pulp::signal::FilterDesign Struct Reference

Filter coefficient generation utilities. More...

#include <filter_design.hpp>

Public Types
using	Coefficients = BiquadCoefficients
	Biquad coefficient set (normalized: a0 = 1).

Static Public Member Functions
static Coefficients	lowpass (float freq_hz, float Q, float sample_rate)
static Coefficients	highpass (float freq_hz, float Q, float sample_rate)
static Coefficients	bandpass (float freq_hz, float Q, float sample_rate)
static Coefficients	notch (float freq_hz, float Q, float sample_rate)
static Coefficients	allpass (float freq_hz, float Q, float sample_rate)
static Coefficients	peaking_eq (float freq_hz, float Q, float gain_db, float sample_rate)
	Peaking EQ filter.
static Coefficients	low_shelf (float freq_hz, float gain_db, float sample_rate, float S=1.0f)
	Low shelf filter.
static Coefficients	high_shelf (float freq_hz, float gain_db, float sample_rate, float S=1.0f)
	High shelf filter.
static std::vector< Coefficients >	butterworth_lowpass (int order, float freq_hz, float sample_rate)
	Generate cascaded biquad coefficients for an Nth-order Butterworth lowpass.
static std::vector< Coefficients >	butterworth_highpass (int order, float freq_hz, float sample_rate)
	Generate cascaded biquad coefficients for an Nth-order Butterworth highpass.

Detailed Description

Filter coefficient generation utilities.

RT contract: scalar biquad coefficient helpers return fixed-size values and are allocation-free, but they are still intended for prepare/control-rate use because retuning filters can reset state. Butterworth helpers return vectors and allocate cascade storage, so they are not audio-thread safe.

Generates biquad coefficients for standard filter types using the Audio EQ Cookbook formulas (Robert Bristow-Johnson).

auto coeffs = FilterDesign::lowpass(1000.0f, 0.707f, 44100.0f);
biquad.set_coefficients(coeffs);
 
// High-order Butterworth via cascaded biquads
auto cascade = FilterDesign::butterworth_lowpass(4, 2000.0f, 44100.0f);
// cascade contains 2 biquad coefficient sets

Member Typedef Documentation

Coefficients

using pulp::signal::FilterDesign::Coefficients = BiquadCoefficients

Biquad coefficient set (normalized: a0 = 1).

Alias of the canonical exchange type in biquad.hpp, so a designed section can be loaded straight into a BiquadT and evaluated by frequency_response.hpp without a conversion step.

Member Function Documentation

allpass()

Coefficients pulp::signal::FilterDesign::allpass ( float freq_hz, float Q, float sample_rate )

inlinestatic

bandpass()

Coefficients pulp::signal::FilterDesign::bandpass ( float freq_hz, float Q, float sample_rate )

inlinestatic

butterworth_highpass()

std::vector< Coefficients > pulp::signal::FilterDesign::butterworth_highpass ( int order, float freq_hz, float sample_rate )

inlinestatic

Generate cascaded biquad coefficients for an Nth-order Butterworth highpass.

butterworth_lowpass()

std::vector< Coefficients > pulp::signal::FilterDesign::butterworth_lowpass ( int order, float freq_hz, float sample_rate )

inlinestatic

Generate cascaded biquad coefficients for an Nth-order Butterworth lowpass.

Parameters

order

Filter order (must be even, e.g. 2, 4, 6, 8).

Returns

Vector of biquad coefficient sets (order/2 sections).

high_shelf()

Coefficients pulp::signal::FilterDesign::high_shelf ( float freq_hz, float gain_db, float sample_rate, float S = 1.0f )

inlinestatic

High shelf filter.

highpass()

Coefficients pulp::signal::FilterDesign::highpass ( float freq_hz, float Q, float sample_rate )

inlinestatic

low_shelf()

Coefficients pulp::signal::FilterDesign::low_shelf ( float freq_hz, float gain_db, float sample_rate, float S = 1.0f )

inlinestatic

Low shelf filter.

lowpass()

Coefficients pulp::signal::FilterDesign::lowpass ( float freq_hz, float Q, float sample_rate )

inlinestatic

notch()

Coefficients pulp::signal::FilterDesign::notch ( float freq_hz, float Q, float sample_rate )

inlinestatic

peaking_eq()

Coefficients pulp::signal::FilterDesign::peaking_eq ( float freq_hz, float Q, float gain_db, float sample_rate )

inlinestatic

Peaking EQ filter.

Parameters

gain_db

Boost/cut in dB.

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

• /home/runner/work/pulp/pulp/core/signal/include/pulp/signal/filter_design.hpp