diff --git a/src/samples_formats.rs b/src/samples_formats.rs
index e11db03..63d5950 100644
--- a/src/samples_formats.rs
+++ b/src/samples_formats.rs
@@ -44,7 +44,7 @@ impl Sample for u16 {
             if value >= 32768 {
                 (value - 32768) as i16
             } else {
-                (value as i16) - 32767
+                (value as i16) - 32767 - 1
             }
         }).collect())
     }
@@ -70,7 +70,7 @@ impl Sample for i16 {
     fn to_vec_u16(input: &[i16]) -> Cow<Vec<u16>, [u16]> {
         Cow::Owned(input.iter().map(|&value| {
             if value < 0 {
-                (value + 32767) as u16
+                (value + 32767) as u16 + 1
             } else {
                 (value as u16) + 32768
             }
@@ -79,7 +79,11 @@ impl Sample for i16 {
 
     fn to_vec_f32(input: &[i16]) -> Cow<Vec<f32>, [f32]> {
         Cow::Owned(input.iter().map(|&value| {
-            value as f32 / 32768.0
+            if value > 0 {
+                value as f32 / 32767.0
+            } else {
+                value as f32 / 32768.0
+            }
         }).collect())
     }
 }
@@ -101,3 +105,64 @@ impl Sample for f32 {
         Cow::Borrowed(input)
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::Sample;
+
+    #[test]
+    fn i16_to_i16() {
+        let out = Sample::to_vec_i16(&[0i16, -467, 32767, -32768]).into_owned();
+        assert_eq!(out, vec![0, -467, 32767, -32768]);
+    }
+
+    #[test]
+    fn i16_to_u16() {
+        let out = Sample::to_vec_u16(&[0i16, -16384, 32767, -32768]).into_owned();
+        assert_eq!(out, vec![32768, 16384, 65535, 0]);
+    }
+
+    #[test]
+    fn i16_to_f32() {
+        let out = Sample::to_vec_f32(&[0i16, -16384, 32767, -32768]).into_owned();
+        assert_eq!(out, vec![0.0, -0.5, 1.0, -1.0]);
+    }
+
+    #[test]
+    fn u16_to_i16() {
+        let out = Sample::to_vec_i16(&[32768u16, 16384, 65535, 0]).into_owned();
+        assert_eq!(out, vec![0, -16384, 32767, -32768]);
+    }
+
+    #[test]
+    fn u16_to_u16() {
+        let out = Sample::to_vec_u16(&[0u16, 467, 32767, 65535]).into_owned();
+        assert_eq!(out, vec![0, 467, 32767, 65535]);
+    }
+
+    #[test]
+    fn u16_to_f32() {
+        let out = Sample::to_vec_f32(&[0u16, 32768, 65535]).into_owned();
+        assert_eq!(out, vec![-1.0, 0.0, 1.0]);
+    }
+
+    #[test]
+    #[ignore]       // TODO: not yet implemented
+    fn f32_to_i16() {
+        let out = Sample::to_vec_i16(&[0.0f32, -0.5, 1.0, -1.0]).into_owned();
+        assert_eq!(out, vec![0, -16384, 32767, -32768]);
+    }
+
+    #[test]
+    #[ignore]       // TODO: not yet implemented
+    fn f32_to_u16() {
+        let out = Sample::to_vec_u16(&[-1.0f32, 0.0, 1.0]).into_owned();
+        assert_eq!(out, vec![0, 32768, 65535]);
+    }
+
+    #[test]
+    fn f32_to_f32() {
+        let out = Sample::to_vec_f32(&[0.1f32, -0.7, 1.0]).into_owned();
+        assert_eq!(out, vec![0.1, -0.7, 1.0]);
+    }
+}