hart_whitenoise.hpp

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#pragma once
 
#include <cstdint>
#include <memory>
#include <random>
#include <string>
 
#include "hart_cliconfig.hpp"
#include "signals/hart_signal.hpp"
 
namespace hart
{
 
/// @brief Produces deterministic white noise
/// @details Outputs a signal uniformly distrubuted between -1.0 and +1.0, thus peaking below 0dB
/// @ingroup Signals
template<typename SampleType>
class WhiteNoise : public Signal<SampleType>
{
public:
 
    /// @brief Creates a Signal that produces white noise
    /// @param randomSeed Seed for the RNG
    /// @details Two signals with the same seed are guaranteed to produce the identical audio
    WhiteNoise (uint_fast32_t randomSeed = CLIConfig::getInstance().getRandomSeed()):
        m_randomSeed (randomSeed)
    {
        reset();
    }
 
    bool supportsNumChannels (size_t /* numChannels */) const override { return true; };
 
    void prepare (double /*sampleRateHz*/, size_t numOutputChannels, size_t /*maxBlockSizeFrames*/) override
    {
        this->setNumChannels (numOutputChannels);
    }
 
    void renderNextBlock (AudioBuffer<SampleType>& output) override
    {
        for (size_t frame = 0; frame < output.getNumFrames(); ++frame)
            for (size_t channel = 0; channel < this->getNumChannels(); ++channel)
                output[channel][frame] = m_uniformRealDistribution (m_randomNumberGenerator);
    }
 
    /// @copybrief Signal::reset()
    /// @details After resetting, WhiteNoise is guaranteed to produce identical audio to the one produced after instantiation
    void reset() override
    {
        m_randomNumberGenerator = std::mt19937 (m_randomSeed);
        m_uniformRealDistribution.reset();
    }
 
    void represent (std::ostream& stream) const override
    {
        stream << "WhiteNoise (" << m_randomSeed << ")";
    }
 
    HART_SIGNAL_DEFINE_COPY_AND_MOVE (WhiteNoise);
 
private:
    const uint_fast32_t m_randomSeed;
    std::mt19937 m_randomNumberGenerator;
    std::uniform_real_distribution<SampleType> m_uniformRealDistribution {(SampleType) -1, (SampleType) 1};
};
 
HART_SIGNAL_DECLARE_ALIASES_FOR (WhiteNoise)
 
}  // namespace hart