Adaptive Silence Detection

Adaptive Silence Detector. More...

Typedefs
typedef struct pjmedia_silence_det	pjmedia_silence_det

Functions
pj_status_t	pjmedia_silence_det_create (pj_pool_t *pool, unsigned clock_rate, unsigned samples_per_frame, pjmedia_silence_det **p_sd)
pj_status_t	pjmedia_silence_det_set_name (pjmedia_silence_det *sd, const char *name)
pj_status_t	pjmedia_silence_det_set_fixed (pjmedia_silence_det *sd, int threshold)
pj_status_t	pjmedia_silence_det_set_adaptive (pjmedia_silence_det *sd, int threshold)
pj_status_t	pjmedia_silence_det_set_params (pjmedia_silence_det *sd, int before_silence, int recalc_time1, int recalc_time2)
pj_status_t	pjmedia_silence_det_disable (pjmedia_silence_det *sd)
pj_bool_t	pjmedia_silence_det_detect (pjmedia_silence_det *sd, const pj_int16_t samples[], pj_size_t count, pj_int32_t *p_level)
pj_int32_t	pjmedia_calc_avg_signal (const pj_int16_t samples[], pj_size_t count)
pj_bool_t	pjmedia_silence_det_apply (pjmedia_silence_det *sd, pj_uint32_t level)

Detailed Description

Typedef Documentation

pjmedia_silence_det

typedef struct pjmedia_silence_det pjmedia_silence_det

Opaque declaration for silence detector.

Function Documentation

pjmedia_silence_det_create()

pj_status_t pjmedia_silence_det_create	(	pj_pool_t *	pool,
		unsigned	clock_rate,
		unsigned	samples_per_frame,
		pjmedia_silence_det **	p_sd
	)

Create voice activity detector with default settings. The default settings are set to adaptive silence detection with the default threshold.

Parameters

pool	Pool for allocating the structure.
clock_rate	Clock rate.
samples_per_frame	Number of samples per frame. The clock_rate and samples_per_frame is only used to calculate the frame time, from which some timing parameters are calculated from.
p_sd	Pointer to receive the silence detector instance.

Returns

PJ_SUCCESS on success.

pjmedia_silence_det_set_name()

pj_status_t pjmedia_silence_det_set_name	(	pjmedia_silence_det *	sd,
		const char *	name
	)

Set silence detector name to identify the particular silence detector instance in the log.

Parameters

sd	The silence detector.
name	Name.

Returns

PJ_SUCCESS on success.

pjmedia_silence_det_set_fixed()

pj_status_t pjmedia_silence_det_set_fixed	(	pjmedia_silence_det *	sd,
		int	threshold
	)

Set the sd to operate in fixed threshold mode. With fixed threshold mode, the threshold will not be changed adaptively.

Parameters

sd	The silence detector
threshold	The silence threshold, or -1 to use default threshold.

Returns

PJ_SUCCESS on success.

pjmedia_silence_det_set_adaptive()

pj_status_t pjmedia_silence_det_set_adaptive	(	pjmedia_silence_det *	sd,
		int	threshold
	)

Set the sd to operate in adaptive mode. This is the default mode when the silence detector is created.

Parameters

sd	The silence detector
threshold	Initial threshold to be set, or -1 to use default threshold.

Returns

PJ_SUCCESS on success.

pjmedia_silence_det_set_params()

pj_status_t pjmedia_silence_det_set_params	(	pjmedia_silence_det *	sd,
		int	before_silence,
		int	recalc_time1,
		int	recalc_time2
	)

Set other silence detector parameters.

Parameters

sd	The silence detector
before_silence	Minimum duration of silence (in msec) before silence is reported. If -1 is specified, then the default value will be used. The default is 400 msec.
recalc_time1	The interval (in msec) to recalculate threshold in non-silence condition when adaptive silence detection is set. If -1 is specified, then the default value will be used. The default is 4000 (msec).
recalc_time2	The interval (in msec) to recalculate threshold in silence condition when adaptive silence detection is set. If -1 is specified, then the default value will be used. The default value is 2000 (msec).

Returns

PJ_SUCCESS on success.

pjmedia_silence_det_disable()

pj_status_t pjmedia_silence_det_disable

(

pjmedia_silence_det *

sd

)

Disable the silence detector.

Parameters

sd	The silence detector

Returns

PJ_SUCCESS on success.

pjmedia_silence_det_detect()

pj_bool_t pjmedia_silence_det_detect	(	pjmedia_silence_det *	sd,
		const pj_int16_t	samples[],
		pj_size_t	count,
		pj_int32_t *	p_level
	)

Perform voice activity detection on the given input samples. This function uses pjmedia_calc_avg_signal() and pjmedia_silence_det_apply() for its calculation.

Parameters

sd	The silence detector instance.
samples	Pointer to 16-bit PCM input samples.
count	Number of samples in the input.
p_level	Optional pointer to receive average signal level of the input samples.

Returns

Non zero if signal is silence.

pjmedia_calc_avg_signal()

pj_int32_t pjmedia_calc_avg_signal	(	const pj_int16_t	samples[],
		pj_size_t	count
	)

Calculate average signal level for the given samples.

Parameters

samples	Pointer to 16-bit PCM samples.
count	Number of samples in the input.

Returns

The average signal level, which simply is total level divided by number of samples.

pjmedia_silence_det_apply()

pj_bool_t pjmedia_silence_det_apply	(	pjmedia_silence_det *	sd,
		pj_uint32_t	level
	)

Perform voice activity detection, given the specified average signal level.

Parameters

sd	The silence detector instance.
level	Signal level.

Returns

Non zero if signal is silence.

References PJ_END_DECL.