Fixed an edge-case error in the LaGrange and Catmull-Rom interpolators when the ratio changes to exactly 1.0

modules/juce_audio_basics/effects/juce_CatmullRomInterpolator.cpp

@@ -27,13 +27,13 @@ struct CatmullRomAlgorithm
 {
     static forcedinline float valueAtOffset (const float* const inputs, const float offset) noexcept
     {
-        const float y0 = inputs[3];
-        const float y1 = inputs[2];
-        const float y2 = inputs[1];
-        const float y3 = inputs[0];
+        auto y0 = inputs[3];
+        auto y1 = inputs[2];
+        auto y2 = inputs[1];
+        auto y3 = inputs[0];
 
-        const float halfY0 = 0.5f * y0;
-        const float halfY3 = 0.5f * y3;
+        auto halfY0 = 0.5f * y0;
+        auto halfY3 = 0.5f * y3;
 
         return y1 + offset * ((0.5f * y2 - halfY0)
                                 + (offset * (((y0 + 2.0f * y2) - (halfY3 + 2.5f * y1))
@@ -48,8 +48,8 @@ void CatmullRomInterpolator::reset() noexcept
 {
     subSamplePos = 1.0;
 
-    for (int i = 0; i < numElementsInArray (lastInputSamples); ++i)
-        lastInputSamples[i] = 0;
+    for (auto& s : lastInputSamples)
+        s = 0;
 }
 
 int CatmullRomInterpolator::process (double actualRatio, const float* in, float* out, int numOut) noexcept

modules/juce_audio_basics/effects/juce_LagrangeInterpolator.cpp

@@ -49,97 +49,67 @@ namespace
     }
 
     template <typename InterpolatorType>
-    static int interpolate (float* lastInputSamples, double& subSamplePos, const double actualRatio,
-                            const float* in, float* out, const int numOut) noexcept
+    static int interpolate (float* lastInputSamples, double& subSamplePos, double actualRatio,
+                            const float* in, float* out, int numOut) noexcept
     {
-        if (actualRatio == 1.0)
+        auto pos = subSamplePos;
+
+        if (actualRatio == 1.0 && pos == 1.0)
         {
             memcpy (out, in, (size_t) numOut * sizeof (float));
             pushInterpolationSamples (lastInputSamples, in, numOut);
             return numOut;
         }
 
-        const float* const originalIn = in;
-        double pos = subSamplePos;
+        int numUsed = 0;
 
-        if (actualRatio < 1.0)
+        while (numOut > 0)
         {
-            for (int i = numOut; --i >= 0;)
+            while (pos >= 1.0)
             {
-                if (pos >= 1.0)
-                {
-                    pushInterpolationSample (lastInputSamples, *in++);
-                    pos -= 1.0;
-                }
-
-                *out++ = InterpolatorType::valueAtOffset (lastInputSamples, (float) pos);
-                pos += actualRatio;
-            }
-        }
-        else
-        {
-            for (int i = numOut; --i >= 0;)
-            {
-                while (pos < actualRatio)
-                {
-                    pushInterpolationSample (lastInputSamples, *in++);
-                    pos += 1.0;
-                }
-
-                pos -= actualRatio;
-                *out++ = InterpolatorType::valueAtOffset (lastInputSamples, jmax (0.0f, 1.0f - (float) pos));
+                pushInterpolationSample (lastInputSamples, in[numUsed++]);
+                pos -= 1.0;
             }
+
+            *out++ = InterpolatorType::valueAtOffset (lastInputSamples, (float) pos);
+            pos += actualRatio;
+            --numOut;
         }
 
         subSamplePos = pos;
-        return (int) (in - originalIn);
+        return numUsed;
     }
 
     template <typename InterpolatorType>
-    static int interpolateAdding (float* lastInputSamples, double& subSamplePos, const double actualRatio,
-                                  const float* in, float* out, const int numOut, const float gain) noexcept
+    static int interpolateAdding (float* lastInputSamples, double& subSamplePos, double actualRatio,
+                                  const float* in, float* out, int numOut, const float gain) noexcept
     {
-        if (actualRatio == 1.0)
+        auto pos = subSamplePos;
+
+        if (actualRatio == 1.0 && pos == 1.0)
         {
             FloatVectorOperations::addWithMultiply (out, in, gain, numOut);
             pushInterpolationSamples (lastInputSamples, in, numOut);
             return numOut;
         }
 
-        const float* const originalIn = in;
-        double pos = subSamplePos;
+        int numUsed = 0;
 
-        if (actualRatio < 1.0)
+        while (numOut > 0)
         {
-            for (int i = numOut; --i >= 0;)
+            while (pos >= 1.0)
             {
-                if (pos >= 1.0)
-                {
-                    pushInterpolationSample (lastInputSamples, *in++);
-                    pos -= 1.0;
-                }
-
-                *out++ += gain * InterpolatorType::valueAtOffset (lastInputSamples, (float) pos);
-                pos += actualRatio;
-            }
-        }
-        else
-        {
-            for (int i = numOut; --i >= 0;)
-            {
-                while (pos < actualRatio)
-                {
-                    pushInterpolationSample (lastInputSamples, *in++);
-                    pos += 1.0;
-                }
-
-                pos -= actualRatio;
-                *out++ += gain * InterpolatorType::valueAtOffset (lastInputSamples, jmax (0.0f, 1.0f - (float) pos));
+                pushInterpolationSample (lastInputSamples, in[numUsed++]);
+                pos -= 1.0;
             }
+
+            *out++ += gain * InterpolatorType::valueAtOffset (lastInputSamples, (float) pos);
+            pos += actualRatio;
+            --numOut;
         }
 
         subSamplePos = pos;
-        return (int) (in - originalIn);
+        return numUsed;
     }
 }
 
@@ -186,8 +156,8 @@ void LagrangeInterpolator::reset() noexcept
 {
     subSamplePos = 1.0;
 
-    for (int i = 0; i < numElementsInArray (lastInputSamples); ++i)
-        lastInputSamples[i] = 0;
+    for (auto& s : lastInputSamples)
+        s = 0;
 }
 
 int LagrangeInterpolator::process (double actualRatio, const float* in, float* out, int numOut) noexcept