Collaboration diagram for RMSFeedbackCompressor:

Public Member Functions
constexpr void	setup (q31_t a, q31_t r, q31_t t, q31_t rat, q31_t fc, q31_t blend, float baseGain)
	takes in all values as knob positions in the range 0-ONE_Q31

void	reset ()
	Reset the state of the compressor so no gain reduction is applied at the start of the next render window.

void	render (std::span< StereoSample > buffer, q31_t volAdjustL, q31_t volAdjustR, q31_t finalVolume)

void	renderVolNeutral (std::span< StereoSample > buffer, q31_t finalVolume)
	This renders at a 'neutral' volume, so that at threshold zero the volume in unchanged.

float	runEnvelope (float current, float desired, float numSamples) const

constexpr q31_t	getAttack () const
	Get the current attack time constant in terms of the full knob range (0 to 2^31)

constexpr float	getAttackMS () const
	Get the current attack time constant in MS for a 3db change.

constexpr int32_t	setAttack (q31_t attack)

constexpr q31_t	getRelease () const
	Get the current release time constant in terms of the full knob range (0 to 2^31)

constexpr float	getReleaseMS () const
	Get the current release time constant in MS for a 3db change.

constexpr int32_t	setRelease (q31_t release)

constexpr q31_t	getThreshold () const
	Get the current theshold as a full-scale (0 to 2^31) number.

constexpr void	setThreshold (q31_t t)

constexpr q31_t	getRatio () const
	Get the current ratio as a full-scale (0 to 2^31) number.

constexpr float	getRatioForDisplay () const
	Get the current ratio as a float.

constexpr int32_t	setRatio (q31_t rat)

q31_t	getSidechain ()
	Get the current sidechain cutoff frequency as a full-scale (0 to 2^31) integer.

constexpr float	getSidechainForDisplay () const
	Get the current sidechain cutoff frequency in hertz.

constexpr int32_t	setSidechain (q31_t f)

constexpr q31_t	getBlend ()
	returns blend in q31

constexpr int32_t	getBlendForDisplay ()
	returns blend as an integer percentage

constexpr int32_t	setBlend (q31_t blend)

constexpr void	setBaseGain (float baseGain)

void	updateER (float numSamples, q31_t finalVolume)
	Update the internal envelope and gain reduction tracking.

float	calcRMS (std::span< StereoSample > buffer)
	Calculate the RMS amplitude, post internal HPF, of the samples.

Public Attributes
uint8_t	gainReduction = 0
	Amount of gain reduction applied during the last render pass, in 6.2 fixed point decibels.

Private Attributes
float	a_ = (-1000.0f / kSampleRate)
	Attack time constant, in inverse samples.

float	r_ = (-1000.0f / kSampleRate)
	Release time constant, in inverse samples.

float	fraction = 0.5

float	er = 0

float	threshdb = 17
	Threshold, in decibels.

float	threshold = 1
	The raw threshold value.

q31_t	hpfA_ = ONE_Q16
	A parameter for the internal HPF.

float	state = 0
	State for the internal envelope follower.

q31_t	currentVolumeL = 0
	Current left channel volume as a 5.26 signed fixed-point number.

q31_t	currentVolumeR = 0
	Current right channel volume as a 5.26 signed fixed-point number.

float	rms = 0
	Log-RMS value of the last render.

float	mean = 0
	Mean value of the last render.

uint32_t	lastSaturationTanHWorkingValue [2] = {0}
	tanh working values for output saturation

bool	onLastTime = false

deluge::dsp::filter::BasicFilterComponent	hpfL

deluge::dsp::filter::BasicFilterComponent	hpfR

float	attackMS = 0

float	releaseMS = 0

float	ratio = 2

float	fc_hz

float	baseGain_

q31_t	thresholdKnobPos = 0

q31_t	ratioKnobPos = 0

q31_t	attackKnobPos = 0

q31_t	releaseKnobPos = 0

q31_t	sideChainKnobPos = 0

q31_t	dry

q31_t	wet

Member Function Documentation

◆ render()

void RMSFeedbackCompressor::render	(	std::span< StereoSample >	buffer,
		q31_t	volAdjustL,
		q31_t	volAdjustR,
		q31_t	finalVolume )

Render the compressor in-place using the provided buffer.

Assumes the input is 24-bit peak-to-peak (-2^23 to 2^23), and keeps the output in that range.

Parameters

buffer	Input and output buffer.
numSamples	Length of the buffer.
volAdjustL	Linear gain to apply to the left channel as a 4.27 signed fixed point number.
volAdjustL	Linear gain to apply to the right channel as a 4.27 signed fixed point number.
finalVolume	Linear peak-to-peak volume scale, as a 3.29 fixed-point integer.

◆ renderVolNeutral()

void RMSFeedbackCompressor::renderVolNeutral	(	std::span< StereoSample >	buffer,
		q31_t	finalVolume )

This renders at a 'neutral' volume, so that at threshold zero the volume in unchanged.

Render the compressor with neutral left/right gain and with the finalVolume tweaked so the compressor applies 0db gain change at theshold zero. Used by the per-clip compressors because the clip volume is applied without the compressor being involved.

◆ runEnvelope()

float RMSFeedbackCompressor::runEnvelope	(	float	current,
		float	desired,
		float	numSamples ) const

nodiscard

Compute an updated envelope value, using the attack time constant if desired > current and the release time constant otherwise.

◆ setAttack()

int32_t RMSFeedbackCompressor::setAttack ( q31_t attack )

inlineconstexpr

Set the attack time constant from a full-scale (0 to 2^31) number.

The parameter is exponentially mapped to a number between 0.5 and 70-ish ms

◆ setBaseGain()

void RMSFeedbackCompressor::setBaseGain ( float baseGain )

inlineconstexpr

Configure the base makeup gain. Since reduction is always negative, we only need to worry about the case where reduction == 0 to determine the maximum headroom. er can not exceed 2.08, so we have 1.35 neppers of headroom.

The song compressor must use 0.8 to maintain compatibility with previous songs.

◆ setBlend()

int32_t RMSFeedbackCompressor::setBlend ( q31_t blend )

inlineconstexpr

update the blend level, where blend is the wet level (i.e. ONE_Q31 is full wet) returns wet percentage

◆ setRatio()

int32_t RMSFeedbackCompressor::setRatio ( q31_t rat )

inlineconstexpr

Set the ratio based on a full-scale (0 to 2^31) number.

A inverse (1/x) mapping is used, where 0 corresponds to a ratio of 2:1, 2^31 corresponds to a ratio of 256:1.

◆ setRelease()

int32_t RMSFeedbackCompressor::setRelease ( q31_t release )

inlineconstexpr

Set the release time constant from a full-scale (0 to 2^31) number.

The parameter is exponentially mapped to a number between 50 and 400-ish ms

◆ setSidechain()

int32_t RMSFeedbackCompressor::setSidechain ( q31_t f )

inlineconstexpr

Set the sidechain cutoff frequency from a full-scale (0 to 2^31) integer.

The parameter is exponentially mapped so 0 to 2^31 corresponds to about 0 to 100hz cutoff.

◆ setThreshold()

void RMSFeedbackCompressor::setThreshold ( q31_t t )

inlineconstexpr

Set the threshold based on a full-scale (0 to 2^31) number.

0 corresponds to a threshold of 0.2, 2^31 corresponds to a theshold of 1.

Member Data Documentation

◆ baseGain_

float RMSFeedbackCompressor::baseGain_

private

How much to bump the envelope follower RMS value and reduction to get approximate iso-volume when the compressor is engaged.

◆ er

float RMSFeedbackCompressor::er = 0

private

Internal (smoothed) version of log of the requested volume.

Maximum value: 2.08 neppers when finalVolume is 0x7fffffff Minimum value: -23.07 neppers when finalVolume is 0

◆ fraction

float RMSFeedbackCompressor::fraction = 0.5

private

1 - (1 / ratio), describes the actual factor by which volume changes should increase or decrease.

The UI currently limits this to 0.5 (a ratio of 2) to 1.0 (a ratio of 256)

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

src/deluge/dsp/compressor/rms_feedback.h
src/deluge/dsp/compressor/rms_feedback.cpp

Public Member Functions

Public Attributes

Private Attributes

Member Function Documentation

◆ render()

◆ renderVolNeutral()

◆ runEnvelope()

◆ setAttack()

◆ setBaseGain()

◆ setBlend()

◆ setRatio()

◆ setRelease()

◆ setSidechain()

◆ setThreshold()

Member Data Documentation

◆ baseGain_

◆ er

◆ fraction