Source code
Revision control
Copy as Markdown
Other Tools
/*
* Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "modules/audio_processing/aecm/aecm_core.h"
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
extern "C" {
#include "common_audio/ring_buffer.h"
#include "common_audio/signal_processing/include/real_fft.h"
}
#include "common_audio/signal_processing/include/signal_processing_library.h"
#include "modules/audio_processing/aecm/echo_control_mobile.h"
#include "modules/audio_processing/utility/delay_estimator_wrapper.h"
#include "rtc_base/checks.h"
#include "rtc_base/numerics/safe_conversions.h"
namespace webrtc {
namespace {
#ifdef AEC_DEBUG
FILE* dfile;
FILE* testfile;
#endif
// Initialization table for echo channel in 8 kHz
static const int16_t kChannelStored8kHz[PART_LEN1] = {
2040, 1815, 1590, 1498, 1405, 1395, 1385, 1418, 1451, 1506, 1562,
1644, 1726, 1804, 1882, 1918, 1953, 1982, 2010, 2025, 2040, 2034,
2027, 2021, 2014, 1997, 1980, 1925, 1869, 1800, 1732, 1683, 1635,
1604, 1572, 1545, 1517, 1481, 1444, 1405, 1367, 1331, 1294, 1270,
1245, 1239, 1233, 1247, 1260, 1282, 1303, 1338, 1373, 1407, 1441,
1470, 1499, 1524, 1549, 1565, 1582, 1601, 1621, 1649, 1676};
// Initialization table for echo channel in 16 kHz
static const int16_t kChannelStored16kHz[PART_LEN1] = {
2040, 1590, 1405, 1385, 1451, 1562, 1726, 1882, 1953, 2010, 2040,
2027, 2014, 1980, 1869, 1732, 1635, 1572, 1517, 1444, 1367, 1294,
1245, 1233, 1260, 1303, 1373, 1441, 1499, 1549, 1582, 1621, 1676,
1741, 1802, 1861, 1921, 1983, 2040, 2102, 2170, 2265, 2375, 2515,
2651, 2781, 2922, 3075, 3253, 3471, 3738, 3976, 4151, 4258, 4308,
4288, 4270, 4253, 4237, 4179, 4086, 3947, 3757, 3484, 3153};
} // namespace
const int16_t WebRtcAecm_kCosTable[] = {
8192, 8190, 8187, 8180, 8172, 8160, 8147, 8130, 8112, 8091, 8067,
8041, 8012, 7982, 7948, 7912, 7874, 7834, 7791, 7745, 7697, 7647,
7595, 7540, 7483, 7424, 7362, 7299, 7233, 7164, 7094, 7021, 6947,
6870, 6791, 6710, 6627, 6542, 6455, 6366, 6275, 6182, 6087, 5991,
5892, 5792, 5690, 5586, 5481, 5374, 5265, 5155, 5043, 4930, 4815,
4698, 4580, 4461, 4341, 4219, 4096, 3971, 3845, 3719, 3591, 3462,
3331, 3200, 3068, 2935, 2801, 2667, 2531, 2395, 2258, 2120, 1981,
1842, 1703, 1563, 1422, 1281, 1140, 998, 856, 713, 571, 428,
285, 142, 0, -142, -285, -428, -571, -713, -856, -998, -1140,
-1281, -1422, -1563, -1703, -1842, -1981, -2120, -2258, -2395, -2531, -2667,
-2801, -2935, -3068, -3200, -3331, -3462, -3591, -3719, -3845, -3971, -4095,
-4219, -4341, -4461, -4580, -4698, -4815, -4930, -5043, -5155, -5265, -5374,
-5481, -5586, -5690, -5792, -5892, -5991, -6087, -6182, -6275, -6366, -6455,
-6542, -6627, -6710, -6791, -6870, -6947, -7021, -7094, -7164, -7233, -7299,
-7362, -7424, -7483, -7540, -7595, -7647, -7697, -7745, -7791, -7834, -7874,
-7912, -7948, -7982, -8012, -8041, -8067, -8091, -8112, -8130, -8147, -8160,
-8172, -8180, -8187, -8190, -8191, -8190, -8187, -8180, -8172, -8160, -8147,
-8130, -8112, -8091, -8067, -8041, -8012, -7982, -7948, -7912, -7874, -7834,
-7791, -7745, -7697, -7647, -7595, -7540, -7483, -7424, -7362, -7299, -7233,
-7164, -7094, -7021, -6947, -6870, -6791, -6710, -6627, -6542, -6455, -6366,
-6275, -6182, -6087, -5991, -5892, -5792, -5690, -5586, -5481, -5374, -5265,
-5155, -5043, -4930, -4815, -4698, -4580, -4461, -4341, -4219, -4096, -3971,
-3845, -3719, -3591, -3462, -3331, -3200, -3068, -2935, -2801, -2667, -2531,
-2395, -2258, -2120, -1981, -1842, -1703, -1563, -1422, -1281, -1140, -998,
-856, -713, -571, -428, -285, -142, 0, 142, 285, 428, 571,
713, 856, 998, 1140, 1281, 1422, 1563, 1703, 1842, 1981, 2120,
2258, 2395, 2531, 2667, 2801, 2935, 3068, 3200, 3331, 3462, 3591,
3719, 3845, 3971, 4095, 4219, 4341, 4461, 4580, 4698, 4815, 4930,
5043, 5155, 5265, 5374, 5481, 5586, 5690, 5792, 5892, 5991, 6087,
6182, 6275, 6366, 6455, 6542, 6627, 6710, 6791, 6870, 6947, 7021,
7094, 7164, 7233, 7299, 7362, 7424, 7483, 7540, 7595, 7647, 7697,
7745, 7791, 7834, 7874, 7912, 7948, 7982, 8012, 8041, 8067, 8091,
8112, 8130, 8147, 8160, 8172, 8180, 8187, 8190};
const int16_t WebRtcAecm_kSinTable[] = {
0, 142, 285, 428, 571, 713, 856, 998, 1140, 1281, 1422,
1563, 1703, 1842, 1981, 2120, 2258, 2395, 2531, 2667, 2801, 2935,
3068, 3200, 3331, 3462, 3591, 3719, 3845, 3971, 4095, 4219, 4341,
4461, 4580, 4698, 4815, 4930, 5043, 5155, 5265, 5374, 5481, 5586,
5690, 5792, 5892, 5991, 6087, 6182, 6275, 6366, 6455, 6542, 6627,
6710, 6791, 6870, 6947, 7021, 7094, 7164, 7233, 7299, 7362, 7424,
7483, 7540, 7595, 7647, 7697, 7745, 7791, 7834, 7874, 7912, 7948,
7982, 8012, 8041, 8067, 8091, 8112, 8130, 8147, 8160, 8172, 8180,
8187, 8190, 8191, 8190, 8187, 8180, 8172, 8160, 8147, 8130, 8112,
8091, 8067, 8041, 8012, 7982, 7948, 7912, 7874, 7834, 7791, 7745,
7697, 7647, 7595, 7540, 7483, 7424, 7362, 7299, 7233, 7164, 7094,
7021, 6947, 6870, 6791, 6710, 6627, 6542, 6455, 6366, 6275, 6182,
6087, 5991, 5892, 5792, 5690, 5586, 5481, 5374, 5265, 5155, 5043,
4930, 4815, 4698, 4580, 4461, 4341, 4219, 4096, 3971, 3845, 3719,
3591, 3462, 3331, 3200, 3068, 2935, 2801, 2667, 2531, 2395, 2258,
2120, 1981, 1842, 1703, 1563, 1422, 1281, 1140, 998, 856, 713,
571, 428, 285, 142, 0, -142, -285, -428, -571, -713, -856,
-998, -1140, -1281, -1422, -1563, -1703, -1842, -1981, -2120, -2258, -2395,
-2531, -2667, -2801, -2935, -3068, -3200, -3331, -3462, -3591, -3719, -3845,
-3971, -4095, -4219, -4341, -4461, -4580, -4698, -4815, -4930, -5043, -5155,
-5265, -5374, -5481, -5586, -5690, -5792, -5892, -5991, -6087, -6182, -6275,
-6366, -6455, -6542, -6627, -6710, -6791, -6870, -6947, -7021, -7094, -7164,
-7233, -7299, -7362, -7424, -7483, -7540, -7595, -7647, -7697, -7745, -7791,
-7834, -7874, -7912, -7948, -7982, -8012, -8041, -8067, -8091, -8112, -8130,
-8147, -8160, -8172, -8180, -8187, -8190, -8191, -8190, -8187, -8180, -8172,
-8160, -8147, -8130, -8112, -8091, -8067, -8041, -8012, -7982, -7948, -7912,
-7874, -7834, -7791, -7745, -7697, -7647, -7595, -7540, -7483, -7424, -7362,
-7299, -7233, -7164, -7094, -7021, -6947, -6870, -6791, -6710, -6627, -6542,
-6455, -6366, -6275, -6182, -6087, -5991, -5892, -5792, -5690, -5586, -5481,
-5374, -5265, -5155, -5043, -4930, -4815, -4698, -4580, -4461, -4341, -4219,
-4096, -3971, -3845, -3719, -3591, -3462, -3331, -3200, -3068, -2935, -2801,
-2667, -2531, -2395, -2258, -2120, -1981, -1842, -1703, -1563, -1422, -1281,
-1140, -998, -856, -713, -571, -428, -285, -142};
// Moves the pointer to the next entry and inserts `far_spectrum` and
// corresponding Q-domain in its buffer.
//
// Inputs:
// - self : Pointer to the delay estimation instance
// - far_spectrum : Pointer to the far end spectrum
// - far_q : Q-domain of far end spectrum
//
void WebRtcAecm_UpdateFarHistory(AecmCore* self,
uint16_t* far_spectrum,
int far_q) {
// Get new buffer position
self->far_history_pos++;
if (self->far_history_pos >= MAX_DELAY) {
self->far_history_pos = 0;
}
// Update Q-domain buffer
self->far_q_domains[self->far_history_pos] = far_q;
// Update far end spectrum buffer
memcpy(&(self->far_history[self->far_history_pos * PART_LEN1]), far_spectrum,
sizeof(uint16_t) * PART_LEN1);
}
// Returns a pointer to the far end spectrum aligned to current near end
// spectrum. The function WebRtc_DelayEstimatorProcessFix(...) should have been
// called before AlignedFarend(...). Otherwise, you get the pointer to the
// previous frame. The memory is only valid until the next call of
// WebRtc_DelayEstimatorProcessFix(...).
//
// Inputs:
// - self : Pointer to the AECM instance.
// - delay : Current delay estimate.
//
// Output:
// - far_q : The Q-domain of the aligned far end spectrum
//
// Return value:
// - far_spectrum : Pointer to the aligned far end spectrum
// NULL - Error
//
const uint16_t* WebRtcAecm_AlignedFarend(AecmCore* self,
int* far_q,
int delay) {
int buffer_position = 0;
RTC_DCHECK(self);
buffer_position = self->far_history_pos - delay;
// Check buffer position
if (buffer_position < 0) {
buffer_position += MAX_DELAY;
}
// Get Q-domain
*far_q = self->far_q_domains[buffer_position];
// Return far end spectrum
return &(self->far_history[buffer_position * PART_LEN1]);
}
// Declare function pointers.
CalcLinearEnergies WebRtcAecm_CalcLinearEnergies;
StoreAdaptiveChannel WebRtcAecm_StoreAdaptiveChannel;
ResetAdaptiveChannel WebRtcAecm_ResetAdaptiveChannel;
AecmCore* WebRtcAecm_CreateCore() {
// Allocate zero-filled memory.
AecmCore* aecm = static_cast<AecmCore*>(calloc(1, sizeof(AecmCore)));
aecm->farFrameBuf =
WebRtc_CreateBuffer(FRAME_LEN + PART_LEN, sizeof(int16_t));
if (!aecm->farFrameBuf) {
WebRtcAecm_FreeCore(aecm);
return NULL;
}
aecm->nearNoisyFrameBuf =
WebRtc_CreateBuffer(FRAME_LEN + PART_LEN, sizeof(int16_t));
if (!aecm->nearNoisyFrameBuf) {
WebRtcAecm_FreeCore(aecm);
return NULL;
}
aecm->nearCleanFrameBuf =
WebRtc_CreateBuffer(FRAME_LEN + PART_LEN, sizeof(int16_t));
if (!aecm->nearCleanFrameBuf) {
WebRtcAecm_FreeCore(aecm);
return NULL;
}
aecm->outFrameBuf =
WebRtc_CreateBuffer(FRAME_LEN + PART_LEN, sizeof(int16_t));
if (!aecm->outFrameBuf) {
WebRtcAecm_FreeCore(aecm);
return NULL;
}
aecm->delay_estimator_farend =
WebRtc_CreateDelayEstimatorFarend(PART_LEN1, MAX_DELAY);
if (aecm->delay_estimator_farend == NULL) {
WebRtcAecm_FreeCore(aecm);
return NULL;
}
aecm->delay_estimator =
WebRtc_CreateDelayEstimator(aecm->delay_estimator_farend, 0);
if (aecm->delay_estimator == NULL) {
WebRtcAecm_FreeCore(aecm);
return NULL;
}
// TODO(bjornv): Explicitly disable robust delay validation until no
// performance regression has been established. Then remove the line.
WebRtc_enable_robust_validation(aecm->delay_estimator, 0);
aecm->real_fft = WebRtcSpl_CreateRealFFT(PART_LEN_SHIFT);
if (aecm->real_fft == NULL) {
WebRtcAecm_FreeCore(aecm);
return NULL;
}
// Init some aecm pointers. 16 and 32 byte alignment is only necessary
// for Neon code currently.
aecm->xBuf = (int16_t*)(((uintptr_t)aecm->xBuf_buf + 31) & ~31);
aecm->dBufClean = (int16_t*)(((uintptr_t)aecm->dBufClean_buf + 31) & ~31);
aecm->dBufNoisy = (int16_t*)(((uintptr_t)aecm->dBufNoisy_buf + 31) & ~31);
aecm->outBuf = (int16_t*)(((uintptr_t)aecm->outBuf_buf + 15) & ~15);
aecm->channelStored =
(int16_t*)(((uintptr_t)aecm->channelStored_buf + 15) & ~15);
aecm->channelAdapt16 =
(int16_t*)(((uintptr_t)aecm->channelAdapt16_buf + 15) & ~15);
aecm->channelAdapt32 =
(int32_t*)(((uintptr_t)aecm->channelAdapt32_buf + 31) & ~31);
return aecm;
}
void WebRtcAecm_InitEchoPathCore(AecmCore* aecm, const int16_t* echo_path) {
int i = 0;
// Reset the stored channel
memcpy(aecm->channelStored, echo_path, sizeof(int16_t) * PART_LEN1);
// Reset the adapted channels
memcpy(aecm->channelAdapt16, echo_path, sizeof(int16_t) * PART_LEN1);
for (i = 0; i < PART_LEN1; i++) {
aecm->channelAdapt32[i] = (int32_t)aecm->channelAdapt16[i] << 16;
}
// Reset channel storing variables
aecm->mseAdaptOld = 1000;
aecm->mseStoredOld = 1000;
aecm->mseThreshold = WEBRTC_SPL_WORD32_MAX;
aecm->mseChannelCount = 0;
}
static void CalcLinearEnergiesC(AecmCore* aecm,
const uint16_t* far_spectrum,
int32_t* echo_est,
uint32_t* far_energy,
uint32_t* echo_energy_adapt,
uint32_t* echo_energy_stored) {
int i;
// Get energy for the delayed far end signal and estimated
// echo using both stored and adapted channels.
for (i = 0; i < PART_LEN1; i++) {
echo_est[i] =
WEBRTC_SPL_MUL_16_U16(aecm->channelStored[i], far_spectrum[i]);
(*far_energy) += (uint32_t)(far_spectrum[i]);
*echo_energy_adapt += aecm->channelAdapt16[i] * far_spectrum[i];
(*echo_energy_stored) += (uint32_t)echo_est[i];
}
}
static void StoreAdaptiveChannelC(AecmCore* aecm,
const uint16_t* far_spectrum,
int32_t* echo_est) {
int i;
// During startup we store the channel every block.
memcpy(aecm->channelStored, aecm->channelAdapt16,
sizeof(int16_t) * PART_LEN1);
// Recalculate echo estimate
for (i = 0; i < PART_LEN; i += 4) {
echo_est[i] =
WEBRTC_SPL_MUL_16_U16(aecm->channelStored[i], far_spectrum[i]);
echo_est[i + 1] =
WEBRTC_SPL_MUL_16_U16(aecm->channelStored[i + 1], far_spectrum[i + 1]);
echo_est[i + 2] =
WEBRTC_SPL_MUL_16_U16(aecm->channelStored[i + 2], far_spectrum[i + 2]);
echo_est[i + 3] =
WEBRTC_SPL_MUL_16_U16(aecm->channelStored[i + 3], far_spectrum[i + 3]);
}
echo_est[i] = WEBRTC_SPL_MUL_16_U16(aecm->channelStored[i], far_spectrum[i]);
}
static void ResetAdaptiveChannelC(AecmCore* aecm) {
int i;
// The stored channel has a significantly lower MSE than the adaptive one for
// two consecutive calculations. Reset the adaptive channel.
memcpy(aecm->channelAdapt16, aecm->channelStored,
sizeof(int16_t) * PART_LEN1);
// Restore the W32 channel
for (i = 0; i < PART_LEN; i += 4) {
aecm->channelAdapt32[i] = (int32_t)aecm->channelStored[i] << 16;
aecm->channelAdapt32[i + 1] = (int32_t)aecm->channelStored[i + 1] << 16;
aecm->channelAdapt32[i + 2] = (int32_t)aecm->channelStored[i + 2] << 16;
aecm->channelAdapt32[i + 3] = (int32_t)aecm->channelStored[i + 3] << 16;
}
aecm->channelAdapt32[i] = (int32_t)aecm->channelStored[i] << 16;
}
// Initialize function pointers for ARM Neon platform.
#if defined(WEBRTC_HAS_NEON)
static void WebRtcAecm_InitNeon(void) {
WebRtcAecm_StoreAdaptiveChannel = WebRtcAecm_StoreAdaptiveChannelNeon;
WebRtcAecm_ResetAdaptiveChannel = WebRtcAecm_ResetAdaptiveChannelNeon;
WebRtcAecm_CalcLinearEnergies = WebRtcAecm_CalcLinearEnergiesNeon;
}
#endif
// Initialize function pointers for MIPS platform.
#if defined(MIPS32_LE)
static void WebRtcAecm_InitMips(void) {
#if defined(MIPS_DSP_R1_LE)
WebRtcAecm_StoreAdaptiveChannel = WebRtcAecm_StoreAdaptiveChannel_mips;
WebRtcAecm_ResetAdaptiveChannel = WebRtcAecm_ResetAdaptiveChannel_mips;
#endif
WebRtcAecm_CalcLinearEnergies = WebRtcAecm_CalcLinearEnergies_mips;
}
#endif
// WebRtcAecm_InitCore(...)
//
// This function initializes the AECM instant created with
// WebRtcAecm_CreateCore(...) Input:
// - aecm : Pointer to the Echo Suppression instance
// - samplingFreq : Sampling Frequency
//
// Output:
// - aecm : Initialized instance
//
// Return value : 0 - Ok
// -1 - Error
//
int WebRtcAecm_InitCore(AecmCore* const aecm, int samplingFreq) {
int i = 0;
int32_t tmp32 = PART_LEN1 * PART_LEN1;
int16_t tmp16 = PART_LEN1;
if (samplingFreq != 8000 && samplingFreq != 16000) {
samplingFreq = 8000;
return -1;
}
// sanity check of sampling frequency
aecm->mult = (int16_t)samplingFreq / 8000;
aecm->farBufWritePos = 0;
aecm->farBufReadPos = 0;
aecm->knownDelay = 0;
aecm->lastKnownDelay = 0;
WebRtc_InitBuffer(aecm->farFrameBuf);
WebRtc_InitBuffer(aecm->nearNoisyFrameBuf);
WebRtc_InitBuffer(aecm->nearCleanFrameBuf);
WebRtc_InitBuffer(aecm->outFrameBuf);
memset(aecm->xBuf_buf, 0, sizeof(aecm->xBuf_buf));
memset(aecm->dBufClean_buf, 0, sizeof(aecm->dBufClean_buf));
memset(aecm->dBufNoisy_buf, 0, sizeof(aecm->dBufNoisy_buf));
memset(aecm->outBuf_buf, 0, sizeof(aecm->outBuf_buf));
aecm->seed = 666;
aecm->totCount = 0;
if (WebRtc_InitDelayEstimatorFarend(aecm->delay_estimator_farend) != 0) {
return -1;
}
if (WebRtc_InitDelayEstimator(aecm->delay_estimator) != 0) {
return -1;
}
// Set far end histories to zero
memset(aecm->far_history, 0, sizeof(uint16_t) * PART_LEN1 * MAX_DELAY);
memset(aecm->far_q_domains, 0, sizeof(int) * MAX_DELAY);
aecm->far_history_pos = MAX_DELAY;
aecm->nlpFlag = 1;
aecm->fixedDelay = -1;
aecm->dfaCleanQDomain = 0;
aecm->dfaCleanQDomainOld = 0;
aecm->dfaNoisyQDomain = 0;
aecm->dfaNoisyQDomainOld = 0;
memset(aecm->nearLogEnergy, 0, sizeof(aecm->nearLogEnergy));
aecm->farLogEnergy = 0;
memset(aecm->echoAdaptLogEnergy, 0, sizeof(aecm->echoAdaptLogEnergy));
memset(aecm->echoStoredLogEnergy, 0, sizeof(aecm->echoStoredLogEnergy));
// Initialize the echo channels with a stored shape.
if (samplingFreq == 8000) {
WebRtcAecm_InitEchoPathCore(aecm, kChannelStored8kHz);
} else {
WebRtcAecm_InitEchoPathCore(aecm, kChannelStored16kHz);
}
memset(aecm->echoFilt, 0, sizeof(aecm->echoFilt));
memset(aecm->nearFilt, 0, sizeof(aecm->nearFilt));
aecm->noiseEstCtr = 0;
aecm->cngMode = AecmTrue;
memset(aecm->noiseEstTooLowCtr, 0, sizeof(aecm->noiseEstTooLowCtr));
memset(aecm->noiseEstTooHighCtr, 0, sizeof(aecm->noiseEstTooHighCtr));
// Shape the initial noise level to an approximate pink noise.
for (i = 0; i < (PART_LEN1 >> 1) - 1; i++) {
aecm->noiseEst[i] = (tmp32 << 8);
tmp16--;
tmp32 -= (int32_t)((tmp16 << 1) + 1);
}
for (; i < PART_LEN1; i++) {
aecm->noiseEst[i] = (tmp32 << 8);
}
aecm->farEnergyMin = WEBRTC_SPL_WORD16_MAX;
aecm->farEnergyMax = WEBRTC_SPL_WORD16_MIN;
aecm->farEnergyMaxMin = 0;
aecm->farEnergyVAD = FAR_ENERGY_MIN; // This prevents false speech detection
// at the beginning.
aecm->farEnergyMSE = 0;
aecm->currentVADValue = 0;
aecm->vadUpdateCount = 0;
aecm->firstVAD = 1;
aecm->startupState = 0;
aecm->supGain = SUPGAIN_DEFAULT;
aecm->supGainOld = SUPGAIN_DEFAULT;
aecm->supGainErrParamA = SUPGAIN_ERROR_PARAM_A;
aecm->supGainErrParamD = SUPGAIN_ERROR_PARAM_D;
aecm->supGainErrParamDiffAB = SUPGAIN_ERROR_PARAM_A - SUPGAIN_ERROR_PARAM_B;
aecm->supGainErrParamDiffBD = SUPGAIN_ERROR_PARAM_B - SUPGAIN_ERROR_PARAM_D;
// Assert a preprocessor definition at compile-time. It's an assumption
// used in assembly code, so check the assembly files before any change.
static_assert(PART_LEN % 16 == 0, "PART_LEN is not a multiple of 16");
// Initialize function pointers.
WebRtcAecm_CalcLinearEnergies = CalcLinearEnergiesC;
WebRtcAecm_StoreAdaptiveChannel = StoreAdaptiveChannelC;
WebRtcAecm_ResetAdaptiveChannel = ResetAdaptiveChannelC;
#if defined(WEBRTC_HAS_NEON)
WebRtcAecm_InitNeon();
#endif
#if defined(MIPS32_LE)
WebRtcAecm_InitMips();
#endif
return 0;
}
// TODO(bjornv): This function is currently not used. Add support for these
// parameters from a higher level
int WebRtcAecm_Control(AecmCore* aecm, int delay, int nlpFlag) {
aecm->nlpFlag = nlpFlag;
aecm->fixedDelay = delay;
return 0;
}
void WebRtcAecm_FreeCore(AecmCore* aecm) {
if (aecm == NULL) {
return;
}
WebRtc_FreeBuffer(aecm->farFrameBuf);
WebRtc_FreeBuffer(aecm->nearNoisyFrameBuf);
WebRtc_FreeBuffer(aecm->nearCleanFrameBuf);
WebRtc_FreeBuffer(aecm->outFrameBuf);
WebRtc_FreeDelayEstimator(aecm->delay_estimator);
WebRtc_FreeDelayEstimatorFarend(aecm->delay_estimator_farend);
WebRtcSpl_FreeRealFFT(aecm->real_fft);
free(aecm);
}
int WebRtcAecm_ProcessFrame(AecmCore* aecm,
const int16_t* farend,
const int16_t* nearendNoisy,
const int16_t* nearendClean,
int16_t* out) {
int16_t outBlock_buf[PART_LEN + 8]; // Align buffer to 8-byte boundary.
int16_t* outBlock = (int16_t*)(((uintptr_t)outBlock_buf + 15) & ~15);
int16_t farFrame[FRAME_LEN];
const int16_t* out_ptr = NULL;
int size = 0;
// Buffer the current frame.
// Fetch an older one corresponding to the delay.
WebRtcAecm_BufferFarFrame(aecm, farend, FRAME_LEN);
WebRtcAecm_FetchFarFrame(aecm, farFrame, FRAME_LEN, aecm->knownDelay);
// Buffer the synchronized far and near frames,
// to pass the smaller blocks individually.
WebRtc_WriteBuffer(aecm->farFrameBuf, farFrame, FRAME_LEN);
WebRtc_WriteBuffer(aecm->nearNoisyFrameBuf, nearendNoisy, FRAME_LEN);
if (nearendClean != NULL) {
WebRtc_WriteBuffer(aecm->nearCleanFrameBuf, nearendClean, FRAME_LEN);
}
// Process as many blocks as possible.
while (WebRtc_available_read(aecm->farFrameBuf) >= PART_LEN) {
int16_t far_block[PART_LEN];
const int16_t* far_block_ptr = NULL;
int16_t near_noisy_block[PART_LEN];
const int16_t* near_noisy_block_ptr = NULL;
WebRtc_ReadBuffer(aecm->farFrameBuf, (void**)&far_block_ptr, far_block,
PART_LEN);
WebRtc_ReadBuffer(aecm->nearNoisyFrameBuf, (void**)&near_noisy_block_ptr,
near_noisy_block, PART_LEN);
if (nearendClean != NULL) {
int16_t near_clean_block[PART_LEN];
const int16_t* near_clean_block_ptr = NULL;
WebRtc_ReadBuffer(aecm->nearCleanFrameBuf, (void**)&near_clean_block_ptr,
near_clean_block, PART_LEN);
if (WebRtcAecm_ProcessBlock(aecm, far_block_ptr, near_noisy_block_ptr,
near_clean_block_ptr, outBlock) == -1) {
return -1;
}
} else {
if (WebRtcAecm_ProcessBlock(aecm, far_block_ptr, near_noisy_block_ptr,
NULL, outBlock) == -1) {
return -1;
}
}
WebRtc_WriteBuffer(aecm->outFrameBuf, outBlock, PART_LEN);
}
// Stuff the out buffer if we have less than a frame to output.
// This should only happen for the first frame.
size = (int)WebRtc_available_read(aecm->outFrameBuf);
if (size < FRAME_LEN) {
WebRtc_MoveReadPtr(aecm->outFrameBuf, size - FRAME_LEN);
}
// Obtain an output frame.
WebRtc_ReadBuffer(aecm->outFrameBuf, (void**)&out_ptr, out, FRAME_LEN);
if (out_ptr != out) {
// ReadBuffer() hasn't copied to `out` in this case.
memcpy(out, out_ptr, FRAME_LEN * sizeof(int16_t));
}
return 0;
}
// WebRtcAecm_AsymFilt(...)
//
// Performs asymmetric filtering.
//
// Inputs:
// - filtOld : Previous filtered value.
// - inVal : New input value.
// - stepSizePos : Step size when we have a positive contribution.
// - stepSizeNeg : Step size when we have a negative contribution.
//
// Output:
//
// Return: - Filtered value.
//
int16_t WebRtcAecm_AsymFilt(const int16_t filtOld,
const int16_t inVal,
const int16_t stepSizePos,
const int16_t stepSizeNeg) {
int16_t retVal;
if ((filtOld == WEBRTC_SPL_WORD16_MAX) | (filtOld == WEBRTC_SPL_WORD16_MIN)) {
return inVal;
}
retVal = filtOld;
if (filtOld > inVal) {
retVal -= (filtOld - inVal) >> stepSizeNeg;
} else {
retVal += (inVal - filtOld) >> stepSizePos;
}
return retVal;
}
// ExtractFractionPart(a, zeros)
//
// returns the fraction part of `a`, with `zeros` number of leading zeros, as an
// int16_t scaled to Q8. There is no sanity check of `a` in the sense that the
// number of zeros match.
static int16_t ExtractFractionPart(uint32_t a, int zeros) {
return (int16_t)(((a << zeros) & 0x7FFFFFFF) >> 23);
}
// Calculates and returns the log of `energy` in Q8. The input `energy` is
// supposed to be in Q(`q_domain`).
static int16_t LogOfEnergyInQ8(uint32_t energy, int q_domain) {
static const int16_t kLogLowValue = PART_LEN_SHIFT << 7;
int16_t log_energy_q8 = kLogLowValue;
if (energy > 0) {
int zeros = WebRtcSpl_NormU32(energy);
int16_t frac = ExtractFractionPart(energy, zeros);
// log2 of `energy` in Q8.
log_energy_q8 += ((31 - zeros) << 8) + frac - (q_domain << 8);
}
return log_energy_q8;
}
// WebRtcAecm_CalcEnergies(...)
//
// This function calculates the log of energies for nearend, farend and
// estimated echoes. There is also an update of energy decision levels, i.e.
// internal VAD.
//
//
// @param aecm [i/o] Handle of the AECM instance.
// @param far_spectrum [in] Pointer to farend spectrum.
// @param far_q [in] Q-domain of farend spectrum.
// @param nearEner [in] Near end energy for current block in
// Q(aecm->dfaQDomain).
// @param echoEst [out] Estimated echo in Q(xfa_q+RESOLUTION_CHANNEL16).
//
void WebRtcAecm_CalcEnergies(AecmCore* aecm,
const uint16_t* far_spectrum,
const int16_t far_q,
const uint32_t nearEner,
int32_t* echoEst) {
// Local variables
uint32_t tmpAdapt = 0;
uint32_t tmpStored = 0;
uint32_t tmpFar = 0;
int i;
int16_t tmp16;
int16_t increase_max_shifts = 4;
int16_t decrease_max_shifts = 11;
int16_t increase_min_shifts = 11;
int16_t decrease_min_shifts = 3;
// Get log of near end energy and store in buffer
// Shift buffer
memmove(aecm->nearLogEnergy + 1, aecm->nearLogEnergy,
sizeof(int16_t) * (MAX_BUF_LEN - 1));
// Logarithm of integrated magnitude spectrum (nearEner)
aecm->nearLogEnergy[0] = LogOfEnergyInQ8(nearEner, aecm->dfaNoisyQDomain);
WebRtcAecm_CalcLinearEnergies(aecm, far_spectrum, echoEst, &tmpFar, &tmpAdapt,
&tmpStored);
// Shift buffers
memmove(aecm->echoAdaptLogEnergy + 1, aecm->echoAdaptLogEnergy,
sizeof(int16_t) * (MAX_BUF_LEN - 1));
memmove(aecm->echoStoredLogEnergy + 1, aecm->echoStoredLogEnergy,
sizeof(int16_t) * (MAX_BUF_LEN - 1));
// Logarithm of delayed far end energy
aecm->farLogEnergy = LogOfEnergyInQ8(tmpFar, far_q);
// Logarithm of estimated echo energy through adapted channel
aecm->echoAdaptLogEnergy[0] =
LogOfEnergyInQ8(tmpAdapt, RESOLUTION_CHANNEL16 + far_q);
// Logarithm of estimated echo energy through stored channel
aecm->echoStoredLogEnergy[0] =
LogOfEnergyInQ8(tmpStored, RESOLUTION_CHANNEL16 + far_q);
// Update farend energy levels (min, max, vad, mse)
if (aecm->farLogEnergy > FAR_ENERGY_MIN) {
if (aecm->startupState == 0) {
increase_max_shifts = 2;
decrease_min_shifts = 2;
increase_min_shifts = 8;
}
aecm->farEnergyMin =
WebRtcAecm_AsymFilt(aecm->farEnergyMin, aecm->farLogEnergy,
increase_min_shifts, decrease_min_shifts);
aecm->farEnergyMax =
WebRtcAecm_AsymFilt(aecm->farEnergyMax, aecm->farLogEnergy,
increase_max_shifts, decrease_max_shifts);
aecm->farEnergyMaxMin = (aecm->farEnergyMax - aecm->farEnergyMin);
// Dynamic VAD region size
tmp16 = 2560 - aecm->farEnergyMin;
if (tmp16 > 0) {
tmp16 = (int16_t)((tmp16 * FAR_ENERGY_VAD_REGION) >> 9);
} else {
tmp16 = 0;
}
tmp16 += FAR_ENERGY_VAD_REGION;
if ((aecm->startupState == 0) | (aecm->vadUpdateCount > 1024)) {
// In startup phase or VAD update halted
aecm->farEnergyVAD = aecm->farEnergyMin + tmp16;
} else {
if (aecm->farEnergyVAD > aecm->farLogEnergy) {
aecm->farEnergyVAD +=
(aecm->farLogEnergy + tmp16 - aecm->farEnergyVAD) >> 6;
aecm->vadUpdateCount = 0;
} else {
aecm->vadUpdateCount++;
}
}
// Put MSE threshold higher than VAD
aecm->farEnergyMSE = aecm->farEnergyVAD + (1 << 8);
}
// Update VAD variables
if (aecm->farLogEnergy > aecm->farEnergyVAD) {
if ((aecm->startupState == 0) | (aecm->farEnergyMaxMin > FAR_ENERGY_DIFF)) {
// We are in startup or have significant dynamics in input speech level
aecm->currentVADValue = 1;
}
} else {
aecm->currentVADValue = 0;
}
if ((aecm->currentVADValue) && (aecm->firstVAD)) {
aecm->firstVAD = 0;
if (aecm->echoAdaptLogEnergy[0] > aecm->nearLogEnergy[0]) {
// The estimated echo has higher energy than the near end signal.
// This means that the initialization was too aggressive. Scale
// down by a factor 8
for (i = 0; i < PART_LEN1; i++) {
aecm->channelAdapt16[i] >>= 3;
}
// Compensate the adapted echo energy level accordingly.
aecm->echoAdaptLogEnergy[0] -= (3 << 8);
aecm->firstVAD = 1;
}
}
}
// WebRtcAecm_CalcStepSize(...)
//
// This function calculates the step size used in channel estimation
//
//
// @param aecm [in] Handle of the AECM instance.
// @param mu [out] (Return value) Stepsize in log2(), i.e. number of
// shifts.
//
//
int16_t WebRtcAecm_CalcStepSize(AecmCore* const aecm) {
int32_t tmp32;
int16_t tmp16;
int16_t mu = MU_MAX;
// Here we calculate the step size mu used in the
// following NLMS based Channel estimation algorithm
if (!aecm->currentVADValue) {
// Far end energy level too low, no channel update
mu = 0;
} else if (aecm->startupState > 0) {
if (aecm->farEnergyMin >= aecm->farEnergyMax) {
mu = MU_MIN;
} else {
tmp16 = (aecm->farLogEnergy - aecm->farEnergyMin);
tmp32 = tmp16 * MU_DIFF;
tmp32 = WebRtcSpl_DivW32W16(tmp32, aecm->farEnergyMaxMin);
mu = MU_MIN - 1 - (int16_t)(tmp32);
// The -1 is an alternative to rounding. This way we get a larger
// stepsize, so we in some sense compensate for truncation in NLMS
}
if (mu < MU_MAX) {
mu = MU_MAX; // Equivalent with maximum step size of 2^-MU_MAX
}
}
return mu;
}
// WebRtcAecm_UpdateChannel(...)
//
// This function performs channel estimation. NLMS and decision on channel
// storage.
//
//
// @param aecm [i/o] Handle of the AECM instance.
// @param far_spectrum [in] Absolute value of the farend signal in Q(far_q)
// @param far_q [in] Q-domain of the farend signal
// @param dfa [in] Absolute value of the nearend signal
// (Q[aecm->dfaQDomain])
// @param mu [in] NLMS step size.
// @param echoEst [i/o] Estimated echo in Q(far_q+RESOLUTION_CHANNEL16).
//
void WebRtcAecm_UpdateChannel(AecmCore* aecm,
const uint16_t* far_spectrum,
const int16_t far_q,
const uint16_t* const dfa,
const int16_t mu,
int32_t* echoEst) {
uint32_t tmpU32no1, tmpU32no2;
int32_t tmp32no1, tmp32no2;
int32_t mseStored;
int32_t mseAdapt;
int i;
int16_t zerosFar, zerosNum, zerosCh, zerosDfa;
int16_t shiftChFar, shiftNum, shift2ResChan;
int16_t tmp16no1;
int16_t xfaQ, dfaQ;
// This is the channel estimation algorithm. It is base on NLMS but has a
// variable step length, which was calculated above.
if (mu) {
for (i = 0; i < PART_LEN1; i++) {
// Determine norm of channel and farend to make sure we don't get overflow
// in multiplication
zerosCh = WebRtcSpl_NormU32(aecm->channelAdapt32[i]);
zerosFar = WebRtcSpl_NormU32((uint32_t)far_spectrum[i]);
if (zerosCh + zerosFar > 31) {
// Multiplication is safe
tmpU32no1 =
WEBRTC_SPL_UMUL_32_16(aecm->channelAdapt32[i], far_spectrum[i]);
shiftChFar = 0;
} else {
// We need to shift down before multiplication
shiftChFar = 32 - zerosCh - zerosFar;
// If zerosCh == zerosFar == 0, shiftChFar is 32. A
// right shift of 32 is undefined. To avoid that, we
// do this check.
tmpU32no1 =
rtc::dchecked_cast<uint32_t>(
shiftChFar >= 32 ? 0 : aecm->channelAdapt32[i] >> shiftChFar) *
far_spectrum[i];
}
// Determine Q-domain of numerator
zerosNum = WebRtcSpl_NormU32(tmpU32no1);
if (dfa[i]) {
zerosDfa = WebRtcSpl_NormU32((uint32_t)dfa[i]);
} else {
zerosDfa = 32;
}
tmp16no1 = zerosDfa - 2 + aecm->dfaNoisyQDomain - RESOLUTION_CHANNEL32 -
far_q + shiftChFar;
if (zerosNum > tmp16no1 + 1) {
xfaQ = tmp16no1;
dfaQ = zerosDfa - 2;
} else {
xfaQ = zerosNum - 2;
dfaQ = RESOLUTION_CHANNEL32 + far_q - aecm->dfaNoisyQDomain -
shiftChFar + xfaQ;
}
// Add in the same Q-domain
tmpU32no1 = WEBRTC_SPL_SHIFT_W32(tmpU32no1, xfaQ);
tmpU32no2 = WEBRTC_SPL_SHIFT_W32((uint32_t)dfa[i], dfaQ);
tmp32no1 = (int32_t)tmpU32no2 - (int32_t)tmpU32no1;
zerosNum = WebRtcSpl_NormW32(tmp32no1);
if ((tmp32no1) && (far_spectrum[i] > (CHANNEL_VAD << far_q))) {
//
// Update is needed
//
// This is what we would like to compute
//
// tmp32no1 = dfa[i] - (aecm->channelAdapt[i] * far_spectrum[i])
// tmp32norm = (i + 1)
// aecm->channelAdapt[i] += (2^mu) * tmp32no1
// / (tmp32norm * far_spectrum[i])
//
// Make sure we don't get overflow in multiplication.
if (zerosNum + zerosFar > 31) {
if (tmp32no1 > 0) {
tmp32no2 =
(int32_t)WEBRTC_SPL_UMUL_32_16(tmp32no1, far_spectrum[i]);
} else {
tmp32no2 =
-(int32_t)WEBRTC_SPL_UMUL_32_16(-tmp32no1, far_spectrum[i]);
}
shiftNum = 0;
} else {
shiftNum = 32 - (zerosNum + zerosFar);
if (tmp32no1 > 0) {
tmp32no2 = (tmp32no1 >> shiftNum) * far_spectrum[i];
} else {
tmp32no2 = -((-tmp32no1 >> shiftNum) * far_spectrum[i]);
}
}
// Normalize with respect to frequency bin
tmp32no2 = WebRtcSpl_DivW32W16(tmp32no2, i + 1);
// Make sure we are in the right Q-domain
shift2ResChan =
shiftNum + shiftChFar - xfaQ - mu - ((30 - zerosFar) << 1);
if (WebRtcSpl_NormW32(tmp32no2) < shift2ResChan) {
tmp32no2 = WEBRTC_SPL_WORD32_MAX;
} else {
tmp32no2 = WEBRTC_SPL_SHIFT_W32(tmp32no2, shift2ResChan);
}
aecm->channelAdapt32[i] =
WebRtcSpl_AddSatW32(aecm->channelAdapt32[i], tmp32no2);
if (aecm->channelAdapt32[i] < 0) {
// We can never have negative channel gain
aecm->channelAdapt32[i] = 0;
}
aecm->channelAdapt16[i] = (int16_t)(aecm->channelAdapt32[i] >> 16);
}
}
}
// END: Adaptive channel update
// Determine if we should store or restore the channel
if ((aecm->startupState == 0) & (aecm->currentVADValue)) {
// During startup we store the channel every block,
// and we recalculate echo estimate
WebRtcAecm_StoreAdaptiveChannel(aecm, far_spectrum, echoEst);
} else {
if (aecm->farLogEnergy < aecm->farEnergyMSE) {
aecm->mseChannelCount = 0;
} else {
aecm->mseChannelCount++;
}
// Enough data for validation. Store channel if we can.
if (aecm->mseChannelCount >= (MIN_MSE_COUNT + 10)) {
// We have enough data.
// Calculate MSE of "Adapt" and "Stored" versions.
// It is actually not MSE, but average absolute error.
mseStored = 0;
mseAdapt = 0;
for (i = 0; i < MIN_MSE_COUNT; i++) {
tmp32no1 = ((int32_t)aecm->echoStoredLogEnergy[i] -
(int32_t)aecm->nearLogEnergy[i]);
tmp32no2 = WEBRTC_SPL_ABS_W32(tmp32no1);
mseStored += tmp32no2;
tmp32no1 = ((int32_t)aecm->echoAdaptLogEnergy[i] -
(int32_t)aecm->nearLogEnergy[i]);
tmp32no2 = WEBRTC_SPL_ABS_W32(tmp32no1);
mseAdapt += tmp32no2;
}
if (((mseStored << MSE_RESOLUTION) < (MIN_MSE_DIFF * mseAdapt)) &
((aecm->mseStoredOld << MSE_RESOLUTION) <
(MIN_MSE_DIFF * aecm->mseAdaptOld))) {
// The stored channel has a significantly lower MSE than the adaptive
// one for two consecutive calculations. Reset the adaptive channel.
WebRtcAecm_ResetAdaptiveChannel(aecm);
} else if (((MIN_MSE_DIFF * mseStored) > (mseAdapt << MSE_RESOLUTION)) &
(mseAdapt < aecm->mseThreshold) &
(aecm->mseAdaptOld < aecm->mseThreshold)) {
// The adaptive channel has a significantly lower MSE than the stored
// one. The MSE for the adaptive channel has also been low for two
// consecutive calculations. Store the adaptive channel.
WebRtcAecm_StoreAdaptiveChannel(aecm, far_spectrum, echoEst);
// Update threshold
if (aecm->mseThreshold == WEBRTC_SPL_WORD32_MAX) {
aecm->mseThreshold = (mseAdapt + aecm->mseAdaptOld);
} else {
int scaled_threshold = aecm->mseThreshold * 5 / 8;
aecm->mseThreshold += ((mseAdapt - scaled_threshold) * 205) >> 8;
}
}
// Reset counter
aecm->mseChannelCount = 0;
// Store the MSE values.
aecm->mseStoredOld = mseStored;
aecm->mseAdaptOld = mseAdapt;
}
}
// END: Determine if we should store or reset channel estimate.
}
// CalcSuppressionGain(...)
//
// This function calculates the suppression gain that is used in the Wiener
// filter.
//
//
// @param aecm [i/n] Handle of the AECM instance.
// @param supGain [out] (Return value) Suppression gain with which to scale
// the noise
// level (Q14).
//
//
int16_t WebRtcAecm_CalcSuppressionGain(AecmCore* const aecm) {
int32_t tmp32no1;
int16_t supGain = SUPGAIN_DEFAULT;
int16_t tmp16no1;
int16_t dE = 0;
// Determine suppression gain used in the Wiener filter. The gain is based on
// a mix of far end energy and echo estimation error. Adjust for the far end
// signal level. A low signal level indicates no far end signal, hence we set
// the suppression gain to 0
if (!aecm->currentVADValue) {
supGain = 0;
} else {
// Adjust for possible double talk. If we have large variations in
// estimation error we likely have double talk (or poor channel).
tmp16no1 = (aecm->nearLogEnergy[0] - aecm->echoStoredLogEnergy[0] -
ENERGY_DEV_OFFSET);
dE = WEBRTC_SPL_ABS_W16(tmp16no1);
if (dE < ENERGY_DEV_TOL) {
// Likely no double talk. The better estimation, the more we can suppress
// signal. Update counters
if (dE < SUPGAIN_EPC_DT) {
tmp32no1 = aecm->supGainErrParamDiffAB * dE;
tmp32no1 += (SUPGAIN_EPC_DT >> 1);
tmp16no1 = (int16_t)WebRtcSpl_DivW32W16(tmp32no1, SUPGAIN_EPC_DT);
supGain = aecm->supGainErrParamA - tmp16no1;
} else {
tmp32no1 = aecm->supGainErrParamDiffBD * (ENERGY_DEV_TOL - dE);
tmp32no1 += ((ENERGY_DEV_TOL - SUPGAIN_EPC_DT) >> 1);
tmp16no1 = (int16_t)WebRtcSpl_DivW32W16(
tmp32no1, (ENERGY_DEV_TOL - SUPGAIN_EPC_DT));
supGain = aecm->supGainErrParamD + tmp16no1;
}
} else {
// Likely in double talk. Use default value
supGain = aecm->supGainErrParamD;
}
}
if (supGain > aecm->supGainOld) {
tmp16no1 = supGain;
} else {
tmp16no1 = aecm->supGainOld;
}
aecm->supGainOld = supGain;
if (tmp16no1 < aecm->supGain) {
aecm->supGain += (int16_t)((tmp16no1 - aecm->supGain) >> 4);
} else {
aecm->supGain += (int16_t)((tmp16no1 - aecm->supGain) >> 4);
}
// END: Update suppression gain
return aecm->supGain;
}
void WebRtcAecm_BufferFarFrame(AecmCore* const aecm,
const int16_t* const farend,
const int farLen) {
int writeLen = farLen, writePos = 0;
// Check if the write position must be wrapped
while (aecm->farBufWritePos + writeLen > FAR_BUF_LEN) {
// Write to remaining buffer space before wrapping
writeLen = FAR_BUF_LEN - aecm->farBufWritePos;
memcpy(aecm->farBuf + aecm->farBufWritePos, farend + writePos,
sizeof(int16_t) * writeLen);
aecm->farBufWritePos = 0;
writePos = writeLen;
writeLen = farLen - writeLen;
}
memcpy(aecm->farBuf + aecm->farBufWritePos, farend + writePos,
sizeof(int16_t) * writeLen);
aecm->farBufWritePos += writeLen;
}
void WebRtcAecm_FetchFarFrame(AecmCore* const aecm,
int16_t* const farend,
const int farLen,
const int knownDelay) {
int readLen = farLen;
int readPos = 0;
int delayChange = knownDelay - aecm->lastKnownDelay;
aecm->farBufReadPos -= delayChange;
// Check if delay forces a read position wrap
while (aecm->farBufReadPos < 0) {
aecm->farBufReadPos += FAR_BUF_LEN;
}
while (aecm->farBufReadPos > FAR_BUF_LEN - 1) {
aecm->farBufReadPos -= FAR_BUF_LEN;
}
aecm->lastKnownDelay = knownDelay;
// Check if read position must be wrapped
while (aecm->farBufReadPos + readLen > FAR_BUF_LEN) {
// Read from remaining buffer space before wrapping
readLen = FAR_BUF_LEN - aecm->farBufReadPos;
memcpy(farend + readPos, aecm->farBuf + aecm->farBufReadPos,
sizeof(int16_t) * readLen);
aecm->farBufReadPos = 0;
readPos = readLen;
readLen = farLen - readLen;
}
memcpy(farend + readPos, aecm->farBuf + aecm->farBufReadPos,
sizeof(int16_t) * readLen);
aecm->farBufReadPos += readLen;
}
} // namespace webrtc