reverb::Equalizer Class Reference

#include <Equalizer.h>

Inheritance diagram for reverb::Equalizer:

Collaboration diagram for reverb::Equalizer:

Public Types
using	Ptr = std::shared_ptr< Equalizer >
Public Types inherited from reverb::Task
using	Ptr = std::shared_ptr< Task >

Public Member Functions
	Equalizer (juce::AudioProcessor *processor, int numFilters=4)
virtual void	updateParams (const juce::AudioProcessorValueTreeState &params, const juce::String &blockId) override
	Read processor parameters and update block parameters as necessary. More...
virtual AudioBlock	exec (AudioBlock ir) override
	Processes the AudioBuffer input with the EQ filters. More...
virtual void	updateSampleRate (double sr) override
	Update sample rate for task block. More...
void	calibrateFilters ()
	Calibrates the individual filter gains so that the total gains are equal to the user defined values. More...
float	getdBAmplitude (float freq)
	Returns the Equalizer amplitude response in dB at a given frequency. More...
int	getNumFilters ()
	Returns the number of filters in the equalizer.
virtual bool	needsToRun () const override
	Tells caller whether block must be run for current block. More...
Public Member Functions inherited from reverb::Task
	Task (juce::AudioProcessor *processor)

Protected Attributes
juce::OwnedArray< Filter >	filterSet
std::vector< float >	EQGains
Protected Attributes inherited from reverb::Task
juce::AudioProcessor *	processor
bool	mustExec = true

Additional Inherited Members
Public Attributes inherited from reverb::Task
double	sampleRate
Protected Member Functions inherited from reverb::Task
float	getParam (const juce::AudioProcessorValueTreeState &params, const juce::String &blockId) const
	Internal method used to get (and check) a parameter's value.

Detailed Description

The Equalizer class cimplements by default four Filter class instances -one low-shelf, two peak filters and one high-shelf - and calibrates their individual gains to balance out the stacking effect thus making sure that the EQ band gains are equal to the ones set by the user.

It acts as an interface between the GUI and the IIR filters. The class can support one low-shelf filter and one high-shelf with any number of peak filters in between; the total number is equal to the numFilters constructor argument. The filter instantiations are done in the class constructor.

Definition at line 30 of file Equalizer.h.

Member Function Documentation

calibrateFilters()

void reverb::Equalizer::calibrateFilters

(

)

Calibrates the individual filter gains so that the total gains are equal to the user defined values.

This function solves a linear equation system of N variables where N = number of filters in order to find the individual gains that, when stacked together, are equal to the user specified values at the frequencies of 0, 21000 Hz and at each single one of the peak filter center frequencies.

The use of decibels is necessary for the gain stacks to behave linearly. The algorithm can be used iteratively and is detailed in the Standford University lecture note available at https://ccrma.stanford.edu/courses/424/handouts.2004/424_Handout22_Filters4_LectureNotes.pdf

Exceptions

ConvergenceException

Definition at line 138 of file Equalizer.cpp.

exec()

AudioBlock reverb::Equalizer::exec ( AudioBlock  ir )

overridevirtual

Processes the AudioBuffer input with the EQ filters.

Parameters

[in]

ir

AudioBuffer to be processed

Implements reverb::Task.

Definition at line 106 of file Equalizer.cpp.

getdBAmplitude()

float reverb::Equalizer::getdBAmplitude

(

float

freq

)

Returns the Equalizer amplitude response in dB at a given frequency.

Parameters

[in]

freq

Frequency at which the filter magnitude is evaluated

Definition at line 232 of file Equalizer.cpp.

needsToRun()

bool reverb::Equalizer::needsToRun ( ) const

overridevirtual

Tells caller whether block must be run for current block.

May be overriden by IR blocks since these are executed sparingly.

Reimplemented from reverb::Task.

Definition at line 255 of file Equalizer.cpp.

updateParams()

void reverb::Equalizer::updateParams ( const juce::AudioProcessorValueTreeState &  params, const juce::String &  blockId  )

overridevirtual

Read processor parameters and update block parameters as necessary.

Parameters

[in]	params	the value tree containing the parameters
[in]	blockId	the Id of the relevant parameter block

Returns

True if any parameters were changed, false otherwise.

Implements reverb::Task.

Definition at line 66 of file Equalizer.cpp.

updateSampleRate()

void reverb::Equalizer::updateSampleRate ( double  sr )

overridevirtual

Update sample rate for task block.

Compares new sample rate with previous value. If different, sets mustExec to true in order to re-run task for new sample rate. Store new sample rate value in object.

Parameters

[in]

sr

Sample rate

Reimplemented from reverb::Task.

Definition at line 119 of file Equalizer.cpp.

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

• Source/Equalizer.h
• Source/Equalizer.cpp