From 4751e9d41a7c733450ff7036f447732187cafa43 Mon Sep 17 00:00:00 2001
From: Tom Poole <thomas.poole@roli.com>
Date: Mon, 18 Feb 2019 23:43:28 +0000
Subject: [PATCH] Added a new templated SmoothedValue class

---
 examples/Audio/MPEDemo.h                      |   2 +-
 examples/BLOCKS/BlocksSynthDemo.h             |   2 +-
 examples/Plugins/DSPModulePluginDemo.h        |   4 +-
 examples/Plugins/SamplerPluginDemo.h          |   8 +-
 .../juce_audio_basics/juce_audio_basics.cpp   |   2 +-
 modules/juce_audio_basics/juce_audio_basics.h |   2 +-
 .../juce_audio_basics/utilities/juce_Reverb.h |   2 +-
 .../utilities/juce_SmoothedValue.cpp          | 296 +++++++++++++++++
 ..._SmoothedValues.h => juce_SmoothedValue.h} | 313 ++++++++----------
 .../utilities/juce_SmoothedValues.cpp         | 285 ----------------
 modules/juce_dsp/containers/juce_AudioBlock.h |   9 +-
 .../juce_dsp/frequency/juce_Convolution.cpp   |   2 +-
 modules/juce_dsp/frequency/juce_Convolution.h |   2 +-
 modules/juce_dsp/juce_dsp.h                   |   1 +
 .../juce_dsp/maths/juce_LogRampedValue.cpp    | 101 ++++++
 modules/juce_dsp/maths/juce_LogRampedValue.h  | 190 +++++++++++
 modules/juce_dsp/processors/juce_Bias.h       |   2 +-
 modules/juce_dsp/processors/juce_Gain.h       |   2 +-
 .../juce_dsp/processors/juce_LadderFilter.h   |   2 +-
 modules/juce_dsp/processors/juce_Oscillator.h |   2 +-
 20 files changed, 743 insertions(+), 486 deletions(-)
 create mode 100644 modules/juce_audio_basics/utilities/juce_SmoothedValue.cpp
 rename modules/juce_audio_basics/utilities/{juce_SmoothedValues.h => juce_SmoothedValue.h} (58%)
 delete mode 100644 modules/juce_audio_basics/utilities/juce_SmoothedValues.cpp
 create mode 100644 modules/juce_dsp/maths/juce_LogRampedValue.cpp
 create mode 100644 modules/juce_dsp/maths/juce_LogRampedValue.h

diff --git a/examples/Audio/MPEDemo.h b/examples/Audio/MPEDemo.h
index 30251011a9..305d829a06 100644
--- a/examples/Audio/MPEDemo.h
+++ b/examples/Audio/MPEDemo.h
@@ -851,7 +851,7 @@ private:
     }
 
     //==============================================================================
-    LinearSmoothedValue<double> level, timbre, frequency;
+    SmoothedValue<double> level, timbre, frequency;
 
     double phase      = 0.0;
     double phaseDelta = 0.0;
diff --git a/examples/BLOCKS/BlocksSynthDemo.h b/examples/BLOCKS/BlocksSynthDemo.h
index b3abc67423..a372918e6a 100644
--- a/examples/BLOCKS/BlocksSynthDemo.h
+++ b/examples/BLOCKS/BlocksSynthDemo.h
@@ -128,7 +128,7 @@ public:
     virtual double renderWaveShape (const double currentPhase) = 0;
 
 private:
-    LinearSmoothedValue<double> amplitude, phaseIncrement;
+    SmoothedValue<double> amplitude, phaseIncrement;
 
     double frequency = 0.0;
     double phasePos = 0.0;
diff --git a/examples/Plugins/DSPModulePluginDemo.h b/examples/Plugins/DSPModulePluginDemo.h
index 5282b77907..c115f49165 100644
--- a/examples/Plugins/DSPModulePluginDemo.h
+++ b/examples/Plugins/DSPModulePluginDemo.h
@@ -498,7 +498,7 @@ private:
     {
         ScopedNoDenormals noDenormals;
 
-        // Input volume applied with a LinearSmoothedValue
+        // Input volume applied with a SmoothedValue
         inputVolume.process (context);
 
         // Pre-highpass filtering, very useful for distortion audio effects
@@ -543,7 +543,7 @@ private:
         convolution.process (context);
         context.isBypassed = wasBypassed;
 
-        // Output volume applied with a LinearSmoothedValue
+        // Output volume applied with a SmoothedValue
         outputVolume.process (context);
     }
 
diff --git a/examples/Plugins/SamplerPluginDemo.h b/examples/Plugins/SamplerPluginDemo.h
index a4f07f9d78..9201bf59a6 100644
--- a/examples/Plugins/SamplerPluginDemo.h
+++ b/examples/Plugins/SamplerPluginDemo.h
@@ -446,10 +446,10 @@ private:
     }
 
     std::shared_ptr<const MPESamplerSound> samplerSound;
-    LinearSmoothedValue<double> level { 0 };
-    LinearSmoothedValue<double> frequency { 0 };
-    LinearSmoothedValue<double> loopBegin;
-    LinearSmoothedValue<double> loopEnd;
+    SmoothedValue<double> level { 0 };
+    SmoothedValue<double> frequency { 0 };
+    SmoothedValue<double> loopBegin;
+    SmoothedValue<double> loopEnd;
     double currentSamplePos { 0 };
     double tailOff { 0 };
     Direction currentDirection { Direction::forward };
diff --git a/modules/juce_audio_basics/juce_audio_basics.cpp b/modules/juce_audio_basics/juce_audio_basics.cpp
index 3f2a661055..c142c6d6c1 100644
--- a/modules/juce_audio_basics/juce_audio_basics.cpp
+++ b/modules/juce_audio_basics/juce_audio_basics.cpp
@@ -60,7 +60,7 @@
 #include "utilities/juce_IIRFilter.cpp"
 #include "utilities/juce_LagrangeInterpolator.cpp"
 #include "utilities/juce_CatmullRomInterpolator.cpp"
-#include "utilities/juce_SmoothedValues.cpp"
+#include "utilities/juce_SmoothedValue.cpp"
 #include "midi/juce_MidiBuffer.cpp"
 #include "midi/juce_MidiFile.cpp"
 #include "midi/juce_MidiKeyboardState.cpp"
diff --git a/modules/juce_audio_basics/juce_audio_basics.h b/modules/juce_audio_basics/juce_audio_basics.h
index 83fe62270d..c6e952ff19 100644
--- a/modules/juce_audio_basics/juce_audio_basics.h
+++ b/modules/juce_audio_basics/juce_audio_basics.h
@@ -89,7 +89,7 @@
 #include "utilities/juce_IIRFilter.h"
 #include "utilities/juce_LagrangeInterpolator.h"
 #include "utilities/juce_CatmullRomInterpolator.h"
-#include "utilities/juce_SmoothedValues.h"
+#include "utilities/juce_SmoothedValue.h"
 #include "utilities/juce_Reverb.h"
 #include "utilities/juce_ADSR.h"
 #include "midi/juce_MidiMessage.h"
diff --git a/modules/juce_audio_basics/utilities/juce_Reverb.h b/modules/juce_audio_basics/utilities/juce_Reverb.h
index 2dd94c5c6f..0ed72b80f2 100644
--- a/modules/juce_audio_basics/utilities/juce_Reverb.h
+++ b/modules/juce_audio_basics/utilities/juce_Reverb.h
@@ -305,7 +305,7 @@ private:
     CombFilter comb [numChannels][numCombs];
     AllPassFilter allPass [numChannels][numAllPasses];
 
-    LinearSmoothedValue<float> damping, feedback, dryGain, wetGain1, wetGain2;
+    SmoothedValue<float> damping, feedback, dryGain, wetGain1, wetGain2;
 
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Reverb)
 };
diff --git a/modules/juce_audio_basics/utilities/juce_SmoothedValue.cpp b/modules/juce_audio_basics/utilities/juce_SmoothedValue.cpp
new file mode 100644
index 0000000000..595ccad7b6
--- /dev/null
+++ b/modules/juce_audio_basics/utilities/juce_SmoothedValue.cpp
@@ -0,0 +1,296 @@
+/*
+  ==============================================================================
+
+   This file is part of the JUCE library.
+   Copyright (c) 2018 - ROLI Ltd.
+
+   JUCE is an open source library subject to commercial or open-source
+   licensing.
+
+   The code included in this file is provided under the terms of the ISC license
+   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
+   To use, copy, modify, and/or distribute this software for any purpose with or
+   without fee is hereby granted provided that the above copyright notice and
+   this permission notice appear in all copies.
+
+   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
+   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
+   DISCLAIMED.
+
+  ==============================================================================
+*/
+
+namespace juce
+{
+
+#if JUCE_UNIT_TESTS
+
+template <class SmoothedValueType>
+class CommonSmoothedValueTests  : public UnitTest
+{
+public:
+    CommonSmoothedValueTests()
+        : UnitTest ("CommonSmoothedValueTests", "SmoothedValues")
+    {}
+
+    void runTest() override
+    {
+        beginTest ("Initial state");
+        {
+            SmoothedValueType sv;
+
+            auto value = sv.getCurrentValue();
+            expectEquals (sv.getTargetValue(), value);
+
+            sv.getNextValue();
+            expectEquals (sv.getCurrentValue(), value);
+            expect (! sv.isSmoothing());
+        }
+
+        beginTest ("Resetting");
+        {
+            auto initialValue = 15.0f;
+
+            SmoothedValueType sv (initialValue);
+            sv.reset (3);
+            expectEquals (sv.getCurrentValue(), initialValue);
+
+            auto targetValue = initialValue + 1.0f;
+            sv.setTargetValue (targetValue);
+            expectEquals (sv.getTargetValue(), targetValue);
+            expectEquals (sv.getCurrentValue(), initialValue);
+            expect (sv.isSmoothing());
+
+            auto currentValue = sv.getNextValue();
+            expect (currentValue > initialValue);
+            expectEquals (sv.getCurrentValue(), currentValue);
+            expectEquals (sv.getTargetValue(), targetValue);
+            expect (sv.isSmoothing());
+
+            sv.reset (5);
+
+            expectEquals (sv.getCurrentValue(), targetValue);
+            expectEquals (sv.getTargetValue(),  targetValue);
+            expect (! sv.isSmoothing());
+
+            sv.getNextValue();
+            expectEquals (sv.getCurrentValue(), targetValue);
+
+            sv.setTargetValue (1.5f);
+            sv.getNextValue();
+
+            float newStart = 0.2f;
+            sv.setCurrentAndTargetValue (newStart);
+            expectEquals (sv.getNextValue(), newStart);
+            expectEquals (sv.getTargetValue(), newStart);
+            expectEquals (sv.getCurrentValue(), newStart);
+            expect (! sv.isSmoothing());
+        }
+
+        beginTest ("Sample rate");
+        {
+            SmoothedValueType svSamples { 3.0f };
+            auto svTime = svSamples;
+
+            auto numSamples = 12;
+
+            svSamples.reset (numSamples);
+            svTime.reset (numSamples * 2, 1.0);
+
+            for (int i = 0; i < numSamples; ++i)
+            {
+                svTime.skip (1);
+                expectWithinAbsoluteError (svSamples.getNextValue(),
+                                           svTime.getNextValue(),
+                                           1.0e-7f);
+            }
+        }
+
+        beginTest ("Block processing");
+        {
+            SmoothedValueType sv (1.0f);
+
+            sv.reset (12);
+            sv.setTargetValue (2.0f);
+
+            const auto numSamples = 15;
+
+            AudioBuffer<float> referenceData (1, numSamples);
+
+            for (int i = 0; i < numSamples; ++i)
+                referenceData.setSample (0, i, sv.getNextValue());
+
+            expect (referenceData.getSample (0, 0) > 0);
+            expect (referenceData.getSample (0, 10) < sv.getTargetValue());
+            expectWithinAbsoluteError (referenceData.getSample (0, 11),
+                                       sv.getTargetValue(),
+                                       1.0e-7f);
+
+            auto getUnitData = [] (int numSamplesToGenerate)
+            {
+                AudioBuffer<float> result (1, numSamplesToGenerate);
+
+                for (int i = 0; i < numSamplesToGenerate; ++i)
+                    result.setSample (0, i, 1.0f);
+
+                return result;
+            };
+
+            auto compareData = [this](const AudioBuffer<float>& test,
+                                      const AudioBuffer<float>& reference)
+            {
+                for (int i = 0; i < test.getNumSamples(); ++i)
+                    expectWithinAbsoluteError (test.getSample (0, i),
+                                               reference.getSample (0, i),
+                                               1.0e-7f);
+            };
+
+            auto testData = getUnitData (numSamples);
+            sv.setCurrentAndTargetValue (1.0f);
+            sv.setTargetValue (2.0f);
+            sv.applyGain (testData.getWritePointer (0), numSamples);
+            compareData (testData, referenceData);
+
+            testData = getUnitData (numSamples);
+            AudioBuffer<float> destData (1, numSamples);
+            sv.setCurrentAndTargetValue (1.0f);
+            sv.setTargetValue (2.0f);
+            sv.applyGain (destData.getWritePointer (0),
+                           testData.getReadPointer (0),
+                           numSamples);
+            compareData (destData, referenceData);
+            compareData (testData, getUnitData (numSamples));
+
+            testData = getUnitData (numSamples);
+            sv.setCurrentAndTargetValue (1.0f);
+            sv.setTargetValue (2.0f);
+            sv.applyGain (testData, numSamples);
+            compareData (testData, referenceData);
+        }
+
+        beginTest ("Skip");
+        {
+            SmoothedValueType sv;
+
+            sv.reset (12);
+            sv.setCurrentAndTargetValue (1.0f);
+            sv.setTargetValue (2.0f);
+
+            Array<float> reference;
+
+            for (int i = 0; i < 15; ++i)
+                reference.add (sv.getNextValue());
+
+            sv.setCurrentAndTargetValue (1.0f);
+            sv.setTargetValue (2.0f);
+
+            expectWithinAbsoluteError (sv.skip (1), reference[0], 1.0e-6f);
+            expectWithinAbsoluteError (sv.skip (1), reference[1], 1.0e-6f);
+            expectWithinAbsoluteError (sv.skip (2), reference[3], 1.0e-6f);
+            sv.skip (3);
+            expectWithinAbsoluteError (sv.getCurrentValue(), reference[6], 1.0e-6f);
+            expectEquals (sv.skip (300), sv.getTargetValue());
+            expectEquals (sv.getCurrentValue(), sv.getTargetValue());
+        }
+
+        beginTest ("Negative");
+        {
+            SmoothedValueType sv;
+
+            auto start = -1.0f, end = -2.0f;
+            auto numValues = 12;
+
+            sv.reset (numValues);
+            sv.setCurrentAndTargetValue (start);
+            sv.setTargetValue (end);
+
+            auto val = sv.skip (3);
+            expect (val < start && val > end);
+
+            auto nextVal = sv.getNextValue();
+            expect (nextVal < val);
+
+            auto endVal = sv.skip (500);
+            expectEquals (endVal, end);
+            expectEquals (sv.getNextValue(), end);
+            expectEquals (sv.getCurrentValue(), end);
+
+            sv.setCurrentAndTargetValue (start);
+            sv.reset (numValues);
+            sv.setTargetValue (end);
+
+            SmoothedValueType positiveSv { -start };
+            positiveSv.reset (numValues);
+            positiveSv.setTargetValue (-end);
+
+            for (int i = 0; i < numValues + 2; ++i)
+                expectEquals (sv.getNextValue(), -positiveSv.getNextValue());
+        }
+    }
+};
+
+static CommonSmoothedValueTests <SmoothedValue<float, ValueSmoothingTypes::Linear>> commonLinearSmoothedValueTests;
+static CommonSmoothedValueTests <SmoothedValue<float, ValueSmoothingTypes::Multiplicative>> commonMultiplicativeSmoothedValueTests;
+
+class SmoothedValueTests  : public UnitTest
+{
+public:
+    SmoothedValueTests()
+        : UnitTest ("SmoothedValueTests", "SmoothedValues")
+    {}
+
+    void runTest() override
+    {
+        beginTest ("Linear moving target");
+        {
+            SmoothedValue<float, ValueSmoothingTypes::Linear> sv;
+
+            sv.reset (12);
+            float initialValue = 0.0f;
+            sv.setCurrentAndTargetValue (initialValue);
+            sv.setTargetValue (1.0f);
+
+            auto delta = sv.getNextValue() - initialValue;
+
+            sv.skip (6);
+
+            auto newInitialValue = sv.getCurrentValue();
+            sv.setTargetValue (newInitialValue + 2.0f);
+            auto doubleDelta = sv.getNextValue() - newInitialValue;
+
+            expectWithinAbsoluteError (doubleDelta, delta * 2.0f, 1.0e-7f);
+        }
+
+        beginTest ("Multiplicative curve");
+        {
+            SmoothedValue<double, ValueSmoothingTypes::Multiplicative> sv;
+
+            auto numSamples = 12;
+            AudioBuffer<double> values (2, numSamples + 1);
+
+            sv.reset (numSamples);
+            sv.setCurrentAndTargetValue (1.0);
+            sv.setTargetValue (2.0f);
+
+            values.setSample (0, 0, sv.getCurrentValue());
+
+            for (int i = 1; i < values.getNumSamples(); ++i)
+                values.setSample (0, i, sv.getNextValue());
+
+            sv.setTargetValue (1.0f);
+            values.setSample (1, values.getNumSamples() - 1, sv.getCurrentValue());
+
+            for (int i = values.getNumSamples() - 2; i >= 0 ; --i)
+                values.setSample (1, i, sv.getNextValue());
+
+            for (int i = 0; i < values.getNumSamples(); ++i)
+                expectWithinAbsoluteError (values.getSample (0, i), values.getSample (1, i), 1.0e-9);
+        }
+    }
+};
+
+static SmoothedValueTests smoothedValueTests;
+
+#endif
+
+} // namespace juce
diff --git a/modules/juce_audio_basics/utilities/juce_SmoothedValues.h b/modules/juce_audio_basics/utilities/juce_SmoothedValue.h
similarity index 58%
rename from modules/juce_audio_basics/utilities/juce_SmoothedValues.h
rename to modules/juce_audio_basics/utilities/juce_SmoothedValue.h
index b874e1aa9f..2875971345 100644
--- a/modules/juce_audio_basics/utilities/juce_SmoothedValues.h
+++ b/modules/juce_audio_basics/utilities/juce_SmoothedValue.h
@@ -27,16 +27,39 @@ namespace juce
 /**
     A base class for the smoothed value classes.
 
+    This class is used to provide common functionality to the SmoothedValue and
+    dsp::LogRampedValue classes.
+
     @tags{Audio}
 */
-template <template<typename> class SmoothedValueClass, typename FloatType>
+template <typename SmoothedValueType>
 class SmoothedValueBase
 {
+private:
+    //==============================================================================
+    template <typename T> struct FloatTypeHelper;
+
+    template <template <typename> class SmoothedValueClass, typename FloatType>
+    struct FloatTypeHelper <SmoothedValueClass <FloatType>>
+    {
+        using Type = FloatType;
+    };
+
+    template <template <typename, typename> class SmoothedValueClass, typename FloatType, typename SmoothingType>
+    struct FloatTypeHelper <SmoothedValueClass <FloatType, SmoothingType>>
+    {
+        using Type = FloatType;
+    };
+
 public:
+    using FloatType = typename FloatTypeHelper<SmoothedValueType>::Type;
+
     //==============================================================================
     /** Constructor. */
     SmoothedValueBase() = default;
 
+    virtual ~SmoothedValueBase() {}
+
     //==============================================================================
     /** Returns true if the current value is currently being interpolated. */
     bool isSmoothing() const noexcept                    { return countdown > 0; }
@@ -130,48 +153,77 @@ public:
         }
     }
 
-protected:
-    //==============================================================================
-    void reset (double sampleRate, double rampLengthInSeconds) noexcept
-    {
-        jassert (sampleRate > 0 && rampLengthInSeconds >= 0);
-        auto& derived = *(static_cast<SmoothedValueClass<FloatType>*> (this));
-        derived.reset ((int) std::floor (rampLengthInSeconds * sampleRate));
-    }
-
-    //==============================================================================
-    FloatType currentValue = 0, target = 0;
-    int countdown = 0;
-
 private:
     //==============================================================================
     FloatType getNextSmoothedValue() noexcept
     {
-        return static_cast<SmoothedValueClass<FloatType>*> (this)->getNextValue();
+        return static_cast <SmoothedValueType*> (this)->getNextValue();
     }
+
+protected:
+    //==============================================================================
+    FloatType currentValue = 0;
+    FloatType target = currentValue;
+    int countdown = 0;
 };
 
 //==============================================================================
 /**
-    Utility class for linearly smoothed values like volume etc. that should
-    not change abruptly but as a linear ramp to avoid audio glitches.
+    A namespace containing a set of types used for specifying the smoothing
+    behaviour of the SmoothedValue class.
+
+    For example:
+    @code
+    SmoothedValue<float, ValueSmoothingTypes::Multiplicative> frequency (1.0f);
+    @endcode
+*/
+namespace ValueSmoothingTypes
+{
+    /** Used to indicate a linear smoothing between values. */
+    struct Linear {};
+
+    /** Used to indicate a smoothing between multiplicative values. */
+    struct Multiplicative {};
+}
+
+//==============================================================================
+/**
+    A utility class for values that need smoothing, like volume, that should not
+    change abruptly to avoid audio glitches.
+
+    To smooth values spread across an exponential range, where the increments
+    between the current and target value are multiplicative (like frequencies),
+    you should pass the multiplicative smoothing type as a template paramater:
+
+    @code
+    SmoothedValue<float, ValueSmoothingTypes::Multiplicative> yourSmoothedValue;
+    @endcode
+
+    Note that when you are using multiplicative smoothing you cannot ever reach a
+    target value of zero!
 
     @tags{Audio}
 */
-template <typename FloatType>
-class LinearSmoothedValue   : public SmoothedValueBase<LinearSmoothedValue, FloatType>
+template <typename FloatType, typename SmoothingType = ValueSmoothingTypes::Linear>
+class SmoothedValue   : public SmoothedValueBase <SmoothedValue <FloatType, SmoothingType>>
 {
 public:
     //==============================================================================
     /** Constructor. */
-    LinearSmoothedValue() = default;
+    SmoothedValue() noexcept
+        : SmoothedValue ((FloatType) (std::is_same<SmoothingType, ValueSmoothingTypes::Linear>::value ? 0 : 1))
+    {
+    }
 
     /** Constructor. */
-    LinearSmoothedValue (FloatType initialValue) noexcept
+    SmoothedValue (FloatType initialValue) noexcept
     {
+        // Multiplicative smoothed values cannot ever reach 0!
+        jassert (! (std::is_same<SmoothingType, ValueSmoothingTypes::Multiplicative>::value && initialValue == 0));
+
         // Visual Studio can't handle base class initialisation with CRTP
         this->currentValue = initialValue;
-        this->target = initialValue;
+        this->target = this->currentValue;
     }
 
     //==============================================================================
@@ -209,9 +261,13 @@ public:
             return;
         }
 
+        // Multiplicative smoothed values cannot ever reach 0!
+        jassert (! (std::is_same<SmoothingType, ValueSmoothingTypes::Multiplicative>::value && newValue == 0));
+
         this->target = newValue;
         this->countdown = stepsToTarget;
-        step = (this->target - this->currentValue) / (FloatType) this->countdown;
+
+        setStepSize();
     }
 
     //==============================================================================
@@ -225,8 +281,10 @@ public:
 
         --(this->countdown);
 
-        this->currentValue = this->isSmoothing() ? this->currentValue + step
-                                                 : this->target;
+        if (this->isSmoothing())
+            setNextValue();
+        else
+            this->currentValue = this->target;
 
         return this->currentValue;
     }
@@ -245,7 +303,8 @@ public:
             return this->target;
         }
 
-        this->currentValue += step * (FloatType) numSamples;
+        skipCurrentValue (numSamples);
+
         this->countdown -= numSamples;
         return this->currentValue;
     }
@@ -273,166 +332,58 @@ public:
     })
 
 private:
+    //==============================================================================
+    template <typename T>
+    using LinearVoid = typename std::enable_if <std::is_same <T, ValueSmoothingTypes::Linear>::value, void>::type;
+
+    template <typename T>
+    using MultiplicativeVoid = typename std::enable_if <std::is_same <T, ValueSmoothingTypes::Multiplicative>::value, void>::type;
+
+    //==============================================================================
+    template <typename T = SmoothingType>
+    LinearVoid<T> setStepSize() noexcept
+    {
+        step = (this->target - this->currentValue) / (FloatType) this->countdown;
+    }
+
+    template <typename T = SmoothingType>
+    MultiplicativeVoid<T> setStepSize()
+    {
+        step = std::exp ((std::log (std::abs (this->target)) - std::log (std::abs (this->currentValue))) / this->countdown);
+    }
+
+    //==============================================================================
+    template <typename T = SmoothingType>
+    LinearVoid<T> setNextValue() noexcept
+    {
+        this->currentValue += step;
+    }
+
+    template <typename T = SmoothingType>
+    MultiplicativeVoid<T> setNextValue() noexcept
+    {
+        this->currentValue *= step;
+    }
+
+    //==============================================================================
+    template <typename T = SmoothingType>
+    LinearVoid<T> skipCurrentValue (int numSamples) noexcept
+    {
+        this->currentValue += step * (FloatType) numSamples;
+    }
+
+    template <typename T = SmoothingType>
+    MultiplicativeVoid<T> skipCurrentValue (int numSamples)
+    {
+        this->currentValue *= (FloatType) std::pow (step, numSamples);
+    }
+
     //==============================================================================
     FloatType step = FloatType();
     int stepsToTarget = 0;
 };
 
-//==============================================================================
-/**
-    Utility class for logarithmically smoothed values.
-
-    Logarithmically smoothed values can be more relevant than linear ones for
-    specific cases such as algorithm change smoothing, using two of them in
-    opposite directions.
-
-    @see LinearSmoothedValue
-
-    @tags{Audio}
-*/
 template <typename FloatType>
-class LogSmoothedValue   : public SmoothedValueBase<LogSmoothedValue, FloatType>
-{
-public:
-    //==============================================================================
-    /** Constructor. */
-    LogSmoothedValue() = default;
-
-    /** Constructor. */
-    LogSmoothedValue (FloatType initialValue) noexcept
-    {
-        // Visual Studio can't handle base class initialisation with CRTP
-        this->currentValue = initialValue;
-        this->target = initialValue;
-    }
-
-    //==============================================================================
-    /** Sets the behaviour of the log ramp.
-        @param midPointAmplitudedB           Sets the amplitude of the mid point in
-                                             decibels, with the target value at 0 dB
-                                             and the initial value at -inf dB
-        @param rateOfChangeShouldIncrease    If true then the ramp starts shallow
-                                             and gets progressively steeper, if false
-                                             then the ramp is initially steep and
-                                             flattens out as you approach the target
-                                             value
-    */
-    void setLogParameters (FloatType midPointAmplitudedB, bool rateOfChangeShouldIncrease) noexcept
-    {
-        jassert (midPointAmplitudedB < (FloatType) 0.0);
-        B = Decibels::decibelsToGain (midPointAmplitudedB);
-
-        increasingRateOfChange = rateOfChangeShouldIncrease;
-    }
-
-    //==============================================================================
-    /** Reset to a new sample rate and ramp length.
-        @param sampleRate           The sample rate
-        @param rampLengthInSeconds  The duration of the ramp in seconds
-    */
-    void reset (double sampleRate, double rampLengthInSeconds) noexcept
-    {
-        jassert (sampleRate > 0 && rampLengthInSeconds >= 0);
-        reset ((int) std::floor (rampLengthInSeconds * sampleRate));
-    }
-
-    /** Set a new ramp length directly in samples.
-        @param numSteps             The number of samples over which the ramp should be active
-        @param increasingRateOfChange     If the log behaviour makes the ramp increase
-                                    slowly at the beginning, rather than at the end
-    */
-    void reset (int numSteps) noexcept
-    {
-        stepsToTarget = numSteps;
-
-        this->setCurrentAndTargetValue (this->target);
-
-        updateRampParameters();
-    }
-
-    //==============================================================================
-    /** Set a new target value.
-
-        @param newValue     The new target value
-        @param force        If true, the value will be set immediately, bypassing the ramp
-    */
-    void setTargetValue (FloatType newValue) noexcept
-    {
-        if (newValue == this->target)
-            return;
-
-        if (stepsToTarget <= 0)
-        {
-            this->setCurrentAndTargetValue (newValue);
-            return;
-        }
-
-        this->target = newValue;
-        this->countdown = stepsToTarget;
-        source = this->currentValue;
-
-        updateRampParameters();
-    }
-
-    //==============================================================================
-    /** Compute the next value.
-        @returns Smoothed value
-    */
-    FloatType getNextValue() noexcept
-    {
-        if (! this->isSmoothing())
-            return this->target;
-
-        --(this->countdown);
-
-        temp *= r; temp += d;
-        this->currentValue = jmap (temp, source, this->target);
-
-        return this->currentValue;
-    }
-
-    //==============================================================================
-    /** Skip the next numSamples samples.
-
-        This is identical to calling getNextValue numSamples times.
-        @see getNextValue
-    */
-    FloatType skip (int numSamples) noexcept
-    {
-        if (numSamples >= this->countdown)
-        {
-            this->setCurrentAndTargetValue (this->target);
-            return this->target;
-        }
-
-        this->countdown -= numSamples;
-
-        auto rN = (FloatType) std::pow (r, numSamples);
-        temp *= rN;
-        temp += d * (rN - (FloatType) 1) / (r - (FloatType) 1);
-
-        this->currentValue = jmap (temp, source, this->target);
-        return this->currentValue;
-    }
-
-private:
-    //==============================================================================
-    void updateRampParameters()
-    {
-        auto D = increasingRateOfChange ? B : (FloatType) 1 - B;
-        auto base = ((FloatType) 1 / D) - (FloatType) 1;
-        r = std::pow (base, (FloatType) 2 / (FloatType) stepsToTarget);
-        auto rN = std::pow (r, (FloatType) stepsToTarget);
-        d = (r - (FloatType) 1) / (rN - (FloatType) 1);
-        temp = 0;
-    }
-
-    //==============================================================================
-    bool increasingRateOfChange = true;
-    FloatType B = Decibels::decibelsToGain ((FloatType) -40);
-
-    int stepsToTarget = 0;
-    FloatType temp = 0, source = 0, r = 0, d = 1;
-};
+using LinearSmoothedValue = SmoothedValue <FloatType, ValueSmoothingTypes::Linear>;
 
 } // namespace juce
diff --git a/modules/juce_audio_basics/utilities/juce_SmoothedValues.cpp b/modules/juce_audio_basics/utilities/juce_SmoothedValues.cpp
deleted file mode 100644
index 52e41ea7b7..0000000000
--- a/modules/juce_audio_basics/utilities/juce_SmoothedValues.cpp
+++ /dev/null
@@ -1,285 +0,0 @@
-/*
-  ==============================================================================
-
-   This file is part of the JUCE library.
-   Copyright (c) 2018 - ROLI Ltd.
-
-   JUCE is an open source library subject to commercial or open-source
-   licensing.
-
-   The code included in this file is provided under the terms of the ISC license
-   http://www.isc.org/downloads/software-support-policy/isc-license. Permission
-   To use, copy, modify, and/or distribute this software for any purpose with or
-   without fee is hereby granted provided that the above copyright notice and
-   this permission notice appear in all copies.
-
-   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
-   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
-   DISCLAIMED.
-
-  ==============================================================================
-*/
-
-namespace juce
-{
-
-#if JUCE_UNIT_TESTS
-
-template <class SmoothedValueType>
-class CommonSmoothedValueTests  : public UnitTest
-{
-public:
-    CommonSmoothedValueTests()
-        : UnitTest ("CommonSmoothedValueTests", "SmoothedValues")
-    {}
-
-    void runTest() override
-    {
-        beginTest ("Initial state");
-        {
-            SmoothedValueType lsv;
-
-            auto value = lsv.getCurrentValue();
-            expectEquals (lsv.getTargetValue(), value);
-
-            lsv.getNextValue();
-            expectEquals (lsv.getCurrentValue(), value);
-            expect (! lsv.isSmoothing());
-        }
-
-        beginTest ("Resetting");
-        {
-            auto initialValue = -5.0f;
-
-            SmoothedValueType lsv (-5.0f);
-            lsv.reset (3);
-            expectEquals (lsv.getCurrentValue(), initialValue);
-
-            auto targetValue = initialValue + 1.0f;
-            lsv.setTargetValue (targetValue);
-            expectEquals (lsv.getTargetValue(), targetValue);
-            expectEquals (lsv.getCurrentValue(), initialValue);
-            expect (lsv.isSmoothing());
-
-            auto currentValue = lsv.getNextValue();
-            expect (currentValue > initialValue);
-            expectEquals (lsv.getCurrentValue(), currentValue);
-            expectEquals (lsv.getTargetValue(), targetValue);
-            expect (lsv.isSmoothing());
-
-            lsv.reset (5);
-
-            expectEquals (lsv.getCurrentValue(), targetValue);
-            expectEquals (lsv.getTargetValue(),  targetValue);
-            expect (! lsv.isSmoothing());
-
-            lsv.getNextValue();
-            expectEquals (lsv.getCurrentValue(), targetValue);
-
-            lsv.setTargetValue (-15.0f);
-            lsv.getNextValue();
-
-            float newStart = -20.0f;
-            lsv.setCurrentAndTargetValue (newStart);
-            expectEquals (lsv.getNextValue(), newStart);
-            expectEquals (lsv.getTargetValue(), newStart);
-            expectEquals (lsv.getCurrentValue(), newStart);
-            expect (! lsv.isSmoothing());
-        }
-
-        beginTest ("Sample rate");
-        {
-            SmoothedValueType lsvSamples { 3.0f };
-            auto lsvTime = lsvSamples;
-
-            auto numSamples = 12;
-
-            lsvSamples.reset (numSamples);
-            lsvTime.reset (numSamples * 2, 1.0);
-
-            for (int i = 0; i < numSamples; ++i)
-            {
-                lsvTime.skip (1);
-                expectWithinAbsoluteError (lsvSamples.getNextValue(),
-                                           lsvTime.getNextValue(),
-                                           1.0e-7f);
-            }
-        }
-
-        beginTest ("Block processing");
-        {
-            SmoothedValueType lsv (1.0f);
-
-            lsv.reset (12);
-            lsv.setTargetValue (2.0f);
-
-            const auto numSamples = 15;
-
-            AudioBuffer<float> referenceData (1, numSamples);
-
-            for (int i = 0; i < numSamples; ++i)
-                referenceData.setSample (0, i, lsv.getNextValue());
-
-            expect (referenceData.getSample (0, 0) > 0);
-            expect (referenceData.getSample (0, 10) < lsv.getTargetValue());
-            expectWithinAbsoluteError (referenceData.getSample (0, 11),
-                                       lsv.getTargetValue(),
-                                       1.0e-7f);
-
-            auto getUnitData = [] (int numSamplesToGenerate)
-            {
-                AudioBuffer<float> result (1, numSamplesToGenerate);
-
-                for (int i = 0; i < numSamplesToGenerate; ++i)
-                    result.setSample (0, i, 1.0f);
-
-                return result;
-            };
-
-            auto compareData = [this](const AudioBuffer<float>& test,
-                                      const AudioBuffer<float>& reference)
-            {
-                for (int i = 0; i < test.getNumSamples(); ++i)
-                    expectWithinAbsoluteError (test.getSample (0, i),
-                                               reference.getSample (0, i),
-                                               1.0e-7f);
-            };
-
-            auto testData = getUnitData (numSamples);
-            lsv.setCurrentAndTargetValue (1.0f);
-            lsv.setTargetValue (2.0f);
-            lsv.applyGain (testData.getWritePointer (0), numSamples);
-            compareData (testData, referenceData);
-
-            testData = getUnitData (numSamples);
-            AudioBuffer<float> destData (1, numSamples);
-            lsv.setCurrentAndTargetValue (1.0f);
-            lsv.setTargetValue (2.0f);
-            lsv.applyGain (destData.getWritePointer (0),
-                           testData.getReadPointer (0),
-                           numSamples);
-            compareData (destData, referenceData);
-            compareData (testData, getUnitData (numSamples));
-
-            testData = getUnitData (numSamples);
-            lsv.setCurrentAndTargetValue (1.0f);
-            lsv.setTargetValue (2.0f);
-            lsv.applyGain (testData, numSamples);
-            compareData (testData, referenceData);
-        }
-
-        beginTest ("Skip");
-        {
-            SmoothedValueType lsv;
-
-            lsv.reset (12);
-            lsv.setCurrentAndTargetValue (0.0f);
-            lsv.setTargetValue (1.0f);
-
-            Array<float> reference;
-
-            for (int i = 0; i < 15; ++i)
-                reference.add (lsv.getNextValue());
-
-            lsv.setCurrentAndTargetValue (0.0f);
-            lsv.setTargetValue (1.0f);
-
-            expectWithinAbsoluteError (lsv.skip (1), reference[0], 1.0e-7f);
-            expectWithinAbsoluteError (lsv.skip (1), reference[1], 1.0e-7f);
-            expectWithinAbsoluteError (lsv.skip (2), reference[3], 1.0e-7f);
-            lsv.skip (3);
-            expectWithinAbsoluteError (lsv.getCurrentValue(), reference[6], 1.0e-7f);
-            expectEquals (lsv.skip (300), lsv.getTargetValue());
-            expectEquals (lsv.getCurrentValue(), lsv.getTargetValue());
-        }
-
-        beginTest ("Moving target");
-        {
-            SmoothedValueType lsv;
-
-            lsv.reset (12);
-            float initialValue = 0.0f;
-            lsv.setCurrentAndTargetValue (initialValue);
-            lsv.setTargetValue (1.0f);
-
-            auto delta = lsv.getNextValue() - initialValue;
-
-            lsv.skip (6);
-
-            auto newInitialValue = lsv.getCurrentValue();
-            lsv.setTargetValue (newInitialValue + 2.0f);
-            auto doubleDelta = lsv.getNextValue() - newInitialValue;
-
-            expectWithinAbsoluteError (doubleDelta, delta * 2.0f, 1.0e-7f);
-        }
-    }
-};
-
-static CommonSmoothedValueTests<LinearSmoothedValue<float>> commonLinearSmoothedValueTests;
-static CommonSmoothedValueTests<LogSmoothedValue   <float>> commonLogSmoothedValueTests;
-
-class LogSmoothedValueTests  : public UnitTest
-{
-public:
-    LogSmoothedValueTests()
-        : UnitTest ("LogSmoothedValueTests", "SmoothedValues")
-    {}
-
-    void runTest() override
-    {
-        beginTest ("Curve");
-        {
-            Array<double> levels = { -0.12243, -1.21245, -12.2342, -22.4683, -30.0, -61.18753 };
-
-            for (auto level : levels)
-            {
-                Array<Range<double>> ranges = { Range<double> (0.0,    1.0),
-                                                Range<double> (-2.345, 0.0),
-                                                Range<double> (-2.63,  3.56),
-                                                Range<double> (3.3,    -0.2) };
-
-                for (auto range : ranges)
-                {
-                    LogSmoothedValue<double> slowStart { range.getStart() } , fastStart { range.getEnd() };
-
-                    auto numSamples = 12;
-                    slowStart.reset (numSamples);
-                    fastStart.reset (numSamples);
-
-                    slowStart.setLogParameters (level, true);
-                    fastStart.setLogParameters (level, false);
-
-                    slowStart.setTargetValue (range.getEnd());
-                    fastStart.setTargetValue (range.getStart());
-
-                    AudioBuffer<double> results (2, numSamples + 1);
-
-                    results.setSample (0, 0, slowStart.getCurrentValue());
-                    results.setSample (1, 0, fastStart.getCurrentValue());
-
-                    for (int i = 1; i < results.getNumSamples(); ++i)
-                    {
-                        results.setSample (0, i, slowStart.getNextValue());
-                        results.setSample (1, i, fastStart.getNextValue());
-                    }
-
-                    for (int i = 0; i < results.getNumSamples(); ++i)
-                        expectWithinAbsoluteError (results.getSample (0, i),
-                                                   results.getSample (1, results.getNumSamples() - (i + 1)),
-                                                   1.0e-7);
-
-                    auto expectedMidpoint = range.getStart() + (range.getLength() * Decibels::decibelsToGain (level));
-                    expectWithinAbsoluteError (results.getSample (0, numSamples / 2),
-                                               expectedMidpoint,
-                                               1.0e-7);
-                }
-            }
-        }
-    }
-};
-
-static LogSmoothedValueTests logSmoothedValueTests;
-
-#endif
-
-} // namespace juce
diff --git a/modules/juce_dsp/containers/juce_AudioBlock.h b/modules/juce_dsp/containers/juce_AudioBlock.h
index 95f6de74f2..a98e60370a 100644
--- a/modules/juce_dsp/containers/juce_AudioBlock.h
+++ b/modules/juce_dsp/containers/juce_AudioBlock.h
@@ -486,7 +486,8 @@ public:
     }
 
     /** Multiplies all channels of the AudioBlock by a smoothly changing value and stores them . */
-    AudioBlock& multiply (LinearSmoothedValue<SampleType>& value) noexcept
+    template <typename SmoothingType>
+    AudioBlock& multiply (SmoothedValue<SampleType, SmoothingType>& value) noexcept
     {
         if (! value.isSmoothing())
         {
@@ -507,7 +508,8 @@ public:
     }
 
     /** Multiplies all channels of the source by a smoothly changing value and stores them in the receiver. */
-    AudioBlock& multiply (AudioBlock src, LinearSmoothedValue<SampleType>& value) noexcept
+    template <typename SmoothingType>
+    AudioBlock& multiply (AudioBlock src, SmoothedValue<SampleType, SmoothingType>& value) noexcept
     {
         jassert (numChannels == src.numChannels);
 
@@ -632,7 +634,8 @@ public:
     forcedinline AudioBlock&                      operator-= (AudioBlock src) noexcept   { return subtract (src); }
     forcedinline AudioBlock& JUCE_VECTOR_CALLTYPE operator*= (SampleType src) noexcept   { return multiply (src); }
     forcedinline AudioBlock&                      operator*= (AudioBlock src) noexcept   { return multiply (src); }
-    forcedinline AudioBlock&                      operator*= (LinearSmoothedValue<SampleType>& value) noexcept   { return multiply (value); }
+    template <typename SmoothingType>
+    forcedinline AudioBlock&                      operator*= (SmoothedValue<SampleType, SmoothingType>& value) noexcept   { return multiply (value); }
 
     //==============================================================================
     // This class can only be used with floating point types
diff --git a/modules/juce_dsp/frequency/juce_Convolution.cpp b/modules/juce_dsp/frequency/juce_Convolution.cpp
index 8c013086fe..99d1906b07 100644
--- a/modules/juce_dsp/frequency/juce_Convolution.cpp
+++ b/modules/juce_dsp/frequency/juce_Convolution.cpp
@@ -1046,7 +1046,7 @@ private:
     OwnedArray<ConvolutionEngine> engines;          // the 4 convolution engines being used
 
     AudioBuffer<float> interpolationBuffer;         // a buffer to do the interpolation between the convolution engines 0-1 and 2-3
-    LogSmoothedValue<float> changeVolumes[4];       // the volumes for each convolution engine during interpolation
+    LogRampedValue<float> changeVolumes[4];         // the volumes for each convolution engine during interpolation
 
     bool mustInterpolate = false;                   // tells if the convolution engines outputs must be currently interpolated
 
diff --git a/modules/juce_dsp/frequency/juce_Convolution.h b/modules/juce_dsp/frequency/juce_Convolution.h
index d8c242fb71..1a4aae40bc 100644
--- a/modules/juce_dsp/frequency/juce_Convolution.h
+++ b/modules/juce_dsp/frequency/juce_Convolution.h
@@ -162,7 +162,7 @@ private:
     double sampleRate;
     bool currentIsBypassed = false;
     bool isActive = false;
-    LinearSmoothedValue<float> volumeDry[2], volumeWet[2];
+    SmoothedValue<float> volumeDry[2], volumeWet[2];
     AudioBlock<float> dryBuffer;
     HeapBlock<char> dryBufferStorage;
 
diff --git a/modules/juce_dsp/juce_dsp.h b/modules/juce_dsp/juce_dsp.h
index 80d9ed4475..2f95207a8f 100644
--- a/modules/juce_dsp/juce_dsp.h
+++ b/modules/juce_dsp/juce_dsp.h
@@ -251,6 +251,7 @@ namespace juce
 #include "maths/juce_Polynomial.h"
 #include "maths/juce_FastMathApproximations.h"
 #include "maths/juce_LookupTable.h"
+#include "maths/juce_LogRampedValue.h"
 #include "containers/juce_AudioBlock.h"
 #include "processors/juce_ProcessContext.h"
 #include "processors/juce_ProcessorWrapper.h"
diff --git a/modules/juce_dsp/maths/juce_LogRampedValue.cpp b/modules/juce_dsp/maths/juce_LogRampedValue.cpp
new file mode 100644
index 0000000000..40f9f188d1
--- /dev/null
+++ b/modules/juce_dsp/maths/juce_LogRampedValue.cpp
@@ -0,0 +1,101 @@
+/*
+  ==============================================================================
+
+   This file is part of the JUCE library.
+   Copyright (c) 2017 - ROLI Ltd.
+
+   JUCE is an open source library subject to commercial or open-source
+   licensing.
+
+   By using JUCE, you agree to the terms of both the JUCE 5 End-User License
+   Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
+   27th April 2017).
+
+   End User License Agreement: www.juce.com/juce-5-licence
+   Privacy Policy: www.juce.com/juce-5-privacy-policy
+
+   Or: You may also use this code under the terms of the GPL v3 (see
+   www.gnu.org/licenses).
+
+   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
+   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
+   DISCLAIMED.
+
+  ==============================================================================
+*/
+
+namespace juce
+{
+namespace dsp
+{
+
+#if JUCE_UNIT_TESTS
+
+static CommonSmoothedValueTests <LogSmoothedValue <float>> commonLogRampedValueTests;
+
+class LogSmoothedValueTests  : public UnitTest
+{
+public:
+    LogSmoothedValueTests()
+        : UnitTest ("LogSmoothedValueTests", "SmoothedValues")
+    {}
+
+    void runTest() override
+    {
+        beginTest ("Curve");
+        {
+            Array<double> levels = { -0.12243, -1.21245, -12.2342, -22.4683, -30.0, -61.18753 };
+
+            for (auto level : levels)
+            {
+                Array<Range<double>> ranges = { Range<double> (0.0,    1.0),
+                                                Range<double> (-2.345, 0.0),
+                                                Range<double> (-2.63,  3.56),
+                                                Range<double> (3.3,    -0.2) };
+
+                for (auto range : ranges)
+                {
+                    LogSmoothedValue<double> slowStart { range.getStart() } , fastStart { range.getEnd() };
+
+                    auto numSamples = 12;
+                    slowStart.reset (numSamples);
+                    fastStart.reset (numSamples);
+
+                    slowStart.setLogParameters (level, true);
+                    fastStart.setLogParameters (level, false);
+
+                    slowStart.setTargetValue (range.getEnd());
+                    fastStart.setTargetValue (range.getStart());
+
+                    AudioBuffer<double> results (2, numSamples + 1);
+
+                    results.setSample (0, 0, slowStart.getCurrentValue());
+                    results.setSample (1, 0, fastStart.getCurrentValue());
+
+                    for (int i = 1; i < results.getNumSamples(); ++i)
+                    {
+                        results.setSample (0, i, slowStart.getNextValue());
+                        results.setSample (1, i, fastStart.getNextValue());
+                    }
+
+                    for (int i = 0; i < results.getNumSamples(); ++i)
+                        expectWithinAbsoluteError (results.getSample (0, i),
+                                                   results.getSample (1, results.getNumSamples() - (i + 1)),
+                                                   1.0e-7);
+
+                    auto expectedMidpoint = range.getStart() + (range.getLength() * Decibels::decibelsToGain (level));
+                    expectWithinAbsoluteError (results.getSample (0, numSamples / 2),
+                                               expectedMidpoint,
+                                               1.0e-7);
+                }
+            }
+        }
+    }
+};
+
+static LogSmoothedValueTests logSmoothedValueTests;
+
+#endif
+
+} // namespace dsp
+} // namespace juce
diff --git a/modules/juce_dsp/maths/juce_LogRampedValue.h b/modules/juce_dsp/maths/juce_LogRampedValue.h
new file mode 100644
index 0000000000..0e045c6c01
--- /dev/null
+++ b/modules/juce_dsp/maths/juce_LogRampedValue.h
@@ -0,0 +1,190 @@
+/*
+  ==============================================================================
+
+   This file is part of the JUCE library.
+   Copyright (c) 2017 - ROLI Ltd.
+
+   JUCE is an open source library subject to commercial or open-source
+   licensing.
+
+   By using JUCE, you agree to the terms of both the JUCE 5 End-User License
+   Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
+   27th April 2017).
+
+   End User License Agreement: www.juce.com/juce-5-licence
+   Privacy Policy: www.juce.com/juce-5-privacy-policy
+
+   Or: You may also use this code under the terms of the GPL v3 (see
+   www.gnu.org/licenses).
+
+   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
+   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
+   DISCLAIMED.
+
+  ==============================================================================
+*/
+
+namespace juce
+{
+namespace dsp
+{
+
+//==============================================================================
+/**
+    Utility class for logarithmically smoothed values.
+
+    Logarithmically smoothed values can be more relevant than linear ones for
+    specific cases such as algorithm change smoothing, using two of them in
+    opposite directions.
+
+    @see SmoothedValue
+
+    @tags{Audio}
+*/
+template <typename FloatType>
+class LogRampedValue   : public SmoothedValueBase <LogRampedValue <FloatType>>
+{
+public:
+    //==============================================================================
+    /** Constructor. */
+    LogRampedValue() = default;
+
+    /** Constructor. */
+    LogRampedValue (FloatType initialValue) noexcept
+    {
+        // Visual Studio can't handle base class initialisation with CRTP
+        this->currentValue = initialValue;
+        this->target = initialValue;
+    }
+
+    //==============================================================================
+    /** Sets the behaviour of the log ramp.
+        @param midPointAmplitudedB           Sets the amplitude of the mid point in
+                                             decibels, with the target value at 0 dB
+                                             and the initial value at -inf dB
+        @param rateOfChangeShouldIncrease    If true then the ramp starts shallow
+                                             and gets progressively steeper, if false
+                                             then the ramp is initially steep and
+                                             flattens out as you approach the target
+                                             value
+    */
+    void setLogParameters (FloatType midPointAmplitudedB, bool rateOfChangeShouldIncrease) noexcept
+    {
+        jassert (midPointAmplitudedB < (FloatType) 0.0);
+        B = Decibels::decibelsToGain (midPointAmplitudedB);
+
+        increasingRateOfChange = rateOfChangeShouldIncrease;
+    }
+
+    //==============================================================================
+    /** Reset to a new sample rate and ramp length.
+        @param sampleRate           The sample rate
+        @param rampLengthInSeconds  The duration of the ramp in seconds
+    */
+    void reset (double sampleRate, double rampLengthInSeconds) noexcept
+    {
+        jassert (sampleRate > 0 && rampLengthInSeconds >= 0);
+        reset ((int) std::floor (rampLengthInSeconds * sampleRate));
+    }
+
+    /** Set a new ramp length directly in samples.
+        @param numSteps                   The number of samples over which the ramp should be active
+        @param increasingRateOfChange     If the log behaviour makes the ramp increase
+                                          slowly at the beginning, rather than at the end
+    */
+    void reset (int numSteps) noexcept
+    {
+        stepsToTarget = numSteps;
+
+        this->setCurrentAndTargetValue (this->target);
+
+        updateRampParameters();
+    }
+
+    //==============================================================================
+    /** Set a new target value.
+
+        @param newValue     The new target value
+        @param force        If true, the value will be set immediately, bypassing the ramp
+    */
+    void setTargetValue (FloatType newValue) noexcept
+    {
+        if (newValue == this->target)
+            return;
+
+        if (stepsToTarget <= 0)
+        {
+            this->setCurrentAndTargetValue (newValue);
+            return;
+        }
+
+        this->target = newValue;
+        this->countdown = stepsToTarget;
+        source = this->currentValue;
+
+        updateRampParameters();
+    }
+
+    //==============================================================================
+    /** Compute the next value.
+        @returns Smoothed value
+    */
+    FloatType getNextValue() noexcept
+    {
+        if (! this->isSmoothing())
+            return this->target;
+
+        --(this->countdown);
+
+        temp *= r; temp += d;
+        this->currentValue = jmap (temp, source, this->target);
+
+        return this->currentValue;
+    }
+
+    //==============================================================================
+    /** Skip the next numSamples samples.
+
+        This is identical to calling getNextValue numSamples times.
+        @see getNextValue
+    */
+    FloatType skip (int numSamples) noexcept
+    {
+        if (numSamples >= this->countdown)
+        {
+            this->setCurrentAndTargetValue (this->target);
+            return this->target;
+        }
+
+        this->countdown -= numSamples;
+
+        auto rN = (FloatType) std::pow (r, numSamples);
+        temp *= rN;
+        temp += d * (rN - (FloatType) 1) / (r - (FloatType) 1);
+
+        this->currentValue = jmap (temp, source, this->target);
+        return this->currentValue;
+    }
+
+private:
+    //==============================================================================
+    void updateRampParameters()
+    {
+        auto D = increasingRateOfChange ? B : (FloatType) 1 - B;
+        auto base = ((FloatType) 1 / D) - (FloatType) 1;
+        r = std::pow (base, (FloatType) 2 / (FloatType) stepsToTarget);
+        auto rN = std::pow (r, (FloatType) stepsToTarget);
+        d = (r - (FloatType) 1) / (rN - (FloatType) 1);
+        temp = 0;
+    }
+
+    //==============================================================================
+    bool increasingRateOfChange = true;
+    FloatType B = Decibels::decibelsToGain ((FloatType) -40);
+
+    int stepsToTarget = 0;
+    FloatType temp = 0, source = 0, r = 0, d = 1;
+};
+
+} // namespace dsp
+} // namespace juce
diff --git a/modules/juce_dsp/processors/juce_Bias.h b/modules/juce_dsp/processors/juce_Bias.h
index 7f3f3db96b..4348cdb3e1 100644
--- a/modules/juce_dsp/processors/juce_Bias.h
+++ b/modules/juce_dsp/processors/juce_Bias.h
@@ -144,7 +144,7 @@ public:
 
 private:
     //==============================================================================
-    LinearSmoothedValue<FloatType> bias;
+    SmoothedValue<FloatType> bias;
     double sampleRate = 0, rampDurationSeconds = 0;
 
     void updateRamp() noexcept
diff --git a/modules/juce_dsp/processors/juce_Gain.h b/modules/juce_dsp/processors/juce_Gain.h
index 6950e52215..3c542b571a 100644
--- a/modules/juce_dsp/processors/juce_Gain.h
+++ b/modules/juce_dsp/processors/juce_Gain.h
@@ -139,7 +139,7 @@ public:
 
 private:
     //==============================================================================
-    LinearSmoothedValue<FloatType> gain;
+    SmoothedValue<FloatType> gain;
     double sampleRate = 0, rampDurationSeconds = 0;
 };
 
diff --git a/modules/juce_dsp/processors/juce_LadderFilter.h b/modules/juce_dsp/processors/juce_LadderFilter.h
index a37382c9e9..8b38aaf784 100644
--- a/modules/juce_dsp/processors/juce_LadderFilter.h
+++ b/modules/juce_dsp/processors/juce_LadderFilter.h
@@ -118,7 +118,7 @@ private:
     std::vector<std::array<Type, numStates>> state;
     std::array<Type, numStates> A;
 
-    LinearSmoothedValue<Type> cutoffTransformSmoother, scaledResonanceSmoother;
+    SmoothedValue<Type> cutoffTransformSmoother, scaledResonanceSmoother;
     Type cutoffTransformValue, scaledResonanceValue;
 
     LookupTableTransform<Type> saturationLUT { [] (Type x) { return std::tanh (x); }, Type (-5), Type (5), 128 };
diff --git a/modules/juce_dsp/processors/juce_Oscillator.h b/modules/juce_dsp/processors/juce_Oscillator.h
index 0c41ee8997..a3a0d6e86b 100644
--- a/modules/juce_dsp/processors/juce_Oscillator.h
+++ b/modules/juce_dsp/processors/juce_Oscillator.h
@@ -243,7 +243,7 @@ private:
     std::function<NumericType (NumericType)> generator;
     std::unique_ptr<LookupTableTransform<NumericType>> lookupTable;
     Array<NumericType> rampBuffer;
-    LinearSmoothedValue<NumericType> frequency { static_cast<NumericType> (440.0) };
+    SmoothedValue<NumericType> frequency { static_cast<NumericType> (440.0) };
     NumericType sampleRate = 48000.0;
     Phase<NumericType> phase;
 };