340 lines
12 KiB
C
340 lines
12 KiB
C
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/*
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==============================================================================
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This file is part of the JUCE library.
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Copyright (c) 2020 - Raw Material Software Limited
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JUCE is an open source library subject to commercial or open-source
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licensing.
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By using JUCE, you agree to the terms of both the JUCE 6 End-User License
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Agreement and JUCE Privacy Policy (both effective as of the 16th June 2020).
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End User License Agreement: www.juce.com/juce-6-licence
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Privacy Policy: www.juce.com/juce-privacy-policy
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Or: You may also use this code under the terms of the GPL v3 (see
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www.gnu.org/licenses).
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JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
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EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
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DISCLAIMED.
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==============================================================================
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*/
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namespace juce
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{
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namespace dsp
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{
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//==============================================================================
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/**
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A collection of structs to pass as the template argument when setting the
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interpolation type for the DelayLine class.
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*/
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namespace DelayLineInterpolationTypes
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{
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/**
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No interpolation between successive samples in the delay line will be
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performed. This is useful when the delay is a constant integer or to
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create lo-fi audio effects.
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@tags{DSP}
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*/
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struct None {};
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/**
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Successive samples in the delay line will be linearly interpolated. This
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type of interpolation has a low compuational cost where the delay can be
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modulated in real time, but it also introduces a low-pass filtering effect
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into your audio signal.
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@tags{DSP}
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*/
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struct Linear {};
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/**
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Successive samples in the delay line will be interpolated using a 3rd order
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Lagrange interpolator. This method incurs more computational overhead than
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linear interpolation but reduces the low-pass filtering effect whilst
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remaining amenable to real time delay modulation.
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@tags{DSP}
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*/
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struct Lagrange3rd {};
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/**
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Successive samples in the delay line will be interpolated using 1st order
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Thiran interpolation. This method is very efficient, and features a flat
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amplitude frequency response in exchange for less accuracy in the phase
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response. This interpolation method is stateful so is unsuitable for
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applications requiring fast delay modulation.
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@tags{DSP}
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*/
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struct Thiran {};
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}
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//==============================================================================
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/**
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A delay line processor featuring several algorithms for the fractional delay
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calculation, block processing, and sample-by-sample processing useful when
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modulating the delay in real time or creating a standard delay effect with
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feedback.
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Note: If you intend to change the delay in real time, you may want to smooth
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changes to the delay systematically using either a ramp or a low-pass filter.
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@see SmoothedValue, FirstOrderTPTFilter
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@tags{DSP}
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*/
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template <typename SampleType, typename InterpolationType = DelayLineInterpolationTypes::Linear>
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class DelayLine
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{
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public:
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//==============================================================================
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/** Default constructor. */
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DelayLine();
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/** Constructor. */
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explicit DelayLine (int maximumDelayInSamples);
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//==============================================================================
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/** Sets the delay in samples. */
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void setDelay (SampleType newDelayInSamples);
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/** Returns the current delay in samples. */
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SampleType getDelay() const;
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//==============================================================================
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/** Initialises the processor. */
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void prepare (const ProcessSpec& spec);
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/** Sets a new maximum delay in samples.
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Also clears the delay line.
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This may allocate internally, so you should never call it from the audio thread.
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*/
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void setMaximumDelayInSamples (int maxDelayInSamples);
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/** Gets the maximum possible delay in samples.
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For very short delay times, the result of getMaximumDelayInSamples() may
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differ from the last value passed to setMaximumDelayInSamples().
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*/
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int getMaximumDelayInSamples() const noexcept { return totalSize - 1; }
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/** Resets the internal state variables of the processor. */
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void reset();
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//==============================================================================
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/** Pushes a single sample into one channel of the delay line.
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Use this function and popSample instead of process if you need to modulate
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the delay in real time instead of using a fixed delay value, or if you want
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to code a delay effect with a feedback loop.
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@see setDelay, popSample, process
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*/
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void pushSample (int channel, SampleType sample);
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/** Pops a single sample from one channel of the delay line.
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Use this function to modulate the delay in real time or implement standard
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delay effects with feedback.
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@param channel the target channel for the delay line.
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@param delayInSamples sets the wanted fractional delay in samples, or -1
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to use the value being used before or set with
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setDelay function.
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@param updateReadPointer should be set to true if you use the function
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once for each sample, or false if you need
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multi-tap delay capabilities.
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@see setDelay, pushSample, process
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*/
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SampleType popSample (int channel, SampleType delayInSamples = -1, bool updateReadPointer = true);
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//==============================================================================
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/** Processes the input and output samples supplied in the processing context.
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Can be used for block processing when the delay is not going to change
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during processing. The delay must first be set by calling setDelay.
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@see setDelay
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*/
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template <typename ProcessContext>
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void process (const ProcessContext& context) noexcept
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{
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const auto& inputBlock = context.getInputBlock();
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auto& outputBlock = context.getOutputBlock();
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const auto numChannels = outputBlock.getNumChannels();
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const auto numSamples = outputBlock.getNumSamples();
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jassert (inputBlock.getNumChannels() == numChannels);
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jassert (inputBlock.getNumChannels() == writePos.size());
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jassert (inputBlock.getNumSamples() == numSamples);
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if (context.isBypassed)
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{
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outputBlock.copyFrom (inputBlock);
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return;
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}
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for (size_t channel = 0; channel < numChannels; ++channel)
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{
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auto* inputSamples = inputBlock.getChannelPointer (channel);
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auto* outputSamples = outputBlock.getChannelPointer (channel);
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for (size_t i = 0; i < numSamples; ++i)
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{
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pushSample ((int) channel, inputSamples[i]);
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outputSamples[i] = popSample ((int) channel);
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}
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}
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}
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private:
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//==============================================================================
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template <typename T = InterpolationType>
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typename std::enable_if <std::is_same <T, DelayLineInterpolationTypes::None>::value, SampleType>::type
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interpolateSample (int channel) const
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{
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auto index = (readPos[(size_t) channel] + delayInt) % totalSize;
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return bufferData.getSample (channel, index);
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}
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template <typename T = InterpolationType>
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typename std::enable_if <std::is_same <T, DelayLineInterpolationTypes::Linear>::value, SampleType>::type
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interpolateSample (int channel) const
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{
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auto index1 = readPos[(size_t) channel] + delayInt;
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auto index2 = index1 + 1;
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if (index2 >= totalSize)
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{
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index1 %= totalSize;
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index2 %= totalSize;
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}
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auto value1 = bufferData.getSample (channel, index1);
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auto value2 = bufferData.getSample (channel, index2);
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return value1 + delayFrac * (value2 - value1);
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}
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template <typename T = InterpolationType>
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typename std::enable_if <std::is_same <T, DelayLineInterpolationTypes::Lagrange3rd>::value, SampleType>::type
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interpolateSample (int channel) const
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{
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auto index1 = readPos[(size_t) channel] + delayInt;
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auto index2 = index1 + 1;
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auto index3 = index2 + 1;
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auto index4 = index3 + 1;
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if (index4 >= totalSize)
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{
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index1 %= totalSize;
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index2 %= totalSize;
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index3 %= totalSize;
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index4 %= totalSize;
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}
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auto* samples = bufferData.getReadPointer (channel);
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auto value1 = samples[index1];
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auto value2 = samples[index2];
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auto value3 = samples[index3];
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auto value4 = samples[index4];
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auto d1 = delayFrac - 1.f;
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auto d2 = delayFrac - 2.f;
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auto d3 = delayFrac - 3.f;
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auto c1 = -d1 * d2 * d3 / 6.f;
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auto c2 = d2 * d3 * 0.5f;
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auto c3 = -d1 * d3 * 0.5f;
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auto c4 = d1 * d2 / 6.f;
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return value1 * c1 + delayFrac * (value2 * c2 + value3 * c3 + value4 * c4);
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}
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template <typename T = InterpolationType>
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typename std::enable_if <std::is_same <T, DelayLineInterpolationTypes::Thiran>::value, SampleType>::type
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interpolateSample (int channel)
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{
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auto index1 = readPos[(size_t) channel] + delayInt;
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auto index2 = index1 + 1;
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if (index2 >= totalSize)
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{
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index1 %= totalSize;
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index2 %= totalSize;
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}
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auto value1 = bufferData.getSample (channel, index1);
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auto value2 = bufferData.getSample (channel, index2);
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auto output = delayFrac == 0 ? value1 : value2 + alpha * (value1 - v[(size_t) channel]);
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v[(size_t) channel] = output;
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return output;
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}
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//==============================================================================
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template <typename T = InterpolationType>
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typename std::enable_if <std::is_same <T, DelayLineInterpolationTypes::None>::value, void>::type
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updateInternalVariables()
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{
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}
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template <typename T = InterpolationType>
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typename std::enable_if <std::is_same <T, DelayLineInterpolationTypes::Linear>::value, void>::type
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updateInternalVariables()
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{
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}
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template <typename T = InterpolationType>
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typename std::enable_if <std::is_same <T, DelayLineInterpolationTypes::Lagrange3rd>::value, void>::type
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updateInternalVariables()
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{
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if (delayInt >= 1)
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{
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delayFrac++;
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delayInt--;
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}
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}
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template <typename T = InterpolationType>
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typename std::enable_if <std::is_same <T, DelayLineInterpolationTypes::Thiran>::value, void>::type
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updateInternalVariables()
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{
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if (delayFrac < (SampleType) 0.618 && delayInt >= 1)
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{
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delayFrac++;
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delayInt--;
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}
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alpha = (1 - delayFrac) / (1 + delayFrac);
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}
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//==============================================================================
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double sampleRate;
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//==============================================================================
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AudioBuffer<SampleType> bufferData;
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std::vector<SampleType> v;
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std::vector<int> writePos, readPos;
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SampleType delay = 0.0, delayFrac = 0.0;
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int delayInt = 0, totalSize = 4;
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SampleType alpha = 0.0;
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};
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} // namespace dsp
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} // namespace juce
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