MDF (Multi-Delay block Frequency) echo cancellation with stream API. More...

#include <MDFEchoCancellationStream.h>

Inheritance diagram for MDFEchoCancellationStream< Allocator >:

Public Member Functions
	MDFEchoCancellationStream (Stream &in, int filterLength, AudioFFTBase &fftDriver, const Allocator &alloc=Allocator())
	Constructor (single channel)

	MDFEchoCancellationStream (Stream &in, int filterLength, AudioFFTBase &fftDriver, const Allocator &alloc=Allocator())
	Constructor (multiple channels)

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 ()

virtual int	available () override

virtual int	availableForWrite () override

virtual bool	begin ()

virtual void	clearNotifyAudioChange ()
	Deletes all change notify subscriptions.

virtual void	end ()

virtual void	flush () override

MDFEchoCancellation< Allocator > &	getEchoCanceller ()
	Get underlying MDF echo canceller instance.

int	getFilterLen ()
	Get filter length.

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

virtual	operator bool ()

size_t	readBytes (uint8_t *buf, size_t len) override
	Read input and remove echo (using buffered playback)

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.

void	reset ()
	Reset echo canceller state.

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

void	setFilterLen (int len)
	Set filter length (number of filter blocks)

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

void	setWriteBufferSize (int size)

size_t	write (const uint8_t *buf, size_t len) override
	Store the output signal (sent to speaker)

virtual size_t	write (uint8_t ch) override

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

Protected Member Functions
int	getFrameSize ()
	Get frame size from FFT configuration.

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

void	notifyAudioChange (AudioInfo info)

void	refillReadBuffer ()

Protected Attributes
int	_timeout = 10

MDFEchoCancellation< Allocator >	canceller

AudioInfo	info

bool	is_notify_active = true

Vector< AudioInfoSupport * >	notify_vector

AudioFFTBase *	p_fft = nullptr

Stream *	p_io = nullptr

RingBuffer< uint8_t >	tmp_in {0}

RingBuffer< uint8_t >	tmp_out {0}

int	write_buffer_size = MAX_SINGLE_CHARS

Detailed Description

template<typename Allocator = std::allocator<uint8_t>>
class audio_tools::MDFEchoCancellationStream< Allocator >

MDF (Multi-Delay block Frequency) echo cancellation with stream API.

This class wraps MDFEchoCancellation and provides a stream-based interface for easy integration with AudioTools streaming pipelines. It processes audio using the high-performance MDF algorithm.

Template Parameters

Allocator Custom allocator for memory management (default: std::allocator)

Constructor & Destructor Documentation

◆ MDFEchoCancellationStream() [1/2]

template<typename Allocator = std::allocator<uint8_t>>

MDFEchoCancellationStream	(	Stream &	in,
		int	filterLength,
		AudioFFTBase &	fftDriver,
		const Allocator &	alloc = `Allocator()`
	)

inline

Constructor (single channel)

Parameters

in	Reference to the input stream (microphone or audio input)
filterLength	Length of echo cancellation filter in samples
fftDriver	FFT driver instance from AudioFFT
alloc	Allocator instance (optional)

◆ MDFEchoCancellationStream() [2/2]

template<typename Allocator = std::allocator<uint8_t>>

MDFEchoCancellationStream	(	Stream &	in,
		int	filterLength,
		AudioFFTBase &	fftDriver,
		const Allocator &	alloc = `Allocator()`
	)

inline

Constructor (multiple channels)

Parameters

in	Reference to the input stream
filterLength	Length of echo cancellation filter in samples
nbMic	Number of microphone channels
nbSpeakers	Number of speaker channels
fftDriver	FFT driver instance from AudioFFT
alloc	Allocator instance (optional)

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()

virtual int available ( )

inlineoverridevirtualinherited

◆ availableForWrite()

virtual int availableForWrite ( )

inlineoverridevirtualinherited

Reimplemented from Print.

Reimplemented in UDPStream, AudioFFTBase, I2SCodecStream, A2DPStream, AbstractURLStream, URLStreamESP32, Equalizer3Bands, Equalizer3BandsPerChannel, I2SStream, MeasuringStream, ProgressStream, FrequencyDetectorAutoCorrelation, FrequencyDetectorZeroCrossing, and VolumeStream.

◆ begin()

virtual bool begin ( )

inlinevirtualinherited

◆ clearNotifyAudioChange()

virtual void clearNotifyAudioChange ( )

inlinevirtualinherited

Deletes all change notify subscriptions.

Reimplemented in RTSPClient< TcpClient, UdpSocket >.

◆ end()

virtual void end ( )

inlinevirtualinherited

◆ flush()

virtual void flush ( )

inlineoverridevirtualinherited

Reimplemented from Print.

Reimplemented in ResampleStream, BufferedTaskStream, and BufferedStream.

◆ getEchoCanceller()

template<typename Allocator = std::allocator<uint8_t>>

MDFEchoCancellation< Allocator > & getEchoCanceller ( )

inline

Get underlying MDF echo canceller instance.

Returns: Reference to MDFEchoCancellation object

◆ getFilterLen()

template<typename Allocator = std::allocator<uint8_t>>

int getFilterLen ( )

inline

Get filter length.

Returns: Current filter length

◆ getFrameSize()

template<typename Allocator = std::allocator<uint8_t>>

int getFrameSize ( )

inlineprotected

Get frame size from FFT configuration.

Returns: Frame size in samples

◆ operator bool()

virtual operator bool ( )

inlinevirtualinherited

Reimplemented in A2DPStream, ICYStreamT< T >, I2SStream, MemoryStream, and Pipeline.

◆ readBytes()

template<typename Allocator = std::allocator<uint8_t>>

size_t readBytes	(	uint8_t *	buf,
		size_t	len
	)

inlineoverridevirtual

Read input and remove echo (using buffered playback)

Parameters

buf	Pointer to buffer to store processed input
len	Number of bytes to read

Returns: Number of bytes read from input

Reimplemented from AudioStream.

◆ removeNotifyAudioChange()

virtual bool removeNotifyAudioChange ( AudioInfoSupport & bi )

inlinevirtualinherited

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

Reimplemented in RTSPClient< TcpClient, UdpSocket >.

◆ setAudioInfo()

template<typename Allocator = std::allocator<uint8_t>>

void setAudioInfo ( AudioInfo info )

inlineoverridevirtual

Defines the input AudioInfo.

Reimplemented from AudioStream.

◆ setFilterLen()

template<typename Allocator = std::allocator<uint8_t>>

void setFilterLen ( int len )

inline

Set filter length (number of filter blocks)

Parameters

len	Length of the adaptive filter in blocks

◆ write() [1/2]

template<typename Allocator = std::allocator<uint8_t>>

size_t write	(	const uint8_t *	buf,
		size_t	len
	)

inlineoverridevirtual

Store the output signal (sent to speaker)

Parameters

buf	Pointer to PCM data sent to the speaker
len	Number of bytes in buf

Returns: Number of bytes processed

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/Sandbox/STT/MDFEchoCancellationStream.h

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ MDFEchoCancellationStream() [1/2]

◆ MDFEchoCancellationStream() [2/2]

Member Function Documentation

◆ addNotifyAudioChange()

◆ audioInfo()

◆ audioInfoOut()

◆ available()

◆ availableForWrite()

◆ begin()

◆ clearNotifyAudioChange()

◆ end()

◆ flush()

◆ getEchoCanceller()

◆ getFilterLen()

◆ getFrameSize()

◆ operator bool()

◆ readBytes()

◆ removeNotifyAudioChange()

◆ setAudioInfo()

◆ setFilterLen()

◆ write() [1/2]

◆ write() [2/2]