Update of /usr/cvsroot/zaptel
In directory mongoose.digium.com:/tmp/cvs-serv25244
Added Files:
mg2ec.h mg2ec_const.h
Log Message:
silly me, forgot to cvs add the new echo can :-) (Bug #5520)
--- NEW FILE: mg2ec.h ---
/*
* ECHO_CAN_MG2
*
* by Michael Gernoth
*
* Based upon kb1ec.h and mec2.h
*
* Copyright (C) 2002, Digium, Inc.
*
* This program is free software and may be used and
* distributed according to the terms of the GNU
* General Public License, incorporated herein by
* reference.
*
* Additional background on the techniques used in this code can be found in:
*
* Messerschmitt, David; Hedberg, David; Cole, Christopher; Haoui, Amine;
* Winship, Peter; "Digital Voice Echo Canceller with a TMS32020,"
* in Digital Signal Processing Applications with the TMS320 Family,
* pp. 415-437, Texas Instruments, Inc., 1986.
*
* A pdf of which is available by searching on the document title at
http://www.ti.com/
*
*/
#ifndef _MG2_ECHO_H
#define _MG2_ECHO_H
#ifdef __KERNEL__
#include <linux/kernel.h>
#include <linux/slab.h>
#define MALLOC(a) kmalloc((a), GFP_KERNEL)
#define FREE(a) kfree(a)
#else
#include <stdlib.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>
#include <math.h>
#define MALLOC(a) malloc(a)
#define FREE(a) free(a)
#endif
#define ABS(a) abs(a!=-32768?a:-32767)
/* Uncomment to provide summary statistics for overall echo can performance
every 4000 samples */
/* #define MEC2_STATS 4000 */
/* Uncomment to generate per-sample statistics - this will severely degrade
system performance and audio quality */
/* #define MEC2_STATS_DETAILED */
/* Get optimized routines for math */
#include "arith.h"
/* Bring in definitions for the various constants and thresholds */
#include "mg2ec_const.h"
#ifndef NULL
#define NULL 0
#endif
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE (!FALSE)
#endif
/* Generic circular buffer definition */
typedef struct {
/* Pointer to the relative 'start' of the buffer */
int idx_d;
/* The absolute size of the buffer */
int size_d;
/* The actual sample - twice as large as we need, however we do store
values at idx_d and idx_d+size_d */
short *buf_d;
} echo_can_cb_s;
/* Echo canceller definition */
typedef struct {
/* an arbitrary ID for this echo can - this really should be settable
from the calling channel... */
int id;
/* absolute time - aka. sample number index - essentially the number of
samples since this can was init'ed */
int i_d;
/* Pre-computed constants */
/* ---------------------- */
/* Number of filter coefficents */
int N_d;
/* Rate of adaptation of filter */
int beta2_i;
/* Accumulators for power computations */
/* ----------------------------------- */
/* reference signal power estimate - aka. Average absolute value of
y(k) */
int Ly_i;
/* ... */
int Lu_i;
/* Accumulators for signal detectors */
/* --------------------------------- */
/* Power estimate of the recent past of the near-end hybrid signal -
aka. Short-time average of: 2 x |s(i)| */
int s_tilde_i;
/* Power estimate of the recent past of the far-end receive signal -
aka. Short-time average of: |y(i)| */
int y_tilde_i;
/* Near end speech detection counter - stores Hangover counter time
remaining, in samples */
int HCNTR_d;
/* Circular buffers and coefficients */
/* --------------------------------- */
/* ... */
int *a_i;
/* ... */
short *a_s;
/* Reference samples of far-end receive signal */
echo_can_cb_s y_s;
/* Reference samples of near-end signal */
echo_can_cb_s s_s;
/* Reference samples of near-end signal minus echo estimate */
echo_can_cb_s u_s;
/* Reference samples of far-end receive signal used to calculate
short-time average */
echo_can_cb_s y_tilde_s;
/* Peak far-end receive signal */
/* --------------------------- */
/* Highest y_tilde value in the sample buffer */
short max_y_tilde;
/* Index of the sample containing the max_y_tilde value */
int max_y_tilde_pos;
#ifdef MEC2_STATS
/* Storage for performance statistics */
int cntr_nearend_speech_frames;
int cntr_residualcorrected_frames;
int cntr_residualcorrected_framesskipped;
int cntr_coeff_updates;
int cntr_coeff_missedupdates;
int avg_Lu_i_toolow;
int avg_Lu_i_ok;
#endif
short lastsig[256];
int lastpos;
} echo_can_state_t;
static inline void init_cb_s(echo_can_cb_s *cb, int len, void *where)
{
cb->buf_d = (short *)where;
cb->idx_d = 0;
cb->size_d = len;
}
static inline void add_cc_s(echo_can_cb_s *cb, short newval)
{
/* Can't use modulus because N+M isn't a power of two (generally) */
cb->idx_d--;
if (cb->idx_d < (int)0)
/* Whoops - the pointer to the 'start' wrapped around so reset
it to the top of the buffer */
cb->idx_d += cb->size_d;
/* Load two copies into memory */
cb->buf_d[cb->idx_d] = newval;
cb->buf_d[cb->idx_d + cb->size_d] = newval;
}
static inline short get_cc_s(echo_can_cb_s *cb, int pos)
{
/* Load two copies into memory */
return cb->buf_d[cb->idx_d + pos];
}
static inline void init_cc(echo_can_state_t *ec, int N, int maxy, int maxu)
{
void *ptr = ec;
unsigned long tmp;
/* Double-word align past end of state */
ptr += sizeof(echo_can_state_t);
tmp = (unsigned long)ptr;
tmp += 3;
tmp &= ~3L;
ptr = (void *)tmp;
/* Reset parameters */
ec->N_d = N;
ec->beta2_i = DEFAULT_BETA1_I;
/* Allocate coefficient memory */
ec->a_i = ptr;
ptr += (sizeof(int) * ec->N_d);
ec->a_s = ptr;
ptr += (sizeof(short) * ec->N_d);
/* Reset Y circular buffer (short version) */
init_cb_s(&ec->y_s, maxy, ptr);
ptr += (sizeof(short) * (maxy) * 2);
/* Reset Sigma circular buffer (short version for FIR filter) */
init_cb_s(&ec->s_s, (1 << DEFAULT_ALPHA_ST_I), ptr);
ptr += (sizeof(short) * (1 << DEFAULT_ALPHA_ST_I) * 2);
init_cb_s(&ec->u_s, maxu, ptr);
ptr += (sizeof(short) * maxu * 2);
/* Allocate a buffer for the reference signal power computation */
init_cb_s(&ec->y_tilde_s, ec->N_d, ptr);
/* Reset the absolute time index */
ec->i_d = (int)0;
/* Reset the power computations (for y and u) */
ec->Ly_i = DEFAULT_CUTOFF_I;
ec->Lu_i = DEFAULT_CUTOFF_I;
#ifdef MEC2_STATS
/* set the identity */
ec->id = (int)&ptr;
/* Reset performance stats */
ec->cntr_nearend_speech_frames = (int)0;
ec->cntr_residualcorrected_frames = (int)0;
ec->cntr_residualcorrected_framesskipped = (int)0;
ec->cntr_coeff_updates = (int)0;
ec->cntr_coeff_missedupdates = (int)0;
ec->avg_Lu_i_toolow = (int)0;
ec->avg_Lu_i_ok = (int)0;
#endif
/* Reset the near-end speech detector */
ec->s_tilde_i = (int)0;
ec->y_tilde_i = (int)0;
ec->HCNTR_d = (int)0;
}
static inline void echo_can_free(echo_can_state_t *ec)
{
FREE(ec);
}
static inline short echo_can_update(echo_can_state_t *ec, short iref, short
isig)
{
/* Declare local variables that are used more than once */
/* ... */
int k;
/* ... */
int rs;
/* ... */
short u;
/* ... */
int Py_i;
/* ... */
int two_beta_i;
/* flow A on pg. 428 */
/* eq. (16): high-pass filter the input to generate the next value;
* push the current value into the circular buffer
*
* sdc_im1_d = sdc_d;
* sdc_d = sig;
* s_i_d = sdc_d;
* s_d = s_i_d;
* s_i_d = (float)(1.0 - gamma_d) * s_i_d
* + (float)(0.5 * (1.0 - gamma_d)) * (sdc_d - sdc_im1_d);
*/
/* Update the Far-end receive signal circular buffers and accumulators
*/
/* -------------------------------------------------------------------
*/
/* Delete the oldest sample from the power estimate accumulator */
ec->y_tilde_i -= abs(get_cc_s(&ec->y_s, (1 << DEFAULT_ALPHA_YT_I) - 1
)) >> DEFAULT_ALPHA_YT_I;
/* Add the new sample to the power estimate accumulator */
ec->y_tilde_i += abs(iref) >> DEFAULT_ALPHA_ST_I;
/* Push a copy of the new sample into its circular buffer */
add_cc_s(&ec->y_s, iref);
/* eq. (2): compute r in fixed-point */
rs = CONVOLVE2(ec->a_s,
ec->y_s.buf_d + ec->y_s.idx_d,
ec->N_d);
rs >>= 15;
ec->lastsig[ec->lastpos++] = isig;
if (ec->lastpos >= 256)
ec->lastpos = 0;
for (k=0; k < 256; k++) {
if (isig != ec->lastsig[k])
break;
}
if (isig == 0) {
u = 0;
} else if (k == 256) {
u = isig;
} else {
if (rs < -32768) {
rs = -32768;
ec->HCNTR_d = DEFAULT_HANGT;
memset(ec->a_i, 0, sizeof(int) * ec->N_d);
memset(ec->a_s, 0, sizeof(short) * ec->N_d);
} else if (rs > 32767) {
rs = 32767;
ec->HCNTR_d = DEFAULT_HANGT;
memset(ec->a_i, 0, sizeof(int) * ec->N_d);
memset(ec->a_s, 0, sizeof(short) * ec->N_d);
}
if (ABS(ABS(rs)-ABS(isig)) > 3000)
{
rs = 0;
memset(ec->a_i, 0, sizeof(int) * ec->N_d);
memset(ec->a_s, 0, sizeof(short) * ec->N_d);
}
/* eq. (3): compute the output value (see figure 3) and the
error
* note: the error is the same as the output signal when
near-end
* speech is not present
*/
u = isig - rs;
if (u / isig < 0)
u = isig - (rs >> 1);
}
/* Push a copy of the output value sample into its circular buffer */
add_cc_s(&ec->u_s, u);
/* Update the Near-end hybrid signal circular buffers and accumulators
*/
/* -------------------------------------------------------------------
*/
/* Delete the oldest sample from the power estimate accumulator */
ec->s_tilde_i -= abs(get_cc_s(&ec->s_s, (1 << DEFAULT_ALPHA_ST_I) - 1
));
/* Add the new sample to the power estimate accumulator */
ec->s_tilde_i += abs(isig);
/* Push a copy of the new sample into it's circular buffer */
add_cc_s(&ec->s_s, isig);
/* Push a copy of the current short-time average of the far-end receive
signal into it's circular buffer */
add_cc_s(&ec->y_tilde_s, ec->y_tilde_i);
/* flow B on pg. 428 */
/* If the hangover timer isn't running then compute the new convergence
factor, otherwise set Py_i to 32768 */
if (!ec->HCNTR_d) {
Py_i = (ec->Ly_i >> DEFAULT_SIGMA_LY_I) * (ec->Ly_i >>
DEFAULT_SIGMA_LY_I);
Py_i >>= 15;
} else {
Py_i = (1 << 15);
}
#if 0
/* Vary rate of adaptation depending on position in the file
* Do not do this for the first (DEFAULT_UPDATE_TIME) secs after speech
* has begun of the file to allow the echo cancellor to estimate the
* channel accurately
* Still needs conversion!
*/
if (ec->start_speech_d != 0 ){
if ( ec->i_d > (DEFAULT_T0 + ec->start_speech_d)*(SAMPLE_FREQ)
){
ec->beta2_d = max_cc_float(MIN_BETA, DEFAULT_BETA1 *
exp((-1/DEFAULT_TAU)*((ec->i_d/(float)SAMPLE_FREQ) - DEFAULT_T0 -
ec->start_speech_d)));
}
} else {
ec->beta2_d = DEFAULT_BETA1;
}
#endif
/* Fixed point, inverted */
ec->beta2_i = DEFAULT_BETA1_I;
/* Fixed point version, inverted */
two_beta_i = (ec->beta2_i * Py_i) >> 15;
if (!two_beta_i)
two_beta_i++;
/* Update the Suppressed signal power estimate accumulator */
/* ------------------------------------------------------- */
/* Delete the oldest sample from the power estimate accumulator */
ec->Lu_i -= abs(get_cc_s(&ec->u_s, (1 << DEFAULT_SIGMA_LU_I) - 1 )) ;
/* Add the new sample to the power estimate accumulator */
ec->Lu_i += abs(u);
/* Update the Far-end reference signal power estimate accumulator */
/* -------------------------------------------------------------- */
/* eq. (10): update power estimate of the reference */
/* Delete the oldest sample from the power estimate accumulator */
ec->Ly_i -= abs(get_cc_s(&ec->y_s, (1 << DEFAULT_SIGMA_LY_I) - 1)) ;
/* Add the new sample to the power estimate accumulator */
ec->Ly_i += abs(iref);
if (ec->Ly_i < DEFAULT_CUTOFF_I)
ec->Ly_i = DEFAULT_CUTOFF_I;
/* Update the Peak far-end receive signal detected */
/* ----------------------------------------------- */
if (ec->y_tilde_i > ec->max_y_tilde) {
/* New highest y_tilde with full life */
ec->max_y_tilde = ec->y_tilde_i;
ec->max_y_tilde_pos = ec->N_d - 1;
} else if (--ec->max_y_tilde_pos < 0) {
/* Time to find new max y tilde... */
ec->max_y_tilde = MAX16(ec->y_tilde_s.buf_d +
ec->y_tilde_s.idx_d, ec->N_d, &ec->max_y_tilde_pos);
}
/* Determine if near end speech was detected in this sample */
/* -------------------------------------------------------- */
if (((ec->s_tilde_i >> (DEFAULT_ALPHA_ST_I - 1)) > ec->max_y_tilde)
&& (ec->max_y_tilde > 0)) {
/* Then start the Hangover counter */
ec->HCNTR_d = DEFAULT_HANGT;
#ifdef MEC2_STATS_DETAILED
printk(KERN_INFO "Reset near end speech timer with: s_tilde_i
%d, stmnt %d, max_y_tilde %d\n", ec->s_tilde_i, (ec->s_tilde_i >>
(DEFAULT_ALPHA_ST_I - 1)), ec->max_y_tilde);
#endif
#ifdef MEC2_STATS
++ec->cntr_nearend_speech_frames;
#endif
} else if (ec->HCNTR_d > (int)0) {
/* otherwise, if it's still non-zero, decrement the Hangover
counter by one sample */
#ifdef MEC2_STATS
++ec->cntr_nearend_speech_frames;
#endif
ec->HCNTR_d--;
}
/* Update coefficients if no near-end speech in this sample (ie.
HCNTR_d = 0)
* and we have enough signal to bother trying to update.
*
--------------------------------------------------------------------------
*/
if (!ec->HCNTR_d && /* no near-end speech
present */
!(ec->i_d % DEFAULT_M)) { /* we only update on
every DEFAULM_M'th sample from the stream */
if (ec->Lu_i > MIN_UPDATE_THRESH_I) { /* there is
sufficient energy above the noise floor to contain meaningful data */
/* so loop over all the
filter coefficients */
#ifdef MEC2_STATS_DETAILED
printk( KERN_INFO "updating coefficients with:
ec->Lu_i %9d\n", ec->Lu_i);
#endif
#ifdef MEC2_STATS
ec->avg_Lu_i_ok = ec->avg_Lu_i_ok + ec->Lu_i;
++ec->cntr_coeff_updates;
#endif
for (k=0; k < ec->N_d; k++) {
/* eq. (7): compute an expectation over
M_d samples */
int grad2;
grad2 = CONVOLVE2(ec->u_s.buf_d +
ec->u_s.idx_d,
ec->y_s.buf_d +
ec->y_s.idx_d + k,
DEFAULT_M);
/* eq. (7): update the coefficient */
ec->a_i[k] += grad2 / two_beta_i;
ec->a_s[k] = ec->a_i[k] >> 16;
}
} else {
#ifdef MEC2_STATS_DETAILED
printk( KERN_INFO "insufficient signal to
update coefficients ec->Lu_i %5d < %5d\n", ec->Lu_i, MIN_UPDATE_THRESH_I);
#endif
#ifdef MEC2_STATS
ec->avg_Lu_i_toolow = ec->avg_Lu_i_toolow +
ec->Lu_i;
++ec->cntr_coeff_missedupdates;
#endif
}
}
/* paragraph below eq. (15): if no near-end speech in the sample and
* the reference signal power estimate > cutoff threshold
* then perform residual error suppression
*/
#ifdef MEC2_STATS_DETAILED
if (ec->HCNTR_d == 0)
printk( KERN_INFO "possibily correcting frame with ec->Ly_i %9d
ec->Lu_i %9d and expression %d\n", ec->Ly_i, ec->Lu_i, (ec->Ly_i/(ec->Lu_i +
1)));
#endif
#ifndef NO_ECHO_SUPPRESSOR
#ifdef AGGRESSIVE_SUPPRESSOR
if ((ec->HCNTR_d < AGGRESSIVE_HCNTR) && (ec->Ly_i > (ec->Lu_i << 1))) {
for (k=0; k < RESIDUAL_SUPRESSION_PASSES; k++) {
u = u * (ec->Lu_i >> DEFAULT_SIGMA_LU_I) / ((ec->Ly_i
>> (DEFAULT_SIGMA_LY_I)) + 1);
}
#ifdef MEC2_STATS_DETAILED
printk( KERN_INFO "aggresively correcting frame with ec->Ly_i
%9d ec->Lu_i %9d expression %d\n", ec->Ly_i, ec->Lu_i, (ec->Ly_i/(ec->Lu_i +
1)));
#endif
#ifdef MEC2_STATS
++ec->cntr_residualcorrected_frames;
#endif
}
#else
if (ec->HCNTR_d == 0) {
if ((ec->Ly_i/(ec->Lu_i + 1)) > DEFAULT_SUPPR_I) {
for (k=0; k < RESIDUAL_SUPRESSION_PASSES; k++) {
u = u * (ec->Lu_i >> DEFAULT_SIGMA_LU_I) /
((ec->Ly_i >> (DEFAULT_SIGMA_LY_I + 2)) + 1);
}
#ifdef MEC2_STATS_DETAILED
printk( KERN_INFO "correcting frame with ec->Ly_i %9d
ec->Lu_i %9d expression %d\n", ec->Ly_i, ec->Lu_i, (ec->Ly_i/(ec->Lu_i + 1)));
#endif
#ifdef MEC2_STATS
++ec->cntr_residualcorrected_frames;
#endif
}
#ifdef MEC2_STATS
else {
++ec->cntr_residualcorrected_framesskipped;
}
#endif
}
#endif
#endif
#if 0
/* This will generate a non-linear supression factor, once converted */
if ((ec->HCNTR_d == 0) &&
((ec->Lu_d/ec->Ly_d) < DEFAULT_SUPPR) &&
(ec->Lu_d/ec->Ly_d > EC_MIN_DB_VALUE)) {
suppr_factor = (10 / (float)(SUPPR_FLOOR - SUPPR_CEIL)) *
log(ec->Lu_d/ec->Ly_d)
- SUPPR_CEIL / (float)(SUPPR_FLOOR -
SUPPR_CEIL);
u_suppr = pow(10.0, (suppr_factor) * RES_SUPR_FACTOR / 10.0) *
u_suppr;
}
#endif
#ifdef MEC2_STATS
/* Periodically dump performance stats */
if ((ec->i_d % MEC2_STATS) == 0) {
/* make sure to avoid div0's! */
if (ec->cntr_coeff_missedupdates > 0)
ec->avg_Lu_i_toolow = (int)(ec->avg_Lu_i_toolow /
ec->cntr_coeff_missedupdates);
else
ec->avg_Lu_i_toolow = -1;
if (ec->cntr_coeff_updates > 0)
ec->avg_Lu_i_ok = (ec->avg_Lu_i_ok /
ec->cntr_coeff_updates);
else
ec->avg_Lu_i_ok = -1;
printk( KERN_INFO "%d: Near end speech: %5d Residuals
corrected/skipped: %5d/%5d Coefficients updated ok/low sig: %3d/%3d Lu_i avg
ok/low sig %6d/%5d\n",
ec->id,
ec->cntr_nearend_speech_frames,
ec->cntr_residualcorrected_frames,
ec->cntr_residualcorrected_framesskipped,
ec->cntr_coeff_updates, ec->cntr_coeff_missedupdates,
ec->avg_Lu_i_ok, ec->avg_Lu_i_toolow);
ec->cntr_nearend_speech_frames = 0;
ec->cntr_residualcorrected_frames = 0;
ec->cntr_residualcorrected_framesskipped = 0;
ec->cntr_coeff_updates = 0;
ec->cntr_coeff_missedupdates = 0;
ec->avg_Lu_i_ok = 0;
ec->avg_Lu_i_toolow = 0;
}
#endif
/* Increment the sample index and return the corrected sample */
ec->i_d++;
return u;
}
static inline echo_can_state_t *echo_can_create(int len, int adaption_mode)
{
echo_can_state_t *ec;
int maxy;
int maxu;
maxy = len + DEFAULT_M;
maxu = DEFAULT_M;
if (maxy < (1 << DEFAULT_ALPHA_YT_I))
maxy = (1 << DEFAULT_ALPHA_YT_I);
if (maxy < (1 << DEFAULT_SIGMA_LY_I))
maxy = (1 << DEFAULT_SIGMA_LY_I);
if (maxu < (1 << DEFAULT_SIGMA_LU_I))
maxu = (1 << DEFAULT_SIGMA_LU_I);
ec = (echo_can_state_t *)MALLOC(sizeof(echo_can_state_t) +
4 +
/* align */
sizeof(int) * len + /* a_i */
sizeof(short) * len + /* a_s */
2 *
sizeof(short) * (maxy) + /* y_s */
2 *
sizeof(short) * (1 << DEFAULT_ALPHA_ST_I) + /* s_s */
2 *
sizeof(short) * (maxu) + /* u_s */
2 *
sizeof(short) * len); /* y_tilde_s */
if (ec) {
memset(ec, 0, sizeof(echo_can_state_t) +
4 +
/* align */
sizeof(int) * len + /* a_i */
sizeof(short) * len + /* a_s */
2 *
sizeof(short) * (maxy) + /* y_s */
2 *
sizeof(short) * (1 << DEFAULT_ALPHA_ST_I) + /* s_s */
2 *
sizeof(short) * (maxu) + /* u_s */
2 *
sizeof(short) * len); /* y_tilde_s */
init_cc(ec, len, maxy, maxu);
}
return ec;
}
static inline int echo_can_traintap(echo_can_state_t *ec, int pos, short val)
{
/* Set the hangover counter to the length of the can to
* avoid adjustments occuring immediately after initial forced training
*/
ec->HCNTR_d = ec->N_d << 1;
if (pos >= ec->N_d)
return 1;
ec->a_i[pos] = val << 17;
ec->a_s[pos] = val << 1;
if (++pos >= ec->N_d)
return 1;
return 0;
}
#endif
--- NEW FILE: mg2ec_const.h ---
/*
Important constants for tuning mg2 echo can
*/
#ifndef _MG2_CONST_H
#define _MG2_CONST_H
/* Convergence (aka. adaptation) speed -- higher means slower */
#define DEFAULT_BETA1_I 2048
/* Constants for various power computations */
#define DEFAULT_SIGMA_LY_I 7
#define DEFAULT_SIGMA_LU_I 7
#define DEFAULT_ALPHA_ST_I 5 /* near-end speech detection
sensitivity factor */
#define DEFAULT_ALPHA_YT_I 5
#define DEFAULT_CUTOFF_I 128
/* Define the near-end speech hangover counter: if near-end speech
* is declared, hcntr is set equal to hangt (see pg. 432)
*/
#define DEFAULT_HANGT 600 /* in samples, so 600 samples = 75ms */
/* define the residual error suppression threshold */
#define DEFAULT_SUPPR_I 16 /* 16 = -24db */
/* This is the minimum reference signal power estimate level
* that will result in filter adaptation.
* If this is too low then background noise will cause the filter
* coefficients to constantly be updated.
*/
#define MIN_UPDATE_THRESH_I 4096
/* The number of samples used to update coefficients using the
* the block update method (M). It should be related back to the
* length of the echo can.
* ie. it only updates coefficients when (sample number MOD default_m) = 0
*
* Getting this wrong may cause an oops. Consider yourself warned!
*/
#define DEFAULT_M 16 /* every 16th sample */
/* If AGGRESSIVE supression is enabled, then we start cancelling residual
* echos again even while there is potentially the very end of a near-side
* signal present.
* This defines how many samples of DEFAULT_HANGT can remain before we
* kick back in
*/
#define AGGRESSIVE_HCNTR 160 /* in samples, so 160 samples = 20ms */
/* This knob controls the number of passes the residual echo supression
* algorithm makes.
*/
#ifdef AGGRESSIVE_SUPPRESSOR
#define RESIDUAL_SUPRESSION_PASSES 2
#else
#define RESIDUAL_SUPRESSION_PASSES 1
#endif
/***************************************************************/
/* The following knobs are not implemented in the current code */
/* we need a dynamic level of suppression varying with the ratio of the
power of the echo to the power of the reference signal this is
done so that we have a smoother background.
we have a higher suppression when the power ratio is closer to
suppr_ceil and reduces logarithmically as we approach suppr_floor.
*/
#define SUPPR_FLOOR -64
#define SUPPR_CEIL -24
/* in a second departure, we calculate the residual error suppression
* as a percentage of the reference signal energy level. The threshold
* is defined in terms of dB below the reference signal.
*/
#define RES_SUPR_FACTOR -20
#endif /* _MG2_CONST_H */
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