commit b04e5cae08b8a7bc27041c1606547f807aaa2fc1
author Per Åhgren <peah@webrtc.org> Fri Apr 20 13:35:15 2018
committer Commit Bot <commit-bot@chromium.org> Tue Apr 24 00:53:33 2018
tree 249262675c1359b005e39406b7dc7f8b12e30c9a
parent e987f2b76567d067e1aeae23400978432c9d68c3

Making the delay estimator more robust to noisy nearends and low echoes

This CL reduces the delay estimator step size to make it react better in
scenarios where the environment is noisy, or the echo level is fairly
low.

Bug: webrtc:9177,chromium:835281
Change-Id: I482d898c91eddc497e1284ee500d26df21a0574a
Reviewed-on: https://webrtc-review.googlesource.com/71486
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22990}

modules/audio_processing/aec3/matched_filter.cc

diff --git a/modules/audio_processing/aec3/matched_filter.cc b/modules/audio_processing/aec3/matched_filter.cc
index 466acd4..d8de2a9 100644
--- a/modules/audio_processing/aec3/matched_filter.cc
+++ b/modules/audio_processing/aec3/matched_filter.cc
@@ -100,10 +100,10 @@
     // Update the matched filter estimate in an NLMS manner.
     if (x2_sum > x2_sum_threshold && !saturation) {
       RTC_DCHECK_LT(0.f, x2_sum);
-      const float alpha = 0.7f * e / x2_sum;
+      const float alpha = 0.1f * e / x2_sum;
       const float32x4_t alpha_128 = vmovq_n_f32(alpha);
 
-      // filter = filter + 0.7 * (y - filter * x) / x * x.
+      // filter = filter + 0.1 * (y - filter * x) / x * x.
       float* h_p = &h[0];
       x_p = &x[x_start_index];
 
@@ -215,10 +215,10 @@
     // Update the matched filter estimate in an NLMS manner.
     if (x2_sum > x2_sum_threshold && !saturation) {
       RTC_DCHECK_LT(0.f, x2_sum);
-      const float alpha = 0.7f * e / x2_sum;
+      const float alpha = 0.1f * e / x2_sum;
       const __m128 alpha_128 = _mm_set1_ps(alpha);
 
-      // filter = filter + 0.7 * (y - filter * x) / x * x.
+      // filter = filter + 0.1 * (y - filter * x) / x * x.
       float* h_p = &h[0];
       x_p = &x[x_start_index];
 
@@ -286,9 +286,9 @@
     // Update the matched filter estimate in an NLMS manner.
     if (x2_sum > x2_sum_threshold && !saturation) {
       RTC_DCHECK_LT(0.f, x2_sum);
-      const float alpha = 0.7f * e / x2_sum;
+      const float alpha = 0.1f * e / x2_sum;
 
-      // filter = filter + 0.7 * (y - filter * x) / x * x.
+      // filter = filter + 0.1 * (y - filter * x) / x * x.
       size_t x_index = x_start_index;
       for (size_t k = 0; k < h.size(); ++k) {
         h[k] += alpha * x[x_index];