echo_david.c File Reference

#include <inttypes.h>
#include <stdlib.h>
#include "floating_fudge.h"
#include <string.h>
#include <stdio.h>
#include "spandsp/telephony.h"
#include "spandsp/logging.h"
#include "spandsp/dc_restore.h"
#include "spandsp/saturated.h"
#include "spandsp/bit_operations.h"
#include "spandsp/echo.h"

Defines
#define	NULL   (void *) 0
#define	MIN_TX_POWER_FOR_ADAPTION   64
#define	MIN_RX_POWER_FOR_ADAPTION   64
#define	DTD_HANGOVER   600
#define	DC_LOG2BETA   3
Functions
echo_can_state_t *	echo_can_create (int len, int adaption_mode)
void	echo_can_free (echo_can_state_t *ec)
void	echo_can_adaption_mode (echo_can_state_t *ec, int adaption_mode)
void	echo_can_flush (echo_can_state_t *ec)
void	echo_can_snapshot (echo_can_state_t *ec)
int16_t	echo_can_update (echo_can_state_t *ec, int16_t tx, int16_t rx)
int16_t	echo_can_hpf_tx (echo_can_state_t *ec, int16_t tx)

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Detailed Description

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Function Documentation

void echo_can_adaption_mode	(	echo_can_state_t *	ec,
		int	adaption_mode
	)

Set the adaption mode of a voice echo canceller context.

Parameters:

	ec	The echo canceller context.
	adaption_mode	The mode.

References echo_can_state_t::adaption_mode.

echo_can_state_t* echo_can_create	(	int	len,
		int	adaption_mode
	)

Create a voice echo canceller context.

Parameters:

len

The length of the canceller, in samples.

Returns:

The new canceller context, or NULL if the canceller could not be created.

References echo_can_state_t::cng_level, echo_can_state_t::cond_met, echo_can_state_t::curr_pos, echo_can_adaption_mode(), echo_can_state_t::fir_state, echo_can_state_t::fir_state_bg, echo_can_state_t::fir_taps16, echo_can_state_t::Lbgn, echo_can_state_t::Lbgn_acc, echo_can_state_t::Lbgn_upper, echo_can_state_t::Lbgn_upper_acc, echo_can_state_t::Lclean, echo_can_state_t::Lclean_bg, echo_can_state_t::Lclean_bgacc, echo_can_state_t::Lcleanacc, echo_can_state_t::log2taps, echo_can_state_t::Lrx, echo_can_state_t::Lrxacc, echo_can_state_t::Ltx, echo_can_state_t::Ltxacc, echo_can_state_t::Pstates, echo_can_state_t::rx_hpf, echo_can_state_t::snapshot, echo_can_state_t::taps, and echo_can_state_t::tx_hpf.

void echo_can_flush

(

echo_can_state_t *

ec

)

Flush (reinitialise) a voice echo canceller context.

Parameters:

ec

The echo canceller context.

References echo_can_state_t::curr_pos, fir16_state_t::curr_pos, echo_can_state_t::fir_state, echo_can_state_t::fir_state_bg, echo_can_state_t::fir_taps16, echo_can_state_t::Lbgn, echo_can_state_t::Lbgn_acc, echo_can_state_t::Lbgn_upper, echo_can_state_t::Lbgn_upper_acc, echo_can_state_t::Lclean, echo_can_state_t::Lclean_bg, echo_can_state_t::Lclean_bgacc, echo_can_state_t::Lcleanacc, echo_can_state_t::Lrx, echo_can_state_t::Lrxacc, echo_can_state_t::Ltx, echo_can_state_t::Ltxacc, echo_can_state_t::nonupdate_dwell, echo_can_state_t::Pstates, echo_can_state_t::rx_hpf, echo_can_state_t::taps, and echo_can_state_t::tx_hpf.

void echo_can_free

(

echo_can_state_t *

ec

)

Free a voice echo canceller context.

Parameters:

ec

The echo canceller context.

References echo_can_state_t::fir_state, echo_can_state_t::fir_state_bg, echo_can_state_t::fir_taps16, and echo_can_state_t::snapshot.

int16_t echo_can_hpf_tx	(	echo_can_state_t *	ec,
		int16_t	tx
	)

Process to high pass filter the tx signal.

Parameters:

	ec	The echo canceller context.
	tx	The transmitted auio sample.

Returns:

The HP filtered transmit sample, send this to your D/A.

References echo_can_state_t::adaption_mode, and echo_can_state_t::tx_hpf.

int16_t echo_can_update	(	echo_can_state_t *	ec,
		int16_t	tx,
		int16_t	rx
	)

Process a sample through a voice echo canceller.

Parameters:

	ec	The echo canceller context.
	tx	The transmitted audio sample.
	rx	The received audio sample.

Returns:

The clean (echo cancelled) received sample.

References echo_can_state_t::adapt, echo_can_state_t::adaption_mode, echo_can_state_t::clean, echo_can_state_t::clean_nlp, echo_can_state_t::cng_filter, echo_can_state_t::cng_level, echo_can_state_t::cng_rndnum, fir16_state_t::coeffs, echo_can_state_t::cond_met, echo_can_state_t::curr_pos, fir16_state_t::curr_pos, echo_can_state_t::factor, echo_can_state_t::fir_state, echo_can_state_t::fir_state_bg, echo_can_state_t::fir_taps16, fir16_state_t::history, echo_can_state_t::Lbgn, echo_can_state_t::Lbgn_acc, echo_can_state_t::Lclean, echo_can_state_t::Lclean_bg, echo_can_state_t::Lclean_bgacc, echo_can_state_t::Lcleanacc, echo_can_state_t::log2taps, echo_can_state_t::Lrx, echo_can_state_t::Lrxacc, echo_can_state_t::Ltx, echo_can_state_t::Ltxacc, echo_can_state_t::nonupdate_dwell, echo_can_state_t::Pstates, echo_can_state_t::rx, echo_can_state_t::rx_hpf, echo_can_state_t::shift, echo_can_state_t::taps, and echo_can_state_t::tx.