Added forced zero AEC output after call startup and echo path changes

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.
  */
 
@@ skipping 307 matching lines @@
   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,
     bool saturated_echo,
     const std::vector<std::vector<float>>& render,
     size_t num_capture_bands,
+    bool force_zero_gain,
     float* high_bands_gain,
     std::array<float, kFftLengthBy2Plus1>* low_band_gain) {
   RTC_DCHECK(high_bands_gain);
   RTC_DCHECK(low_band_gain);
 
-  // Choose margin to use.
-  const float margin = saturated_echo ? 0.001f : 0.01f;
-  switch (optimization_) {
+  if (!force_zero_gain) {
+    // Choose margin to use.
+    const float margin = saturated_echo ? 0.001f : 0.01f;
+    switch (optimization_) {
 #if defined(WEBRTC_ARCH_X86_FAMILY)
-    case Aec3Optimization::kSse2:
-      aec3::ComputeGains_SSE2(
-          nearend_power, residual_echo_power, comfort_noise_power, margin,
-          &previous_gain_squared_, &previous_masker_, low_band_gain);
-      break;
+      case Aec3Optimization::kSse2:
+        aec3::ComputeGains_SSE2(
+            nearend_power, residual_echo_power, comfort_noise_power, margin,
+            &previous_gain_squared_, &previous_masker_, low_band_gain);
+        break;
 #endif
-    default:
-      aec3::ComputeGains(nearend_power, residual_echo_power,
-                         comfort_noise_power, margin, &previous_gain_squared_,
-                         &previous_masker_, low_band_gain);
-  }
+      default:
+        aec3::ComputeGains(nearend_power, residual_echo_power,
+                           comfort_noise_power, margin, &previous_gain_squared_,
+                           &previous_masker_, low_band_gain);
+    }
 
-  if (num_capture_bands > 1) {
-    // Compute the gain for upper frequencies.
-    const float min_high_band_gain =
-        HighFrequencyGainBound(saturated_echo, render);
-    *high_bands_gain =
-        *std::min_element(low_band_gain->begin() + 32, low_band_gain->end());
+    if (num_capture_bands > 1) {
+      // Compute the gain for upper frequencies.
+      const float min_high_band_gain =
+          HighFrequencyGainBound(saturated_echo, render);
+      *high_bands_gain =
+          *std::min_element(low_band_gain->begin() + 32, low_band_gain->end());
 
-    *high_bands_gain = std::min(*high_bands_gain, min_high_band_gain);
+      *high_bands_gain = std::min(*high_bands_gain, min_high_band_gain);
 
+    } else {
+      *high_bands_gain = 1.f;
+    }
   } else {
-    *high_bands_gain = 1.f;
+    previous_gain_squared_.fill(0.f);
+    std::copy(comfort_noise_power.begin(), comfort_noise_power.end(),
+              previous_masker_.begin());
+    low_band_gain->fill(0.f);
+    *high_bands_gain = 0.f;

[aleloi, 2017/04/10 09:35:51]

I think this function will be a bit more simple if it is rearranged as

if (force_zero_gain) {
  // handle special zero gain case
  return;
} 
// handle main case:
...

[peah-webrtc, 2017/04/10 09:57:24]

That is indeed a much better way to write this. Great!

Done!

   }
 }
 
 }  // namespace webrtc