hart_gaindb.hpp

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#pragma once
 
#include <algorithm>  // fill()
#include <iomanip>
#include <vector>
 
#include "hart_dsp.hpp"
#include "hart_precision.hpp"
#include "hart_utils.hpp"
 
namespace hart
{
 
/// @brief Applies gain in decibels to the signal
/// @note For automation, consider using @ref GainLinear instead, because the two classes produce different curve shapes.
/// @ingroup DSP
template <typename SampleType>
class GainDb:
    public hart::DSP<SampleType>
{
public:
    enum Params
    {
        gainDb  ///< Gain in decibels
    };
 
    /// @brief Constructor
    /// @param gainDb Initial gain in decibels
    GainDb (double gainDb = 0.0):
        m_initialGainDb (gainDb),
        m_gainLinear (decibelsToRatio (gainDb))
    {
    }
 
    void prepare (double /* sampleRateHz */, size_t /* numInputChannels */, size_t /* numOutputChannels */, size_t maxBlockSizeFrames) override
    {
        m_gainEnvelopeValuesLinear.resize (this->hasEnvelopeFor (Params::gainDb) ? maxBlockSizeFrames : 0);
    }
 
    void process (const AudioBuffer<SampleType>& input, AudioBuffer<SampleType>& output, const EnvelopeBuffers& envelopeBuffers) override
    {
        const size_t numInputChannels = input.getNumChannels();
        const size_t numOutputChannels = output.getNumChannels();
        hassert (output.getNumFrames() == input.getNumFrames());
 
        if (! supportsChannelLayout (numInputChannels, numOutputChannels))
            HART_THROW_OR_RETURN_VOID (hart::ChannelLayoutError, "Unsupported channel configuration");
 
        const bool hasGainEnvelope = ! envelopeBuffers.empty() && contains (envelopeBuffers, (int) Params::gainDb);
        const bool multiplexerMode = numInputChannels != numOutputChannels;
 
        if (hasGainEnvelope)
        {
            auto& gainEnvelopeValuesDb = envelopeBuffers. at(Params::gainDb);
            hassert (gainEnvelopeValuesDb.size() == m_gainEnvelopeValuesLinear.size());
 
            for (size_t i = 0; i < m_gainEnvelopeValuesLinear.size(); ++i)
                m_gainEnvelopeValuesLinear[i] = decibelsToRatio (gainEnvelopeValuesDb[i]);
 
            if (multiplexerMode)
                processEnvelopedGainAsMultiplexer (input, output);
            else
                processEnvelopedGainAsMultiChannel (input, output);
 
            return;
        }
 
        // No gain envelope
        if (multiplexerMode)
            processConstantGainAsMultiplexer (input, output);
        else
            processConstantGainAsMultiChannel (input, output);
    }
 
    void reset() override {}
 
    /// @param id Only @ref GainDb::gainDb is accepted
    /// @param value Gain in decibels
    void setValue (int id, double value) override
    {
        if (id == Params::gainDb)
            m_gainLinear = decibelsToRatio (value);
    }
 
    /// @param id Only @ref GainDb::gainDb is accepted
    /// @retval (value) Gain in decibels
    double getValue (int id) const override
    {
        if (id == Params::gainDb)
            return ratioToDecibels (m_gainLinear);
 
        return 0.0;
    }
 
    /// @brief Checks if the DSP supports given i/o configuration
    /// @details Supports either 1-to-n or n-to-n configurations 
    virtual bool supportsChannelLayout (size_t numInputChannels, size_t numOutputChannels) const override
    {
        if (numInputChannels == numOutputChannels)
            return true;
 
        if (numInputChannels == 1)
            return true;
 
        return false;
    }
 
    virtual void represent (std::ostream& stream) const override
    {
        stream << dbPrecision << "GainDb (" << m_initialGainDb << "_dB)";
    }
 
    /// @param id Only @ref GainDb::gainDb is accepted
    /// retval (bool) true for GainDb::gainDb, else otherwise
    bool supportsEnvelopeFor (int id) const override
    {
        return id == Params::gainDb;
    }
 
    HART_DSP_DEFINE_COPY_AND_MOVE (GainDb);
 
private:
    double m_initialGainDb;
    double m_gainLinear;
    std::vector<double> m_gainEnvelopeValuesLinear;
 
    void processConstantGainAsMultiChannel (const AudioBuffer<SampleType>& input, AudioBuffer<SampleType>& output)
    {
        for (size_t channel = 0; channel < input.getNumChannels(); ++channel)
            for (size_t frame = 0; frame < input.getNumFrames(); ++frame)
                output[channel][frame] = input[channel][frame] * (SampleType) m_gainLinear;
    }
 
    void processConstantGainAsMultiplexer (const AudioBuffer<SampleType>& input, AudioBuffer<SampleType>& output)
    {
        for (size_t channel = 0; channel < output.getNumChannels(); ++channel)
            for (size_t frame = 0; frame < input.getNumFrames(); ++frame)
                output[channel][frame] = input[0][frame] * (SampleType) m_gainLinear;
    }
 
    void processEnvelopedGainAsMultiChannel (const AudioBuffer<SampleType>& input, AudioBuffer<SampleType>& output)
    {
        for (size_t channel = 0; channel < input.getNumChannels(); ++channel)
            for (size_t frame = 0; frame < input.getNumFrames(); ++frame)
                output[channel][frame] = input[channel][frame] * (SampleType) m_gainEnvelopeValuesLinear[frame];
    }
 
    void processEnvelopedGainAsMultiplexer (const AudioBuffer<SampleType>& input, AudioBuffer<SampleType>& output)
    {
        for (size_t channel = 0; channel < output.getNumChannels(); ++channel)
            for (size_t frame = 0; frame < input.getNumFrames(); ++frame)
                output[channel][frame] = input[0][frame] * (SampleType) m_gainEnvelopeValuesLinear[frame];
    }
};
 
HART_DSP_DECLARE_ALIASES_FOR (GainDb)
 
}  // namespace hart