Use saturating_add for the samples, and fix the mixer

src/conversions/sample.rs

@@ -1,6 +1,4 @@
 use std::marker::PhantomData;
-use std::ops::Add;
-use std::ops::AddAssign;
 use cpal;
 
 /// Converts the samples data type to `O`.
@@ -65,16 +63,18 @@ impl<I, O> ExactSizeIterator for DataConverter<I, O>
 ///
 /// You can implement this trait on your own type as well if you wish so.
 ///
-pub trait Sample: cpal::Sample + Add + AddAssign {
+pub trait Sample: cpal::Sample {
     /// Linear interpolation between two samples.
     ///
     /// The result should be equal to
     /// `first * numerator / denominator + second * (1 - numerator / denominator)`.
-    // TODO: remove ; not necessary
     fn lerp(first: Self, second: Self, numerator: u32, denominator: u32) -> Self;
     /// Multiplies the value of this sample by the given amount.
     fn amplify(self, value: f32) -> Self;
 
+    /// Calls `saturating_add` on the sample.
+    fn saturating_add(self, other: Self) -> Self;
+
     /// Returns the value corresponding to the absence of sound.
     fn zero_value() -> Self;
 
@@ -100,6 +100,11 @@ impl Sample for u16 {
         self.to_i16().amplify(value).to_u16()
     }
 
+    #[inline]
+    fn saturating_add(self, other: u16) -> u16 {
+        self.saturating_add(other)
+    }
+
     #[inline]
     fn zero_value() -> u16 {
         32768
@@ -144,6 +149,11 @@ impl Sample for i16 {
         ((self as f32) * value) as i16
     }
 
+    #[inline]
+    fn saturating_add(self, other: i16) -> i16 {
+        self.saturating_add(other)
+    }
+
     #[inline]
     fn zero_value() -> i16 {
         0
@@ -191,6 +201,11 @@ impl Sample for f32 {
         self * value
     }
 
+    #[inline]
+    fn saturating_add(self, other: f32) -> f32 {
+        self + other
+    }
+
     #[inline]
     fn zero_value() -> f32 {
         0.0

src/dynamic_mixer.rs

@@ -106,7 +106,7 @@ impl<S> Iterator for DynamicMixer<S> where S: Sample + Send + 'static {
         let mut sum = S::zero_value();
         for (num, src) in self.current_sources.iter_mut().enumerate() {
             if let Some(val) = src.next() {
-                sum += val;
+                sum = sum.saturating_add(val);
             } else {
                 to_drop.push(num);
             }

src/source/mix.rs

@@ -47,11 +47,10 @@ impl<I1, I2> Iterator for Mix<I1, I2>
         let s1 = self.input1.next();
         let s2 = self.input2.next();
 
-        // FIXME: shouldn't lerp, this is wrong
         match (s1, s2) {
-            (Some(s1), Some(s2)) => Some(Sample::lerp(s1, s2, 1, 2)),
-            (Some(s1), None) => Some(Sample::lerp(s1, Sample::zero_value(), 1, 2)),
-            (None, Some(s2)) => Some(Sample::lerp(s2, Sample::zero_value(), 1, 2)),
+            (Some(s1), Some(s2)) => Some(s1.saturating_add(s2)),
+            (Some(s1), None) => Some(s1),
+            (None, Some(s2)) => Some(s2),
             (None, None) => None,
         }
     }