int AEC::doAEC(int d, int x)
{
// Mic Highpass Filter - to remove DC
d = acMic.highpass(d);
// Mic Highpass Filter - cut-off below 300Hz
d = cutoff.highpass(d);
// Amplify, for e.g. Soundcards with -6dB max. volume
d = (gain * d) / 65536;
// ambient mic level estimation
micAvg += (labs(65536 * d) - micAvg) / 10000;
// Spk Highpass Filter - to remove DC
x = acSpk.highpass(x);
// Double Talk Detector
int update = !dtd(d, x);
// Acoustic Echo Cancellation
d = nlms_pw(d, x, update);
// Acoustic Echo Suppression
if (update) {
// Non Linear Processor (NLP): attenuate low volumes
// NLPAttenuation -6dB = d * 0.5 or d / 2
d /= 2;
}
return d;
}
/* This function is expected to update the samples in sb to remove echo - once
* it completes, they are ready to go out the tx side of the hybrid */
void echo_update_tx(echo *e, SAMPLE_BLOCK *sb)
{
size_t i;
int any_doubletalk = 0;
for (i=0; i<sb->count; i++)
{
SAMPLE rx_s, tx_s;
float tx, rx;
rx_s = cbuffer_pop(e->rx_buf);
tx_s = sb->s[i];
tx = (float)tx_s;
rx = (float)rx_s;
/* High-pass filter - filter out sub-300Hz signals */
tx = update_fir(e->hp, tx);
/* Geigel double-talk detector */
int update = !dtd(e, tx);
/* nlms-pw */
tx = nlms_pw(e, tx, rx, update);
/* If we're not talking, let's attenuate our signal */
if (update)
{
tx *= M12dB;
}
else
{
any_doubletalk = 1;
}
/* clipping */
tx = clip(tx);
sb->s[i] = (int)tx;
}
VERBOSE_LOG("%s\n", any_doubletalk ? "doubletalk" : " ");
}
int AEC::doAEC(int d, int x)
{
REAL s0 = (REAL)d;
REAL s1 = (REAL)x;
// Mic Highpass Filter - to remove DC
s0 = hp00.highpass(s0);
// Mic Highpass Filter - telephone users are used to 300Hz cut-off
s0 = hp0.highpass(s0);
// ambient mic level estimation
s0avg += 1e-4f*(fabsf(s0) - s0avg);
// Spk Highpass Filter - to remove DC
s1 = hp1.highpass(s1);
// Double Talk Detector
int update = !dtd(s0, s1);
// Acoustic Echo Cancellation
s0 = nlms_pw(s0, s1, update);
// Acoustic Echo Suppression
if (update) {
// Non Linear Processor (NLP): attenuate low volumes
s0 *= NLPAttenuation;
}
// Saturation
if (s0 > MAXPCM) {
return (int)MAXPCM;
} else if (s0 < -MAXPCM) {
return (int)-MAXPCM;
} else {
return (int)(s0);
}
}