Steve also has some nice notes on echo cancellers in echo.h
-
References:
[1] Ochiai, Areseki, and Ogihara, "Echo Canceller with Two Echo
Mark, Pawel, and Pavel.
*/
-#include <linux/kernel.h> /* We're doing kernel work */
+#include <linux/kernel.h> /* We're doing kernel work */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#define MIN_TX_POWER_FOR_ADAPTION 64
#define MIN_RX_POWER_FOR_ADAPTION 64
-#define DTD_HANGOVER 600 /* 600 samples, or 75ms */
-#define DC_LOG2BETA 3 /* log2() of DC filter Beta */
+#define DTD_HANGOVER 600 /* 600 samples, or 75ms */
+#define DC_LOG2BETA 3 /* log2() of DC filter Beta */
/*-----------------------------------------------------------------------*\
FUNCTIONS
/* adapting coeffs using the traditional stochastic descent (N)LMS algorithm */
-
#ifdef __bfin__
-static void __inline__ lms_adapt_bg(struct oslec_state *ec, int clean, int shift)
+static void __inline__ lms_adapt_bg(struct oslec_state *ec, int clean,
+ int shift)
{
- int i, j;
- int offset1;
- int offset2;
- int factor;
- int exp;
- int16_t *phist;
- int n;
-
- if (shift > 0)
- factor = clean << shift;
- else
- factor = clean >> -shift;
-
- /* Update the FIR taps */
-
- offset2 = ec->curr_pos;
- offset1 = ec->taps - offset2;
- phist = &ec->fir_state_bg.history[offset2];
-
- /* st: and en: help us locate the assembler in echo.s */
-
- //asm("st:");
- n = ec->taps;
- for (i = 0, j = offset2; i < n; i++, j++)
- {
- exp = *phist++ * factor;
- ec->fir_taps16[1][i] += (int16_t) ((exp+(1<<14)) >> 15);
- }
- //asm("en:");
-
- /* Note the asm for the inner loop above generated by Blackfin gcc
- 4.1.1 is pretty good (note even parallel instructions used):
-
- R0 = W [P0++] (X);
- R0 *= R2;
- R0 = R0 + R3 (NS) ||
- R1 = W [P1] (X) ||
- nop;
- R0 >>>= 15;
- R0 = R0 + R1;
- W [P1++] = R0;
-
- A block based update algorithm would be much faster but the
- above can't be improved on much. Every instruction saved in
- the loop above is 2 MIPs/ch! The for loop above is where the
- Blackfin spends most of it's time - about 17 MIPs/ch measured
- with speedtest.c with 256 taps (32ms). Write-back and
- Write-through cache gave about the same performance.
- */
+ int i, j;
+ int offset1;
+ int offset2;
+ int factor;
+ int exp;
+ int16_t *phist;
+ int n;
+
+ if (shift > 0)
+ factor = clean << shift;
+ else
+ factor = clean >> -shift;
+
+ /* Update the FIR taps */
+
+ offset2 = ec->curr_pos;
+ offset1 = ec->taps - offset2;
+ phist = &ec->fir_state_bg.history[offset2];
+
+ /* st: and en: help us locate the assembler in echo.s */
+
+ //asm("st:");
+ n = ec->taps;
+ for (i = 0, j = offset2; i < n; i++, j++) {
+ exp = *phist++ * factor;
+ ec->fir_taps16[1][i] += (int16_t) ((exp + (1 << 14)) >> 15);
+ }
+ //asm("en:");
+
+ /* Note the asm for the inner loop above generated by Blackfin gcc
+ 4.1.1 is pretty good (note even parallel instructions used):
+
+ R0 = W [P0++] (X);
+ R0 *= R2;
+ R0 = R0 + R3 (NS) ||
+ R1 = W [P1] (X) ||
+ nop;
+ R0 >>>= 15;
+ R0 = R0 + R1;
+ W [P1++] = R0;
+
+ A block based update algorithm would be much faster but the
+ above can't be improved on much. Every instruction saved in
+ the loop above is 2 MIPs/ch! The for loop above is where the
+ Blackfin spends most of it's time - about 17 MIPs/ch measured
+ with speedtest.c with 256 taps (32ms). Write-back and
+ Write-through cache gave about the same performance.
+ */
}
/*
*/
#else
-static __inline__ void lms_adapt_bg(struct oslec_state *ec, int clean, int shift)
+static __inline__ void lms_adapt_bg(struct oslec_state *ec, int clean,
+ int shift)
{
- int i;
-
- int offset1;
- int offset2;
- int factor;
- int exp;
-
- if (shift > 0)
- factor = clean << shift;
- else
- factor = clean >> -shift;
-
- /* Update the FIR taps */
-
- offset2 = ec->curr_pos;
- offset1 = ec->taps - offset2;
-
- for (i = ec->taps - 1; i >= offset1; i--)
- {
- exp = (ec->fir_state_bg.history[i - offset1]*factor);
- ec->fir_taps16[1][i] += (int16_t) ((exp+(1<<14)) >> 15);
- }
- for ( ; i >= 0; i--)
- {
- exp = (ec->fir_state_bg.history[i + offset2]*factor);
- ec->fir_taps16[1][i] += (int16_t) ((exp+(1<<14)) >> 15);
- }
+ int i;
+
+ int offset1;
+ int offset2;
+ int factor;
+ int exp;
+
+ if (shift > 0)
+ factor = clean << shift;
+ else
+ factor = clean >> -shift;
+
+ /* Update the FIR taps */
+
+ offset2 = ec->curr_pos;
+ offset1 = ec->taps - offset2;
+
+ for (i = ec->taps - 1; i >= offset1; i--) {
+ exp = (ec->fir_state_bg.history[i - offset1] * factor);
+ ec->fir_taps16[1][i] += (int16_t) ((exp + (1 << 14)) >> 15);
+ }
+ for (; i >= 0; i--) {
+ exp = (ec->fir_state_bg.history[i + offset2] * factor);
+ ec->fir_taps16[1][i] += (int16_t) ((exp + (1 << 14)) >> 15);
+ }
}
#endif
-
struct oslec_state *oslec_create(int len, int adaption_mode)
{
- struct oslec_state *ec;
- int i;
-
- ec = kzalloc(sizeof(*ec), GFP_KERNEL);
- if (!ec)
- return NULL;
-
- ec->taps = len;
- ec->log2taps = top_bit(len);
- ec->curr_pos = ec->taps - 1;
-
- for (i = 0; i < 2; i++) {
- ec->fir_taps16[i] = kcalloc(ec->taps, sizeof(int16_t), GFP_KERNEL);
- if (!ec->fir_taps16[i])
- goto error_oom;
- }
-
- fir16_create(&ec->fir_state,
- ec->fir_taps16[0],
- ec->taps);
- fir16_create(&ec->fir_state_bg,
- ec->fir_taps16[1],
- ec->taps);
-
- for(i=0; i<5; i++) {
- ec->xvtx[i] = ec->yvtx[i] = ec->xvrx[i] = ec->yvrx[i] = 0;
- }
-
- ec->cng_level = 1000;
- oslec_adaption_mode(ec, adaption_mode);
-
- ec->snapshot = kcalloc(ec->taps, sizeof(int16_t), GFP_KERNEL);
- if (!ec->snapshot)
- goto error_oom;
-
- ec->cond_met = 0;
- ec->Pstates = 0;
- ec->Ltxacc = ec->Lrxacc = ec->Lcleanacc = ec->Lclean_bgacc = 0;
- ec->Ltx = ec->Lrx = ec->Lclean = ec->Lclean_bg = 0;
- ec->tx_1 = ec->tx_2 = ec->rx_1 = ec->rx_2 = 0;
- ec->Lbgn = ec->Lbgn_acc = 0;
- ec->Lbgn_upper = 200;
- ec->Lbgn_upper_acc = ec->Lbgn_upper << 13;
-
- return ec;
-
-error_oom:
- for (i = 0; i < 2; i++)
- kfree(ec->fir_taps16[i]);
-
- kfree(ec);
- return NULL;
+ struct oslec_state *ec;
+ int i;
+
+ ec = kzalloc(sizeof(*ec), GFP_KERNEL);
+ if (!ec)
+ return NULL;
+
+ ec->taps = len;
+ ec->log2taps = top_bit(len);
+ ec->curr_pos = ec->taps - 1;
+
+ for (i = 0; i < 2; i++) {
+ ec->fir_taps16[i] =
+ kcalloc(ec->taps, sizeof(int16_t), GFP_KERNEL);
+ if (!ec->fir_taps16[i])
+ goto error_oom;
+ }
+
+ fir16_create(&ec->fir_state, ec->fir_taps16[0], ec->taps);
+ fir16_create(&ec->fir_state_bg, ec->fir_taps16[1], ec->taps);
+
+ for (i = 0; i < 5; i++) {
+ ec->xvtx[i] = ec->yvtx[i] = ec->xvrx[i] = ec->yvrx[i] = 0;
+ }
+
+ ec->cng_level = 1000;
+ oslec_adaption_mode(ec, adaption_mode);
+
+ ec->snapshot = kcalloc(ec->taps, sizeof(int16_t), GFP_KERNEL);
+ if (!ec->snapshot)
+ goto error_oom;
+
+ ec->cond_met = 0;
+ ec->Pstates = 0;
+ ec->Ltxacc = ec->Lrxacc = ec->Lcleanacc = ec->Lclean_bgacc = 0;
+ ec->Ltx = ec->Lrx = ec->Lclean = ec->Lclean_bg = 0;
+ ec->tx_1 = ec->tx_2 = ec->rx_1 = ec->rx_2 = 0;
+ ec->Lbgn = ec->Lbgn_acc = 0;
+ ec->Lbgn_upper = 200;
+ ec->Lbgn_upper_acc = ec->Lbgn_upper << 13;
+
+ return ec;
+
+ error_oom:
+ for (i = 0; i < 2; i++)
+ kfree(ec->fir_taps16[i]);
+
+ kfree(ec);
+ return NULL;
}
+
EXPORT_SYMBOL_GPL(oslec_create);
void oslec_free(struct oslec_state *ec)
fir16_free(&ec->fir_state);
fir16_free(&ec->fir_state_bg);
- for (i = 0; i < 2; i++)
+ for (i = 0; i < 2; i++)
kfree(ec->fir_taps16[i]);
kfree(ec->snapshot);
kfree(ec);
}
+
EXPORT_SYMBOL_GPL(oslec_free);
void oslec_adaption_mode(struct oslec_state *ec, int adaption_mode)
{
- ec->adaption_mode = adaption_mode;
+ ec->adaption_mode = adaption_mode;
}
+
EXPORT_SYMBOL_GPL(oslec_adaption_mode);
void oslec_flush(struct oslec_state *ec)
{
- int i;
+ int i;
- ec->Ltxacc = ec->Lrxacc = ec->Lcleanacc = ec->Lclean_bgacc = 0;
- ec->Ltx = ec->Lrx = ec->Lclean = ec->Lclean_bg = 0;
- ec->tx_1 = ec->tx_2 = ec->rx_1 = ec->rx_2 = 0;
+ ec->Ltxacc = ec->Lrxacc = ec->Lcleanacc = ec->Lclean_bgacc = 0;
+ ec->Ltx = ec->Lrx = ec->Lclean = ec->Lclean_bg = 0;
+ ec->tx_1 = ec->tx_2 = ec->rx_1 = ec->rx_2 = 0;
- ec->Lbgn = ec->Lbgn_acc = 0;
- ec->Lbgn_upper = 200;
- ec->Lbgn_upper_acc = ec->Lbgn_upper << 13;
+ ec->Lbgn = ec->Lbgn_acc = 0;
+ ec->Lbgn_upper = 200;
+ ec->Lbgn_upper_acc = ec->Lbgn_upper << 13;
- ec->nonupdate_dwell = 0;
+ ec->nonupdate_dwell = 0;
- fir16_flush(&ec->fir_state);
- fir16_flush(&ec->fir_state_bg);
- ec->fir_state.curr_pos = ec->taps - 1;
- ec->fir_state_bg.curr_pos = ec->taps - 1;
- for (i = 0; i < 2; i++)
- memset(ec->fir_taps16[i], 0, ec->taps*sizeof(int16_t));
+ fir16_flush(&ec->fir_state);
+ fir16_flush(&ec->fir_state_bg);
+ ec->fir_state.curr_pos = ec->taps - 1;
+ ec->fir_state_bg.curr_pos = ec->taps - 1;
+ for (i = 0; i < 2; i++)
+ memset(ec->fir_taps16[i], 0, ec->taps * sizeof(int16_t));
- ec->curr_pos = ec->taps - 1;
- ec->Pstates = 0;
+ ec->curr_pos = ec->taps - 1;
+ ec->Pstates = 0;
}
+
EXPORT_SYMBOL_GPL(oslec_flush);
-void oslec_snapshot(struct oslec_state *ec) {
- memcpy(ec->snapshot, ec->fir_taps16[0], ec->taps*sizeof(int16_t));
+void oslec_snapshot(struct oslec_state *ec)
+{
+ memcpy(ec->snapshot, ec->fir_taps16[0], ec->taps * sizeof(int16_t));
}
+
EXPORT_SYMBOL_GPL(oslec_snapshot);
/* Dual Path Echo Canceller ------------------------------------------------*/
int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx)
{
- int32_t echo_value;
- int clean_bg;
- int tmp, tmp1;
-
- /* Input scaling was found be required to prevent problems when tx
- starts clipping. Another possible way to handle this would be the
- filter coefficent scaling. */
-
- ec->tx = tx; ec->rx = rx;
- tx >>=1;
- rx >>=1;
-
- /*
- Filter DC, 3dB point is 160Hz (I think), note 32 bit precision required
- otherwise values do not track down to 0. Zero at DC, Pole at (1-Beta)
- only real axis. Some chip sets (like Si labs) don't need
- this, but something like a $10 X100P card does. Any DC really slows
- down convergence.
-
- Note: removes some low frequency from the signal, this reduces
- the speech quality when listening to samples through headphones
- but may not be obvious through a telephone handset.
-
- Note that the 3dB frequency in radians is approx Beta, e.g. for
- Beta = 2^(-3) = 0.125, 3dB freq is 0.125 rads = 159Hz.
- */
-
- if (ec->adaption_mode & ECHO_CAN_USE_RX_HPF) {
- tmp = rx << 15;
+ int32_t echo_value;
+ int clean_bg;
+ int tmp, tmp1;
+
+ /* Input scaling was found be required to prevent problems when tx
+ starts clipping. Another possible way to handle this would be the
+ filter coefficent scaling. */
+
+ ec->tx = tx;
+ ec->rx = rx;
+ tx >>= 1;
+ rx >>= 1;
+
+ /*
+ Filter DC, 3dB point is 160Hz (I think), note 32 bit precision required
+ otherwise values do not track down to 0. Zero at DC, Pole at (1-Beta)
+ only real axis. Some chip sets (like Si labs) don't need
+ this, but something like a $10 X100P card does. Any DC really slows
+ down convergence.
+
+ Note: removes some low frequency from the signal, this reduces
+ the speech quality when listening to samples through headphones
+ but may not be obvious through a telephone handset.
+
+ Note that the 3dB frequency in radians is approx Beta, e.g. for
+ Beta = 2^(-3) = 0.125, 3dB freq is 0.125 rads = 159Hz.
+ */
+
+ if (ec->adaption_mode & ECHO_CAN_USE_RX_HPF) {
+ tmp = rx << 15;
#if 1
- /* Make sure the gain of the HPF is 1.0. This can still saturate a little under
- impulse conditions, and it might roll to 32768 and need clipping on sustained peak
- level signals. However, the scale of such clipping is small, and the error due to
- any saturation should not markedly affect the downstream processing. */
- tmp -= (tmp >> 4);
+ /* Make sure the gain of the HPF is 1.0. This can still saturate a little under
+ impulse conditions, and it might roll to 32768 and need clipping on sustained peak
+ level signals. However, the scale of such clipping is small, and the error due to
+ any saturation should not markedly affect the downstream processing. */
+ tmp -= (tmp >> 4);
#endif
- ec->rx_1 += -(ec->rx_1>>DC_LOG2BETA) + tmp - ec->rx_2;
+ ec->rx_1 += -(ec->rx_1 >> DC_LOG2BETA) + tmp - ec->rx_2;
+
+ /* hard limit filter to prevent clipping. Note that at this stage
+ rx should be limited to +/- 16383 due to right shift above */
+ tmp1 = ec->rx_1 >> 15;
+ if (tmp1 > 16383)
+ tmp1 = 16383;
+ if (tmp1 < -16383)
+ tmp1 = -16383;
+ rx = tmp1;
+ ec->rx_2 = tmp;
+ }
- /* hard limit filter to prevent clipping. Note that at this stage
- rx should be limited to +/- 16383 due to right shift above */
- tmp1 = ec->rx_1 >> 15;
- if (tmp1 > 16383) tmp1 = 16383;
- if (tmp1 < -16383) tmp1 = -16383;
- rx = tmp1;
- ec->rx_2 = tmp;
- }
+ /* Block average of power in the filter states. Used for
+ adaption power calculation. */
- /* Block average of power in the filter states. Used for
- adaption power calculation. */
+ {
+ int new, old;
+
+ /* efficient "out with the old and in with the new" algorithm so
+ we don't have to recalculate over the whole block of
+ samples. */
+ new = (int)tx *(int)tx;
+ old = (int)ec->fir_state.history[ec->fir_state.curr_pos] *
+ (int)ec->fir_state.history[ec->fir_state.curr_pos];
+ ec->Pstates +=
+ ((new - old) + (1 << ec->log2taps)) >> ec->log2taps;
+ if (ec->Pstates < 0)
+ ec->Pstates = 0;
+ }
- {
- int new, old;
+ /* Calculate short term average levels using simple single pole IIRs */
- /* efficient "out with the old and in with the new" algorithm so
- we don't have to recalculate over the whole block of
- samples. */
- new = (int)tx * (int)tx;
- old = (int)ec->fir_state.history[ec->fir_state.curr_pos] *
- (int)ec->fir_state.history[ec->fir_state.curr_pos];
- ec->Pstates += ((new - old) + (1<<ec->log2taps)) >> ec->log2taps;
- if (ec->Pstates < 0) ec->Pstates = 0;
- }
-
- /* Calculate short term average levels using simple single pole IIRs */
-
- ec->Ltxacc += abs(tx) - ec->Ltx;
- ec->Ltx = (ec->Ltxacc + (1<<4)) >> 5;
- ec->Lrxacc += abs(rx) - ec->Lrx;
- ec->Lrx = (ec->Lrxacc + (1<<4)) >> 5;
-
- /* Foreground filter ---------------------------------------------------*/
-
- ec->fir_state.coeffs = ec->fir_taps16[0];
- echo_value = fir16(&ec->fir_state, tx);
- ec->clean = rx - echo_value;
- ec->Lcleanacc += abs(ec->clean) - ec->Lclean;
- ec->Lclean = (ec->Lcleanacc + (1<<4)) >> 5;
-
- /* Background filter ---------------------------------------------------*/
-
- echo_value = fir16(&ec->fir_state_bg, tx);
- clean_bg = rx - echo_value;
- ec->Lclean_bgacc += abs(clean_bg) - ec->Lclean_bg;
- ec->Lclean_bg = (ec->Lclean_bgacc + (1<<4)) >> 5;
-
- /* Background Filter adaption -----------------------------------------*/
-
- /* Almost always adap bg filter, just simple DT and energy
- detection to minimise adaption in cases of strong double talk.
- However this is not critical for the dual path algorithm.
- */
- ec->factor = 0;
- ec->shift = 0;
- if ((ec->nonupdate_dwell == 0)) {
- int P, logP, shift;
-
- /* Determine:
-
- f = Beta * clean_bg_rx/P ------ (1)
-
- where P is the total power in the filter states.
-
- The Boffins have shown that if we obey (1) we converge
- quickly and avoid instability.
-
- The correct factor f must be in Q30, as this is the fixed
- point format required by the lms_adapt_bg() function,
- therefore the scaled version of (1) is:
-
- (2^30) * f = (2^30) * Beta * clean_bg_rx/P
- factor = (2^30) * Beta * clean_bg_rx/P ----- (2)
-
- We have chosen Beta = 0.25 by experiment, so:
-
- factor = (2^30) * (2^-2) * clean_bg_rx/P
-
- (30 - 2 - log2(P))
- factor = clean_bg_rx 2 ----- (3)
-
- To avoid a divide we approximate log2(P) as top_bit(P),
- which returns the position of the highest non-zero bit in
- P. This approximation introduces an error as large as a
- factor of 2, but the algorithm seems to handle it OK.
-
- Come to think of it a divide may not be a big deal on a
- modern DSP, so its probably worth checking out the cycles
- for a divide versus a top_bit() implementation.
- */
-
- P = MIN_TX_POWER_FOR_ADAPTION + ec->Pstates;
- logP = top_bit(P) + ec->log2taps;
- shift = 30 - 2 - logP;
- ec->shift = shift;
-
- lms_adapt_bg(ec, clean_bg, shift);
- }
-
- /* very simple DTD to make sure we dont try and adapt with strong
- near end speech */
-
- ec->adapt = 0;
- if ((ec->Lrx > MIN_RX_POWER_FOR_ADAPTION) && (ec->Lrx > ec->Ltx))
- ec->nonupdate_dwell = DTD_HANGOVER;
- if (ec->nonupdate_dwell)
- ec->nonupdate_dwell--;
+ ec->Ltxacc += abs(tx) - ec->Ltx;
+ ec->Ltx = (ec->Ltxacc + (1 << 4)) >> 5;
+ ec->Lrxacc += abs(rx) - ec->Lrx;
+ ec->Lrx = (ec->Lrxacc + (1 << 4)) >> 5;
- /* Transfer logic ------------------------------------------------------*/
+ /* Foreground filter --------------------------------------------------- */
- /* These conditions are from the dual path paper [1], I messed with
- them a bit to improve performance. */
+ ec->fir_state.coeffs = ec->fir_taps16[0];
+ echo_value = fir16(&ec->fir_state, tx);
+ ec->clean = rx - echo_value;
+ ec->Lcleanacc += abs(ec->clean) - ec->Lclean;
+ ec->Lclean = (ec->Lcleanacc + (1 << 4)) >> 5;
- if ((ec->adaption_mode & ECHO_CAN_USE_ADAPTION) &&
- (ec->nonupdate_dwell == 0) &&
- (8*ec->Lclean_bg < 7*ec->Lclean) /* (ec->Lclean_bg < 0.875*ec->Lclean) */ &&
- (8*ec->Lclean_bg < ec->Ltx) /* (ec->Lclean_bg < 0.125*ec->Ltx) */ )
- {
- if (ec->cond_met == 6) {
- /* BG filter has had better results for 6 consecutive samples */
- ec->adapt = 1;
- memcpy(ec->fir_taps16[0], ec->fir_taps16[1], ec->taps*sizeof(int16_t));
- }
- else
- ec->cond_met++;
- }
- else
- ec->cond_met = 0;
+ /* Background filter --------------------------------------------------- */
- /* Non-Linear Processing ---------------------------------------------------*/
+ echo_value = fir16(&ec->fir_state_bg, tx);
+ clean_bg = rx - echo_value;
+ ec->Lclean_bgacc += abs(clean_bg) - ec->Lclean_bg;
+ ec->Lclean_bg = (ec->Lclean_bgacc + (1 << 4)) >> 5;
- ec->clean_nlp = ec->clean;
- if (ec->adaption_mode & ECHO_CAN_USE_NLP)
- {
- /* Non-linear processor - a fancy way to say "zap small signals, to avoid
- residual echo due to (uLaw/ALaw) non-linearity in the channel.". */
+ /* Background Filter adaption ----------------------------------------- */
- if ((16*ec->Lclean < ec->Ltx))
- {
- /* Our e/c has improved echo by at least 24 dB (each factor of 2 is 6dB,
- so 2*2*2*2=16 is the same as 6+6+6+6=24dB) */
- if (ec->adaption_mode & ECHO_CAN_USE_CNG)
- {
- ec->cng_level = ec->Lbgn;
-
- /* Very elementary comfort noise generation. Just random
- numbers rolled off very vaguely Hoth-like. DR: This
- noise doesn't sound quite right to me - I suspect there
- are some overlfow issues in the filtering as it's too
- "crackly". TODO: debug this, maybe just play noise at
- high level or look at spectrum.
- */
-
- ec->cng_rndnum = 1664525U*ec->cng_rndnum + 1013904223U;
- ec->cng_filter = ((ec->cng_rndnum & 0xFFFF) - 32768 + 5*ec->cng_filter) >> 3;
- ec->clean_nlp = (ec->cng_filter*ec->cng_level*8) >> 14;
-
- }
- else if (ec->adaption_mode & ECHO_CAN_USE_CLIP)
- {
- /* This sounds much better than CNG */
- if (ec->clean_nlp > ec->Lbgn)
- ec->clean_nlp = ec->Lbgn;
- if (ec->clean_nlp < -ec->Lbgn)
- ec->clean_nlp = -ec->Lbgn;
+ /* Almost always adap bg filter, just simple DT and energy
+ detection to minimise adaption in cases of strong double talk.
+ However this is not critical for the dual path algorithm.
+ */
+ ec->factor = 0;
+ ec->shift = 0;
+ if ((ec->nonupdate_dwell == 0)) {
+ int P, logP, shift;
+
+ /* Determine:
+
+ f = Beta * clean_bg_rx/P ------ (1)
+
+ where P is the total power in the filter states.
+
+ The Boffins have shown that if we obey (1) we converge
+ quickly and avoid instability.
+
+ The correct factor f must be in Q30, as this is the fixed
+ point format required by the lms_adapt_bg() function,
+ therefore the scaled version of (1) is:
+
+ (2^30) * f = (2^30) * Beta * clean_bg_rx/P
+ factor = (2^30) * Beta * clean_bg_rx/P ----- (2)
+
+ We have chosen Beta = 0.25 by experiment, so:
+
+ factor = (2^30) * (2^-2) * clean_bg_rx/P
+
+ (30 - 2 - log2(P))
+ factor = clean_bg_rx 2 ----- (3)
+
+ To avoid a divide we approximate log2(P) as top_bit(P),
+ which returns the position of the highest non-zero bit in
+ P. This approximation introduces an error as large as a
+ factor of 2, but the algorithm seems to handle it OK.
+
+ Come to think of it a divide may not be a big deal on a
+ modern DSP, so its probably worth checking out the cycles
+ for a divide versus a top_bit() implementation.
+ */
+
+ P = MIN_TX_POWER_FOR_ADAPTION + ec->Pstates;
+ logP = top_bit(P) + ec->log2taps;
+ shift = 30 - 2 - logP;
+ ec->shift = shift;
+
+ lms_adapt_bg(ec, clean_bg, shift);
}
- else
- {
- /* just mute the residual, doesn't sound very good, used mainly
- in G168 tests */
- ec->clean_nlp = 0;
- }
- }
- else {
- /* Background noise estimator. I tried a few algorithms
- here without much luck. This very simple one seems to
- work best, we just average the level using a slow (1 sec
- time const) filter if the current level is less than a
- (experimentally derived) constant. This means we dont
- include high level signals like near end speech. When
- combined with CNG or especially CLIP seems to work OK.
- */
- if (ec->Lclean < 40) {
- ec->Lbgn_acc += abs(ec->clean) - ec->Lbgn;
- ec->Lbgn = (ec->Lbgn_acc + (1<<11)) >> 12;
- }
- }
- }
-
- /* Roll around the taps buffer */
- if (ec->curr_pos <= 0)
- ec->curr_pos = ec->taps;
- ec->curr_pos--;
-
- if (ec->adaption_mode & ECHO_CAN_DISABLE)
- ec->clean_nlp = rx;
-
- /* Output scaled back up again to match input scaling */
-
- return (int16_t) ec->clean_nlp << 1;
+
+ /* very simple DTD to make sure we dont try and adapt with strong
+ near end speech */
+
+ ec->adapt = 0;
+ if ((ec->Lrx > MIN_RX_POWER_FOR_ADAPTION) && (ec->Lrx > ec->Ltx))
+ ec->nonupdate_dwell = DTD_HANGOVER;
+ if (ec->nonupdate_dwell)
+ ec->nonupdate_dwell--;
+
+ /* Transfer logic ------------------------------------------------------ */
+
+ /* These conditions are from the dual path paper [1], I messed with
+ them a bit to improve performance. */
+
+ if ((ec->adaption_mode & ECHO_CAN_USE_ADAPTION) &&
+ (ec->nonupdate_dwell == 0) &&
+ (8 * ec->Lclean_bg <
+ 7 * ec->Lclean) /* (ec->Lclean_bg < 0.875*ec->Lclean) */ &&
+ (8 * ec->Lclean_bg <
+ ec->Ltx) /* (ec->Lclean_bg < 0.125*ec->Ltx) */ ) {
+ if (ec->cond_met == 6) {
+ /* BG filter has had better results for 6 consecutive samples */
+ ec->adapt = 1;
+ memcpy(ec->fir_taps16[0], ec->fir_taps16[1],
+ ec->taps * sizeof(int16_t));
+ } else
+ ec->cond_met++;
+ } else
+ ec->cond_met = 0;
+
+ /* Non-Linear Processing --------------------------------------------------- */
+
+ ec->clean_nlp = ec->clean;
+ if (ec->adaption_mode & ECHO_CAN_USE_NLP) {
+ /* Non-linear processor - a fancy way to say "zap small signals, to avoid
+ residual echo due to (uLaw/ALaw) non-linearity in the channel.". */
+
+ if ((16 * ec->Lclean < ec->Ltx)) {
+ /* Our e/c has improved echo by at least 24 dB (each factor of 2 is 6dB,
+ so 2*2*2*2=16 is the same as 6+6+6+6=24dB) */
+ if (ec->adaption_mode & ECHO_CAN_USE_CNG) {
+ ec->cng_level = ec->Lbgn;
+
+ /* Very elementary comfort noise generation. Just random
+ numbers rolled off very vaguely Hoth-like. DR: This
+ noise doesn't sound quite right to me - I suspect there
+ are some overlfow issues in the filtering as it's too
+ "crackly". TODO: debug this, maybe just play noise at
+ high level or look at spectrum.
+ */
+
+ ec->cng_rndnum =
+ 1664525U * ec->cng_rndnum + 1013904223U;
+ ec->cng_filter =
+ ((ec->cng_rndnum & 0xFFFF) - 32768 +
+ 5 * ec->cng_filter) >> 3;
+ ec->clean_nlp =
+ (ec->cng_filter * ec->cng_level * 8) >> 14;
+
+ } else if (ec->adaption_mode & ECHO_CAN_USE_CLIP) {
+ /* This sounds much better than CNG */
+ if (ec->clean_nlp > ec->Lbgn)
+ ec->clean_nlp = ec->Lbgn;
+ if (ec->clean_nlp < -ec->Lbgn)
+ ec->clean_nlp = -ec->Lbgn;
+ } else {
+ /* just mute the residual, doesn't sound very good, used mainly
+ in G168 tests */
+ ec->clean_nlp = 0;
+ }
+ } else {
+ /* Background noise estimator. I tried a few algorithms
+ here without much luck. This very simple one seems to
+ work best, we just average the level using a slow (1 sec
+ time const) filter if the current level is less than a
+ (experimentally derived) constant. This means we dont
+ include high level signals like near end speech. When
+ combined with CNG or especially CLIP seems to work OK.
+ */
+ if (ec->Lclean < 40) {
+ ec->Lbgn_acc += abs(ec->clean) - ec->Lbgn;
+ ec->Lbgn = (ec->Lbgn_acc + (1 << 11)) >> 12;
+ }
+ }
+ }
+
+ /* Roll around the taps buffer */
+ if (ec->curr_pos <= 0)
+ ec->curr_pos = ec->taps;
+ ec->curr_pos--;
+
+ if (ec->adaption_mode & ECHO_CAN_DISABLE)
+ ec->clean_nlp = rx;
+
+ /* Output scaled back up again to match input scaling */
+
+ return (int16_t) ec->clean_nlp << 1;
}
+
EXPORT_SYMBOL_GPL(oslec_update);
/* This function is seperated from the echo canceller is it is usually called
precision, which noise shapes things, giving very clean DC removal.
*/
-int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx) {
- int tmp, tmp1;
+int16_t oslec_hpf_tx(struct oslec_state * ec, int16_t tx)
+{
+ int tmp, tmp1;
- if (ec->adaption_mode & ECHO_CAN_USE_TX_HPF) {
- tmp = tx << 15;
+ if (ec->adaption_mode & ECHO_CAN_USE_TX_HPF) {
+ tmp = tx << 15;
#if 1
- /* Make sure the gain of the HPF is 1.0. The first can still saturate a little under
- impulse conditions, and it might roll to 32768 and need clipping on sustained peak
- level signals. However, the scale of such clipping is small, and the error due to
- any saturation should not markedly affect the downstream processing. */
- tmp -= (tmp >> 4);
+ /* Make sure the gain of the HPF is 1.0. The first can still saturate a little under
+ impulse conditions, and it might roll to 32768 and need clipping on sustained peak
+ level signals. However, the scale of such clipping is small, and the error due to
+ any saturation should not markedly affect the downstream processing. */
+ tmp -= (tmp >> 4);
#endif
- ec->tx_1 += -(ec->tx_1>>DC_LOG2BETA) + tmp - ec->tx_2;
- tmp1 = ec->tx_1 >> 15;
- if (tmp1 > 32767) tmp1 = 32767;
- if (tmp1 < -32767) tmp1 = -32767;
- tx = tmp1;
- ec->tx_2 = tmp;
- }
-
- return tx;
+ ec->tx_1 += -(ec->tx_1 >> DC_LOG2BETA) + tmp - ec->tx_2;
+ tmp1 = ec->tx_1 >> 15;
+ if (tmp1 > 32767)
+ tmp1 = 32767;
+ if (tmp1 < -32767)
+ tmp1 = -32767;
+ tx = tmp1;
+ ec->tx_2 = tmp;
+ }
+
+ return tx;
}
+
EXPORT_SYMBOL_GPL(oslec_hpf_tx);
MODULE_LICENSE("GPL");
16 bit integer FIR descriptor. This defines the working state for a single
instance of an FIR filter using 16 bit integer coefficients.
*/
-typedef struct
-{
+typedef struct {
int taps;
int curr_pos;
const int16_t *coeffs;
instance of an FIR filter using 32 bit integer coefficients, and filtering
16 bit integer data.
*/
-typedef struct
-{
+typedef struct {
int taps;
int curr_pos;
const int32_t *coeffs;
Floating point FIR descriptor. This defines the working state for a single
instance of an FIR filter using floating point coefficients and data.
*/
-typedef struct
-{
+typedef struct {
int taps;
int curr_pos;
const float *coeffs;
float *history;
} fir_float_state_t;
-static __inline__ const int16_t *fir16_create(fir16_state_t *fir,
- const int16_t *coeffs,
- int taps)
+static __inline__ const int16_t *fir16_create(fir16_state_t * fir,
+ const int16_t * coeffs, int taps)
{
fir->taps = taps;
fir->curr_pos = taps - 1;
fir->coeffs = coeffs;
#if defined(USE_MMX) || defined(USE_SSE2) || defined(__bfin__)
- fir->history = kcalloc(2*taps, sizeof(int16_t), GFP_KERNEL);
+ fir->history = kcalloc(2 * taps, sizeof(int16_t), GFP_KERNEL);
#else
fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
#endif
return fir->history;
}
-static __inline__ void fir16_flush(fir16_state_t *fir)
+static __inline__ void fir16_flush(fir16_state_t * fir)
{
#if defined(USE_MMX) || defined(USE_SSE2) || defined(__bfin__)
- memset(fir->history, 0, 2*fir->taps*sizeof(int16_t));
+ memset(fir->history, 0, 2 * fir->taps * sizeof(int16_t));
#else
- memset(fir->history, 0, fir->taps*sizeof(int16_t));
+ memset(fir->history, 0, fir->taps * sizeof(int16_t));
#endif
}
-static __inline__ void fir16_free(fir16_state_t *fir)
+static __inline__ void fir16_free(fir16_state_t * fir)
{
kfree(fir->history);
}
#ifdef __bfin__
static inline int32_t dot_asm(short *x, short *y, int len)
{
- int dot;
-
- len--;
-
- __asm__
- (
- "I0 = %1;\n\t"
- "I1 = %2;\n\t"
- "A0 = 0;\n\t"
- "R0.L = W[I0++] || R1.L = W[I1++];\n\t"
- "LOOP dot%= LC0 = %3;\n\t"
- "LOOP_BEGIN dot%=;\n\t"
- "A0 += R0.L * R1.L (IS) || R0.L = W[I0++] || R1.L = W[I1++];\n\t"
- "LOOP_END dot%=;\n\t"
- "A0 += R0.L*R1.L (IS);\n\t"
- "R0 = A0;\n\t"
- "%0 = R0;\n\t"
- : "=&d" (dot)
- : "a" (x), "a" (y), "a" (len)
- : "I0", "I1", "A1", "A0", "R0", "R1"
- );
-
- return dot;
+ int dot;
+
+ len--;
+
+ __asm__("I0 = %1;\n\t"
+ "I1 = %2;\n\t"
+ "A0 = 0;\n\t"
+ "R0.L = W[I0++] || R1.L = W[I1++];\n\t"
+ "LOOP dot%= LC0 = %3;\n\t"
+ "LOOP_BEGIN dot%=;\n\t"
+ "A0 += R0.L * R1.L (IS) || R0.L = W[I0++] || R1.L = W[I1++];\n\t"
+ "LOOP_END dot%=;\n\t"
+ "A0 += R0.L*R1.L (IS);\n\t"
+ "R0 = A0;\n\t"
+ "%0 = R0;\n\t"
+ :"=&d"(dot)
+ :"a"(x), "a"(y), "a"(len)
+ :"I0", "I1", "A1", "A0", "R0", "R1"
+ );
+
+ return dot;
}
#endif
-static __inline__ int16_t fir16(fir16_state_t *fir, int16_t sample)
+static __inline__ int16_t fir16(fir16_state_t * fir, int16_t sample)
{
- int32_t y;
+ int32_t y;
#if defined(USE_MMX)
- int i;
- mmx_t *mmx_coeffs;
- mmx_t *mmx_hist;
-
- fir->history[fir->curr_pos] = sample;
- fir->history[fir->curr_pos + fir->taps] = sample;
-
- mmx_coeffs = (mmx_t *) fir->coeffs;
- mmx_hist = (mmx_t *) &fir->history[fir->curr_pos];
- i = fir->taps;
- pxor_r2r(mm4, mm4);
- /* 8 samples per iteration, so the filter must be a multiple of 8 long. */
- while (i > 0)
- {
- movq_m2r(mmx_coeffs[0], mm0);
- movq_m2r(mmx_coeffs[1], mm2);
- movq_m2r(mmx_hist[0], mm1);
- movq_m2r(mmx_hist[1], mm3);
- mmx_coeffs += 2;
- mmx_hist += 2;
- pmaddwd_r2r(mm1, mm0);
- pmaddwd_r2r(mm3, mm2);
- paddd_r2r(mm0, mm4);
- paddd_r2r(mm2, mm4);
- i -= 8;
- }
- movq_r2r(mm4, mm0);
- psrlq_i2r(32, mm0);
- paddd_r2r(mm0, mm4);
- movd_r2m(mm4, y);
- emms();
+ int i;
+ mmx_t *mmx_coeffs;
+ mmx_t *mmx_hist;
+
+ fir->history[fir->curr_pos] = sample;
+ fir->history[fir->curr_pos + fir->taps] = sample;
+
+ mmx_coeffs = (mmx_t *) fir->coeffs;
+ mmx_hist = (mmx_t *) & fir->history[fir->curr_pos];
+ i = fir->taps;
+ pxor_r2r(mm4, mm4);
+ /* 8 samples per iteration, so the filter must be a multiple of 8 long. */
+ while (i > 0) {
+ movq_m2r(mmx_coeffs[0], mm0);
+ movq_m2r(mmx_coeffs[1], mm2);
+ movq_m2r(mmx_hist[0], mm1);
+ movq_m2r(mmx_hist[1], mm3);
+ mmx_coeffs += 2;
+ mmx_hist += 2;
+ pmaddwd_r2r(mm1, mm0);
+ pmaddwd_r2r(mm3, mm2);
+ paddd_r2r(mm0, mm4);
+ paddd_r2r(mm2, mm4);
+ i -= 8;
+ }
+ movq_r2r(mm4, mm0);
+ psrlq_i2r(32, mm0);
+ paddd_r2r(mm0, mm4);
+ movd_r2m(mm4, y);
+ emms();
#elif defined(USE_SSE2)
- int i;
- xmm_t *xmm_coeffs;
- xmm_t *xmm_hist;
-
- fir->history[fir->curr_pos] = sample;
- fir->history[fir->curr_pos + fir->taps] = sample;
-
- xmm_coeffs = (xmm_t *) fir->coeffs;
- xmm_hist = (xmm_t *) &fir->history[fir->curr_pos];
- i = fir->taps;
- pxor_r2r(xmm4, xmm4);
- /* 16 samples per iteration, so the filter must be a multiple of 16 long. */
- while (i > 0)
- {
- movdqu_m2r(xmm_coeffs[0], xmm0);
- movdqu_m2r(xmm_coeffs[1], xmm2);
- movdqu_m2r(xmm_hist[0], xmm1);
- movdqu_m2r(xmm_hist[1], xmm3);
- xmm_coeffs += 2;
- xmm_hist += 2;
- pmaddwd_r2r(xmm1, xmm0);
- pmaddwd_r2r(xmm3, xmm2);
- paddd_r2r(xmm0, xmm4);
- paddd_r2r(xmm2, xmm4);
- i -= 16;
- }
- movdqa_r2r(xmm4, xmm0);
- psrldq_i2r(8, xmm0);
- paddd_r2r(xmm0, xmm4);
- movdqa_r2r(xmm4, xmm0);
- psrldq_i2r(4, xmm0);
- paddd_r2r(xmm0, xmm4);
- movd_r2m(xmm4, y);
+ int i;
+ xmm_t *xmm_coeffs;
+ xmm_t *xmm_hist;
+
+ fir->history[fir->curr_pos] = sample;
+ fir->history[fir->curr_pos + fir->taps] = sample;
+
+ xmm_coeffs = (xmm_t *) fir->coeffs;
+ xmm_hist = (xmm_t *) & fir->history[fir->curr_pos];
+ i = fir->taps;
+ pxor_r2r(xmm4, xmm4);
+ /* 16 samples per iteration, so the filter must be a multiple of 16 long. */
+ while (i > 0) {
+ movdqu_m2r(xmm_coeffs[0], xmm0);
+ movdqu_m2r(xmm_coeffs[1], xmm2);
+ movdqu_m2r(xmm_hist[0], xmm1);
+ movdqu_m2r(xmm_hist[1], xmm3);
+ xmm_coeffs += 2;
+ xmm_hist += 2;
+ pmaddwd_r2r(xmm1, xmm0);
+ pmaddwd_r2r(xmm3, xmm2);
+ paddd_r2r(xmm0, xmm4);
+ paddd_r2r(xmm2, xmm4);
+ i -= 16;
+ }
+ movdqa_r2r(xmm4, xmm0);
+ psrldq_i2r(8, xmm0);
+ paddd_r2r(xmm0, xmm4);
+ movdqa_r2r(xmm4, xmm0);
+ psrldq_i2r(4, xmm0);
+ paddd_r2r(xmm0, xmm4);
+ movd_r2m(xmm4, y);
#elif defined(__bfin__)
- fir->history[fir->curr_pos] = sample;
- fir->history[fir->curr_pos + fir->taps] = sample;
- y = dot_asm((int16_t*)fir->coeffs, &fir->history[fir->curr_pos], fir->taps);
+ fir->history[fir->curr_pos] = sample;
+ fir->history[fir->curr_pos + fir->taps] = sample;
+ y = dot_asm((int16_t *) fir->coeffs, &fir->history[fir->curr_pos],
+ fir->taps);
#else
- int i;
- int offset1;
- int offset2;
-
- fir->history[fir->curr_pos] = sample;
-
- offset2 = fir->curr_pos;
- offset1 = fir->taps - offset2;
- y = 0;
- for (i = fir->taps - 1; i >= offset1; i--)
- y += fir->coeffs[i]*fir->history[i - offset1];
- for ( ; i >= 0; i--)
- y += fir->coeffs[i]*fir->history[i + offset2];
+ int i;
+ int offset1;
+ int offset2;
+
+ fir->history[fir->curr_pos] = sample;
+
+ offset2 = fir->curr_pos;
+ offset1 = fir->taps - offset2;
+ y = 0;
+ for (i = fir->taps - 1; i >= offset1; i--)
+ y += fir->coeffs[i] * fir->history[i - offset1];
+ for (; i >= 0; i--)
+ y += fir->coeffs[i] * fir->history[i + offset2];
#endif
- if (fir->curr_pos <= 0)
- fir->curr_pos = fir->taps;
- fir->curr_pos--;
- return (int16_t) (y >> 15);
+ if (fir->curr_pos <= 0)
+ fir->curr_pos = fir->taps;
+ fir->curr_pos--;
+ return (int16_t) (y >> 15);
}
-static __inline__ const int16_t *fir32_create(fir32_state_t *fir,
- const int32_t *coeffs,
- int taps)
+static __inline__ const int16_t *fir32_create(fir32_state_t * fir,
+ const int32_t * coeffs, int taps)
{
- fir->taps = taps;
- fir->curr_pos = taps - 1;
- fir->coeffs = coeffs;
- fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
- return fir->history;
+ fir->taps = taps;
+ fir->curr_pos = taps - 1;
+ fir->coeffs = coeffs;
+ fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
+ return fir->history;
}
-static __inline__ void fir32_flush(fir32_state_t *fir)
+static __inline__ void fir32_flush(fir32_state_t * fir)
{
- memset(fir->history, 0, fir->taps*sizeof(int16_t));
+ memset(fir->history, 0, fir->taps * sizeof(int16_t));
}
-static __inline__ void fir32_free(fir32_state_t *fir)
+static __inline__ void fir32_free(fir32_state_t * fir)
{
- kfree(fir->history);
+ kfree(fir->history);
}
-static __inline__ int16_t fir32(fir32_state_t *fir, int16_t sample)
+static __inline__ int16_t fir32(fir32_state_t * fir, int16_t sample)
{
- int i;
- int32_t y;
- int offset1;
- int offset2;
-
- fir->history[fir->curr_pos] = sample;
- offset2 = fir->curr_pos;
- offset1 = fir->taps - offset2;
- y = 0;
- for (i = fir->taps - 1; i >= offset1; i--)
- y += fir->coeffs[i]*fir->history[i - offset1];
- for ( ; i >= 0; i--)
- y += fir->coeffs[i]*fir->history[i + offset2];
- if (fir->curr_pos <= 0)
- fir->curr_pos = fir->taps;
- fir->curr_pos--;
- return (int16_t) (y >> 15);
+ int i;
+ int32_t y;
+ int offset1;
+ int offset2;
+
+ fir->history[fir->curr_pos] = sample;
+ offset2 = fir->curr_pos;
+ offset1 = fir->taps - offset2;
+ y = 0;
+ for (i = fir->taps - 1; i >= offset1; i--)
+ y += fir->coeffs[i] * fir->history[i - offset1];
+ for (; i >= 0; i--)
+ y += fir->coeffs[i] * fir->history[i + offset2];
+ if (fir->curr_pos <= 0)
+ fir->curr_pos = fir->taps;
+ fir->curr_pos--;
+ return (int16_t) (y >> 15);
}
#endif
projects / linux-2.6-omap-h63xx.git / commitdiff