OpenShot Audio Library | OpenShotAudio: juce_Windowing.cpp Source File

OpenShot Audio Library | OpenShotAudio 0.3.1

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juce_Windowing.cpp
1/*
2 ==============================================================================
3
4 This file is part of the JUCE library.
5 Copyright (c) 2017 - ROLI Ltd.
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 5 End-User License
11 Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
12 27th April 2017).
13
14 End User License Agreement: www.juce.com/juce-5-licence
15 Privacy Policy: www.juce.com/juce-5-privacy-policy
16
17 Or: You may also use this code under the terms of the GPL v3 (see
18 www.gnu.org/licenses).
19
20 JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
21 EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
22 DISCLAIMED.
23
24 ==============================================================================
25*/
26
27namespace juce
28{
29namespace dsp
30{
31
32template <typename FloatType>
33static inline FloatType ncos (size_t order, size_t i, size_t size) noexcept
34{
35 return std::cos (static_cast<FloatType> (order * i)
36 * MathConstants<FloatType>::pi / static_cast<FloatType> (size - 1));
37}
38
39template <typename FloatType>
40WindowingFunction<FloatType>::WindowingFunction (size_t size, WindowingMethod type, bool normalise, FloatType beta)
41{
42 fillWindowingTables (size, type, normalise, beta);
43}
44
45template <typename FloatType>
46 void WindowingFunction<FloatType>::fillWindowingTables (size_t size, WindowingMethod type,
47 bool normalise, FloatType beta) noexcept
48{
49 windowTable.resize (static_cast<int> (size));
50 fillWindowingTables (windowTable.getRawDataPointer(), size, type, normalise, beta);
51}
52
53template <typename FloatType>
54 void WindowingFunction<FloatType>::fillWindowingTables (FloatType* samples, size_t size,
55 WindowingMethod type, bool normalise,
56 FloatType beta) noexcept
57{
58 switch (type)
59 {
60 case rectangular:
61 {
62 for (size_t i = 0; i < size; ++i)
63 samples[i] = static_cast<FloatType> (1);
64 }
65 break;
66
67 case triangular:
68 {
69 auto halfSlots = static_cast<FloatType> (0.5) * static_cast<FloatType> (size - 1);
70
71 for (size_t i = 0; i < size; ++i)
72 samples[i] = static_cast<FloatType> (1.0) - std::abs ((static_cast<FloatType> (i) - halfSlots) / halfSlots);
73 }
74 break;
75
76 case hann:
77 {
78 for (size_t i = 0; i < size; ++i)
79 {
80 auto cos2 = ncos<FloatType> (2, i, size);
81 samples[i] = static_cast<FloatType> (0.5 - 0.5 * cos2);
82 }
83 }
84 break;
85
86 case hamming:
87 {
88 for (size_t i = 0; i < size; ++i)
89 {
90 auto cos2 = ncos<FloatType> (2, i, size);
91 samples[i] = static_cast<FloatType> (0.54 - 0.46 * cos2);
92 }
93 }
94 break;
95
96 case blackman:
97 {
98 constexpr FloatType alpha = 0.16f;
99
100 for (size_t i = 0; i < size; ++i)
101 {
102 auto cos2 = ncos<FloatType> (2, i, size);
103 auto cos4 = ncos<FloatType> (4, i, size);
104
105 samples[i] = static_cast<FloatType> (0.5 * (1 - alpha) - 0.5 * cos2 + 0.5 * alpha * cos4);
106 }
107 }
108 break;
109
110 case blackmanHarris:
111 {
112 for (size_t i = 0; i < size; ++i)
113 {
114 auto cos2 = ncos<FloatType> (2, i, size);
115 auto cos4 = ncos<FloatType> (4, i, size);
116 auto cos6 = ncos<FloatType> (6, i, size);
117
118 samples[i] = static_cast<FloatType> (0.35875 - 0.48829 * cos2 + 0.14128 * cos4 - 0.01168 * cos6);
119 }
120 }
121 break;
122
123 case flatTop:
124 {
125 for (size_t i = 0; i < size; ++i)
126 {
127 auto cos2 = ncos<FloatType> (2, i, size);
128 auto cos4 = ncos<FloatType> (4, i, size);
129 auto cos6 = ncos<FloatType> (6, i, size);
130 auto cos8 = ncos<FloatType> (8, i, size);
131
132 samples[i] = static_cast<FloatType> (1.0 - 1.93 * cos2 + 1.29 * cos4 - 0.388 * cos6 + 0.028 * cos8);
133 }
134 }
135 break;
136
137 case kaiser:
138 {
139 const double factor = 1.0 / SpecialFunctions::besselI0 (beta);
140
141 for (size_t i = 0; i < size; ++i)
142 samples[i] = static_cast<FloatType> (SpecialFunctions::besselI0 (beta * std::sqrt (1.0 - std::pow ((i - 0.5 * (size - 1.0))
143 / ( 0.5 * (size - 1.0)), 2.0)))
144 * factor);
145 }
146 break;
147
148 default:
149 jassertfalse;
150 break;
151 }
152
153 // DC frequency amplitude must be one
154 if (normalise)
155 {
156 FloatType sum (0);
157
158 for (size_t i = 0; i < size; ++i)
159 sum += samples[i];
160
161 auto factor = static_cast<FloatType> (size) / sum;
162
163 FloatVectorOperations::multiply (samples, factor, static_cast<int> (size));
164 }
165}
166
167template <typename FloatType>
168 void WindowingFunction<FloatType>::multiplyWithWindowingTable (FloatType* samples, size_t size) noexcept
169{
170 FloatVectorOperations::multiply (samples, windowTable.getRawDataPointer(), jmin (static_cast<int> (size), windowTable.size()));
171}
172
173template <typename FloatType>
174 const char* WindowingFunction<FloatType>::getWindowingMethodName (WindowingMethod type) noexcept
175{
176 switch (type)
177 {
178 case rectangular: return "Rectangular";
179 case triangular: return "Triangular";
180 case hann: return "Hann";
181 case hamming: return "Hamming";
182 case blackman: return "Blackman";
183 case blackmanHarris: return "Blackman-Harris";
184 case flatTop: return "Flat Top";
185 case kaiser: return "Kaiser";
186 default: jassertfalse; return "";
187 }
188}
189
190template class WindowingFunction<float>;
191template class WindowingFunction<double>;
192
193} // namespace dsp
194} // namespace juce
juce::FloatVectorOperations::multiply
static void JUCE_CALLTYPE multiply(float *dest, const float *src, int numValues) noexcept
Definition: juce_FloatVectorOperations.cpp:754
juce::dsp::WindowingFunction
Definition: juce_Windowing.h:44
juce::dsp::WindowingFunction::WindowingMethod
WindowingMethod
Definition: juce_Windowing.h:49
juce::dsp::WindowingFunction::multiplyWithWindowingTable
void multiplyWithWindowingTable(FloatType *samples, size_t size) noexcept
Definition: juce_Windowing.cpp:168
juce::dsp::WindowingFunction::WindowingFunction
WindowingFunction(size_t size, WindowingMethod, bool normalise=true, FloatType beta=0)
Definition: juce_Windowing.cpp:40
juce::dsp::WindowingFunction::getWindowingMethodName
static const char * getWindowingMethodName(WindowingMethod) noexcept
Definition: juce_Windowing.cpp:174
juce::dsp::WindowingFunction::fillWindowingTables
void fillWindowingTables(size_t size, WindowingMethod type, bool normalise=true, FloatType beta=0) noexcept
Definition: juce_Windowing.cpp:46
juce::MathConstants::pi
static const FloatType pi
Definition: juce_MathsFunctions.h:365
juce::dsp::SpecialFunctions::besselI0
static double besselI0(double x) noexcept
Definition: juce_SpecialFunctions.cpp:32