dtmf.h File Reference

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Classes
struct	dtmf_tx_state_t
struct	dtmf_rx_state_t
Defines
#define	_SPANDSP_DTMF_H_
#define	MAX_DTMF_DIGITS   128
Typedefs
typedef void(*)	dtmf_rx_callback_t (void *user_data, const char *digits, int len)
Functions
int	dtmf_tx (dtmf_tx_state_t *s, int16_t amp[], int max_samples)
	Generate a buffer of DTMF tones.
size_t	dtmf_tx_put (dtmf_tx_state_t *s, const char *digits, ssize_t len)
	Put a string of digits in a DTMF generator's input buffer.
dtmf_tx_state_t *	dtmf_tx_init (dtmf_tx_state_t *s)
	Initialise a DTMF tone generator context.
void	dtmf_rx_set_realtime_callback (dtmf_rx_state_t *s, tone_report_func_t callback, void *user_data)
	Set a realtime callback for a DTMF receiver context.
void	dtmf_rx_parms (dtmf_rx_state_t *s, int filter_dialtone, int twist, int reverse_twist)
	Adjust a DTMF receiver context.
int	dtmf_rx (dtmf_rx_state_t *s, const int16_t amp[], int samples)
	Process a block of received DTMF audio samples.
int	dtmf_rx_status (dtmf_rx_state_t *s)
	Get the status of DTMF detection during processing of the last audio chunk.
size_t	dtmf_rx_get (dtmf_rx_state_t *s, char *digits, int max)
	Get a string of digits from a DTMF receiver's output buffer.
dtmf_rx_state_t *	dtmf_rx_init (dtmf_rx_state_t *s, dtmf_rx_callback_t callback, void *user_data)
	Initialise a DTMF receiver context.

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Detailed Description

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Function Documentation

int dtmf_rx	(	dtmf_rx_state_t *	s,
		const int16_t	amp[],
		int	samples
	)

Process a block of received DTMF audio samples.

Process a block of received DTMF audio samples.

Parameters:

	s	The DTMF receiver context.
	amp	The audio sample buffer.
	samples	The number of samples in the buffer.

Returns:

The number of samples unprocessed.

size_t dtmf_rx_get	(	dtmf_rx_state_t *	s,
		char *	digits,
		int	max
	)

Get a string of digits from a DTMF receiver's output buffer.

Parameters:

	s	The DTMF receiver context.
	digits	The buffer for the received digits.
	max	The maximum number of digits to be returned,

Returns:

The number of digits actually returned.

dtmf_rx_state_t* dtmf_rx_init	(	dtmf_rx_state_t *	s,
		dtmf_rx_callback_t	callback,
		void *	user_data
	)

Initialise a DTMF receiver context.

Parameters:

	s	The DTMF receiver context.
	callback	An optional callback routine, used to report received digits. If no callback routine is set, digits may be collected, using the dtmf_rx_get() function.
	user_data	An opaque pointer which is associated with the context, and supplied in callbacks.

Returns:

A pointer to the DTMF receiver context.

void dtmf_rx_parms	(	dtmf_rx_state_t *	s,
		int	filter_dialtone,
		int	twist,
		int	reverse_twist
	)

Adjust a DTMF receiver context.

Parameters:

	s	The DTMF receiver context.
	filter_dialtone	TRUE to enable filtering of dialtone, FALSE to disable, < 0 to leave unchanged.
	twist	Acceptable twist, in dB. < 0 to leave unchanged.
	reverse_twist	Acceptable reverse twist, in dB. < 0 to leave unchanged.

void dtmf_rx_set_realtime_callback	(	dtmf_rx_state_t *	s,
		tone_report_func_t	callback,
		void *	user_data
	)

Set a realtime callback for a DTMF receiver context.

Set a optional realtime callback for a DTMF receiver context. This function is called immediately a confirmed state change occurs in the received DTMF. It is called with the ASCII value for a DTMF tone pair, or zero to indicate no tone is being received.

Parameters:

	s	The DTMF receiver context.
	callback	Callback routine used to report the start and end of digits.
	user_data	An opaque pointer which is associated with the context, and supplied in callbacks.

int dtmf_rx_status

(

dtmf_rx_state_t *

s

)

Get the status of DTMF detection during processing of the last audio chunk.

Get the status of DTMF detection during processing of the last audio chunk.

Parameters:

s

The DTMF receiver context.

Returns:

The current digit status. Either 'x' for a "maybe" condition, or the digit being detected.

int dtmf_tx	(	dtmf_tx_state_t *	s,
		int16_t	amp[],
		int	max_samples
	)

Generate a buffer of DTMF tones.

Parameters:

	s	The DTMF generator context.
	amp	The buffer for the generated signal.
	max_samples	The required number of generated samples.

Returns:

The number of samples actually generated. This may be less than max_samples if the input buffer empties.

dtmf_tx_state_t* dtmf_tx_init

(

dtmf_tx_state_t *

s

)

Initialise a DTMF tone generator context.

Parameters:

s

The DTMF generator context.

Returns:

A pointer to the DTMF generator context.

size_t dtmf_tx_put	(	dtmf_tx_state_t *	s,
		const char *	digits,
		ssize_t	len
	)

Put a string of digits in a DTMF generator's input buffer.

Parameters:

	s	The DTMF generator context.
	digits	The string of digits to be added.
	len	The length of the string of digits. If negative, the string is assumed to be a NULL terminated string.

Returns:

The number of digits actually added. This may be less than the length of the digit string, if the buffer fills up.

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