1 files changed, 47 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/audio_processing/echo_detector/mean_variance_estimator.cc b/third_party/libwebrtc/modules/audio_processing/echo_detector/mean_variance_estimator.cc
new file mode 100644
index 0000000000..a9ebb8cd92
--- /dev/null
+++ b/third_party/libwebrtc/modules/audio_processing/echo_detector/mean_variance_estimator.cc
@@ -0,0 +1,47 @@
+/*
+ *  Copyright (c) 2016 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 "modules/audio_processing/echo_detector/mean_variance_estimator.h"
+
+#include <cmath>
+
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+namespace {
+
+// Parameter controlling the adaptation speed.
+constexpr float kAlpha = 0.001f;
+
+}  // namespace
+
+void MeanVarianceEstimator::Update(float value) {
+  mean_ = (1.f - kAlpha) * mean_ + kAlpha * value;
+  variance_ =
+      (1.f - kAlpha) * variance_ + kAlpha * (value - mean_) * (value - mean_);
+  RTC_DCHECK(std::isfinite(mean_));
+  RTC_DCHECK(std::isfinite(variance_));
+}
+
+float MeanVarianceEstimator::std_deviation() const {
+  RTC_DCHECK_GE(variance_, 0.f);
+  return sqrtf(variance_);
+}
+
+float MeanVarianceEstimator::mean() const {
+  return mean_;
+}
+
+void MeanVarianceEstimator::Clear() {
+  mean_ = 0.f;
+  variance_ = 0.f;
+}
+
+}  // namespace webrtc