Finalization of the first version of EchoCanceller 3

webrtc/modules/audio_processing/aec3/suppression_gain.cc

+/*
+ *  Copyright (c) 2017 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 "webrtc/modules/audio_processing/aec3/suppression_gain.h"
+
+#include "webrtc/typedefs.h"
+#if defined(WEBRTC_ARCH_X86_FAMILY)
+#include <emmintrin.h>
+#endif
+#include <math.h>
+#include <algorithm>
+#include <functional>
+
+namespace webrtc {
+namespace {
+
+constexpr int kNumIterations = 2;
+constexpr float kEchoMaskingMargin = 1.f / 10.f;
+constexpr float kBandMaskingFactor = 1.f / 2.f;
+constexpr float kTimeMaskingFactor = 1.f / 10.f;
+
+}  // namespace
+
+namespace aec3 {
+
+#if defined(WEBRTC_ARCH_X86_FAMILY)
+
+// Optimized SSE2 code for the gain computation.
+// TODO(peah): Add further optimizations, in particular for the divisions.
+void ComputeGains_SSE2(
+    const std::array<float, kFftLengthBy2Plus1>& nearend_power,
+    const std::array<float, kFftLengthBy2Plus1>& residual_echo_power,
+    const std::array<float, kFftLengthBy2Plus1>& comfort_noise_power,
+    float strong_nearend_margin,
+    std::array<float, kFftLengthBy2Minus1>* previous_gain_squared,
+    std::array<float, kFftLengthBy2Minus1>* previous_masker,
+    std::array<float, kFftLengthBy2Plus1>* gain) {
+  std::array<float, kFftLengthBy2Minus1> masker;
+  std::array<float, kFftLengthBy2Minus1> same_band_masker;
+  std::array<float, kFftLengthBy2Minus1> one_by_residual_echo_power;
+  std::array<bool, kFftLengthBy2Minus1> strong_nearend;
+  std::array<float, kFftLengthBy2Plus1> neighboring_bands_masker;
+  std::array<float, kFftLengthBy2Plus1>* gain_squared = gain;
+
+  // Precompute 1/residual_echo_power.
+  std::transform(residual_echo_power.begin() + 1, residual_echo_power.end() - 1,
+                 one_by_residual_echo_power.begin(),
+                 [](float a) { return a > 0.f ? 1.f / a : -1.f; });
+
+  // Precompute indicators for bands with strong nearend.
+  std::transform(
+      residual_echo_power.begin() + 1, residual_echo_power.end() - 1,
+      nearend_power.begin() + 1, strong_nearend.begin(),
+      [&](float a, float b) { return a <= strong_nearend_margin * b; });
+
+  //  Precompute masker for the same band.
+  std::transform(comfort_noise_power.begin() + 1, comfort_noise_power.end() - 1,
+                 previous_masker->begin(), same_band_masker.begin(),
+                 [&](float a, float b) { return a + kTimeMaskingFactor * b; });
+
+  for (int k = 0; k < kNumIterations; ++k) {
+    if (k == 0) {
+      // Add masker from the same band.
+      std::copy(same_band_masker.begin(), same_band_masker.end(),
+                masker.begin());
+    } else {
+      // Add masker for neighboring bands.
+      std::transform(nearend_power.begin(), nearend_power.end(),
+                     gain_squared->begin(), neighboring_bands_masker.begin(),
+                     std::multiplies<float>());
+      std::transform(neighboring_bands_masker.begin(),
+                     neighboring_bands_masker.end(),
+                     comfort_noise_power.begin(),
+                     neighboring_bands_masker.begin(), std::plus<float>());
+      std::transform(
+          neighboring_bands_masker.begin(), neighboring_bands_masker.end() - 2,
+          neighboring_bands_masker.begin() + 2, masker.begin(),
+          [&](float a, float b) { return kBandMaskingFactor * (a + b); });
+
+      // Add masker from the same band.
+      std::transform(same_band_masker.begin(), same_band_masker.end(),
+                     masker.begin(), masker.begin(), std::plus<float>());
+    }
+
+    // Compute new gain as:
+    // G2(t,f) = (comfort_noise_power(t,f) + G2(t-1)*nearend_power(t-1)) *
+    //           kTimeMaskingFactor
+    //           * kEchoMaskingMargin / residual_echo_power(t,f).
+    // or
+    // G2(t,f) = ((comfort_noise_power(t,f) + G2(t-1) *
+    //             nearend_power(t-1)) * kTimeMaskingFactor +
+    //            (comfort_noise_power(t, f-1) + comfort_noise_power(t, f+1) +
+    //             (G2(t,f-1)*nearend_power(t, f-1) +
+    //              G2(t,f+1)*nearend_power(t, f+1)) *
+    //             kTimeMaskingFactor) * kBandMaskingFactor)
+    //           * kEchoMaskingMargin / residual_echo_power(t,f).
+    std::transform(
+        masker.begin(), masker.end(), one_by_residual_echo_power.begin(),
+        gain_squared->begin() + 1, [&](float a, float b) {
+          return b >= 0 ? std::min(kEchoMaskingMargin * a * b, 1.f) : 1.f;
+        });
+
+    // Limit gain for bands with strong nearend.
+    std::transform(gain_squared->begin() + 1, gain_squared->end() - 1,
+                   strong_nearend.begin(), gain_squared->begin() + 1,
+                   [](float a, bool b) { return b ? 1.f : a; });
+
+    // Limit the allowed gain update over time.
+    std::transform(gain_squared->begin() + 1, gain_squared->end() - 1,
+                   previous_gain_squared->begin(), gain_squared->begin() + 1,
+                   [](float a, float b) {
+                     return b < 0.0001f ? std::min(a, 0.0001f)
+                                        : std::min(a, b * 2.f);
+                   });
+
+    (*gain_squared)[0] = (*gain_squared)[1];
+    (*gain_squared)[kFftLengthBy2] = (*gain_squared)[kFftLengthBy2Minus1];
+  }
+
+  std::copy(gain_squared->begin() + 1, gain_squared->end() - 1,
+            previous_gain_squared->begin());
+
+  std::transform(gain_squared->begin() + 1, gain_squared->end() - 1,
+                 nearend_power.begin() + 1, previous_masker->begin(),
+                 std::multiplies<float>());
+  std::transform(previous_masker->begin(), previous_masker->end(),
+                 comfort_noise_power.begin() + 1, previous_masker->begin(),
+                 std::plus<float>());
+
+  for (size_t k = 0; k < kFftLengthBy2; k += 4) {
+    __m128 g = _mm_loadu_ps(&(*gain_squared)[k]);
+    g = _mm_sqrt_ps(g);
+    _mm_storeu_ps(&(*gain)[k], g);
+  }
+
+  (*gain)[kFftLengthBy2] = sqrtf((*gain)[kFftLengthBy2]);
+}
+
+#endif
+
+void ComputeGains(
+    const std::array<float, kFftLengthBy2Plus1>& nearend_power,
+    const std::array<float, kFftLengthBy2Plus1>& residual_echo_power,
+    const std::array<float, kFftLengthBy2Plus1>& comfort_noise_power,
+    float strong_nearend_margin,
+    std::array<float, kFftLengthBy2Minus1>* previous_gain_squared,
+    std::array<float, kFftLengthBy2Minus1>* previous_masker,
+    std::array<float, kFftLengthBy2Plus1>* gain) {
+  std::array<float, kFftLengthBy2Minus1> masker;
+  std::array<float, kFftLengthBy2Minus1> same_band_masker;
+  std::array<float, kFftLengthBy2Minus1> one_by_residual_echo_power;
+  std::array<bool, kFftLengthBy2Minus1> strong_nearend;
+  std::array<float, kFftLengthBy2Plus1> neighboring_bands_masker;
+  std::array<float, kFftLengthBy2Plus1>* gain_squared = gain;
+
+  // Precompute 1/residual_echo_power.
+  std::transform(residual_echo_power.begin() + 1, residual_echo_power.end() - 1,
+                 one_by_residual_echo_power.begin(),
+                 [](float a) { return a > 0.f ? 1.f / a : -1.f; });
+
+  // Precompute indicators for bands with strong nearend.
+  std::transform(
+      residual_echo_power.begin() + 1, residual_echo_power.end() - 1,
+      nearend_power.begin() + 1, strong_nearend.begin(),
+      [&](float a, float b) { return a <= strong_nearend_margin * b; });
+
+  //  Precompute masker for the same band.
+  std::transform(comfort_noise_power.begin() + 1, comfort_noise_power.end() - 1,
+                 previous_masker->begin(), same_band_masker.begin(),
+                 [&](float a, float b) { return a + kTimeMaskingFactor * b; });
+
+  for (int k = 0; k < kNumIterations; ++k) {
+    if (k == 0) {
+      // Add masker from the same band.
+      std::copy(same_band_masker.begin(), same_band_masker.end(),
+                masker.begin());
+    } else {
+      // Add masker for neightboring bands.
+      std::transform(nearend_power.begin(), nearend_power.end(),
+                     gain_squared->begin(), neighboring_bands_masker.begin(),
+                     std::multiplies<float>());
+      std::transform(neighboring_bands_masker.begin(),
+                     neighboring_bands_masker.end(),
+                     comfort_noise_power.begin(),
+                     neighboring_bands_masker.begin(), std::plus<float>());
+      std::transform(
+          neighboring_bands_masker.begin(), neighboring_bands_masker.end() - 2,
+          neighboring_bands_masker.begin() + 2, masker.begin(),
+          [&](float a, float b) { return kBandMaskingFactor * (a + b); });
+
+      // Add masker from the same band.
+      std::transform(same_band_masker.begin(), same_band_masker.end(),
+                     masker.begin(), masker.begin(), std::plus<float>());
+    }
+
+    // Compute new gain as:
+    // G2(t,f) = (comfort_noise_power(t,f) + G2(t-1)*nearend_power(t-1)) *
+    //           kTimeMaskingFactor
+    //           * kEchoMaskingMargin / residual_echo_power(t,f).
+    // or
+    // G2(t,f) = ((comfort_noise_power(t,f) + G2(t-1) *
+    //             nearend_power(t-1)) * kTimeMaskingFactor +
+    //            (comfort_noise_power(t, f-1) + comfort_noise_power(t, f+1) +
+    //             (G2(t,f-1)*nearend_power(t, f-1) +
+    //              G2(t,f+1)*nearend_power(t, f+1)) *
+    //             kTimeMaskingFactor) * kBandMaskingFactor)
+    //           * kEchoMaskingMargin / residual_echo_power(t,f).
+    std::transform(
+        masker.begin(), masker.end(), one_by_residual_echo_power.begin(),
+        gain_squared->begin() + 1, [&](float a, float b) {
+          return b >= 0 ? std::min(kEchoMaskingMargin * a * b, 1.f) : 1.f;
+        });
+
+    // Limit gain for bands with strong nearend.
+    std::transform(gain_squared->begin() + 1, gain_squared->end() - 1,
+                   strong_nearend.begin(), gain_squared->begin() + 1,
+                   [](float a, bool b) { return b ? 1.f : a; });
+
+    // Limit the allowed gain update over time.
+    std::transform(gain_squared->begin() + 1, gain_squared->end() - 1,
+                   previous_gain_squared->begin(), gain_squared->begin() + 1,
+                   [](float a, float b) {
+                     return b < 0.0001f ? std::min(a, 0.0001f)
+                                        : std::min(a, b * 2.f);
+                   });
+
+    (*gain_squared)[0] = (*gain_squared)[1];
+    (*gain_squared)[kFftLengthBy2] = (*gain_squared)[kFftLengthBy2Minus1];
+  }
+
+  std::copy(gain_squared->begin() + 1, gain_squared->end() - 1,
+            previous_gain_squared->begin());
+
+  std::transform(gain_squared->begin() + 1, gain_squared->end() - 1,
+                 nearend_power.begin() + 1, previous_masker->begin(),
+                 std::multiplies<float>());
+  std::transform(previous_masker->begin(), previous_masker->end(),
+                 comfort_noise_power.begin() + 1, previous_masker->begin(),
+                 std::plus<float>());
+
+  std::transform(gain_squared->begin(), gain_squared->end(), gain->begin(),
+                 [](float a) { return sqrtf(a); });
+}
+
+}  // namespace aec3
+
+SuppressionGain::SuppressionGain(Aec3Optimization optimization)
+    : optimization_(optimization) {
+  previous_gain_squared_.fill(1.f);
+  previous_masker_.fill(0.f);
+}
+
+void SuppressionGain::GetGain(
+    const std::array<float, kFftLengthBy2Plus1>& nearend_power,
+    const std::array<float, kFftLengthBy2Plus1>& residual_echo_power,
+    const std::array<float, kFftLengthBy2Plus1>& comfort_noise_power,
+    float strong_nearend_margin,
+    std::array<float, kFftLengthBy2Plus1>* gain) {
+  RTC_DCHECK(gain);
+  switch (optimization_) {
+#if defined(WEBRTC_ARCH_X86_FAMILY)
+    case Aec3Optimization::kSse2:
+      aec3::ComputeGains_SSE2(nearend_power, residual_echo_power,
+                              comfort_noise_power, strong_nearend_margin,
+                              &previous_gain_squared_, &previous_masker_, gain);
+      break;
+#endif
+    default:
+      aec3::ComputeGains(nearend_power, residual_echo_power,
+                         comfort_noise_power, strong_nearend_margin,
+                         &previous_gain_squared_, &previous_masker_, gain);
+  }
+}
+
+}  // namespace webrtc