plc.h File Reference

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Classes
struct	plc_state_t
Defines
#define	_SPANDSP_PLC_H_
#define	PLC_PITCH_MIN   120
#define	PLC_PITCH_MAX   40
#define	PLC_PITCH_OVERLAP_MAX   (PLC_PITCH_MIN >> 2)
#define	CORRELATION_SPAN   160
#define	PLC_HISTORY_LEN   (CORRELATION_SPAN + PLC_PITCH_MIN)
Functions
int	plc_rx (plc_state_t *s, int16_t amp[], int len)
	Process a block of received audio samples for PLC.
int	plc_fillin (plc_state_t *s, int16_t amp[], int len)
	Fill-in a block of missing audio samples.
plc_state_t *	plc_init (plc_state_t *s)
	Initialise a PLC context.
int	plc_free (plc_state_t *s)

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Detailed Description

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Define Documentation

#define CORRELATION_SPAN   160

The length over which the AMDF function looks for similarity (20 ms)

Referenced by plc_fillin().

#define PLC_HISTORY_LEN   (CORRELATION_SPAN + PLC_PITCH_MIN)

History buffer length. The buffer much also be at leat 1.25 times PLC_PITCH_MIN, but that is much smaller than the buffer needs to be for the pitch assessment.

Referenced by plc_fillin().

#define PLC_PITCH_MAX   40

Maximum allowed pitch (200 Hz)

Referenced by plc_fillin().

#define PLC_PITCH_MIN   120

Minimum allowed pitch (66 Hz)

Referenced by plc_fillin().

#define PLC_PITCH_OVERLAP_MAX   (PLC_PITCH_MIN >> 2)

Maximum pitch OLA window

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Function Documentation

int plc_fillin	(	plc_state_t *	s,
		int16_t	amp[],
		int	len
	)

Fill-in a block of missing audio samples.

Fill-in a block of missing audio samples.

Parameters:

	s	The packet loss concealer context.
	amp	The audio sample buffer.
	len	The number of samples to be synthesised.

Returns:

The number of samples synthesized.

References CORRELATION_SPAN, plc_state_t::history, plc_state_t::missing_samples, plc_state_t::pitch, plc_state_t::pitch_offset, plc_state_t::pitchbuf, PLC_HISTORY_LEN, PLC_PITCH_MAX, and PLC_PITCH_MIN.

int plc_free

(

plc_state_t *

s

)

Free a packet loss concealer context.

Parameters:

s

The packet loss concealer context.

Returns:

0 for OK.

plc_state_t* plc_init

(

plc_state_t *

s

)

Initialise a PLC context.

Initialise a packet loss concealer context.

Parameters:

s

The packet loss concealer context.

Returns:

A pointer to the the packet loss concealer context.

int plc_rx	(	plc_state_t *	s,
		int16_t	amp[],
		int	len
	)

Process a block of received audio samples for PLC.

Process a block of received audio samples for PLC.

Parameters:

	s	The packet loss concealer context.
	amp	The audio sample buffer.
	len	The number of samples in the buffer.

Returns:

The number of samples in the buffer.

References plc_state_t::missing_samples, plc_state_t::pitch, plc_state_t::pitch_offset, and plc_state_t::pitchbuf.