Voice activity detector class. More...

#include <snowboy-detect.h>

Inheritance diagram for snowboy::SnowboyVad:

Public Member Functions
	SnowboyVad (const std::string &resource_filename)
	Default constructor. More...

bool	Reset ()
	Resets the vad. More...

int	RunVad (const std::string &data, bool is_end=false)
	Runs the VAD algorithm. More...

int	RunVad (const float *const data, const int array_length, bool is_end=false)
	Runs vad on float samples. More...

int	RunVad (const int16_t *const data, const int array_length, bool is_end=false)
	Runs vad on int16_t samples. More...

int	RunVad (const int32_t *const data, const int array_length, bool is_end=false)
	Runs vad on int32_t samples. More...

void	SetAudioGain (const float audio_gain)
	Apply a fixed gain to the input audio. More...

void	ApplyFrontend (const bool apply_frontend)
	Enable or disable audio frontend (NS & AGC). More...

int	SampleRate () const
	Returns the expected sample rate for audio provided to RunDetection(). More...

int	NumChannels () const
	Returns the expected number of channels for audio provided to RunDetection(). More...

int	BitsPerSample () const
	Returns the expected number of bits for audio provided to RunDetection(). More...

	~SnowboyVad ()
	Destructor.

Friends
class	testing::Inspector

Detailed Description

Voice activity detector class.

Class that only does voice activity detection without trying to match any hotwords. Do not use this in addition to SnowboyDetect, since SnowboyDetect contains a VAD pipeline as well.

Constructor & Destructor Documentation

◆ SnowboyVad()

snowboy::SnowboyVad::SnowboyVad ( const std::string & resource_filename )

Default constructor.

Constructor that takes a resource file.

Parameters

[in] resource_filename Filename of resource file.

Member Function Documentation

◆ ApplyFrontend()

void snowboy::SnowboyVad::ApplyFrontend ( const bool apply_frontend )

Enable or disable audio frontend (NS & AGC).

If <apply_frontend> is true, then apply frontend audio processing; otherwise turns the audio processing off. Frontend audio processing includes algorithms such as automatic gain control (AGC), noise suppression (NS) and so on. Generally adding frontend audio processing helps the performance, but if the model is not trained with frontend audio processing, it may decrease the performance. The general rule of thumb is:

For personal models, set it to false.
For universal models, follow the instruction of each published model

Parameters

[in] apply_frontend New frontend state

◆ BitsPerSample()

int snowboy::SnowboyVad::BitsPerSample ( ) const

Returns the expected number of bits for audio provided to RunDetection().

Returns: The expected number of bits.

◆ NumChannels()

int snowboy::SnowboyVad::NumChannels ( ) const

Returns the expected number of channels for audio provided to RunDetection().

Returns: The expected number of channels.

◆ Reset()

bool snowboy::SnowboyVad::Reset ( )

Resets the vad.

After reset the pipeline will behave identical to a freshly constructed instance.

Returns: true on success
false on error

◆ RunVad() [1/4]

int snowboy::SnowboyVad::RunVad	(	const float *const	data,
		const int	array_length,
		bool	is_end = `false`
	)

Runs vad on float samples.

If NumChannels() > 1, e.g., NumChannels() == 2, then the array is as follows:

d1c1, d1c2, d2c1, d2c2, d3c1, d3c2, ..., dNc1, dNc2

where d1c1 means data point 1 of channel 1.

Parameters

[in]	data	Small chunk of data to be detected.
[in]	array_length	Length of the data array in elements.
[in]	is_end	Set it to true if it is the end of a utterance or file.

Returns: See RunVad(const std::string&, bool) for details

◆ RunVad() [2/4]

int snowboy::SnowboyVad::RunVad	(	const int16_t *const	data,
		const int	array_length,
		bool	is_end = `false`
	)

Runs vad on int16_t samples.

If NumChannels() > 1, e.g., NumChannels() == 2, then the array is as follows:

d1c1, d1c2, d2c1, d2c2, d3c1, d3c2, ..., dNc1, dNc2

where d1c1 means data point 1 of channel 1.

Parameters

[in]	data	Small chunk of data to be detected.
[in]	array_length	Length of the data array in elements.
[in]	is_end	Set it to true if it is the end of a utterance or file.

Returns: See RunVad(const std::string&, bool) for details

◆ RunVad() [3/4]

int snowboy::SnowboyVad::RunVad	(	const int32_t *const	data,
		const int	array_length,
		bool	is_end = `false`
	)

Runs vad on int32_t samples.

If NumChannels() > 1, e.g., NumChannels() == 2, then the array is as follows:

d1c1, d1c2, d2c1, d2c2, d3c1, d3c2, ..., dNc1, dNc2

where d1c1 means data point 1 of channel 1.

Parameters

[in]	data	Small chunk of data to be detected.
[in]	array_length	Length of the data array in elements.
[in]	is_end	Set it to true if it is the end of a utterance or file.

Returns: See RunVad(const std::string&, bool) for details

◆ RunVad() [4/4]

int snowboy::SnowboyVad::RunVad	(	const std::string &	data,
		bool	is_end = `false`
	)

Runs the VAD algorithm.

Supported audio format is WAVE (with linear PCM, 8-bits unsigned integer, 16-bits signed integer or 32-bits signed integer). See SampleRate(), NumChannels() and BitsPerSample() for the required sampling rate, number of channels and bits per sample values. You are supposed to provide a small chunk of data (e.g., 0.1 second) each time you call RunDetection(). Larger chunk usually leads to longer delay, but less CPU usage.

Returns

Code	Info
-2	Silence.
-1	Error.
0	No event.

Parameters

[in]	data	Small chunk of data to be detected. See above for the supported data format.
[in]	is_end	Set it to true if it is the end of a utterance or file.

◆ SampleRate()

int snowboy::SnowboyVad::SampleRate ( ) const

Returns the expected sample rate for audio provided to RunDetection().

Returns: The expected samplerate.

◆ SetAudioGain()

void snowboy::SnowboyVad::SetAudioGain ( const float audio_gain )

Apply a fixed gain to the input audio.

In case you have a very weak microphone, you can use this function to boost input audio level.

Parameters

[in] audio_gain Gain to apply. A gain of 1 means no volume change.

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

lib/snowboy-detect.h
lib/snowboy-detect.cpp

Public Member Functions

Friends

Detailed Description

Constructor & Destructor Documentation

◆ SnowboyVad()

Member Function Documentation

◆ ApplyFrontend()

◆ BitsPerSample()

◆ NumChannels()

◆ Reset()

◆ RunVad() [1/4]

◆ RunVad() [2/4]

◆ RunVad() [3/4]

◆ RunVad() [4/4]

◆ SampleRate()

◆ SetAudioGain()