3 Band Equalizer with per-channel frequency and gain control Allows independent frequency and gain settings for each audio channel. Each channel can have different low/high frequency cutoffs and different gain values for low, medium, and high frequency bands. More...

#include <Equalizer3Bands.h>

Inheritance diagram for Equalizer3BandsPerChannel:

Classes
struct	EQSTATE

Public Member Functions
	Equalizer3BandsPerChannel (AudioOutput &out)

	Equalizer3BandsPerChannel (AudioStream &stream)

	Equalizer3BandsPerChannel (Print &out)

	Equalizer3BandsPerChannel (Stream &in)

	~Equalizer3BandsPerChannel ()

virtual void	addNotifyAudioChange (AudioInfoSupport &bi)
	Adds target to be notified about audio changes.

virtual AudioInfo	audioInfo () override
	provides the actual input AudioInfo

virtual AudioInfo	audioInfoOut ()

int	available () override

int	availableForWrite () override

bool	begin ()

bool	begin (ConfigEqualizer3Bands &config)

virtual void	clearNotifyAudioChange ()
	Deletes all change notify subscriptions.

ConfigEqualizer3Bands &	config ()

ConfigEqualizer3Bands	defaultConfig ()

void	end () override

virtual void	flush () override

bool	getChannelFrequencies (int channel, int &freq_low_val, int &freq_high_val)

bool	getChannelGains (int channel, float &gain_low_val, float &gain_medium_val, float &gain_high_val)

bool	isNotifyActive ()
	Checks if the automatic AudioInfo update is active.

virtual	operator bool ()

size_t	readBytes (uint8_t *data, size_t len) override

virtual size_t	readSilence (uint8_t *buffer, size_t length)
	Source to generate silence: just sets the buffer to 0.

virtual bool	removeNotifyAudioChange (AudioInfoSupport &bi)
	Removes a target in order not to be notified about audio changes.

virtual void	setAudioInfo (AudioInfo info) override
	Defines the input AudioInfo.

void	setChannelFrequencies (int channel, int freq_low_val, int freq_high_val)

void	setChannelGains (int channel, float gain_low_val, float gain_medium_val, float gain_high_val)

void	setNotifyActive (bool flag)
	Deactivate/Reactivate automatic AudioInfo updates: (default is active)

void	setOutput (Print &out) override
	Defines/Changes the output target.

void	setStream (Stream &io) override
	Defines/Changes the input & output.

void	setWriteBufferSize (int size)

size_t	write (const uint8_t *data, size_t len) override

virtual size_t	write (uint8_t ch) override

virtual void	writeSilence (size_t len)
	Writes len bytes of silence (=0).

Protected Member Functions
void	allocateChannelArrays (int num_channels)

void	ensureChannelArraysAllocated ()
	Ensures that per-channel arrays are allocated and properly sized.

void	filterSamples (const uint8_t *data, size_t len)

virtual int	not_supported (int out, const char *msg="")

void	notifyAudioChange (AudioInfo info)

void	refillReadBuffer ()
	Refill small read buffer (e.g. 8 bytes) to avoid single byte reads when calling read()

float	sample (int channel, float sample_val)

Protected Attributes
int	_timeout = 10

ConfigEqualizer3Bands	cfg
	Default configuration instance.

Vector< int >	freq_high
	High frequency cutoffs per channel (Hz)

Vector< int >	freq_low
	Low frequency cutoffs per channel (Hz)

Vector< float >	gain_high
	High frequency gains per channel.

Vector< float >	gain_low
	Low frequency gains per channel.

Vector< float >	gain_medium
	Medium frequency gains per channel.

AudioInfo	info

bool	is_active = false

bool	is_notify_active = true

int	max_state_count = 0
	Maximum number of allocated channel states.

Vector< AudioInfoSupport * >	notify_vector

ConfigEqualizer3Bands *	p_cfg = &cfg
	Pointer to active configuration.

Print *	p_print = nullptr
	Output stream for write operations.

Stream *	p_stream = nullptr
	Input/output stream for read operations.

struct audio_tools::Equalizer3BandsPerChannel::EQSTATE *	state = nullptr

RingBuffer< uint8_t >	tmp_in {0}

RingBuffer< uint8_t >	tmp_out {0}

const float	vsa
	Very small amount for denormal fix.

int	write_buffer_size = MAX_SINGLE_CHARS

Detailed Description

3 Band Equalizer with per-channel frequency and gain control Allows independent frequency and gain settings for each audio channel. Each channel can have different low/high frequency cutoffs and different gain values for low, medium, and high frequency bands.

Author: pschatzmann

Constructor & Destructor Documentation

◆ Equalizer3BandsPerChannel() [1/4]

Equalizer3BandsPerChannel ( Print & out )

inline

Constructor with Print output

Parameters

out	Print stream for output

◆ Equalizer3BandsPerChannel() [2/4]

Equalizer3BandsPerChannel ( Stream & in )

inline

Constructor with Stream input

Parameters

in	Stream for input

◆ Equalizer3BandsPerChannel() [3/4]

Equalizer3BandsPerChannel ( AudioOutput & out )

inline

Constructor with AudioOutput

Parameters

out	AudioOutput for output with automatic audio change notifications

◆ Equalizer3BandsPerChannel() [4/4]

Equalizer3BandsPerChannel ( AudioStream & stream )

inline

Constructor with AudioStream

Parameters

stream AudioStream for input/output with automatic audio change notifications

◆ ~Equalizer3BandsPerChannel()

~Equalizer3BandsPerChannel ( )

inline

Member Function Documentation

◆ addNotifyAudioChange()

virtual void addNotifyAudioChange ( AudioInfoSupport & bi )

inlinevirtualinherited

Adds target to be notified about audio changes.

Reimplemented in CodecNOP, EncodedAudioOutput, EncodedAudioStream, AACDecoderFDK, DecoderBasic, CodecChain, MP3DecoderHelix, MP3DecoderMAD, OggContainerDecoder, RTSPClient< TcpClient, UdpSocket >, Pipeline, and Pipeline::ModifyingStreamAdapter.

◆ allocateChannelArrays()

void allocateChannelArrays ( int num_channels )

inlineprotected

Allocates and initializes per-channel frequency and gain arrays

Parameters

num_channels Number of channels to allocate arrays for

◆ audioInfo()

virtual AudioInfo audioInfo ( )

inlineoverridevirtualinherited

provides the actual input AudioInfo

Implements AudioInfoSupport.

Reimplemented in JupyterAudioT< T >, MozziStream, TimerCallbackAudioStream, EncodedAudioStream, PureDataStream, AdapterAudioOutputToAudioStream, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, and InputMerge< T >.

◆ audioInfoOut()

virtual AudioInfo audioInfoOut ( )

inlinevirtualinherited

provides the actual output AudioInfo: this is usually the same as audioInfo() unless we use a transforming stream

Reimplemented in PureDataStream, PWMAudioOutput, ChannelFormatConverterStreamT< T >, ChannelFormatConverterStream, NumberFormatConverterStreamT< TFrom, TTo >, NumberFormatConverterStream, FormatConverterStream, Pipeline, ResampleStream, and ResampleStreamT< TInterpolator >.

◆ available()

int available ( )

inlineoverridevirtual

Get available data for reading

Returns: Number of bytes available for reading

Reimplemented from BaseStream.

◆ availableForWrite()

int availableForWrite ( )

inlineoverridevirtual

Get available space for writing

Returns: Number of bytes available for writing

Reimplemented from BaseStream.

◆ begin() [1/2]

bool begin ( )

inlinevirtual

Initialize the equalizer using the current configuration

Returns: true if initialization was successful

Reimplemented from BaseStream.

◆ begin() [2/2]

bool begin ( ConfigEqualizer3Bands & config )

inline

Initialize the equalizer with the given configuration

Parameters

config Configuration settings for the equalizer

Returns: true if initialization was successful

◆ clearNotifyAudioChange()

virtual void clearNotifyAudioChange ( )

inlinevirtualinherited

Deletes all change notify subscriptions.

Reimplemented in RTSPClient< TcpClient, UdpSocket >.

◆ config()

ConfigEqualizer3Bands & config ( )

inline

◆ defaultConfig()

ConfigEqualizer3Bands defaultConfig ( )

inline

◆ end()

void end ( )

inlineoverridevirtual

Reimplemented from BaseStream.

◆ ensureChannelArraysAllocated()

void ensureChannelArraysAllocated ( )

inlineprotected

Ensures that per-channel arrays are allocated and properly sized.

◆ filterSamples()

void filterSamples	(	const uint8_t *	data,
		size_t	len
	)

inlineprotected

Applies per-channel 3-band equalization to audio samples

Parameters

data	Pointer to audio data buffer
len	Length of the data buffer in bytes

◆ flush()

virtual void flush ( )

inlineoverridevirtualinherited

Reimplemented from Print.

Reimplemented in PureDataStream, URLStreamBufferedT< T >, URLStreamBufferedT< ICYStream >, AudioStreamWrapper, ResampleStream, URLStream, BufferedTaskStream, I2SStream, MemoryStream, RingBufferStream, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, and BufferedStream.

◆ getChannelFrequencies()

bool getChannelFrequencies	(	int	channel,
		int &	freq_low_val,
		int &	freq_high_val
	)

inline

Get frequency parameters for a specific channel

Parameters

channel	Channel index (0-based)
freq_low_val	Reference to store the low frequency cutoff
freq_high_val	Reference to store the high frequency cutoff

Returns: true if successful, false if channel index is invalid

◆ getChannelGains()

bool getChannelGains	(	int	channel,
		float &	gain_low_val,
		float &	gain_medium_val,
		float &	gain_high_val
	)

inline

Get gain parameters for a specific channel

Parameters

channel	Channel index (0-based)
gain_low_val	Reference to store the low frequency gain
gain_medium_val	Reference to store the medium frequency gain
gain_high_val	Reference to store the high frequency gain

Returns: true if successful, false if channel index is invalid

◆ isNotifyActive()

bool isNotifyActive ( )

inlineinherited

Checks if the automatic AudioInfo update is active.

◆ not_supported()

virtual int not_supported	(	int	out,
		const char *	msg = `""`
	)

inlineprotectedvirtualinherited

◆ notifyAudioChange()

void notifyAudioChange ( AudioInfo info )

inlineprotectedinherited

◆ operator bool()

virtual operator bool ( )

inlinevirtualinherited

Reimplemented in A2DPStream, ICYStreamT< T >, AudioBLEStream, AudioFFTBase, PortAudioStream, URLStream, I2SStream, AdapterAudioOutputToAudioStream, TimedStream, MemoryStream, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, and Pipeline.

◆ readBytes()

size_t readBytes	(	uint8_t *	data,
		size_t	len
	)

inlineoverridevirtual

Read and process audio data through the per-channel equalizer

Parameters

data	Buffer to store processed audio data
len	Maximum number of bytes to read

Returns: Number of bytes actually read and processed

Reimplemented from AudioStream.

◆ readSilence()

virtual size_t readSilence	(	uint8_t *	buffer,
		size_t	length
	)

inlinevirtualinherited

Source to generate silence: just sets the buffer to 0.

◆ refillReadBuffer()

void refillReadBuffer ( )

inlineprotectedinherited

Refill small read buffer (e.g. 8 bytes) to avoid single byte reads when calling read()

◆ removeNotifyAudioChange()

virtual bool removeNotifyAudioChange ( AudioInfoSupport & bi )

inlinevirtualinherited

Removes a target in order not to be notified about audio changes.

Reimplemented in RTSPClient< TcpClient, UdpSocket >.

◆ sample()

float sample	(	int	channel,
		float	sample_val
	)

inlineprotected

Processes a single sample through the 3-band equalizer for a specific channel

Parameters

channel	The channel number to process
sample_val	The input sample value

Returns: The processed sample value with per-channel equalization applied

◆ setAudioInfo()

virtual void setAudioInfo ( AudioInfo info )

inlineoverridevirtual

Defines the input AudioInfo.

Reimplemented from AudioStream.

◆ setChannelFrequencies()

void setChannelFrequencies	(	int	channel,
		int	freq_low_val,
		int	freq_high_val
	)

inline

Set frequency parameters for a specific channel

Parameters

channel	Channel index (0-based)
freq_low_val	Low frequency cutoff in Hz
freq_high_val	High frequency cutoff in Hz

◆ setChannelGains()

void setChannelGains	(	int	channel,
		float	gain_low_val,
		float	gain_medium_val,
		float	gain_high_val
	)

inline

Set gain parameters for a specific channel

Parameters

channel	Channel index (0-based)
gain_low_val	Gain multiplier for low frequencies (0.0-2.0)
gain_medium_val	Gain multiplier for medium frequencies (0.0-2.0)
gain_high_val	Gain multiplier for high frequencies (0.0-2.0)

◆ setNotifyActive()

void setNotifyActive ( bool flag )

inlineinherited

Deactivate/Reactivate automatic AudioInfo updates: (default is active)

◆ setOutput()

void setOutput ( Print & out )

inlineoverridevirtual

Defines/Changes the output target.

Implements ModifyingStream.

◆ setStream()

void setStream ( Stream & io )

inlineoverridevirtual

Defines/Changes the input & output.

Implements ModifyingStream.

◆ setWriteBufferSize()

void setWriteBufferSize ( int size )

inlineinherited

◆ write() [1/2]

size_t write	(	const uint8_t *	data,
		size_t	len
	)

inlineoverridevirtual

Process and write audio data through the per-channel equalizer

Parameters

data	Pointer to audio data buffer
len	Length of data in bytes

Returns: Number of bytes written

Reimplemented from AudioStream.

◆ write() [2/2]

virtual size_t write ( uint8_t ch )

inlineoverridevirtualinherited

Reimplemented in MemoryStream, AudioStreamWrapper, BufferedTaskStream, RingBufferStream, BufferedStream, and URLStream.

◆ writeSilence()

virtual void writeSilence ( size_t len )

inlinevirtualinherited

Writes len bytes of silence (=0).

Member Data Documentation

◆ _timeout

int _timeout = 10

protectedinherited

◆ cfg

ConfigEqualizer3Bands cfg

protected

Default configuration instance.

◆ freq_high

Vector<int> freq_high

protected

High frequency cutoffs per channel (Hz)

◆ freq_low

Vector<int> freq_low

protected

Low frequency cutoffs per channel (Hz)

◆ gain_high

Vector<float> gain_high

protected

High frequency gains per channel.

◆ gain_low

Vector<float> gain_low

protected

Low frequency gains per channel.

◆ gain_medium

Vector<float> gain_medium

protected

Medium frequency gains per channel.

◆ info

AudioInfo info

protectedinherited

◆ is_active

bool is_active = false

protected

◆ is_notify_active

bool is_notify_active = true

protectedinherited

◆ max_state_count

int max_state_count = 0

protected

Maximum number of allocated channel states.

◆ notify_vector

Vector<AudioInfoSupport*> notify_vector

protectedinherited

◆ p_cfg

ConfigEqualizer3Bands* p_cfg = &cfg

protected

Pointer to active configuration.

◆ p_print

Print* p_print = nullptr

protected

Output stream for write operations.

◆ p_stream

Stream* p_stream = nullptr

protected

Input/output stream for read operations.

◆ state

struct audio_tools::Equalizer3BandsPerChannel::EQSTATE* state = nullptr

protected

◆ tmp_in

RingBuffer<uint8_t> tmp_in {0}

protectedinherited

◆ tmp_out

RingBuffer<uint8_t> tmp_out {0}

protectedinherited

◆ vsa

const float vsa

protected

Initial value:

=

(1.0 / 4294967295.0)

Very small amount for denormal fix.

◆ write_buffer_size

int write_buffer_size = MAX_SINGLE_CHARS

protectedinherited

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

src/AudioTools/CoreAudio/AudioFilter/Equalizer3Bands.h

Classes

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Equalizer3BandsPerChannel() [1/4]

◆ Equalizer3BandsPerChannel() [2/4]

◆ Equalizer3BandsPerChannel() [3/4]

◆ Equalizer3BandsPerChannel() [4/4]

◆ ~Equalizer3BandsPerChannel()

Member Function Documentation

◆ addNotifyAudioChange()

◆ allocateChannelArrays()

◆ audioInfo()

◆ audioInfoOut()

◆ available()

◆ availableForWrite()

◆ begin() [1/2]

◆ begin() [2/2]

◆ clearNotifyAudioChange()

◆ config()

◆ defaultConfig()

◆ end()

◆ ensureChannelArraysAllocated()

◆ filterSamples()

◆ flush()

◆ getChannelFrequencies()

◆ getChannelGains()

◆ isNotifyActive()

◆ not_supported()

◆ notifyAudioChange()

◆ operator bool()

◆ readBytes()

◆ readSilence()

◆ refillReadBuffer()

◆ removeNotifyAudioChange()

◆ sample()

◆ setAudioInfo()

◆ setChannelFrequencies()

◆ setChannelGains()

◆ setNotifyActive()

◆ setOutput()

◆ setStream()

◆ setWriteBufferSize()

◆ write() [1/2]

◆ write() [2/2]

◆ writeSilence()

Member Data Documentation

◆ _timeout

◆ cfg

◆ freq_high

◆ freq_low

◆ gain_high

◆ gain_low

◆ gain_medium

◆ info

◆ is_active

◆ is_notify_active

◆ max_state_count

◆ notify_vector

◆ p_cfg

◆ p_print

◆ p_stream

◆ state

◆ tmp_in

◆ tmp_out

◆ vsa

◆ write_buffer_size