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-rw-r--r--drivers/staging/echo/echo.c835
1 files changed, 421 insertions, 414 deletions
diff --git a/drivers/staging/echo/echo.c b/drivers/staging/echo/echo.c
index 4a281b14fc5..b8f2c5e9dee 100644
--- a/drivers/staging/echo/echo.c
+++ b/drivers/staging/echo/echo.c
@@ -74,7 +74,6 @@
Steve also has some nice notes on echo cancellers in echo.h
-
References:
[1] Ochiai, Areseki, and Ogihara, "Echo Canceller with Two Echo
@@ -105,20 +104,18 @@
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 malloc(a) kmalloc((a), GFP_KERNEL)
-#define free(a) kfree(a)
#include "bit_operations.h"
#include "echo.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
@@ -126,59 +123,58 @@
/* adapting coeffs using the traditional stochastic descent (N)LMS algorithm */
-
-#ifdef __BLACKFIN_ASM__
-static void __inline__ lms_adapt_bg(echo_can_state_t *ec, int clean, int shift)
+#ifdef __bfin__
+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.
+ */
}
/*
@@ -200,392 +196,393 @@ static void __inline__ lms_adapt_bg(echo_can_state_t *ec, int clean, int shift)
*/
#else
-static __inline__ void lms_adapt_bg(echo_can_state_t *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
-/*- End of function --------------------------------------------------------*/
-
-echo_can_state_t *echo_can_create(int len, int adaption_mode)
+struct oslec_state *oslec_create(int len, int adaption_mode)
{
- echo_can_state_t *ec;
- int i;
- int j;
-
- ec = kmalloc(sizeof(*ec), GFP_KERNEL);
- if (ec == NULL)
- return NULL;
- memset(ec, 0, sizeof(*ec));
-
- ec->taps = len;
- ec->log2taps = top_bit(len);
- ec->curr_pos = ec->taps - 1;
-
- for (i = 0; i < 2; i++)
- {
- if ((ec->fir_taps16[i] = (int16_t *) malloc((ec->taps)*sizeof(int16_t))) == NULL)
- {
- for (j = 0; j < i; j++)
- kfree(ec->fir_taps16[j]);
- kfree(ec);
- return NULL;
- }
- memset(ec->fir_taps16[i], 0, (ec->taps)*sizeof(int16_t));
- }
-
- 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;
- echo_can_adaption_mode(ec, adaption_mode);
-
- ec->snapshot = (int16_t*)malloc(ec->taps*sizeof(int16_t));
- memset(ec->snapshot, 0, sizeof(int16_t)*ec->taps);
-
- 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;
+ 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;
}
-/*- End of function --------------------------------------------------------*/
-void echo_can_free(echo_can_state_t *ec)
+EXPORT_SYMBOL_GPL(oslec_create);
+
+void oslec_free(struct oslec_state *ec)
{
int i;
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);
}
-/*- End of function --------------------------------------------------------*/
-void echo_can_adaption_mode(echo_can_state_t *ec, int adaption_mode)
+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;
}
-/*- End of function --------------------------------------------------------*/
-void echo_can_flush(echo_can_state_t *ec)
+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;
}
-/*- End of function --------------------------------------------------------*/
-void echo_can_snapshot(echo_can_state_t *ec) {
- memcpy(ec->snapshot, ec->fir_taps16[0], ec->taps*sizeof(int16_t));
+EXPORT_SYMBOL_GPL(oslec_flush);
+
+void oslec_snapshot(struct oslec_state *ec)
+{
+ memcpy(ec->snapshot, ec->fir_taps16[0], ec->taps * sizeof(int16_t));
}
-/*- End of function --------------------------------------------------------*/
+
+EXPORT_SYMBOL_GPL(oslec_snapshot);
/* Dual Path Echo Canceller ------------------------------------------------*/
-int16_t echo_can_update(echo_can_state_t *ec, int16_t tx, int16_t rx)
+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;
}
-/*- End of function --------------------------------------------------------*/
+EXPORT_SYMBOL_GPL(oslec_update);
/* This function is seperated from the echo canceller is it is usually called
as part of the tx process. See rx HP (DC blocking) filter above, it's
@@ -608,25 +605,35 @@ int16_t echo_can_update(echo_can_state_t *ec, int16_t tx, int16_t rx)
precision, which noise shapes things, giving very clean DC removal.
*/
-int16_t echo_can_hpf_tx(echo_can_state_t *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");
+MODULE_AUTHOR("David Rowe");
+MODULE_DESCRIPTION("Open Source Line Echo Canceller");
+MODULE_VERSION("0.3.0");
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-20 03:53:59 +0000