OpenShot Audio Library | OpenShotAudio 0.4.0

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juce_LadderFilter.cpp
1/*
2 ==============================================================================
3
4 This file is part of the JUCE library.
5 Copyright (c) 2022 - Raw Material Software Limited
6
7 JUCE is an open source library subject to commercial or open-source
8 licensing.
9
10 By using JUCE, you agree to the terms of both the JUCE 7 End-User License
11 Agreement and JUCE Privacy Policy.
12
13 End User License Agreement: www.juce.com/juce-7-licence
14 Privacy Policy: www.juce.com/juce-privacy-policy
15
16 Or: You may also use this code under the terms of the GPL v3 (see
17 www.gnu.org/licenses).
18
19 JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
20 EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
21 DISCLAIMED.
22
23 ==============================================================================
24*/
25
26 namespace juce::dsp
27{
28
29//==============================================================================
30 template <typename SampleType>
31 LadderFilter<SampleType>::LadderFilter() : state (2)
32{
33 setSampleRate (SampleType (1000)); // intentionally setting unrealistic default
34 // sample rate to catch missing initialisation bugs
35 setResonance (SampleType (0));
36 setDrive (SampleType (1.2));
37
38 mode = Mode::LPF24;
39 setMode (Mode::LPF12);
40}
41
42//==============================================================================
43 template <typename SampleType>
44 void LadderFilter<SampleType>::setMode (Mode newMode) noexcept
45{
46 if (newMode == mode)
47 return;
48
49 switch (newMode)
50 {
51 case Mode::LPF12: A = {{ SampleType (0), SampleType (0), SampleType (1), SampleType (0), SampleType (0) }}; comp = SampleType (0.5); break;
52 case Mode::HPF12: A = {{ SampleType (1), SampleType (-2), SampleType (1), SampleType (0), SampleType (0) }}; comp = SampleType (0); break;
53 case Mode::BPF12: A = {{ SampleType (0), SampleType (0), SampleType (-1), SampleType (1), SampleType (0) }}; comp = SampleType (0.5); break;
54 case Mode::LPF24: A = {{ SampleType (0), SampleType (0), SampleType (0), SampleType (0), SampleType (1) }}; comp = SampleType (0.5); break;
55 case Mode::HPF24: A = {{ SampleType (1), SampleType (-4), SampleType (6), SampleType (-4), SampleType (1) }}; comp = SampleType (0); break;
56 case Mode::BPF24: A = {{ SampleType (0), SampleType (0), SampleType (1), SampleType (-2), SampleType (1) }}; comp = SampleType (0.5); break;
57 default: jassertfalse; break;
58 }
59
60 static constexpr auto outputGain = SampleType (1.2);
61
62 for (auto& a : A)
63 a *= outputGain;
64
65 mode = newMode;
66 reset();
67}
68
69//==============================================================================
70 template <typename SampleType>
71 void LadderFilter<SampleType>::prepare (const ProcessSpec& spec)
72{
73 setSampleRate (SampleType (spec.sampleRate));
74 setNumChannels (spec.numChannels);
75 reset();
76}
77
78//==============================================================================
79 template <typename SampleType>
80 void LadderFilter<SampleType>::reset() noexcept
81{
82 for (auto& s : state)
83 s.fill (SampleType (0));
84
85 cutoffTransformSmoother.setCurrentAndTargetValue (cutoffTransformSmoother.getTargetValue());
86 scaledResonanceSmoother.setCurrentAndTargetValue (scaledResonanceSmoother.getTargetValue());
87}
88
89//==============================================================================
90 template <typename SampleType>
91 void LadderFilter<SampleType>::setCutoffFrequencyHz (SampleType newCutoff) noexcept
92{
93 jassert (newCutoff > SampleType (0));
94 cutoffFreqHz = newCutoff;
95 updateCutoffFreq();
96}
97
98//==============================================================================
99 template <typename SampleType>
100 void LadderFilter<SampleType>::setResonance (SampleType newResonance) noexcept
101{
102 jassert (newResonance >= SampleType (0) && newResonance <= SampleType (1));
103 resonance = newResonance;
104 updateResonance();
105}
106
107//==============================================================================
108 template <typename SampleType>
109 void LadderFilter<SampleType>::setDrive (SampleType newDrive) noexcept
110{
111 jassert (newDrive >= SampleType (1));
112
113 drive = newDrive;
114 gain = std::pow (drive, SampleType (-2.642)) * SampleType (0.6103) + SampleType (0.3903);
115 drive2 = drive * SampleType (0.04) + SampleType (0.96);
116 gain2 = std::pow (drive2, SampleType (-2.642)) * SampleType (0.6103) + SampleType (0.3903);
117}
118
119//==============================================================================
120 template <typename SampleType>
121SampleType LadderFilter<SampleType>::processSample (SampleType inputValue, size_t channelToUse) noexcept
122{
123 auto& s = state[channelToUse];
124
125 const auto a1 = cutoffTransformValue;
126 const auto g = a1 * SampleType (-1) + SampleType (1);
127 const auto b0 = g * SampleType (0.76923076923);
128 const auto b1 = g * SampleType (0.23076923076);
129
130 const auto dx = gain * saturationLUT (drive * inputValue);
131 const auto a = dx + scaledResonanceValue * SampleType (-4) * (gain2 * saturationLUT (drive2 * s[4]) - dx * comp);
132
133 const auto b = b1 * s[0] + a1 * s[1] + b0 * a;
134 const auto c = b1 * s[1] + a1 * s[2] + b0 * b;
135 const auto d = b1 * s[2] + a1 * s[3] + b0 * c;
136 const auto e = b1 * s[3] + a1 * s[4] + b0 * d;
137
138 s[0] = a;
139 s[1] = b;
140 s[2] = c;
141 s[3] = d;
142 s[4] = e;
143
144 return a * A[0] + b * A[1] + c * A[2] + d * A[3] + e * A[4];
145}
146
147//==============================================================================
148 template <typename SampleType>
149 void LadderFilter<SampleType>::updateSmoothers() noexcept
150{
151 cutoffTransformValue = cutoffTransformSmoother.getNextValue();
152 scaledResonanceValue = scaledResonanceSmoother.getNextValue();
153}
154
155//==============================================================================
156 template <typename SampleType>
157 void LadderFilter<SampleType>::setSampleRate (SampleType newValue) noexcept
158{
159 jassert (newValue > SampleType (0));
160 cutoffFreqScaler = SampleType (-2.0 * juce::MathConstants<double>::pi) / newValue;
161
162 static constexpr SampleType smootherRampTimeSec = SampleType (0.05);
163 cutoffTransformSmoother.reset (newValue, smootherRampTimeSec);
164 scaledResonanceSmoother.reset (newValue, smootherRampTimeSec);
165
166 updateCutoffFreq();
167}
168
169//==============================================================================
170 template class LadderFilter<float>;
171 template class LadderFilter<double>;
172
173} // namespace juce::dsp
juce::dsp::LadderFilter
Definition juce_LadderFilter.h:46
juce::dsp::LadderFilter::LadderFilter
LadderFilter()
Definition juce_LadderFilter.cpp:31
juce::dsp::LadderFilter::setCutoffFrequencyHz
void setCutoffFrequencyHz(SampleType newCutoff) noexcept
Definition juce_LadderFilter.cpp:91
juce::dsp::LadderFilter::prepare
void prepare(const ProcessSpec &spec)
Definition juce_LadderFilter.cpp:71
juce::dsp::LadderFilter::setDrive
void setDrive(SampleType newDrive) noexcept
Definition juce_LadderFilter.cpp:109
juce::dsp::LadderFilter::setMode
void setMode(Mode newMode) noexcept
Definition juce_LadderFilter.cpp:44
juce::dsp::LadderFilter::reset
void reset() noexcept
Definition juce_LadderFilter.cpp:80
juce::dsp::LadderFilter::setResonance
void setResonance(SampleType newResonance) noexcept
Definition juce_LadderFilter.cpp:100
juce::MathConstants
Definition juce_MathsFunctions.h:139
juce::dsp::ProcessSpec
Definition juce_ProcessContext.h:36
juce::dsp::ProcessSpec::numChannels
uint32 numChannels
Definition juce_ProcessContext.h:44
juce::dsp::ProcessSpec::sampleRate
double sampleRate
Definition juce_ProcessContext.h:38