3 Band Equalizer with identical settings for all channels More...

#include <Equalizer.h>

Inheritance diagram for Equalizer3Bands:

Classes
struct	EQSTATE
	Filter state for each channel. More...

Public Member Functions
	Equalizer3Bands (AudioOutput &out)

	Equalizer3Bands (AudioStream &stream)

	Equalizer3Bands (Print &out)

	Equalizer3Bands (Stream &in)

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 ()

virtual void	flush () override

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

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

void	setOutput (Print &out) override

void	setStream (Stream &io) override

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	filterSamples (const uint8_t *data, size_t len)

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

void	notifyAudioChange (AudioInfo info)

void	refillReadBuffer ()

float	sample (EQSTATE &es, float sample)

Protected Attributes
int	_timeout = 10

ConfigEqualizer3Bands	cfg
	Default configuration instance.

AudioInfo	info

bool	is_active = false
	Indicates if the equalizer is active.

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::Equalizer3Bands::EQSTATE *	state = nullptr

RingBuffer< uint8_t >	tmp_in {0}

RingBuffer< uint8_t >	tmp_out {0}

const float	vsa = (1.0 / 4294967295.0)
	Very small amount for denormal fix.

int	write_buffer_size = MAX_SINGLE_CHARS

Detailed Description

3 Band Equalizer with identical settings for all channels

Digital 3-band equalizer implementation inspired from https://www.musicdsp.org/en/latest/Filters/236-3-band-equaliser.html

This equalizer applies the same frequency response and gain settings to all audio channels. The audio spectrum is divided into three bands:

Low: DC to freq_low Hz (controlled by gain_low)
Medium: freq_low to freq_high Hz (controlled by gain_medium)
High: freq_high to Nyquist frequency (controlled by gain_high)

Each band uses a 4-pole filter implementation for smooth frequency response. If you need different settings per channel, use Equalizer3BandsPerChannel instead.

After calling begin() you can update the gain parameters of the ConfigEqualizer3Bands directly w/o calling any other methods. If you change the freq. parameters, you need to call begin() again.

Author: pschatzmann

Constructor & Destructor Documentation

◆ Equalizer3Bands() [1/4]

Equalizer3Bands ( Print & out )

inline

Constructor with Print output stream

Parameters

out	Print stream where processed audio will be written

◆ Equalizer3Bands() [2/4]

Equalizer3Bands ( Stream & in )

inline

Constructor with bidirectional Stream

Parameters

in	Stream for both input and output

◆ Equalizer3Bands() [3/4]

Equalizer3Bands ( AudioOutput & out )

inline

Constructor with AudioOutput (includes automatic audio format notifications)

Parameters

out	AudioOutput where processed audio will be written

◆ Equalizer3Bands() [4/4]

Equalizer3Bands ( AudioStream & stream )

inline

Constructor with AudioStream (includes automatic audio format notifications)

Parameters

stream AudioStream for both input and output

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, MP3DecoderHelix, MP3DecoderMAD, OggContainerDecoder, Pipeline, and Pipeline::ModifyingStreamAdapter.

◆ audioInfo()

virtual AudioInfo audioInfo ( )

inlineoverridevirtualinherited

provides the actual input AudioInfo

Implements AudioInfoSupport.

Reimplemented in JupyterAudioT< T >, MozziStream, TimerCallbackAudioStream, 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

Reimplemented from BaseStream.

◆ begin() [2/2]

bool begin ( ConfigEqualizer3Bands & config )

inline

Initialize the equalizer with the provided configuration

Parameters

config Configuration settings including frequencies and gains

Returns: true if initialization was successful

◆ config()

ConfigEqualizer3Bands & config ( )

inline

Access to the current configuration

Returns: Reference to the configuration object

◆ defaultConfig()

ConfigEqualizer3Bands & defaultConfig ( )

inline

Access to the default configuration

Returns: Reference to the default configuration object

◆ end()

void end ( )

inlinevirtual

Reimplemented from BaseStream.

◆ filterSamples()

void filterSamples	(	const uint8_t *	data,
		size_t	len
	)

inlineprotected

Apply 3-band equalization to audio samples

Parameters

data	Pointer to audio data buffer (modified in-place)
len	Length of data buffer in bytes

◆ flush()

virtual void flush ( )

inlineoverridevirtualinherited

Reimplemented from Print.

Reimplemented in ResampleStream, BufferedTaskStream, and BufferedStream.

◆ operator bool()

virtual operator bool ( )

inlinevirtualinherited

Reimplemented in A2DPStream, I2SStream, MemoryStream, and Pipeline.

◆ readBytes()

size_t readBytes	(	uint8_t *	data,
		size_t	len
	)

inlineoverridevirtual

Read and process audio data through the 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.

◆ sample()

float sample	(	EQSTATE &	es,
		float	sample
	)

inlineprotected

Process a single audio sample through the 3-band equalizer

Parameters

es	Reference to the filter state for this channel
sample	Input sample value (normalized float)

Returns: Processed sample value with equalization applied

◆ setAudioInfo()

virtual void setAudioInfo ( AudioInfo info )

inlineoverridevirtual

Called automatically when audio format changes

Parameters

info	New audio format information

Reimplemented from AudioStream.

◆ setOutput()

void setOutput ( Print & out )

inlineoverridevirtual

Defines/Changes the output target

Parameters

out	Print stream where processed audio will be written

Implements ModifyingStream.

◆ setStream()

void setStream ( Stream & io )

inlineoverridevirtual

Defines/Changes the input & output stream

Parameters

io	Stream to use for both reading and writing audio data

Implements ModifyingStream.

◆ write() [1/2]

size_t write	(	const uint8_t *	data,
		size_t	len
	)

inlineoverridevirtual

Process and write audio data through the 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 BufferedTaskStream, and BufferedStream.

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

src/AudioTools/CoreAudio/AudioFilter/Equalizer.h

Classes

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Equalizer3Bands() [1/4]

◆ Equalizer3Bands() [2/4]

◆ Equalizer3Bands() [3/4]

◆ Equalizer3Bands() [4/4]

Member Function Documentation

◆ addNotifyAudioChange()

◆ audioInfo()

◆ audioInfoOut()

◆ available()

◆ availableForWrite()

◆ begin() [1/2]

◆ begin() [2/2]

◆ config()

◆ defaultConfig()

◆ end()

◆ filterSamples()

◆ flush()

◆ operator bool()

◆ readBytes()

◆ sample()

◆ setAudioInfo()

◆ setOutput()

◆ setStream()

◆ write() [1/2]

◆ write() [2/2]