OpalSilenceDetector Class Reference

#include <silencedetect.h>

Inheritance diagram for OpalSilenceDetector:


Basic operations
const PNotifier &	GetReceiveHandler () const
void	SetParameters (const Params &params, const int clockRate=0)
void	SetClockRate (const int clockRate)
int	GetClockRate () const
Mode	GetStatus (PBoolean isInTalkBurst, unsigned currentThreshold) const
virtual unsigned	GetAverageSignalLevel (const BYTE *buffer, PINDEX size)=0
	PDECLARE_NOTIFIER (RTP_DataFrame, OpalSilenceDetector, ReceivedPacket)
PNotifier	receiveHandler
Mode	mode
unsigned	signalDeadband
unsigned	silenceDeadband
unsigned	adaptivePeriod
int	clockRate
unsigned	lastTimestamp
unsigned	receivedTime
unsigned	levelThreshold
unsigned	signalMinimum
unsigned	silenceMaximum
unsigned	signalReceivedTime
unsigned	silenceReceivedTime
bool	inTalkBurst
PMutex	inUse
Public Types
	NoSilenceDetection
	FixedSilenceDetection
	AdaptiveSilenceDetection
	NumModes
enum	Mode { NoSilenceDetection, FixedSilenceDetection, AdaptiveSilenceDetection, NumModes }
Public Member Functions
Construction
	OpalSilenceDetector (const Params &newParam)
Data Structures
struct	Params

Member Enumeration Documentation

enum OpalSilenceDetector::Mode

Enumerator:

NoSilenceDetection
FixedSilenceDetection
AdaptiveSilenceDetection
NumModes

Constructor & Destructor Documentation

OpalSilenceDetector::OpalSilenceDetector ( const Params & newParam )

Create a new detector. Default clock rate is 8000.

Parameters:

newParam

New parameters for silence detector

Member Function Documentation

virtual unsigned OpalSilenceDetector::GetAverageSignalLevel	(	const BYTE *	buffer,
		PINDEX	size
	)			`[pure virtual]`

Get the average signal level in the stream. This is called from within the silence detection algorithm to calculate the average signal level of the last data frame read from the stream.

The default behaviour returns UINT_MAX which indicates that the average signal has no meaning for the stream.

Parameters:

buffer	RTP payload being detected
size	Size of payload buffer

Implemented in OpalPCM16SilenceDetector, and OpalLineSilenceDetector.

int OpalSilenceDetector::GetClockRate ( ) const [inline]

Get the cyrrent sampling clock rate.

const PNotifier& OpalSilenceDetector::GetReceiveHandler ( ) const [inline]

Mode OpalSilenceDetector::GetStatus	(	PBoolean *	isInTalkBurst,
		unsigned *	currentThreshold
	)			const

Get silence detection status

The inTalkBurst value is PTrue if packet transmission is enabled and PFalse if it is being suppressed due to silence.

The currentThreshold value is the value from 0 to 32767 which is used as the threshold value for 16 bit PCM data.

OpalSilenceDetector::PDECLARE_NOTIFIER	(	RTP_DataFrame	,
		OpalSilenceDetector	,
		ReceivedPacket
	)			`[protected]`

void OpalSilenceDetector::SetClockRate ( const int clockRate )

Set the sampling clock rate for the preprocessor. Adusts the interpretation of time values. This may be called while audio is being transferred, but if in adaptive mode calling this will reset the filter.

Parameters:

clockRate

Sampling clock rate for the preprocessor

void OpalSilenceDetector::SetParameters	(	const Params &	params,
		const int	clockRate = `0`
	)

Set the silence detector parameters. This adjusts the silence detector "agression". The deadband and adaptive periods are in ms units to work for any clock rate. The clock rate value is optional: 0 leaves value unchanged. This may be called while audio is being transferred, but if in adaptive mode calling this will reset the filter.

Parameters: