AEC3: Move decimator filters to the new notation
Preparing for changing the filters of the decimator by moving the old
filters to the new zero, pole, gain notation.
Bug: webrtc:9288,chromium:846615
Change-Id: I2b01a2555d34617e0bf251c782703753f72cd56f
Reviewed-on: https://webrtc-review.googlesource.com/81189
Reviewed-by: Per Åhgren <peah@webrtc.org>
Commit-Queue: Gustaf Ullberg <gustaf@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23528}diff --git a/modules/audio_processing/aec3/cascaded_biquad_filter.cc b/modules/audio_processing/aec3/cascaded_biquad_filter.cc
index 5881d60..333d226 100644
--- a/modules/audio_processing/aec3/cascaded_biquad_filter.cc
+++ b/modules/audio_processing/aec3/cascaded_biquad_filter.cc
@@ -15,8 +15,14 @@
CascadedBiQuadFilter::BiQuadParam::BiQuadParam(std::complex<float> zero,
std::complex<float> pole,
- float gain)
- : zero(zero), pole(pole), gain(gain) {}
+ float gain,
+ bool mirror_zero_along_i_axis)
+ : zero(zero),
+ pole(pole),
+ gain(gain),
+ mirror_zero_along_i_axis(mirror_zero_along_i_axis) {}
+
+CascadedBiQuadFilter::BiQuadParam::BiQuadParam(const BiQuadParam&) = default;
CascadedBiQuadFilter::BiQuad::BiQuad(
const CascadedBiQuadFilter::BiQuadParam& param)
@@ -27,10 +33,20 @@
float p_i = std::imag(param.pole);
float gain = param.gain;
- coefficients.b[0] = gain * 1.f;
- coefficients.b[1] = gain * -2.f * z_r;
- coefficients.b[2] = gain * (z_r * z_r + z_i * z_i);
+ if (param.mirror_zero_along_i_axis) {
+ // Assuming zeroes at z_r and -z_r.
+ RTC_DCHECK(z_i == 0.f);
+ coefficients.b[0] = gain * 1.f;
+ coefficients.b[1] = 0.f;
+ coefficients.b[2] = gain * -(z_r * z_r);
+ } else {
+ // Assuming zeros at (z_r + z_i*i) and (z_r - z_i*i).
+ coefficients.b[0] = gain * 1.f;
+ coefficients.b[1] = gain * -2.f * z_r;
+ coefficients.b[2] = gain * (z_r * z_r + z_i * z_i);
+ }
+ // Assuming poles at (p_r + p_i*i) and (p_r - p_i*i).
coefficients.a[0] = -2.f * p_r;
coefficients.a[1] = p_r * p_r + p_i * p_i;
}
diff --git a/modules/audio_processing/aec3/cascaded_biquad_filter.h b/modules/audio_processing/aec3/cascaded_biquad_filter.h
index feae68d..1e09fa6 100644
--- a/modules/audio_processing/aec3/cascaded_biquad_filter.h
+++ b/modules/audio_processing/aec3/cascaded_biquad_filter.h
@@ -24,10 +24,15 @@
class CascadedBiQuadFilter {
public:
struct BiQuadParam {
- BiQuadParam(std::complex<float> zero, std::complex<float> pole, float gain);
+ BiQuadParam(std::complex<float> zero,
+ std::complex<float> pole,
+ float gain,
+ bool mirror_zero_along_i_axis = false);
+ BiQuadParam(const BiQuadParam&);
std::complex<float> zero;
std::complex<float> pole;
float gain;
+ bool mirror_zero_along_i_axis;
};
struct BiQuadCoefficients {
diff --git a/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc b/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc
index 0f1b0db..57f4b04 100644
--- a/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc
+++ b/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc
@@ -123,4 +123,18 @@
EXPECT_NEAR(filter.coefficients.a[1], 0.57406192f, epsilon);
}
+// Verifies the conversion from zero, pole, gain to filter coefficients for
+// bandpass filter.
+TEST(CascadedBiquadFilter, BiQuadParamBandPass) {
+ CascadedBiQuadFilter::BiQuadParam param(
+ {1.0f, 0.0f}, {1.11022302e-16f, 0.71381051f}, 0.2452372752527856f, true);
+ CascadedBiQuadFilter::BiQuad filter(param);
+ const float epsilon = 1e-6f;
+ EXPECT_NEAR(filter.coefficients.b[0], 0.24523728f, epsilon);
+ EXPECT_NEAR(filter.coefficients.b[1], 0.f, epsilon);
+ EXPECT_NEAR(filter.coefficients.b[2], -0.24523728f, epsilon);
+ EXPECT_NEAR(filter.coefficients.a[0], -2.22044605e-16f, epsilon);
+ EXPECT_NEAR(filter.coefficients.a[1], 5.09525449e-01f, epsilon);
+}
+
} // namespace webrtc
diff --git a/modules/audio_processing/aec3/decimator.cc b/modules/audio_processing/aec3/decimator.cc
index 8fffc8a..0ebc7db 100644
--- a/modules/audio_processing/aec3/decimator.cc
+++ b/modules/audio_processing/aec3/decimator.cc
@@ -14,53 +14,42 @@
namespace webrtc {
namespace {
-// b, a = signal.butter(2, 3400/8000.0, 'lowpass', analog=False) which are the
-// same as b, a = signal.butter(2, 1700/4000.0, 'lowpass', analog=False).
-const CascadedBiQuadFilter::BiQuadCoefficients kLowPassFilterCoefficients2 = {
- {0.22711796f, 0.45423593f, 0.22711796f},
- {-0.27666461f, 0.18513647f}};
-constexpr int kNumFilters2 = 3;
+// signal.butter(2, 3400/8000.0, 'lowpass', analog=False)
+const std::vector<CascadedBiQuadFilter::BiQuadParam> kLowPassFilterDS2 = {
+ {{-1.f, 0.f}, {0.13833231f, 0.40743176f}, 0.22711796393486466f},
+ {{-1.f, 0.f}, {0.13833231f, 0.40743176f}, 0.22711796393486466f},
+ {{-1.f, 0.f}, {0.13833231f, 0.40743176f}, 0.22711796393486466f}};
-// b, a = signal.butter(2, 750/8000.0, 'lowpass', analog=False) which are the
-// same as b, a = signal.butter(2, 375/4000.0, 'lowpass', analog=False).
-const CascadedBiQuadFilter::BiQuadCoefficients kLowPassFilterCoefficients4 = {
- {0.0179f, 0.0357f, 0.0179f},
- {-1.5879f, 0.6594f}};
-constexpr int kNumFilters4 = 3;
+// signal.butter(2, 750/8000.0, 'lowpass', analog=False)
+const std::vector<CascadedBiQuadFilter::BiQuadParam> kLowPassFilterDS4 = {
+ {{-1.f, 0.f}, {0.79396855f, 0.17030506f}, 0.017863192751682862f},
+ {{-1.f, 0.f}, {0.79396855f, 0.17030506f}, 0.017863192751682862f},
+ {{-1.f, 0.f}, {0.79396855f, 0.17030506f}, 0.017863192751682862f}};
-// 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;
+// signal.cheby1(1, 6, [1000/8000, 2000/8000], btype='bandpass', analog=False)
+const std::vector<CascadedBiQuadFilter::BiQuadParam> kBandPassFilterDS8 = {
+ {{1.f, 0.f}, {0.7601815f, 0.46423542f}, 0.10330478266505948f, true},
+ {{1.f, 0.f}, {0.7601815f, 0.46423542f}, 0.10330478266505948f, true},
+ {{1.f, 0.f}, {0.7601815f, 0.46423542f}, 0.10330478266505948f, true},
+ {{1.f, 0.f}, {0.7601815f, 0.46423542f}, 0.10330478266505948f, true},
+ {{1.f, 0.f}, {0.7601815f, 0.46423542f}, 0.10330478266505948f, true}};
-// b, a = signal.butter(2, 1000/8000.0, 'highpass', analog=False)
-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;
+// signal.butter(2, 1000/8000.0, 'highpass', analog=False)
+const std::vector<CascadedBiQuadFilter::BiQuadParam> kHighPassFilter = {
+ {{1.f, 0.f}, {0.72712179f, 0.21296904f}, 0.7570763753338849f}};
+const std::vector<CascadedBiQuadFilter::BiQuadParam> kPassThroughFilter = {};
} // namespace
Decimator::Decimator(size_t down_sampling_factor)
: down_sampling_factor_(down_sampling_factor),
- anti_aliasing_filter_(
- down_sampling_factor_ == 4
- ? kLowPassFilterCoefficients4
- : (down_sampling_factor_ == 8 ? kBandPassFilterCoefficients8
- : kLowPassFilterCoefficients2),
- down_sampling_factor_ == 4
- ? kNumFilters4
- : (down_sampling_factor_ == 8 ? kNumFilters8 : kNumFilters2)),
- noise_reduction_filter_(
- kHighPassFilterCoefficients,
- down_sampling_factor_ == 4
- ? kNumFiltersHP4
- : (down_sampling_factor_ == 8 ? kNumFiltersHP8
- : kNumFiltersHP2)) {
+ anti_aliasing_filter_(down_sampling_factor_ == 4
+ ? kLowPassFilterDS4
+ : (down_sampling_factor_ == 8
+ ? kBandPassFilterDS8
+ : kLowPassFilterDS2)),
+ noise_reduction_filter_(down_sampling_factor_ == 8 ? kPassThroughFilter
+ : kHighPassFilter) {
RTC_DCHECK(down_sampling_factor_ == 2 || down_sampling_factor_ == 4 ||
down_sampling_factor_ == 8);
}