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AEC3: Delay estimator uses bandpass filtered signal with downsampling factor 8

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Letting the delay estimator operate at a sampling frequency of 2 kHz
with audio between 0 and 1 kHz makes it sensitive to noisy environments.
This CL bandpass filters the 16 kHz signal before downsampling to 2 kHz
in a way that the downsampled 2 kHz signal contains audio between 1 and
2 kHz. It also sets downsampling factor 8 as default which significantly
reduces computational complexity.

Bug: webrtc:9288,chromium:846615
Change-Id: Iaf67898a1a14326cd61bb7f81c14d3c12a697c8d
Reviewed-on: https://webrtc-review.googlesource.com/78703
Commit-Queue: Gustaf Ullberg <gustaf@webrtc.org>
Reviewed-by: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23395}
This commit is contained in:
Gustaf Ullberg 2018-05-25 10:12:58 +02:00 committed by Commit Bot
parent 90d05e9230
commit 78b1c4a487
5 changed files with 51 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
api/audio/echo_canceller3_config.h
View File

@ -21,7 +21,7 @@ struct EchoCanceller3Config {
EchoCanceller3Config(const EchoCanceller3Config& e);
struct Delay {
size_t default_delay = 5;
size_t down_sampling_factor = 4;
size_t down_sampling_factor = 8;
size_t num_filters = 5;
size_t api_call_jitter_blocks = 26;
size_t min_echo_path_delay_blocks = 0;

34
modules/audio_processing/aec3/decimator.cc
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@ -28,32 +28,39 @@ const CascadedBiQuadFilter::BiQuadCoefficients kLowPassFilterCoefficients4 = {
{-1.5879f, 0.6594f}};
constexpr int kNumFilters4 = 3;
// b, a = signal.butter(2, 800/8000.0, 'lowpass', analog=False) which are the
// same as b, a = signal.butter(2, 400/4000.0, 'lowpass', analog=False).
const CascadedBiQuadFilter::BiQuadCoefficients kLowPassFilterCoefficients8 = {
{0.02008337f, 0.04016673f, 0.02008337f},
{-1.56101808f, 0.64135154f}};
constexpr int kNumFilters8 = 4;
// b, a = signal.cheby1(1, 6, [1000/8000, 2000/8000], btype='bandpass',
// analog=False)
const CascadedBiQuadFilter::BiQuadCoefficients kBandPassFilterCoefficients8 = {
{0.10330478f, 0.f, -0.10330478f},
{-1.520363f, 0.79339043f}};
constexpr int kNumFilters8 = 5;
// b, a = signal.butter(2, 1000/8000.0, 'highpass', analog=False)
const CascadedBiQuadFilter::BiQuadCoefficients kHighPassFilterCoefficients4 = {
const CascadedBiQuadFilter::BiQuadCoefficients kHighPassFilterCoefficients = {
{0.75707638f, -1.51415275f, 0.75707638f},
{-1.45424359f, 0.57406192f}};
constexpr int kNumFiltersHP2 = 1;
constexpr int kNumFiltersHP4 = 1;
constexpr int kNumFiltersHP8 = 0;
} // namespace
Decimator::Decimator(size_t down_sampling_factor)
: down_sampling_factor_(down_sampling_factor),
low_pass_filter_(
anti_aliasing_filter_(
down_sampling_factor_ == 4
? kLowPassFilterCoefficients4
: (down_sampling_factor_ == 8 ? kLowPassFilterCoefficients8
: (down_sampling_factor_ == 8 ? kBandPassFilterCoefficients8
: kLowPassFilterCoefficients2),
down_sampling_factor_ == 4
? kNumFilters4
: (down_sampling_factor_ == 8 ? kNumFilters8 : kNumFilters2)),
high_pass_filter_(kHighPassFilterCoefficients4, kNumFiltersHP4) {
noise_reduction_filter_(
kHighPassFilterCoefficients,
down_sampling_factor_ == 4
? kNumFiltersHP4
: (down_sampling_factor_ == 8 ? kNumFiltersHP8
: kNumFiltersHP2)) {
RTC_DCHECK(down_sampling_factor_ == 2 || down_sampling_factor_ == 4 ||
down_sampling_factor_ == 8);
}
@ -65,11 +72,10 @@ void Decimator::Decimate(rtc::ArrayView<const float> in,
std::array<float, kBlockSize> x;
// Limit the frequency content of the signal to avoid aliasing.
low_pass_filter_.Process(in, x);
anti_aliasing_filter_.Process(in, x);
// High-pass filter to reduce the impact of near-end noise.
if (down_sampling_factor_ == 4)
high_pass_filter_.Process(x, x);
// Reduce the impact of near-end noise.
noise_reduction_filter_.Process(x);
// Downsample the signal.
for (size_t j = 0, k = 0; j < out.size(); ++j, k += down_sampling_factor_) {

4
modules/audio_processing/aec3/decimator.h
View File

@ -30,8 +30,8 @@ class Decimator {
private:
const size_t down_sampling_factor_;
CascadedBiQuadFilter low_pass_filter_;
CascadedBiQuadFilter high_pass_filter_;
CascadedBiQuadFilter anti_aliasing_filter_;
CascadedBiQuadFilter noise_reduction_filter_;
RTC_DISALLOW_COPY_AND_ASSIGN(Decimator);
};

12
modules/audio_processing/aec3/echo_path_delay_estimator.cc
View File

@ -16,14 +16,24 @@
#include "modules/audio_processing/aec3/aec3_common.h"
#include "modules/audio_processing/logging/apm_data_dumper.h"
#include "rtc_base/checks.h"
#include "system_wrappers/include/field_trial.h"
namespace webrtc {
namespace {
size_t GetDownSamplingFactor(const EchoCanceller3Config& config) {
// Do not use down sampling factor 8 if kill switch is triggered.
return (config.delay.down_sampling_factor == 8 &&
field_trial::IsEnabled("WebRTC-Aec3DownSamplingFactor8KillSwitch"))
? 4
: config.delay.down_sampling_factor;
}
} // namespace
EchoPathDelayEstimator::EchoPathDelayEstimator(
ApmDataDumper* data_dumper,
const EchoCanceller3Config& config)
: data_dumper_(data_dumper),
down_sampling_factor_(config.delay.down_sampling_factor),
down_sampling_factor_(GetDownSamplingFactor(config)),
sub_block_size_(down_sampling_factor_ != 0
? kBlockSize / down_sampling_factor_
: kBlockSize),

25
modules/audio_processing/aec3/render_delay_buffer.cc
View File

@ -35,6 +35,14 @@ bool EnableZeroExternalDelayHeadroom() {
"WebRTC-Aec3ZeroExternalDelayHeadroomKillSwitch");
}
size_t GetDownSamplingFactor(const EchoCanceller3Config& config) {
// Do not use down sampling factor 8 if kill switch is triggered.
return (config.delay.down_sampling_factor == 8 &&
field_trial::IsEnabled("WebRTC-Aec3DownSamplingFactor8KillSwitch"))
? 4
: config.delay.down_sampling_factor;
}
class RenderDelayBufferImpl final : public RenderDelayBuffer {
public:
RenderDelayBufferImpl(const EchoCanceller3Config& config, size_t num_bands);
@ -63,6 +71,7 @@ class RenderDelayBufferImpl final : public RenderDelayBuffer {
std::unique_ptr<ApmDataDumper> data_dumper_;
const Aec3Optimization optimization_;
const EchoCanceller3Config config_;
size_t down_sampling_factor_;
const bool use_zero_external_delay_headroom_;
const int sub_block_size_;
MatrixBuffer blocks_;
@ -168,12 +177,12 @@ RenderDelayBufferImpl::RenderDelayBufferImpl(const EchoCanceller3Config& config,
new ApmDataDumper(rtc::AtomicOps::Increment(&instance_count_))),
optimization_(DetectOptimization()),
config_(config),
down_sampling_factor_(GetDownSamplingFactor(config)),
use_zero_external_delay_headroom_(EnableZeroExternalDelayHeadroom()),
sub_block_size_(
static_cast<int>(config.delay.down_sampling_factor > 0
? kBlockSize / config.delay.down_sampling_factor
: kBlockSize)),
blocks_(GetRenderDelayBufferSize(config.delay.down_sampling_factor,
sub_block_size_(static_cast<int>(down_sampling_factor_ > 0
? kBlockSize / down_sampling_factor_
: kBlockSize)),
blocks_(GetRenderDelayBufferSize(down_sampling_factor_,
config.delay.num_filters,
config.filter.main.length_blocks),
num_bands,
@ -182,9 +191,9 @@ RenderDelayBufferImpl::RenderDelayBufferImpl(const EchoCanceller3Config& config,
ffts_(blocks_.buffer.size()),
delay_(config_.delay.default_delay),
echo_remover_buffer_(&blocks_, &spectra_, &ffts_),
low_rate_(GetDownSampledBufferSize(config.delay.down_sampling_factor,
low_rate_(GetDownSampledBufferSize(down_sampling_factor_,
config.delay.num_filters)),
render_decimator_(config.delay.down_sampling_factor),
render_decimator_(down_sampling_factor_),
zero_block_(num_bands, std::vector<float>(kBlockSize, 0.f)),
fft_(),
render_ds_(sub_block_size_, 0.f),
@ -433,7 +442,7 @@ void RenderDelayBufferImpl::InsertBlock(
block[0].data(), 16000, 1);
render_decimator_.Decimate(block[0], ds);
data_dumper_->DumpWav("aec3_render_decimator_output", ds.size(), ds.data(),
16000 / config_.delay.down_sampling_factor, 1);
16000 / down_sampling_factor_, 1);
std::copy(ds.rbegin(), ds.rend(), lr.buffer.begin() + lr.write);
fft_.PaddedFft(block[0], b.buffer[previous_write][0], &f.buffer[f.write]);
f.buffer[f.write].Spectrum(optimization_, s.buffer[s.write]);