FrequencyDetectorZeroCrossing Class Reference

Detects frequency using upward zero crossings in audio samples. More...

#include <FrequencyDetector.h>

Inheritance diagram for FrequencyDetectorZeroCrossing:

Classes
struct	ChannelState
	Holds state for each channel during zero crossing detection. More...

Public Member Functions
	FrequencyDetectorZeroCrossing ()=default
	Default constructor.
	FrequencyDetectorZeroCrossing (Print &out)
	Construct with output stream.
	FrequencyDetectorZeroCrossing (Stream &in)
	Construct with input stream.
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
	Returns the number of bytes available for reading.
int	availableForWrite () override
	Returns the number of bytes available for writing.
virtual bool	begin ()
bool	begin (AudioInfo info)
	Initialize with audio configuration.
virtual void	clearNotifyAudioChange ()
	Deletes all change notify subscriptions.
virtual void	end ()
virtual void	flush () override
float	frequency (int channel)
	Returns the last detected frequency for the given channel.
bool	isNotifyActive ()
	Checks if the automatic AudioInfo update is active.
virtual	operator bool ()
size_t	readBytes (uint8_t *data, size_t len) override
	Reads bytes from the input stream and processes them for frequency detection.
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 newInfo) override
	Defines the input AudioInfo.
void	setFrequencyCallback (void(*callback)(int channel, float freq))
	Sets a callback function to be called when a new frequency is detected.
void	setNotifyActive (bool flag)
	Deactivate/Reactivate automatic AudioInfo updates: (default is active)
void	setWriteBufferSize (int size)
virtual size_t	write (const uint8_t *data, size_t len) override
	Writes bytes to the output stream and processes them for frequency detection.
virtual size_t	write (uint8_t ch) override
virtual void	writeSilence (size_t len)
	Writes len bytes of silence (=0).

Protected Member Functions
template<class T >
void	detect (T *samples, size_t len)
	Detects frequency for all channels using zero crossing method.
template<class T >
void	detectChannel (int channel, T *samples, size_t len)
	Detects frequency for a single channel by counting upward zero crossings.
virtual int	not_supported (int out, const char *msg="")
void	notifyAudioChange (AudioInfo info)
void	refillReadBuffer ()

Protected Attributes
int	_timeout = 10
bool	active = false
	Counting active flag (unused, kept for compatibility)
int	count = 0
	Sample count (unused, kept for compatibility)
void(*	freq_callback )(int channel, float freq)
	Frequency callback function.
AudioInfo	info
bool	is_notify_active = true
Vector< AudioInfoSupport * >	notify_vector
Stream *	p_in = nullptr
	Input stream pointer.
Print *	p_out = nullptr
	Output stream pointer.
Vector< ChannelState >	states
	State for each channel.
RingBuffer< uint8_t >	tmp_in {0}
RingBuffer< uint8_t >	tmp_out {0}
int	write_buffer_size = MAX_SINGLE_CHARS

Detailed Description

Detects frequency using upward zero crossings in audio samples.

This class estimates the frequency by counting the number of samples between upward zero crossings (negative to positive transitions). It supports multiple channels and different sample formats.

Usage:

• Feed audio data via write() or readBytes().
• Call frequency(channel) to get the detected frequency for a channel.
• Optionally, set a callback to be notified when a new frequency is detected.

Constructor & Destructor Documentation

FrequencyDetectorZeroCrossing() [1/2]

FrequencyDetectorZeroCrossing ( Print &  out )

inline

Construct with output stream.

Parameters

out	Output stream for writing audio data.

FrequencyDetectorZeroCrossing() [2/2]

FrequencyDetectorZeroCrossing ( Stream &  in )

inline

Construct with input stream.

Parameters

in	Input stream for reading audio data.

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

Returns the number of bytes available for reading.

Reimplemented from BaseStream.

availableForWrite()

int availableForWrite ( )

inlineoverridevirtual

Returns the number of bytes available for writing.

Reimplemented from BaseStream.

begin() [1/2]

virtual bool begin ( )

inlinevirtualinherited

Reimplemented in AudioOutputWithCallback, SPDIFOutput, VS1053Stream, WM8960Stream, ESPNowStream, TimerCallbackAudioStream, FrequencyDetectorAutoCorrelation, AudioFFTBase, HLSStreamT< URLStream >, AnalogAudioArduino, AnalogAudioStream, MemoryStream, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, FormatConverterStream, QueueStream< T >, QueueStream< uint8_t >, DynamicMemoryStream, and Pipeline.

begin() [2/2]

bool begin ( AudioInfo  info )

inline

Initialize with audio configuration.

Parameters

info	AudioInfo structure describing the audio format.

Returns

true if initialization succeeded.

detect()

template<class T >

void detect ( T *  samples, size_t  len  )

inlineprotected

Detects frequency for all channels using zero crossing method.

Template Parameters

T	Sample type (int16_t, int24_t, int32_t)

Parameters

samples	Pointer to audio samples.
len	Number of samples.

detectChannel()

template<class T >

void detectChannel ( int  channel, T *  samples, size_t  len  )

inlineprotected

Detects frequency for a single channel by counting upward zero crossings.

Template Parameters

T	Sample type.

Parameters

channel	Channel index.
samples	Pointer to audio samples.
len	Number of samples.

end()

virtual void end ( )

inlinevirtualinherited

Reimplemented in FaustStream< DSP >, I2SCodecStream, VS1053Stream, WM8960Stream, ESPNowStream, I2SStream, TimerCallbackAudioStream, AudioFFTBase, AudioKitStream, HLSStreamT< URLStream >, AnalogAudioStream, HttpRequest, ICYStreamT< T >, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, InputMixer< T >, InputMerge< T >, QueueStream< T >, QueueStream< uint8_t >, and Pipeline.

flush()

virtual void flush ( )

inlineoverridevirtualinherited

Reimplemented from Print.

Reimplemented in ResampleStream, BufferedTaskStream, and BufferedStream.

frequency()

float frequency ( int  channel )

inline

Returns the last detected frequency for the given channel.

Parameters

channel

Channel index.

Returns

Detected frequency in Hz, or 0 if invalid channel.

operator bool()

virtual operator bool ( )

inlinevirtualinherited

Reimplemented in A2DPStream, I2SStream, MemoryStream, and Pipeline.

readBytes()

size_t readBytes ( uint8_t *  data, size_t  len  )

inlineoverridevirtual

Reads bytes from the input stream and processes them for frequency detection.

Parameters

data	Buffer to store read bytes.
len	Number of bytes to read.

Returns

Number of bytes actually read.

Reimplemented from AudioStream.

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, AdapterAudioOutputToAudioStream, TimedStream, MeasuringStream, ProgressStream, CallbackStream, VolumeMeter, FormatConverterStream, FadeStream, Pipeline::ModifyingStreamAdapter, PureDataStream, GeneratedSoundStream< T >, GeneratedSoundStream< int16_t >, NumberFormatConverterStreamT< TFrom, TTo >, NumberFormatConverterStream, Pipeline, ResampleStream, and ResampleStreamT< TInterpolator >.

setFrequencyCallback()

void setFrequencyCallback ( void(*)(int channel, float freq)  callback )

inline

Sets a callback function to be called when a new frequency is detected.

Parameters

callback

Function pointer: void callback(int channel, float freq)

write() [1/2]

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

inlineoverridevirtual

Writes bytes to the output stream and processes them for frequency detection.

Parameters

data	Buffer containing audio data.
len	Number of bytes to write.

Returns

Number of bytes actually written.

Reimplemented from AudioStream.

write() [2/2]

virtual size_t write ( uint8_t  ch )

inlineoverridevirtualinherited

Reimplemented in BufferedTaskStream, and BufferedStream.

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

• src/AudioTools/CoreAudio/FrequencyDetector.h