Adding BlockMeanCalculator for AEC.

webrtc/modules/audio_processing/utility/mean_calculator_unittest.cc

+/*
+ *  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 "testing/gtest/include/gtest/gtest.h"
+
+#include "webrtc/modules/audio_processing/utility/mean_calculator.h"
+
+namespace webrtc {
+
+TEST(MeanCalculatorTest, Correctness) {
+  const size_t kWindowLength = 10;
+  MeanCalculator mean_calculator(kWindowLength);
+  size_t i = 0;
+  float reference = 0.0;
+
+  for (; i < kWindowLength; ++i) {
+    EXPECT_EQ(mean_calculator.GetNumberNewSamples(), i % kWindowLength);
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+  for (; i < 3 * kWindowLength; ++i) {
+    const size_t new_samples = i % kWindowLength;
+    if (new_samples == 0) {
+      // Sum of (i - kWindowLength) ... (i - 1)
+      reference = i - 0.5 * (1 + kWindowLength);
+    }
+    EXPECT_EQ(mean_calculator.GetNumberNewSamples(), new_samples);
+    EXPECT_EQ(reference, mean_calculator.GetLatestMean());
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+}
+
+TEST(MeanCalculatorTest, Reset) {
+  const size_t kWindowLength = 10;
+  MeanCalculator mean_calculator(kWindowLength);
+  for (size_t i = 0; i < kWindowLength - 1; ++i) {
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+  EXPECT_EQ(mean_calculator.GetNumberNewSamples(), kWindowLength - 1);
+  mean_calculator.Reset();
+  for (size_t i = 0; i < kWindowLength; ++i) {
+    EXPECT_EQ(mean_calculator.GetNumberNewSamples(), i);
+    mean_calculator.AddSample(static_cast<float>(i));
+  }
+  EXPECT_EQ(mean_calculator.GetNumberNewSamples(), 0u);
+  EXPECT_EQ(mean_calculator.GetLatestMean(), 0.5 * (kWindowLength - 1));
+}
+
+}  // namespace webrtc