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https://github.com/juce-framework/JUCE.git
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255 lines
9.3 KiB
C++
255 lines
9.3 KiB
C++
/*
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==============================================================================
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This file is part of the JUCE framework.
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Copyright (c) Raw Material Software Limited
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JUCE is an open source framework subject to commercial or open source
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licensing.
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By downloading, installing, or using the JUCE framework, or combining the
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JUCE framework with any other source code, object code, content or any other
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copyrightable work, you agree to the terms of the JUCE End User Licence
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Agreement, and all incorporated terms including the JUCE Privacy Policy and
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the JUCE Website Terms of Service, as applicable, which will bind you. If you
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do not agree to the terms of these agreements, we will not license the JUCE
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framework to you, and you must discontinue the installation or download
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process and cease use of the JUCE framework.
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JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
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JUCE Privacy Policy: https://juce.com/juce-privacy-policy
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JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/
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Or:
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You may also use this code under the terms of the AGPLv3:
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https://www.gnu.org/licenses/agpl-3.0.en.html
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THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
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WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
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MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.
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==============================================================================
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*/
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namespace juce
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{
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/**
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A collection of different interpolators for resampling streams of floats.
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@see GenericInterpolator, WindowedSincInterpolator, LagrangeInterpolator,
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CatmullRomInterpolator, LinearInterpolator, ZeroOrderHoldInterpolator
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@tags{Audio}
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*/
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class Interpolators
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{
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private:
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struct WindowedSincTraits
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{
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static constexpr float algorithmicLatency = 100.0f;
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static forcedinline float windowedSinc (float firstFrac, int index) noexcept
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{
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auto index2 = index + 1;
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auto frac = firstFrac;
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auto value1 = lookupTable[index];
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auto value2 = lookupTable[index2];
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return value1 + (frac * (value2 - value1));
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}
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static forcedinline float valueAtOffset (const float* const inputs, const float offset, int indexBuffer) noexcept
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{
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const int numCrossings = 100;
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const float floatCrossings = (float) numCrossings;
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float result = 0.0f;
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auto samplePosition = indexBuffer;
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float firstFrac = 0.0f;
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float lastSincPosition = -1.0f;
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int index = 0, sign = -1;
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for (int i = -numCrossings; i <= numCrossings; ++i)
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{
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auto sincPosition = (1.0f - offset) + (float) i;
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if (i == -numCrossings || (sincPosition >= 0 && lastSincPosition < 0))
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{
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auto indexFloat = (sincPosition >= 0.f ? sincPosition : -sincPosition) * 100.0f;
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auto indexFloored = std::floor (indexFloat);
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index = (int) indexFloored;
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firstFrac = indexFloat - indexFloored;
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sign = (sincPosition < 0 ? -1 : 1);
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}
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if (exactlyEqual (sincPosition, 0.0f))
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result += inputs[samplePosition];
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else if (sincPosition < floatCrossings && sincPosition > -floatCrossings)
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result += inputs[samplePosition] * windowedSinc (firstFrac, index);
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if (++samplePosition == numCrossings * 2)
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samplePosition = 0;
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lastSincPosition = sincPosition;
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index += 100 * sign;
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}
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return result;
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}
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static const float lookupTable[10001];
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};
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struct LagrangeTraits
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{
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static constexpr float algorithmicLatency = 2.0f;
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static float valueAtOffset (const float*, float, int) noexcept;
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};
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struct CatmullRomTraits
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{
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//==============================================================================
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static constexpr float algorithmicLatency = 2.0f;
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static forcedinline float valueAtOffset (const float* const inputs, const float offset, int index) noexcept
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{
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auto y0 = inputs[index]; if (++index == 4) index = 0;
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auto y1 = inputs[index]; if (++index == 4) index = 0;
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auto y2 = inputs[index]; if (++index == 4) index = 0;
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auto y3 = inputs[index];
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auto halfY0 = 0.5f * y0;
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auto halfY3 = 0.5f * y3;
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return y1 + offset * ((0.5f * y2 - halfY0)
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+ (offset * (((y0 + 2.0f * y2) - (halfY3 + 2.5f * y1))
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+ (offset * ((halfY3 + 1.5f * y1) - (halfY0 + 1.5f * y2))))));
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}
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};
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struct LinearTraits
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{
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static constexpr float algorithmicLatency = 1.0f;
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static forcedinline float valueAtOffset (const float* const inputs, const float offset, int index) noexcept
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{
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auto y0 = inputs[index];
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auto y1 = inputs[index == 0 ? 1 : 0];
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return y1 * offset + y0 * (1.0f - offset);
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}
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};
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struct ZeroOrderHoldTraits
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{
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static constexpr float algorithmicLatency = 0.0f;
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static forcedinline float valueAtOffset (const float* const inputs, const float, int) noexcept
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{
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return inputs[0];
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}
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};
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public:
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using WindowedSinc = GenericInterpolator<WindowedSincTraits, 200>;
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using Lagrange = GenericInterpolator<LagrangeTraits, 5>;
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using CatmullRom = GenericInterpolator<CatmullRomTraits, 4>;
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using Linear = GenericInterpolator<LinearTraits, 2>;
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using ZeroOrderHold = GenericInterpolator<ZeroOrderHoldTraits, 1>;
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};
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//==============================================================================
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/**
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An interpolator for resampling a stream of floats using high order windowed
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(hann) sinc interpolation, recommended for high quality resampling.
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Note that the resampler is stateful, so when there's a break in the continuity
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of the input stream you're feeding it, you should call reset() before feeding
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it any new data. And like with any other stateful filter, if you're resampling
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multiple channels, make sure each one uses its own WindowedSincInterpolator
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object.
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@see GenericInterpolator
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@see LagrangeInterpolator, CatmullRomInterpolator, LinearInterpolator,
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ZeroOrderHoldInterpolator
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@tags{Audio}
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*/
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using WindowedSincInterpolator = Interpolators::WindowedSinc;
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/**
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An interpolator for resampling a stream of floats using 4-point lagrange interpolation.
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Note that the resampler is stateful, so when there's a break in the continuity
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of the input stream you're feeding it, you should call reset() before feeding
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it any new data. And like with any other stateful filter, if you're resampling
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multiple channels, make sure each one uses its own LagrangeInterpolator object.
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@see GenericInterpolator
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@see CatmullRomInterpolator, WindowedSincInterpolator, LinearInterpolator,
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ZeroOrderHoldInterpolator
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@tags{Audio}
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*/
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using LagrangeInterpolator = Interpolators::Lagrange;
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/**
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An interpolator for resampling a stream of floats using Catmull-Rom interpolation.
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Note that the resampler is stateful, so when there's a break in the continuity
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of the input stream you're feeding it, you should call reset() before feeding
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it any new data. And like with any other stateful filter, if you're resampling
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multiple channels, make sure each one uses its own CatmullRomInterpolator object.
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@see GenericInterpolator
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@see LagrangeInterpolator, WindowedSincInterpolator, LinearInterpolator,
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ZeroOrderHoldInterpolator
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@tags{Audio}
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*/
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using CatmullRomInterpolator = Interpolators::CatmullRom;
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/**
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An interpolator for resampling a stream of floats using linear interpolation.
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Note that the resampler is stateful, so when there's a break in the continuity
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of the input stream you're feeding it, you should call reset() before feeding
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it any new data. And like with any other stateful filter, if you're resampling
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multiple channels, make sure each one uses its own LinearInterpolator object.
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@see GenericInterpolator
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@see LagrangeInterpolator, CatmullRomInterpolator, WindowedSincInterpolator,
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ZeroOrderHoldInterpolator
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@tags{Audio}
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*/
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using LinearInterpolator = Interpolators::Linear;
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/**
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An interpolator for resampling a stream of floats using zero order hold
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interpolation.
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Note that the resampler is stateful, so when there's a break in the continuity
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of the input stream you're feeding it, you should call reset() before feeding
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it any new data. And like with any other stateful filter, if you're resampling
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multiple channels, make sure each one uses its own ZeroOrderHoldInterpolator
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object.
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@see GenericInterpolator
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@see LagrangeInterpolator, CatmullRomInterpolator, WindowedSincInterpolator,
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LinearInterpolator
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@tags{Audio}
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*/
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using ZeroOrderHoldInterpolator = Interpolators::ZeroOrderHold;
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} // namespace juce
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