Adding full initial version of delay estimation functionality in echo canceller 3

webrtc/modules/audio_processing/aec3/decimator_by_4_unittest.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/decimator_by_4.h"
+
+#include <math.h>
+#include <algorithm>
+#include <array>
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include "webrtc/modules/audio_processing/aec3/aec3_constants.h"
+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+
+namespace {
+
+std::string ProduceDebugText(int sample_rate_hz) {
+  std::ostringstream ss;
+  ss << "Sample rate: " << sample_rate_hz;
+  return ss.str();
+}
+
+constexpr float kPi = 3.141592f;
+constexpr size_t kNumStartupBlocks = 50;
+constexpr size_t kNumBlocks = 1000;
+
+void ProduceDecimatedSinusoidalOutputPower(int rate,

[hlundin-webrtc, 2017/02/06 09:13:18]

sample_rate

[peah-webrtc, 2017/02/06 11:25:38]

Done.

+                                           float sinusoidal_frequency,
+                                           double* input_power,
+                                           double* output_power) {
+  float input[kBlockSize * kNumBlocks];
+
+  // Produce a sinusoid  of frequency 3/8 * sample rate.

[hlundin-webrtc, 2017/02/06 09:13:18]

Two spaces between "sinusoid" and "of". And comment is no longer accurate.

[peah-webrtc, 2017/02/06 11:25:38]

Ah, thanks!

Done.

+  for (size_t k = 0; k < kBlockSize * kNumBlocks; ++k) {
+    input[k] = 32767.f * sin(2.f * kPi * sinusoidal_frequency * k / rate);
+  }
+
+  DecimatorBy4 decimator;
+  std::array<float, kSubBlockSize * kNumBlocks> output;
+
+  for (size_t k = 0; k < kNumBlocks; ++k) {
+    std::array<float, kSubBlockSize> sub_block;
+
+    decimator.Decimate(
+        rtc::ArrayView<const float>(&input[k * kBlockSize], kBlockSize),
+        &sub_block);
+
+    std::copy(sub_block.begin(), sub_block.end(),
+              output.begin() + k * kSubBlockSize);
+  }
+
+  RTC_DCHECK_GT(kNumBlocks, kNumStartupBlocks);

[hlundin-webrtc, 2017/02/06 09:13:18]

ASSERT_GT.
Don't crash the test binary.

[peah-webrtc, 2017/02/06 11:25:38]

Done.

+  rtc::ArrayView<const float> input_to_evaluate(
+      &input[kNumStartupBlocks * kBlockSize],
+      (kNumBlocks - kNumStartupBlocks) * kBlockSize);
+  rtc::ArrayView<const float> output_to_evaluate(
+      &output[kNumStartupBlocks * kSubBlockSize],
+      (kNumBlocks - kNumStartupBlocks) * kSubBlockSize);
+  *input_power =
+      std::inner_product(input_to_evaluate.begin(), input_to_evaluate.end(),
+                         input_to_evaluate.begin(), 0.) /

[hlundin-webrtc, 2017/02/06 09:13:18]

Looks a bit odd with just "0."; maybe write "0.f" instead?

[peah-webrtc, 2017/02/06 11:25:38]

I actually think that 0.0 would be the correct here, as the output is double.
However, I think it is just confusing to not consistently use floats in this
code so I change the doubles to float, which means that I can do the same for
the constants. 

Done.

+      input_to_evaluate.size();
+  *output_power =
+      std::inner_product(output_to_evaluate.begin(), output_to_evaluate.end(),
+                         output_to_evaluate.begin(), 0.) /

[hlundin-webrtc, 2017/02/06 09:13:18]

Same here.

[peah-webrtc, 2017/02/06 11:25:38]

Done.

+      output_to_evaluate.size();
+}
+
+}  // namespace
+
+// Verifies that there is little aliasing from upper frequencies in the
+// downsampling.
+TEST(DecimatorBy4, NoLeakageFromUpperFrequencies) {
+  double input_power;
+  double output_power;
+  for (auto rate : {8000, 16000, 32000, 48000}) {
+    ProduceDebugText(rate);
+    ProduceDecimatedSinusoidalOutputPower(rate, 3.f / 8.f * rate, &input_power,
+                                          &output_power);
+    EXPECT_GT(0.0001f * input_power, output_power);
+  }
+}
+
+// Verifies that the impact of low-frequency content is small during the
+// downsampling.
+TEST(DecimatorBy4, NoImpactOnLowerFrequencies) {
+  double input_power;
+  double output_power;
+  for (auto rate : {8000, 16000, 32000, 48000}) {
+    ProduceDebugText(rate);
+    ProduceDecimatedSinusoidalOutputPower(rate, 200.f, &input_power,
+                                          &output_power);
+    EXPECT_LT(0.7f * input_power, output_power);
+  }
+}
+
+#if RTC_DCHECK_IS_ON && GTEST_HAS_DEATH_TEST && !defined(WEBRTC_ANDROID)
+// Verifies the check for the input size.
+TEST(DecimatorBy4, WrongInputSize) {
+  DecimatorBy4 decimator;
+  std::vector<float> x(std::vector<float>(kBlockSize - 1, 0.f));
+  std::array<float, kSubBlockSize> x_downsampled;
+  EXPECT_DEATH(decimator.Decimate(x, &x_downsampled), "");
+}
+
+// Verifies the check for non-null output.
+TEST(DecimatorBy4, WrongOutputSize) {

[hlundin-webrtc, 2017/02/06 09:13:18]

The name of the test is not consistent with the comment, or what the test
actually does.

[peah-webrtc, 2017/02/06 11:25:38]

Not fully sure that I understood your comment correctly but I changed the
wording of the comment in the code a bit. What it should mean is that it
verifies that the output parameter is not null.

PTAL

[hlundin-webrtc, 2017/02/06 14:33:34]

But the test name is WrongOutputSize.

[peah-webrtc, 2017/02/07 05:40:57]

(facepalm) Thanks! I cannot see how I could miss that.

Done.

+  DecimatorBy4 decimator;
+  std::vector<float> x(std::vector<float>(kBlockSize, 0.f));
+

[hlundin-webrtc, 2017/02/06 09:13:18]

You can drop this blank line.

[peah-webrtc, 2017/02/06 11:25:38]

Done.

+  EXPECT_DEATH(decimator.Decimate(x, nullptr), "");
+}
+
+#endif
+
+}  // namespace webrtc