Equalizer3Bands Class Reference

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

#include <Equalizer3Bands.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)
	~Equalizer3Bands ()
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 ()
	Refill small read buffer (e.g. 8 bytes) to avoid single byte reads when calling read()
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
	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.

Warning

begin(ConfigEqualizer3Bands&) needs a reference, so do not provide it any stack objects!

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

~Equalizer3Bands()

~Equalizer3Bands ( )

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.

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

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

clearNotifyAudioChange()

virtual void clearNotifyAudioChange ( )

inlinevirtualinherited

Deletes all change notify subscriptions.

Reimplemented in RTSPClient< TcpClient, UdpSocket >.

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

Copy of the default configuration

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

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 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 ( 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.

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

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.

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 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.

info

AudioInfo info

protectedinherited

is_active

bool is_active = false

protected

Indicates if the equalizer is active.

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::Equalizer3Bands::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

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

• src/AudioTools/CoreAudio/AudioFilter/Equalizer3Bands.h