pulp::signal::CompressorT< SampleType > Class Template Reference

#include <compressor.hpp>

Classes
struct	Params

Public Member Functions
void	set_params (const Params &p)
void	set_ballistics (CompressorBallistics ballistics) noexcept
	Select how gain reduction is smoothed (see CompressorBallistics).
CompressorBallistics	ballistics () const noexcept
void	set_sample_rate (SampleType sr)
void	set_sidechain_hpf_hz (SampleType hz)
	Set the sidechain high-pass cutoff (Hz).
SampleType	sidechain_hpf_hz () const
void	set_lookahead_ms (SampleType ms)
	Set the lookahead in milliseconds.
SampleType	lookahead_ms () const
int	latency_samples () const
	Latency reported to the host = lookahead in samples (0 when off).
SampleType	process (SampleType input)
	Process one sample.
SampleType	process_with_sidechain (SampleType input, SampleType sidechain)
	Process one sample with an explicit sidechain detector input.
void	process (SampleType *buffer, int num_samples)
	Process a block in place; the buffer is also the sidechain.
void	process_with_sidechain (SampleType *buffer, const SampleType *sidechain, int num_samples)
	Process a block with a separate sidechain input.
SampleType	attack_coefficient () const
	Envelope smoothing coefficients in force for the current parameters and sample rate: the per-sample step toward a lower (attack) or higher (release) gain target is coefficient * (target_db - envelope_db).
SampleType	release_coefficient () const
SampleType	gain_reduction_db () const
GainReduction	gain_reduction () const noexcept
	Canonical non-negative gain-reduction magnitude for shared meters.
void	reset ()

Static Public Member Functions
static SampleType	detector_level_db (SampleType detector)
	Detector level in dB for one sample: 20 log10(|x|), floored at -200 dB.
static SampleType	gain_computer_db (SampleType input_db, const Params &params)
	The static curve: gain change in dB (<= 0) for a detector level in dB under params (threshold, ratio and knee; attack, release and makeup do not enter).
static SampleType	ballistic_coefficient (SampleType time_ms, SampleType sample_rate)
	One-pole smoothing coefficient for a time constant in ms: 1 - exp(-1 / (tau fs)), or 1 (instant) for a non-positive time.
static SampleType	branching_step (SampleType envelope, SampleType target, SampleType attack, SampleType release)
	One step of the branching ballistics: the envelope (gain change in dB) moves toward target with the attack coefficient when more reduction is asked for and the release coefficient otherwise.
static SampleType	decoupled_hold (SampleType hold, SampleType target, SampleType release)
	The decoupled ballistics' peak hold on gain changes (<= 0 dB): it jumps to any deeper reduction at once and otherwise decays toward the target with the release coefficient (Giannoulis et al.
static SampleType	db_to_gain (SampleType db)
	Linear gain for a gain change in dB (FastMath for float).

Member Function Documentation

attack_coefficient()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::attack_coefficient ( ) const

inline

Envelope smoothing coefficients in force for the current parameters and sample rate: the per-sample step toward a lower (attack) or higher (release) gain target is coefficient * (target_db - envelope_db).

ballistic_coefficient()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::ballistic_coefficient ( SampleType time_ms, SampleType sample_rate )

inlinestatic

One-pole smoothing coefficient for a time constant in ms: 1 - exp(-1 / (tau fs)), or 1 (instant) for a non-positive time.

ballistics()

template<typename SampleType = float>

CompressorBallistics pulp::signal::CompressorT< SampleType >::ballistics ( ) const

inlinenoexcept

branching_step()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::branching_step ( SampleType envelope, SampleType target, SampleType attack, SampleType release )

inlinestatic

One step of the branching ballistics: the envelope (gain change in dB) moves toward target with the attack coefficient when more reduction is asked for and the release coefficient otherwise.

db_to_gain()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::db_to_gain ( SampleType db )

inlinestatic

Linear gain for a gain change in dB (FastMath for float).

decoupled_hold()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::decoupled_hold ( SampleType hold, SampleType target, SampleType release )

inlinestatic

The decoupled ballistics' peak hold on gain changes (<= 0 dB): it jumps to any deeper reduction at once and otherwise decays toward the target with the release coefficient (Giannoulis et al.

's y1 = max(x, aR y1 + (1 - aR) x) with the sign flipped). The envelope then follows the hold: envelope + attack * (hold - envelope).

detector_level_db()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::detector_level_db ( SampleType detector )

inlinestatic

Detector level in dB for one sample: 20 log10(|x|), floored at -200 dB.

Float uses FastMath's branch-free conversion.

gain_computer_db()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::gain_computer_db ( SampleType input_db, const Params & params )

inlinestatic

The static curve: gain change in dB (<= 0) for a detector level in dB under params (threshold, ratio and knee; attack, release and makeup do not enter).

Written as selects over precomputed candidates so the block path's static-curve pass vectorizes.

gain_reduction()

template<typename SampleType = float>

GainReduction pulp::signal::CompressorT< SampleType >::gain_reduction ( ) const

inlinenoexcept

Canonical non-negative gain-reduction magnitude for shared meters.

gain_reduction_db()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::gain_reduction_db ( ) const

inline

latency_samples()

template<typename SampleType = float>

int pulp::signal::CompressorT< SampleType >::latency_samples ( ) const

inline

Latency reported to the host = lookahead in samples (0 when off).

lookahead_ms()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::lookahead_ms ( ) const

inline

process() [1/2]

template<typename SampleType = float>

void pulp::signal::CompressorT< SampleType >::process ( SampleType * buffer, int num_samples )

inline

Process a block in place; the buffer is also the sidechain.

Same as process_with_sidechain(buffer, buffer, num_samples).

process() [2/2]

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::process ( SampleType input )

inline

Process one sample.

The sidechain signal defaults to input, matching the original non-sidechain behavior.

process_with_sidechain() [1/2]

template<typename SampleType = float>

void pulp::signal::CompressorT< SampleType >::process_with_sidechain ( SampleType * buffer, const SampleType * sidechain, int num_samples )

inline

Process a block with a separate sidechain input.

Both buffers must be at least num_samples long.

Equivalent to calling process_with_sidechain(SampleType, SampleType) per sample, including the reset at a non-finite sample, but run in kSnapChunkSamples chunks of three passes each (detector and static curve, envelope recursion, gain), so the transcendental work in the outer passes vectorizes. The float path computes the same values; the envelope's denormal snap runs once per chunk (see run_chunks()).

process_with_sidechain() [2/2]

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::process_with_sidechain ( SampleType input, SampleType sidechain )

inline

Process one sample with an explicit sidechain detector input.

sidechain is the signal that drives the envelope follower; input is the signal that gets the gain applied.

release_coefficient()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::release_coefficient ( ) const

inline

reset()

template<typename SampleType = float>

void pulp::signal::CompressorT< SampleType >::reset ( )

inline

set_ballistics()

template<typename SampleType = float>

void pulp::signal::CompressorT< SampleType >::set_ballistics ( CompressorBallistics ballistics )

inlinenoexcept

Select how gain reduction is smoothed (see CompressorBallistics).

Takes effect from the next sample; the detector state carries over.

set_lookahead_ms()

template<typename SampleType = float>

void pulp::signal::CompressorT< SampleType >::set_lookahead_ms ( SampleType ms )

inline

Set the lookahead in milliseconds.

The dry input is delayed by this amount so the envelope follower can react before the transient arrives. 0 disables lookahead (default). Maximum supported lookahead is 50 ms — beyond that the internal ring buffer is too large for low-latency contexts.

set_params()

template<typename SampleType = float>

void pulp::signal::CompressorT< SampleType >::set_params ( const Params & p )

inline

set_sample_rate()

template<typename SampleType = float>

void pulp::signal::CompressorT< SampleType >::set_sample_rate ( SampleType sr )

inline

set_sidechain_hpf_hz()

template<typename SampleType = float>

void pulp::signal::CompressorT< SampleType >::set_sidechain_hpf_hz ( SampleType hz )

inline

Set the sidechain high-pass cutoff (Hz).

0 disables the HPF and the sidechain detector sees the raw signal. Typical values: 80–200 Hz for "duck on bass" prevention. The filter is a second-order Butterworth biquad (Q ≈ 0.707).

sidechain_hpf_hz()

template<typename SampleType = float>

SampleType pulp::signal::CompressorT< SampleType >::sidechain_hpf_hz ( ) const

inline

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

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