#include <LMSEchoCancellationStream.h>

Inheritance diagram for LMSEchoCancellationStream< T >:

Public Member Functions
	LMSEchoCancellationStream (Stream &in, size_t lag_samples=0, size_t buffer_size=512, size_t filter_len=32, float mu=0.001f)
	Constructor.

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 ()

void	cancel (const T rec, const T play, T *out, size_t len)
	Process echo cancellation on arrays of samples.

virtual void	clearNotifyAudioChange ()
	Deletes all change notify subscriptions.

virtual void	end ()

virtual void	flush () override

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 (subtract output signal with lag)

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 the internal buffer and lag state.

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

void	setFilterLen (size_t len)
	Set the filter length for the adaptive filter.

void	setLag (size_t lag_samples)
	Set the lag (delay) in samples for echo cancellation.

void	setMu (float mu)
	Set the adaptation rate (mu) for the LMS algorithm.

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
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()

Protected Attributes
int	_timeout = 10

float	adaptation_rate = 0.01f

size_t	buffer_size

Vector< float >	filter

size_t	filter_len

AudioInfo	info

bool	is_notify_active = true

size_t	lag

Vector< AudioInfoSupport * >	notify_vector

Stream *	p_io = nullptr

RingBuffer< T >	ring_buffer {0}

RingBuffer< uint8_t >	tmp_in {0}

RingBuffer< uint8_t >	tmp_out {0}

int	write_buffer_size = MAX_SINGLE_CHARS

Constructor & Destructor Documentation

◆ LMSEchoCancellationStream()

template<typename T = int16_t>

LMSEchoCancellationStream	(	Stream &	in,
		size_t	lag_samples = `0`,
		size_t	buffer_size = `512`,
		size_t	filter_len = `32`,
		float	mu = `0.001f`
	)

inline

Constructor.

Parameters

in	Reference to the input stream (microphone or audio input)
lag_samples	Number of samples to delay the echo subtraction (default: 0)
buffer_size	Size of the internal ring buffer (default: 512)

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

Reimplemented from Stream.

Reimplemented in AudioKitStream, AudioLoRa, URLStreamBufferedT< T >, URLStreamBufferedT< ICYStream >, VBANStream, AudioStreamWrapper, LoRaStream, FaustStream< DSP >, AudioFFTBase, AudioMP34DT05, I2SCodecStream, MiniAudioStream, StdioStream, TfLiteAudioStream, A2DPStream, ESPNowStream, HammingFEC< bytecount, block_t >, HLSStreamT< URLStream >, HttpRequest, ICYStreamT< T >, URLStream, BufferedTaskStream, ReedSolomonFEC< bytecount, additional_bytes >, UDPStream, AnalogAudioArduino, AnalogAudioStream, AudioEffectStreamT< T >, Equalizer3Bands, Equalizer3BandsPerChannel, I2SStream, ReformatBaseStream, TimedStream, MemoryStream, RingBufferStream, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, BufferedStream, ConverterStream< T >, MeasuringStream, ProgressStream, Throttle, InputMerge< T >, CallbackStream, FilteredStream< T, TF >, FilteredStream< int16_t, int16_t >, ChannelFormatConverterStreamT< T >, ChannelFormatConverterStream, NumberFormatConverterStreamT< TFrom, TTo >, NumberFormatConverterStream, CatStream, QueueStream< T >, QueueStream< uint8_t >, DynamicMemoryStream, FadeStream, FrequencyDetectorAutoCorrelation, FrequencyDetectorZeroCrossing, Pipeline, Pipeline::ModifyingStreamAdapter, VolumeStream, FileLoopT< FileType >, FileLoopT< File >, AudioBLEClient, AudioBLEClient, AudioBLEServer, and AudioBLEServer.

◆ availableForWrite()

virtual int availableForWrite ( )

inlineoverridevirtualinherited

Reimplemented from Print.

Reimplemented in AudioLoRa, UDPStream, VBANStream, AudioStreamWrapper, ConverterStream< T >, LoRaStream, EncodedAudioStream, FaustStream< DSP >, AudioFFTBase, I2SCodecStream, MiniAudioStream, StdioStream, A2DPStream, ESPNowStream, HammingFEC< bytecount, block_t >, AbstractURLStream, URLStreamESP32, ReedSolomonFEC< bytecount, additional_bytes >, AnalogAudioArduino, AnalogAudioStream, AudioEffectStreamT< T >, Equalizer3Bands, Equalizer3BandsPerChannel, I2SStream, ReformatBaseStream, TimedStream, MemoryStream, RingBufferStream, MeasuringStream, ProgressStream, Throttle, FilteredStream< T, TF >, FilteredStream< int16_t, int16_t >, ChannelFormatConverterStreamT< T >, ChannelFormatConverterStream, NumberFormatConverterStreamT< TFrom, TTo >, NumberFormatConverterStream, QueueStream< T >, QueueStream< uint8_t >, DynamicMemoryStream, FadeStream, FrequencyDetectorAutoCorrelation, FrequencyDetectorZeroCrossing, Pipeline, VolumeStream, AudioBLEClient, AudioBLEClient, AudioBLEServer, and AudioBLEServer.

◆ begin()

virtual bool begin ( )

inlinevirtualinherited

Reimplemented in AudioOutputWithCallback, AudioMP34DT05, I2SCodecStream, MozziStream, PureDataStream, SPDIFOutput, VS1053Stream, WM8960Stream, AdaptiveResamplingStream, AudioLoRa, ESPNowStream, VBANStream, AudioEffectStreamT< T >, Equalizer3Bands, Equalizer3BandsPerChannel, I2SStream, AudioStreamWrapper, TimerCallbackAudioStream, FrequencyDetectorAutoCorrelation, GoertzelStream, ResampleStreamT< TInterpolator >, FileLoopT< FileType >, FileLoopT< File >, LoRaStream, EncodedAudioStream, AudioBoardStream, AudioFFTBase, AudioKitStream, MiniAudioStream, PortAudioStream, StdioStream, HLSStreamT< URLStream >, AnalogAudioArduino, AnalogAudioStream, AdapterAudioOutputToAudioStream, TimedStream, MemoryStream, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, MeasuringStream, ProgressStream, Throttle, InputMerge< T >, CallbackStream, FilteredStream< T, TF >, FilteredStream< int16_t, int16_t >, VolumeMeter, AudioInputMonitor, ChannelFormatConverterStreamT< T >, ChannelFormatConverterStream, NumberFormatConverterStreamT< TFrom, TTo >, NumberFormatConverterStream, FormatConverterStream, CatStream, QueueStream< T >, QueueStream< uint8_t >, DynamicMemoryStream, Pipeline, Pipeline::ModifyingStreamAdapter, ResampleStream, VolumeStream, and EqualizerNBands< SampleT, AccT, NUM_TAPS, NUM_BANDS >.

◆ cancel()

template<typename T = int16_t>

void cancel	(	const T *	rec,
		const T *	play,
		T *	out,
		size_t	len
	)

inline

Process echo cancellation on arrays of samples.

Parameters

rec	Pointer to received (microphone) signal samples
play	Pointer to playback (speaker) signal samples
out	Pointer to output buffer for echo-cancelled signal
len	Number of samples to process

◆ clearNotifyAudioChange()

virtual void clearNotifyAudioChange ( )

inlinevirtualinherited

Deletes all change notify subscriptions.

Reimplemented in RTSPClient< TcpClient, UdpSocket >.

◆ end()

virtual void end ( )

inlinevirtualinherited

Reimplemented in FaustStream< DSP >, AudioMP34DT05, I2SCodecStream, MozziStream, PureDataStream, SPDIFOutput, VS1053Stream, WM8960Stream, AdaptiveResamplingStream, AudioLoRa, ESPNowStream, BufferedTaskStream, URLStreamBufferedT< T >, URLStreamBufferedT< ICYStream >, Equalizer3Bands, I2SStream, AudioStreamWrapper, TimerCallbackAudioStream, FormatConverterStream, GoertzelStream, FileLoopT< FileType >, FileLoopT< File >, EqualizerNBands< SampleT, AccT, NUM_TAPS, NUM_BANDS >, LoRaStream, EncodedAudioStream, AudioFFTBase, AudioKitStream, MiniAudioStream, PortAudioStream, StdioStream, A2DPStream, HLSStreamT< URLStream >, HttpRequest, ICYStreamT< T >, URLStream, URLStreamESP32, AnalogAudioArduino, AnalogAudioStream, AudioEffectStreamT< T >, Equalizer3BandsPerChannel, ReformatBaseStream, AdapterAudioOutputToAudioStream, MemoryStream, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, InputMixer< T >, InputMerge< T >, CallbackStream, FilteredStream< T, TF >, FilteredStream< int16_t, int16_t >, ChannelFormatConverterStream, NumberFormatConverterStream, CatStream, QueueStream< T >, QueueStream< uint8_t >, DynamicMemoryStream, Pipeline, Pipeline::ModifyingStreamAdapter, VolumeStream, AudioBLEClient, AudioBLEClient, AudioBLEServer, AudioBLEServer, AbstractURLStream, and AudioBLEStream.

◆ 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.

◆ 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()

template<typename T = int16_t>

size_t readBytes	(	uint8_t *	buf,
		size_t	len
	)

inlineoverridevirtual

Read input and remove echo (subtract output signal with lag)

Parameters

buf	Pointer to buffer to store processed input (T*)
len	Number of bytes to read

Returns: Number of bytes read from input

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 >.

◆ reset()

template<typename T = int16_t>

void reset ( )

inline

Reset the internal buffer and lag state.

◆ setAudioInfo()

virtual void setAudioInfo ( AudioInfo info )

inlineoverridevirtualinherited

Defines the input AudioInfo.

Implements AudioInfoSupport.

Reimplemented in VS1053Stream, WM8960Stream, ChannelFormatConverterStreamT< T >, ChannelFormatConverterStream, VolumeStream, MiniAudioStream, PortAudioStream, I2SCodecStream, MozziStream, SPDIFOutput, AudioLoRa, AnalogAudioStream, I2SStream, TimerCallbackAudioStream, AudioBLEStream, LoRaStream, AudioFFTBase, AudioKitStream, VBANStream, AnalogAudioArduino, Equalizer3Bands, Equalizer3BandsPerChannel, AdapterAudioOutputToAudioStream, TimedStream, MeasuringStream, ProgressStream, CallbackStream, VolumeMeter, AudioInputMonitor, FormatConverterStream, FadeStream, GoertzelStream, Pipeline::ModifyingStreamAdapter, MDFEchoCancellationStream< Allocator >, EncodedAudioStream, PureDataStream, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, NumberFormatConverterStreamT< TFrom, TTo >, NumberFormatConverterStream, Pipeline, ResampleStream, and ResampleStreamT< TInterpolator >.

◆ setFilterLen()

template<typename T = int16_t>

void setFilterLen ( size_t len )

inline

Set the filter length for the adaptive filter.

Parameters

len	Length of the adaptive filter

◆ setLag()

template<typename T = int16_t>

void setLag ( size_t lag_samples )

inline

Set the lag (delay) in samples for echo cancellation.

Parameters

lag_samples Number of samples to delay the echo subtraction

◆ setMu()

template<typename T = int16_t>

void setMu ( float mu )

inline

Set the adaptation rate (mu) for the LMS algorithm.

Parameters

mu	Adaptation rate

◆ setNotifyActive()

void setNotifyActive ( bool flag )

inlineinherited

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

◆ setWriteBufferSize()

void setWriteBufferSize ( int size )

inlineinherited

◆ write() [1/2]

template<typename T = int16_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 (T*)
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 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

◆ adaptation_rate

template<typename T = int16_t>

float adaptation_rate = 0.01f

protected

◆ buffer_size

template<typename T = int16_t>

size_t buffer_size

protected

◆ filter

template<typename T = int16_t>

Vector<float> filter

protected

◆ filter_len

template<typename T = int16_t>

size_t filter_len

protected

◆ info

AudioInfo info

protectedinherited

◆ is_notify_active

bool is_notify_active = true

protectedinherited

◆ lag

template<typename T = int16_t>

size_t lag

protected

◆ notify_vector

Vector<AudioInfoSupport*> notify_vector

protectedinherited

◆ p_io

template<typename T = int16_t>

Stream* p_io = nullptr

protected

◆ ring_buffer

template<typename T = int16_t>

RingBuffer<T> ring_buffer {0}

protected

◆ tmp_in

RingBuffer<uint8_t> tmp_in {0}

protectedinherited

◆ tmp_out

RingBuffer<uint8_t> tmp_out {0}

protectedinherited

◆ write_buffer_size

int write_buffer_size = MAX_SINGLE_CHARS

protectedinherited

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

src/AudioTools/Sandbox/STT/LMSEchoCancellationStream.h

Public Member Functions

Protected Member Functions

Protected Attributes

Constructor & Destructor Documentation

◆ LMSEchoCancellationStream()

Member Function Documentation

◆ addNotifyAudioChange()

◆ audioInfo()

◆ audioInfoOut()

◆ available()

◆ availableForWrite()

◆ begin()

◆ cancel()

◆ clearNotifyAudioChange()

◆ end()

◆ flush()

◆ isNotifyActive()

◆ not_supported()

◆ notifyAudioChange()

◆ operator bool()

◆ readBytes()

◆ readSilence()

◆ refillReadBuffer()

◆ removeNotifyAudioChange()

◆ reset()

◆ setAudioInfo()

◆ setFilterLen()

◆ setLag()

◆ setMu()

◆ setNotifyActive()

◆ setWriteBufferSize()

◆ write() [1/2]

◆ write() [2/2]

◆ writeSilence()

Member Data Documentation

◆ _timeout

◆ adaptation_rate

◆ buffer_size

◆ filter

◆ filter_len

◆ info

◆ is_notify_active

◆ lag

◆ notify_vector

◆ p_io

◆ ring_buffer

◆ tmp_in

◆ tmp_out

◆ write_buffer_size