Added first layer of the echo canceller 3 functionality

webrtc/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc

Index: webrtc/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc
diff --git a/webrtc/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc b/webrtc/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4fb018e981de83ce78d0dc1ec35a274785f99d16
--- /dev/null
+++ b/webrtc/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc
@@ -0,0 +1,87 @@
+/*
+ *  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 <vector>
+
+#include "webrtc/modules/audio_processing/aec3/cascaded_biquad_filter.h"

[hlundin-webrtc, 2016/12/22 10:23:56]

This goes first.

[peah-webrtc, 2016/12/22 16:40:03]

Done.

+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+
+namespace {
+

[hlundin-webrtc, 2016/12/22 10:23:56]

Can you comment on how you arrived at these coefficients? Matlab command?

[peah-webrtc, 2016/12/22 16:40:03]

Done.

+const CascadedBiQuadFilter::BiQuadCoefficients kHighPassFilterCoefficients = {
+    {0.972613898499844, -1.945227796999688, 0.972613898499844},
+    {-1.944477657767094, 0.945977936232282}};
+
+const CascadedBiQuadFilter::BiQuadCoefficients kTransparentCoefficients = {
+    {1.f, 0.f, 0.f},
+    {0.f, 0.f}};
+
+const CascadedBiQuadFilter::BiQuadCoefficients kBlockingCoefficients = {
+    {0.f, 0.f, 0.f},
+    {0.f, 0.f}};
+
+std::vector<float> CreateInputWithIncreasingValues(size_t vector_length) {
+  std::vector<float> v(vector_length);
+  for (size_t k = 0; k < v.size(); ++k) {
+    v[k] = k;
+  }
+  return v;
+}
+
+}  // namespace
+
+// Verifies that the filter applies an effect which removes the input signal.
+// The test also verifies that the in-place Process API call works as intended.
+TEST(CascadedBiquadFilter, BlockingConfiguration) {
+  std::vector<float> values = CreateInputWithIncreasingValues(1000);
+
+  CascadedBiQuadFilter filter(kBlockingCoefficients, 1);
+  filter.Process(values);
+
+  for (float v : values) {

[hlundin-webrtc, 2016/12/22 10:23:56]

You can do 
EXPECT_EQ(std::vector<float>(1000, 0.f), values);

GTest works pretty well with STL containers.

[ivoc, 2016/12/22 13:38:13]

Out of curiosity, what does it show when one of the 1000 numbers doesn't match?
Just the wrong one?

[hlundin-webrtc, 2016/12/22 13:51:30]

Turns out it prints out the first few (approx. 25) elements, even if the error
is elsewhere. So, not ideal, but the current code isn't either, imo. You'll
probably have to dig deeper than what the default printout gives anyway, so then
I prefer the shorter code.

[peah-webrtc, 2016/12/22 16:40:03]

Wow! That's supernice!!!
Done.

[peah-webrtc, 2016/12/22 16:40:03]

I got the following output:
[ RUN      ] CascadedBiquadFilter.BlockingConfiguration
../../webrtc/modules/audio_processing/aec3/cascaded_biquad_filter_unittest.cc:53:
Failure
Value of: values
  Actual: { 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, ... }
Expected: std::vector<float>(1000, 0.f)
Which is: { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, ... }
[  FAILED  ] CascadedBiquadFilter.BlockingConfiguration (0 ms)

[peah-webrtc, 2016/12/22 16:40:03]

Acknowledged.

+    EXPECT_EQ(0.f, v);
+  }
+}
+
+// Verifies that the filter is able to form a zero-mean output from a
+// non-zeromean input signal when coefficients for a high-pass filter are
+// applied. The test also verifies that the filter works with multiple biquads.
+TEST(CascadedBiquadFilter, HighPassConfiguration) {
+  std::vector<float> values(1000);
+  for (size_t k = 0; k < values.size(); ++k) {
+    values[k] = 1.f;
+  }
+
+  CascadedBiQuadFilter filter(kHighPassFilterCoefficients, 2);
+  filter.Process(values);
+
+  for (size_t k = values.size() / 2; k < values.size(); ++k) {
+    EXPECT_NEAR(0.f, values[k], 1e-5);
+  }
+}
+
+// Verifies that the filter is able to produce a transparent effect with no
+// impact on the data when the proper coefficients are applied. The test also
+// verifies that the non-in-place Process API call works as intended.
+TEST(CascadedBiquadFilter, TransparentConfiguration) {
+  const std::vector<float> input = CreateInputWithIncreasingValues(1000);
+  std::vector<float> output(input.size());
+
+  CascadedBiQuadFilter filter(kTransparentCoefficients, 1);
+  filter.Process(input, output);
+
+  for (size_t k = 0; k < input.size(); ++k) {

[hlundin-webrtc, 2016/12/22 10:23:56]

You can just do EXPECT_EQ(input, output).

[peah-webrtc, 2016/12/22 16:40:03]

Done.

+    EXPECT_EQ(input[k], output[k]);
+  }
+}
+
+}  // namespace webrtc