal: S, activate_threshold: <<S::Frame as Frame>::Sample as Sample>::Float, deactivate_threshold: <<S::Frame as Frame>::Sample as Sample>::Float) -> NoiseGate<S> {
+        Self {
+            open: false,
+            signal,
+            buffer: Fixed::from(vec![<S::Frame as Frame>::EQUILIBRIUM; 4096]),
+            activate_threshold,
+            deactivate_threshold,
+        }
+    }
+}
+
+impl<S: Signal> Signal for NoiseGate<S> {
+    type Frame = S::Frame;
+
+    fn next(&mut self) -> Self::Frame {
+        let frame = self.signal.next();
+        self.buffer.push(frame);
+
+        if self.open && self.buffer
+            .iter()
+            .all(|f| f.to_float_frame()
+                .channels()
+                .all(|s| abs(s - <<<S::Frame as Frame>::Sample as Sample>::Float as Sample>::EQUILIBRIUM) <= self.deactivate_threshold)) {
+            self.open = false;
+        } else if !self.open && self.buffer
+            .iter()
+            .any(|f| f.to_float_frame()
+                .channels()
+                .any(|s| abs(s - <<<S::Frame as Frame>::Sample as Sample>::Float as Sample>::EQUILIBRIUM) >= self.activate_threshold)) {
+            self.open = true;
+        }
+
+        if self.open {
+            frame
+        } else {
+            S::Frame::EQUILIBRIUM
+        }
+    }
+
+    fn is_exhausted(&self) -> bool {
+        self.signal.is_exhausted()
+    }
+}
+
+fn abs<S: SignedSample>(sample: S) -> S {
+    let zero = S::EQUILIBRIUM;
+    if sample >= zero {
+        sample
+    } else {
+        -sample
+    }
+}
\ No newline at end of file
-- 
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