GraphicEQ Class Reference

Multi-band graphic equalizer with configurable band count and per-channel control. More...

#include <gin_graphiceq.h>

Public Types
enum	NumBands {   Bands5 = 5 , Bands7 = 7 , Bands10 = 10 , Bands15 = 15 ,   Bands31 = 31 }
	Number of bands configuration. More...

Public Member Functions
	GraphicEQ (NumBands bands=Bands31)
	Creates a graphic equalizer with the specified number of bands.
void	setSampleRate (double sr)
	Sets the sample rate for processing.
void	setBlockSize (int blockSize)
	Sets the maximum block size for processing.
void	setNumChannels (int ch)
	Sets the number of audio channels.
int	getNumBands () const
	Gets the number of bands.
int	getNumChannels () const
	Gets the number of channels.
void	reset ()
	Resets the filter state for all bands and channels.
void	setBandGain (int channel, int band, float gainDb)
	Sets the gain for a specific band on a specific channel.
float	getBandGain (int channel, int band) const
	Gets the gain for a specific band on a specific channel.
float	getBandFrequency (int band) const
	Gets the center frequency for a specific band.
void	setAllBandGains (int channel, const float *gains)
	Sets the gain for all bands on a specific channel.
void	flatten (int channel)
	Sets all bands on a specific channel to 0 dB (flat response).
void	flattenAll ()
	Sets all bands on all channels to 0 dB (flat response).
float	getFrequencyResponse (int channel, float frequency) const
	Gets the frequency response magnitude for a specific channel at a given frequency.
float	getFrequencyResponseDb (int channel, float frequency) const
	Gets the frequency response in dB for a specific channel at a given frequency.
void	process (juce::AudioSampleBuffer &buffer)
	Processes an audio buffer through the equalizer.

Detailed Description

Multi-band graphic equalizer with configurable band count and per-channel control.

GraphicEQ provides a professional graphic equalizer with selectable band counts (5, 7, 10, 15, or 31 bands) using ISO standard center frequencies. Each channel can have independent gain settings, and frequency response can be queried per channel.

Key Features:

• Selectable band count (5, 7, 10, 15, or 31 bands)
• Configurable number of channels
• Independent gain control per channel per band
• Per-channel frequency response calculation
• Uses gin::Filter internally for high-quality processing

Band Configurations:

• 5 bands: 60, 250, 1k, 4k, 16k Hz
• 7 bands: 63, 160, 400, 1k, 2.5k, 6.3k, 16k Hz
• 10 bands: 31.5, 63, 125, 250, 500, 1k, 2k, 4k, 8k, 16k Hz
• 15 bands: 25, 40, 63, 100, 160, 250, 400, 630, 1k, 1.6k, 2.5k, 4k, 6.3k, 10k, 16k Hz
• 31 bands: ISO 1/3 octave from 20Hz to 20kHz

Usage:

GraphicEQ eq(GraphicEQ::Bands31);
eq.setNumChannels(2);
eq.setSampleRate(44100.0);
 
eq.setBandGain(0, 0, 3.0f);   // Channel 0, Band 0: +3dB
eq.setBandGain(1, 0, -3.0f);  // Channel 1, Band 0: -3dB
 
eq.process(audioBuffer);
 
// Get frequency response for channel 0 at 1kHz
float response = eq.getFrequencyResponse(0, 1000.0f);

See also

EQ, Filter

Member Enumeration Documentation

NumBands

enum GraphicEQ::NumBands

Number of bands configuration.

Enumerator
Bands5
Bands7
Bands10
Bands15
Bands31

Constructor & Destructor Documentation

GraphicEQ()

GraphicEQ::GraphicEQ

(

NumBands

bands = Bands31

)

Creates a graphic equalizer with the specified number of bands.

Parameters

bands

Number of bands (5, 7, 10, 15, or 31)

References Bands31.

Member Function Documentation

setSampleRate()

void GraphicEQ::setSampleRate

(

double

sr

)

Sets the sample rate for processing.

Parameters

sampleRate

Sample rate in Hz

setBlockSize()

void GraphicEQ::setBlockSize

(

int

blockSize

)

Sets the maximum block size for processing.

Call this before processing to allocate working buffers.

Parameters

blockSize

Maximum number of samples per block

setNumChannels()

void GraphicEQ::setNumChannels

(

int

ch

)

Sets the number of audio channels.

Parameters

ch	Number of channels

References Filter::bandpass, and Filter::db12.

getNumBands()

int GraphicEQ::getNumBands

(

)

const

Gets the number of bands.

Returns

Number of bands

getNumChannels()

int GraphicEQ::getNumChannels

(

)

const

Gets the number of channels.

Returns

Number of channels

reset()

void GraphicEQ::reset

(

)

Resets the filter state for all bands and channels.

setBandGain()

void GraphicEQ::setBandGain	(	int	channel,
		int	band,
		float	gainDb )

Sets the gain for a specific band on a specific channel.

Parameters

channel	Channel index
band	Band index
gainDb	Gain in decibels (positive = boost, negative = cut)

getBandGain()

float GraphicEQ::getBandGain	(	int	channel,
		int	band ) const

Gets the gain for a specific band on a specific channel.

Parameters

channel	Channel index
band	Band index

Returns

Gain in decibels

getBandFrequency()

float GraphicEQ::getBandFrequency

(

int

band

)

const

Gets the center frequency for a specific band.

Parameters

band	Band index

Returns

Center frequency in Hz

setAllBandGains()

void GraphicEQ::setAllBandGains	(	int	channel,
		const float *	gains )

Sets the gain for all bands on a specific channel.

Parameters

channel	Channel index
gains	Array of gain values in dB (must have numBands elements)

flatten()

void GraphicEQ::flatten

(

int

channel

)

Sets all bands on a specific channel to 0 dB (flat response).

Parameters

channel

Channel index

Referenced by flattenAll().

flattenAll()

void GraphicEQ::flattenAll

(

)

Sets all bands on all channels to 0 dB (flat response).

References flatten().

getFrequencyResponse()

float GraphicEQ::getFrequencyResponse	(	int	channel,
		float	frequency ) const

Gets the frequency response magnitude for a specific channel at a given frequency.

Parameters

channel	Channel index
frequency	Frequency in Hz

Returns

Response magnitude (linear scale, 1.0 = unity gain)

Referenced by getFrequencyResponseDb().

getFrequencyResponseDb()

float GraphicEQ::getFrequencyResponseDb	(	int	channel,
		float	frequency ) const

Gets the frequency response in dB for a specific channel at a given frequency.

Parameters

channel	Channel index
frequency	Frequency in Hz

Returns

Response in decibels

References getFrequencyResponse().

process()

void GraphicEQ::process

(

juce::AudioSampleBuffer &

buffer

)

Processes an audio buffer through the equalizer.

Parameters

buffer

Audio buffer to process in-place

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

• gin_graphiceq.h