marvin::dsp::filters::Biquad< SampleType, NumStages > Class Template Reference

A cascading direct form ii biquad filter. More...

#include <marvin_Biquad.h>

Public Member Functions
void	setCoeffs (size_t stage, BiquadCoefficients< SampleType > coeffs) noexcept
SampleType	operator() (SampleType x) noexcept
void	reset () noexcept

Detailed Description

template<FloatType SampleType, size_t NumStages>
class marvin::dsp::filters::Biquad< SampleType, NumStages >

A cascading direct form ii biquad filter.

Biquads have a tendency to "blow up" at high modulation frequencies, so keep in mind that a StateVariableFilter (coming soon) might be a better choice if that's the kind of thing you need. Uses a coeffs as the numerators (zeroes) and b coeffs as the denominators (poles).
Usage example:

class Processor final {
public:
    void initialise(double sampleRate) {
        const auto coeffs = marvin::dsp::filters::rbj::lowpass<float>(sampleRate, 1000.0f, 0.5f);
        m_lpf.setCoeffs(0, coeffs);
    }
 
    [[nodiscard]] float operator()(float x) noexcept {
        const auto filtered = m_lpf(x);
        return filtered;
    }
 
    void reset() noexcept {
        m_lpf.reset();
    }
 
private:
    marvin::dsp::filters::Biquad<float, 1> m_lpf;
};

Member Function Documentation

operator()()

template<FloatType SampleType, size_t NumStages>

SampleType marvin::dsp::filters::Biquad< SampleType, NumStages >::operator() ( SampleType x )

inlinenodiscardnoexcept

Processes a sample through the biquad cascade.

Parameters

x	The sample to filter.

Returns

The filtered sample.

reset()

template<FloatType SampleType, size_t NumStages>

void marvin::dsp::filters::Biquad< SampleType, NumStages >::reset ( )

inlinenoexcept

Initialises the filter to its default state (does not zero the coefficients).

setCoeffs()

template<FloatType SampleType, size_t NumStages>

void marvin::dsp::filters::Biquad< SampleType, NumStages >::setCoeffs ( size_t stage, BiquadCoefficients< SampleType > coeffs )

inlinenoexcept

Sets the coeffs the Biquad should use. Note that BiquadCoefficients is trivially copyable (and is just a POD type), so this function can be (and should be) called on the audio thread - the BiquadCoefficients class' members aren't atomic.

Parameters

stage	The stage to assign these coefficients to. Must be less than NumStages.
coeffs	The coeffs to set.

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The documentation for this class was generated from the following file:

• /home/runner/work/mostly-harmless/mostly-harmless/modules/marvin/include/marvin/dsp/filters/biquad/marvin_Biquad.h