Decimates a higher sample rate into a lower one. More...

#include <AsyncAudioDecimator.h>

Inheritance diagram for Async::AudioDecimator:

Public Member Functions
	AudioDecimator (int decimation_factor, const float *filter_coeff, int taps)
	Constructor.

	~AudioDecimator (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
virtual 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

Decimates a higher sample rate into a lower one.

Author: Tobias Blomberg / SM0SVX

Date: 2008-04-06

This audio pipe class will decimate an audio stream down to a lower sampling rate. Decimation is a process where the sampling rate is reduced by an integer factor. To reduce the rate a lowpass filter must first be applied. This filter is built into this component. However, the filter coefficients (FIR) must be calculated manually.

Use this web page to calculate the coefficients: http://www.dsptutor.freeuk.com/remez/RemezFIRFilterDesign.html

This implementation is based on the multirate FAQ at dspguru.com: http://dspguru.com/info/faqs/mrfaq.htm

Definition at line 116 of file AsyncAudioDecimator.h.

Constructor & Destructor Documentation

◆ AudioDecimator()

Async::AudioDecimator::AudioDecimator	(	int	decimation_factor,
		const float *	filter_coeff,
		int	taps )

Constructor.

Parameters

decimation_factor	The decimation factor
filter_coeff	An array holding the filter coefficients
taps	The numer of taps in the filter

◆ ~AudioDecimator()

Async::AudioDecimator::~AudioDecimator ( void )

Destructor.

Member Function Documentation

◆ processSamples()

virtual void Async::AudioDecimator::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 should be reimplemented by the inheriting 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:

AsyncAudioDecimator.h