Convolution: Compensate for volume changes when resampling IRs

When normalisation is disabled, the Convolution will now adjust the gain
of the IR using the ratio of the source and destination sampling rates.
This should keep the output level constant when the Convolution's
sampling rate is changed.

modules/juce_dsp/frequency/juce_Convolution.cpp

@@ -781,6 +781,8 @@ private:
 
         if (wantsNormalise == Convolution::Normalise::yes)
             normaliseImpulseResponse (resampled);
+        else
+            resampled.applyGain ((float) (originalSampleRate / processSpec.sampleRate));
 
         const auto currentLatency = jmax (processSpec.maximumBlockSize, (uint32) latency.latencyInSamples);
         const auto maxBufferSize = shouldBeZeroLatency ? static_cast<int> (processSpec.maximumBlockSize)

modules/juce_dsp/frequency/juce_Convolution_test.cpp

@@ -514,6 +514,9 @@ public:
 
                     AudioBuffer<float> result (original.getNumChannels(), finalSize);
                     resamplingSource.getNextAudioBlock ({ &result, 0, result.getNumSamples() });
+
+                    result.applyGain ((float) resampleRatio);
+
                     return result;
                 }();
 
@@ -550,10 +553,10 @@ public:
             const auto ramp = makeRamp (static_cast<int> (spec.maximumBlockSize) * 8);
             using BlockSize = decltype (spec.maximumBlockSize);
 
-            for (auto latency : { /*static_cast<BlockSize> (0),
+            for (auto latency : { static_cast<BlockSize> (0),
                                   spec.maximumBlockSize / 3,
                                   spec.maximumBlockSize,
-                                  spec.maximumBlockSize * 2, */
+                                  spec.maximumBlockSize * 2,
                                   static_cast<BlockSize> (spec.maximumBlockSize * 2.5) })
             {
                 testConvolution (spec,