Async::AudioCompressor Class Reference

A class to do audio compression/limiting. More...

#include <AsyncAudioCompressor.h>

Inheritance diagram for Async::AudioCompressor:

Public Member Functions
	AudioCompressor (void)
	Default constuctor.
	~AudioCompressor (void)
	Destructor.
void	setThreshold (double thresh_db)
	Set the compression threshold.
void	setRatio (double ratio)
	Set the compression ratio.
void	setAttack (double attack_ms)
	Set the compressor attack time.
void	setDecay (double decay_ms)
	Set the compressor decay time.
void	setOutputGain (float gain)
	Set the output gain.
void	reset (void)
	Reset the compressor.
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

A class to do audio compression/limiting.

Author

Tobias Blomberg / SM0SVX

Date

2006-05-01

Use this audio pipe class to do compression on an audio stream. Compression is a method to reduce the dynamic range of an audio signal. After it has been compressed it can be amplified to get a more audible end result.

This audio pipe component is mostly untested and is based on some ripped off code which I really have not checked how it performs or if it works at all...

Definition at line 169 of file AsyncAudioCompressor.h.

Constructor & Destructor Documentation

AudioCompressor()

Async::AudioCompressor::AudioCompressor

(

void

)

Default constuctor.

~AudioCompressor()

Async::AudioCompressor::~AudioCompressor

(

void

)

Destructor.

Member Function Documentation

processSamples()

virtual void Async::AudioCompressor::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.

reset()

void Async::AudioCompressor::reset

(

void

)

Reset the compressor.

setAttack()

void Async::AudioCompressor::setAttack ( double attack_ms )

inline

Set the compressor attack time.

Parameters

attack_ms

The attack time in milliseconds

Definition at line 201 of file AsyncAudioCompressor.h.

References Async::EnvelopeDetector::setTc().

setDecay()

void Async::AudioCompressor::setDecay ( double decay_ms )

inline

Set the compressor decay time.

Parameters

decay_ms

The decay time in milliseconds

Definition at line 207 of file AsyncAudioCompressor.h.

References Async::EnvelopeDetector::setTc().

setOutputGain()

void Async::AudioCompressor::setOutputGain

(

float

gain

)

Set the output gain.

Parameters

gain	The gain to set.

The output gain is the amplification applied to the audio signal before it leaves the compressor. If gain > 1 the signal is amplified. If gain < 1 the signal is attenuated.

setRatio()

void Async::AudioCompressor::setRatio ( double ratio )

inline

Set the compression ratio.

Parameters

ratio

The compression ratio (ex 0.1 == 10:1)

Definition at line 195 of file AsyncAudioCompressor.h.

setThreshold()

void Async::AudioCompressor::setThreshold ( double thresh_db )

inline

Set the compression threshold.

Parameters

thresh_db

The compression threshold in dB

The threshold is the level, in dB, the signal must rise to before the compressor kicks in.

Definition at line 189 of file AsyncAudioCompressor.h.

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

• AsyncAudioCompressor.h