Packet Lost Concealment (PLC)
[Audio Manipulation Algorithms]

Packet lost compensation algorithm. More...

Typedefs
typedef typedefPJ_BEGIN_DECL struct pjmedia_plc	pjmedia_plc
Functions
pj_status_t	pjmedia_plc_create (pj_pool_t *pool, unsigned clock_rate, unsigned samples_per_frame, unsigned options, pjmedia_plc **p_plc)
pj_status_t	pjmedia_plc_save (pjmedia_plc *plc, pj_int16_t *frame)
pj_status_t	pjmedia_plc_generate (pjmedia_plc *plc, pj_int16_t *frame)

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Detailed Description

This section describes PJMEDIA's implementation of Packet Lost Concealment algorithm. This algorithm is used to implement PLC for codecs that do not have built-in support for one (e.g. G.711 or GSM codecs).

The PLC algorithm (either built-in or external) is embedded in PJMEDIA codec instance, and application can conceal lost frames by calling recover() member of the codec's member operation (pjmedia_codec_op).

See also Concealing Lost Frames for more info.

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Typedef Documentation

typedef typedefPJ_BEGIN_DECL struct pjmedia_plc pjmedia_plc

Opaque declaration for PLC.

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Function Documentation

pj_status_t pjmedia_plc_create	(	pj_pool_t *	pool,
		unsigned	clock_rate,
		unsigned	samples_per_frame,
		unsigned	options,
		pjmedia_plc **	p_plc
	)

Create PLC session. This function will select the PLC algorithm to use based on the arguments.

Parameters:

	pool	Pool to allocate memory for the PLC.
	clock_rate	Media sampling rate.
	samples_per_frame	Number of samples per frame.
	options	Must be zero for now.
	p_plc	Pointer to receive the PLC instance.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_plc_save	(	pjmedia_plc *	plc,
		pj_int16_t *	frame
	)

Save a good frame to PLC.

Parameters:

	plc	The PLC session.
	frame	The good frame to be stored to PLC. This frame must have the same length as the configured samples per frame.

Returns:

PJ_SUCCESS on success.

pj_status_t pjmedia_plc_generate	(	pjmedia_plc *	plc,
		pj_int16_t *	frame
	)

Generate a replacement for lost frame.

Parameters:

	plc	The PLC session.
	frame	Buffer to receive the generated frame. This buffer must be able to store the frame.

Returns:

PJ_SUCCESS on success.