Fix/sinc nan

src/interpolate.rs

@@ -323,7 +323,7 @@ where
         (0..max_depth).fold(Self::Frame::equilibrium(), |mut v, n| {
             v = {
                 let a = PI * (phil + n as f64);
-                let first = sin(a) / a;
+                let first = if a == 0.0 { 1.0 } else { sin(a) / a };
                 let second = 0.5 + 0.5 * cos(a / (phil + max_depth as f64));
                 v.zip_map(self.frames[nr - n], |vs, r_lag| {
                     vs.add_amp(
@@ -335,7 +335,7 @@ where
             };
 
             let a = PI * (phir + n as f64);
-            let first = sin(a) / a;
+            let first = if a == 0.0 { 1.0 } else { sin(a) / a };
             let second = 0.5 + 0.5 * cos(a / (phir + max_depth as f64));
             v.zip_map(self.frames[nl + n], |vs, r_lag| {
                 vs.add_amp(

tests/interpolate.rs

@@ -2,7 +2,8 @@
 
 extern crate sample;
 
-use sample::interpolate::{Converter, Floor, Linear};
+use sample::interpolate::{Converter, Floor, Linear, Sinc};
+use sample::ring_buffer;
 use sample::{signal, Signal};
 
 #[test]
@@ -53,3 +54,18 @@ fn test_scale_playback_rate() {
         &[[0.0], [0.5], [1.0], [0.5], [0.0], [-0.5], [-1.0], [-0.5]][..]
     );
 }
+
+#[test]
+fn test_sinc() {
+    let foo = [[0.0f64], [1.0], [0.0], [-1.0]];
+    let source = signal::from_iter(foo.iter().cloned());
+
+    let frames = ring_buffer::Fixed::from(vec![[0.0]; 50]);
+    let interp = Sinc::new(frames);
+    let resampled = source.from_hz_to_hz(interp, 44100.0, 11025.0);
+
+    assert_eq!(
+        resampled.until_exhausted().find(|sample| sample[0].is_nan()),
+        None
+    );
+}