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juce_Windowing.cpp
/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2022 - Raw Material Software Limited
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 7 End-User License
Agreement and JUCE Privacy Policy.
End User License Agreement: www.juce.com/juce-7-licence
Privacy Policy: www.juce.com/juce-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::dsp
{
template <typename FloatType>
static FloatType ncos (size_t order, size_t i, size_t size) noexcept
{
return std::cos (static_cast<FloatType> (order * i)
* MathConstants<FloatType>::pi / static_cast<FloatType> (size - 1));
}
template <typename FloatType>
WindowingFunction<FloatType>::WindowingFunction (size_t size, WindowingMethod type, bool normalise, FloatType beta)
{
fillWindowingTables (size, type, normalise, beta);
}
template <typename FloatType>
void WindowingFunction<FloatType>::fillWindowingTables (size_t size, WindowingMethod type,
bool normalise, FloatType beta) noexcept
{
windowTable.resize (static_cast<int> (size));
fillWindowingTables (windowTable.getRawDataPointer(), size, type, normalise, beta);
}
template <typename FloatType>
void WindowingFunction<FloatType>::fillWindowingTables (FloatType* samples, size_t size,
WindowingMethod type, bool normalise,
FloatType beta) noexcept
{
switch (type)
{
case rectangular:
{
for (size_t i = 0; i < size; ++i)
samples[i] = static_cast<FloatType> (1);
}
break;
case triangular:
{
auto halfSlots = static_cast<FloatType> (0.5) * static_cast<FloatType> (size - 1);
for (size_t i = 0; i < size; ++i)
samples[i] = static_cast<FloatType> (1.0) - std::abs ((static_cast<FloatType> (i) - halfSlots) / halfSlots);
}
break;
case hann:
{
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
samples[i] = static_cast<FloatType> (0.5 - 0.5 * cos2);
}
}
break;
case hamming:
{
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
samples[i] = static_cast<FloatType> (0.54 - 0.46 * cos2);
}
}
break;
case blackman:
{
constexpr FloatType alpha = 0.16f;
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
auto cos4 = ncos<FloatType> (4, i, size);
samples[i] = static_cast<FloatType> (0.5 * (1 - alpha) - 0.5 * cos2 + 0.5 * alpha * cos4);
}
}
break;
case blackmanHarris:
{
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
auto cos4 = ncos<FloatType> (4, i, size);
auto cos6 = ncos<FloatType> (6, i, size);
samples[i] = static_cast<FloatType> (0.35875 - 0.48829 * cos2 + 0.14128 * cos4 - 0.01168 * cos6);
}
}
break;
case flatTop:
{
for (size_t i = 0; i < size; ++i)
{
auto cos2 = ncos<FloatType> (2, i, size);
auto cos4 = ncos<FloatType> (4, i, size);
auto cos6 = ncos<FloatType> (6, i, size);
auto cos8 = ncos<FloatType> (8, i, size);
samples[i] = static_cast<FloatType> (1.0 - 1.93 * cos2 + 1.29 * cos4 - 0.388 * cos6 + 0.028 * cos8);
}
}
break;
case kaiser:
{
const double factor = 1.0 / SpecialFunctions::besselI0 (beta);
const auto doubleSize = (double) size;
for (size_t i = 0; i < size; ++i)
samples[i] = static_cast<FloatType> (SpecialFunctions::besselI0 (beta * std::sqrt (1.0 - std::pow (((double) i - 0.5 * (doubleSize - 1.0))
/ ( 0.5 * (doubleSize - 1.0)), 2.0)))
* factor);
}
break;
case numWindowingMethods:
default:
jassertfalse;
break;
}
// DC frequency amplitude must be one
if (normalise)
{
FloatType sum (0);
for (size_t i = 0; i < size; ++i)
sum += samples[i];
auto factor = static_cast<FloatType> (size) / sum;
FloatVectorOperations::multiply (samples, factor, static_cast<int> (size));
}
}
template <typename FloatType>
void WindowingFunction<FloatType>::multiplyWithWindowingTable (FloatType* samples, size_t size) const noexcept
{
FloatVectorOperations::multiply (samples, windowTable.getRawDataPointer(), jmin (static_cast<int> (size), windowTable.size()));
}
template <typename FloatType>
const char* WindowingFunction<FloatType>::getWindowingMethodName (WindowingMethod type) noexcept
{
switch (type)
{
case rectangular: return "Rectangular";
case triangular: return "Triangular";
case hann: return "Hann";
case hamming: return "Hamming";
case blackman: return "Blackman";
case blackmanHarris: return "Blackman-Harris";
case flatTop: return "Flat Top";
case kaiser: return "Kaiser";
case numWindowingMethods:
default: jassertfalse; return "";
}
}
template class WindowingFunction<float>;
template class WindowingFunction<double>;
} // namespace juce::dsp
juce::dsp::WindowingFunction
Definition juce_Windowing.h:41
juce::dsp::WindowingFunction::WindowingMethod
WindowingMethod
Definition juce_Windowing.h:46
juce::dsp::WindowingFunction::WindowingFunction
WindowingFunction(size_t size, WindowingMethod, bool normalise=true, FloatType beta=0)
Definition juce_Windowing.cpp:37
juce::dsp::WindowingFunction::getWindowingMethodName
static const char * getWindowingMethodName(WindowingMethod) noexcept
Definition juce_Windowing.cpp:173
juce::dsp::WindowingFunction::multiplyWithWindowingTable
void multiplyWithWindowingTable(FloatType *samples, size_t size) const noexcept
Definition juce_Windowing.cpp:167
juce::dsp::WindowingFunction::fillWindowingTables
void fillWindowingTables(size_t size, WindowingMethod type, bool normalise=true, FloatType beta=0) noexcept
Definition juce_Windowing.cpp:43
juce::MathConstants::pi
static constexpr FloatType pi
Definition juce_MathsFunctions.h:141
juce::dsp::SpecialFunctions::besselI0
static double besselI0(double x) noexcept
Definition juce_SpecialFunctions.cpp:29