g711.h File Reference

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Defines
#define	G711_ALAW_IDLE_OCTET   0x5D
#define	G711_ULAW_IDLE_OCTET   0xFF
#define	G711_ULAW_BIAS   0x84
#define	G711_ALAW_AMI_MASK   0x55
Typedefs
typedef struct g711_state_s	g711_state_t
Enumerations
enum	{ G711_ALAW = 0, G711_ULAW }
Functions
uint8_t	alaw_to_ulaw (uint8_t alaw)
	Transcode from A-law to u-law, using the procedure defined in G.711.
uint8_t	ulaw_to_alaw (uint8_t ulaw)
	Transcode from u-law to A-law, using the procedure defined in G.711.
int	g711_decode (g711_state_t *s, int16_t amp[], const uint8_t g711_data[], int g711_bytes)
	Decode from u-law or A-law to linear.
int	g711_encode (g711_state_t *s, uint8_t g711_data[], const int16_t amp[], int len)
	Encode from linear to u-law or A-law.
int	g711_transcode (g711_state_t *s, uint8_t g711_out[], const uint8_t g711_in[], int g711_bytes)
	Transcode between u-law and A-law.
g711_state_t *	g711_init (g711_state_t *s, int mode)
int	g711_release (g711_state_t *s)
int	g711_free (g711_state_t *s)

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Detailed Description

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Define Documentation

#define G711_ALAW_AMI_MASK   0x55

The A-law alternate mark inversion mask

#define G711_ALAW_IDLE_OCTET   0x5D

Idle value for A-law channels

#define G711_ULAW_BIAS   0x84

Bias for u-law encoding from linear.

#define G711_ULAW_IDLE_OCTET   0xFF

Idle value for u-law channels

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Typedef Documentation

typedef struct g711_state_s g711_state_t

G.711 state

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Function Documentation

uint8_t alaw_to_ulaw

(

uint8_t

alaw

)

Transcode from A-law to u-law, using the procedure defined in G.711.

Parameters:

alaw	The A-law sample to transcode.

Returns:

The best matching u-law value.

int g711_decode	(	g711_state_t *	s,
		int16_t	amp[],
		const uint8_t	g711_data[],
		int	g711_bytes
	)

Decode from u-law or A-law to linear.

Parameters:

s	The G.711 context.
amp	The linear audio buffer.
g711_data	The G.711 data.
g711_bytes	The number of G.711 samples to decode.

Returns:

The number of samples of linear audio produced.

int g711_encode	(	g711_state_t *	s,
		uint8_t	g711_data[],
		const int16_t	amp[],
		int	len
	)

Encode from linear to u-law or A-law.

Parameters:

s	The G.711 context.
g711_data	The G.711 data.
amp	The linear audio buffer.
len	The number of samples to encode.

Returns:

The number of G.711 samples produced.

int g711_free

(

g711_state_t *

s

)

Free a G.711 encode or decode context.

Parameters:

s	The G.711 context.

Returns:

0 for OK.

g711_state_t* g711_init	(	g711_state_t *	s,
		int	mode
	)

Initialise a G.711 encode or decode context.

Parameters:

s	The G.711 context.
mode	The G.711 mode.

Returns:

A pointer to the G.711 context, or NULL for error.

int g711_release

(

g711_state_t *

s

)

Release a G.711 encode or decode context.

Parameters:

s	The G.711 context.

Returns:

0 for OK.

int g711_transcode	(	g711_state_t *	s,
		uint8_t	g711_out[],
		const uint8_t	g711_in[],
		int	g711_bytes
	)

Transcode between u-law and A-law.

Parameters:

s	The G.711 context.
g711_out	The resulting G.711 data.
g711_in	The original G.711 data.
g711_bytes	The number of G.711 samples to transcode.

Returns:

The number of G.711 samples produced.

uint8_t ulaw_to_alaw

(

uint8_t

ulaw

)

Transcode from u-law to A-law, using the procedure defined in G.711.

Parameters:

ulaw	The u-law sample to transcode.

Returns:

The best matching A-law value.