A class to add gaussian white noise to an audio stream. More...

#include <AsyncAudioNoiseAdder.h>

Inheritance diagram for Async::AudioNoiseAdder:

Public Member Functions
	AudioNoiseAdder (float level_db)
	Constuctor.

	~AudioNoiseAdder (void)
	Destructor.

Public Member Functions inherited from Async::AudioProcessor
	AudioProcessor (void)
	Default constuctor.

virtual	~AudioProcessor (void)
	Destructor.

int	writeSamples (const float *samples, int len)
	Write audio to the filter.

void	flushSamples (void)
	Order a flush of all samples.

void	resumeOutput (void)
	Resume output to the sink if previously stopped.

void	allSamplesFlushed (void)
	All samples have been flushed by the sink.

Public Member Functions inherited from Async::AudioSink
	AudioSink (void)
	Default constuctor.

virtual	~AudioSink (void)
	Destructor.

bool	registerSource (AudioSource *source)
	Register an audio source to provide samples to this sink.

void	unregisterSource (void)
	Unregister the previously registered audio source.

bool	isRegistered (void) const
	Check if an audio source has been registered.

AudioSource *	source (void) const
	Get the registered audio source.

Public Member Functions inherited from Async::AudioSource
	AudioSource (void)
	Default constuctor.

virtual	~AudioSource (void)
	Destructor.

bool	registerSink (AudioSink *sink, bool managed=false)
	Register an audio sink to provide samples to.

void	unregisterSink (void)
	Unregister the previously registered audio sink.

bool	isRegistered (void) const
	Check if an audio sink has been registered.

AudioSink *	sink (void) const
	Get the registered audio sink.

bool	sinkManaged (void) const
	Check if the sink is managed or not.

void	handleAllSamplesFlushed (void)
	The registered sink has flushed all samples.

Protected Member Functions
void	processSamples (float dest, const float src, int count)
	Process incoming samples and put them into the output buffer.

Protected Member Functions inherited from Async::AudioProcessor
void	setInputOutputSampleRate (int input_rate, int output_rate)
	Set the input and output sample rates.

Protected Member Functions inherited from Async::AudioSink
void	sourceResumeOutput (void)
	Tell the source that we are ready to accept more samples.

void	sourceAllSamplesFlushed (void)
	Tell the source that all samples have been flushed.

bool	setHandler (AudioSink *handler)
	Setup another sink to handle the incoming audio.

void	clearHandler (void)
	Clear a handler that was previously setup with setHandler.

AudioSink *	handler (void) const

Protected Member Functions inherited from Async::AudioSource
int	sinkWriteSamples (const float *samples, int len)

void	sinkFlushSamples (void)

bool	setHandler (AudioSource *handler)
	Setup another source to handle the outgoing audio.

AudioSource *	handler (void) const

void	clearHandler (void)
	Clear a handler that was previously setup with setHandler.

Detailed Description

A class to add gaussian white noise to an audio stream.

Author: Tobias Blomberg / SM0SVX

Date: 2015-03-08

This class implement a noise generator that add white gaussian noise to an audio stream. The noise is generated using the Box-Muller transform which for example is described on Wikipedia:

http://en.wikipedia.org/wiki/Box%E2%80%93Muller_transform

The class is not implemented as a pure audio source but rather as an audio pipe component that should be inserted in the audio path.

Definition at line 121 of file AsyncAudioNoiseAdder.h.

Constructor & Destructor Documentation

◆ AudioNoiseAdder()

Async::AudioNoiseAdder::AudioNoiseAdder ( float level_db )

Constuctor.

Parameters

level_db The noise level in dB

The level_db parameter deserve some clarification. A level of 0dB give the same power as in a full scale sine wave. This make it possible to add noise to a generated signal under controlled conditions. For example, if a sine wave is generated in SvxLink with a level of 0dB and noise is added with a level of -10dB, we get a signal to noise ratio (SNR) of 10dB.

◆ ~AudioNoiseAdder()

Async::AudioNoiseAdder::~AudioNoiseAdder ( void )

Destructor.

Member Function Documentation

◆ processSamples()

void Async::AudioNoiseAdder::processSamples	(	float *	dest,
		const float *	src,
		int	count )

protectedvirtual

Process incoming samples and put them into the output buffer.

Parameters

dest	Destination buffer
src	Source buffer
count	Number of samples in the source buffer

This function is called from the base class to do the actual processing of the incoming samples. All samples must be processed, otherwise they are lost and the output buffer will contain garbage.

Implements Async::AudioProcessor.

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

AsyncAudioNoiseAdder.h