Added a bitexactness test for the noise suppressor.

This CL also extracts part of the functionality used
in the bitexactness test for the high-pass filter into
a separate file in order to be able to reuse that
functionality in bitexactness tests for the other
submodules in APM (including the bitexactness test for
the noise suppressor).

BUG=wertc:5336

Review URL: https://codereview.webrtc.org/1783203002

Cr-Commit-Position: refs/heads/master@{#12061}
diff --git a/webrtc/modules/audio_processing/high_pass_filter_bitexactness_unittest.cc b/webrtc/modules/audio_processing/high_pass_filter_bitexactness_unittest.cc
index 161677b..ba53bfa 100644
--- a/webrtc/modules/audio_processing/high_pass_filter_bitexactness_unittest.cc
+++ b/webrtc/modules/audio_processing/high_pass_filter_bitexactness_unittest.cc
@@ -14,52 +14,11 @@
 #include "webrtc/modules/audio_processing/audio_buffer.h"
 #include "webrtc/modules/audio_processing/high_pass_filter_impl.h"
 #include "webrtc/modules/audio_processing/test/audio_buffer_tools.h"
+#include "webrtc/modules/audio_processing/test/bitexactness_tools.h"
 
 namespace webrtc {
 namespace {
 
-// Test to see whether two vectors are identical and report any
-// differences.
-::testing::AssertionResult AssertVectorsNotEqual(
-    const char* m_expr,
-    const char* n_expr,
-    const std::vector<float>& output,
-    const std::vector<float>& reference) {
-  // Compare the output in the reference in a soft manner.
-  bool equal = true;
-  const float threshold = 1.0f / 32768.0f;
-  for (size_t k = 0; k < reference.size(); ++k) {
-    if (fabs(output[k] - reference[k]) > threshold) {
-      equal = false;
-      break;
-    }
-  }
-
-  // If the vectors are deemed not to be similar, return a report of the
-  // difference.
-  if (!equal) {
-    // Lambda function that produces a formatted string with the data in the
-    // vector.
-    auto print_vector_in_c_format = [](std::vector<float> v,
-                                       size_t num_values_to_print) {
-      std::string s = "{ ";
-      for (size_t k = 0; k < num_values_to_print; ++k) {
-        s += std::to_string(v[k]) + "f";
-        s += (k < (num_values_to_print - 1)) ? ", " : "";
-      }
-      return s + " }";
-    };
-
-    return ::testing::AssertionFailure()
-           << "Actual: " << print_vector_in_c_format(output, reference.size())
-           << std::endl
-           << std::endl
-           << "Expected: "
-           << print_vector_in_c_format(reference, reference.size())
-           << std::endl;
-  }
-  return ::testing::AssertionSuccess();
-}
 
 // Process one frame of data and produce the output.
 std::vector<float> ProcessOneFrame(const std::vector<float>& frame_input,
@@ -72,8 +31,9 @@
 
   test::CopyVectorToAudioBuffer(stream_config, frame_input, &audio_buffer);
   high_pass_filter->ProcessCaptureAudio(&audio_buffer);
-  std::vector<float> frame_output =
-      test::ExtractVectorFromAudioBuffer(stream_config, &audio_buffer);
+  std::vector<float> frame_output;
+  test::ExtractVectorFromAudioBuffer(stream_config, &audio_buffer,
+                                     &frame_output);
   return frame_output;
 }
 
@@ -122,7 +82,9 @@
             reference_frame_length);
   }
 
-  EXPECT_PRED_FORMAT2(AssertVectorsNotEqual, output_to_verify, reference);
+  const float kTolerance = 1.0f / 32768.0f;
+  EXPECT_TRUE(test::BitExactFrame(reference_frame_length, num_channels,
+                                  reference, output_to_verify, kTolerance));
 }
 
 // Method for forming a vector out of an array.
diff --git a/webrtc/modules/audio_processing/noise_suppression_bitexactness_unittest.cc b/webrtc/modules/audio_processing/noise_suppression_bitexactness_unittest.cc
new file mode 100644
index 0000000..38551d3
--- /dev/null
+++ b/webrtc/modules/audio_processing/noise_suppression_bitexactness_unittest.cc
@@ -0,0 +1,260 @@
+/*
+ *  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 "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/base/array_view.h"
+#include "webrtc/modules/audio_processing/audio_buffer.h"
+#include "webrtc/modules/audio_processing/noise_suppression_impl.h"
+#include "webrtc/modules/audio_processing/test/audio_buffer_tools.h"
+#include "webrtc/modules/audio_processing/test/bitexactness_tools.h"
+
+namespace webrtc {
+namespace {
+
+const int kNumFramesToProcess = 1000;
+
+// Process one frame of data and produce the output.
+void ProcessOneFrame(int sample_rate_hz,
+                     AudioBuffer* capture_buffer,
+                     NoiseSuppressionImpl* noise_suppressor) {
+  if (sample_rate_hz > AudioProcessing::kSampleRate16kHz) {
+    capture_buffer->SplitIntoFrequencyBands();
+  }
+
+  noise_suppressor->AnalyzeCaptureAudio(capture_buffer);
+  noise_suppressor->ProcessCaptureAudio(capture_buffer);
+
+  if (sample_rate_hz > AudioProcessing::kSampleRate16kHz) {
+    capture_buffer->MergeFrequencyBands();
+  }
+}
+
+// Processes a specified amount of frames, verifies the results and reports
+// any errors.
+void RunBitexactnessTest(int sample_rate_hz,
+                         size_t num_channels,
+                         NoiseSuppressionImpl::Level level,
+                         float speech_probability_reference,
+                         rtc::ArrayView<const float> noise_estimate_reference,
+                         rtc::ArrayView<const float> output_reference) {
+  rtc::CriticalSection crit_capture;
+  NoiseSuppressionImpl noise_suppressor(&crit_capture);
+  noise_suppressor.Initialize(num_channels, sample_rate_hz);
+  noise_suppressor.Enable(true);
+  noise_suppressor.set_level(level);
+
+  int samples_per_channel = rtc::CheckedDivExact(sample_rate_hz, 100);
+  const StreamConfig capture_config(sample_rate_hz, num_channels, false);
+  AudioBuffer capture_buffer(
+      capture_config.num_frames(), capture_config.num_channels(),
+      capture_config.num_frames(), capture_config.num_channels(),
+      capture_config.num_frames());
+  test::InputAudioFile capture_file(
+      test::GetApmCaptureTestVectorFileName(sample_rate_hz));
+  std::vector<float> capture_input(samples_per_channel * num_channels);
+  for (size_t frame_no = 0; frame_no < kNumFramesToProcess; ++frame_no) {
+    ReadFloatSamplesFromStereoFile(samples_per_channel, num_channels,
+                                   &capture_file, capture_input);
+
+    test::CopyVectorToAudioBuffer(capture_config, capture_input,
+                                  &capture_buffer);
+
+    ProcessOneFrame(sample_rate_hz, &capture_buffer, &noise_suppressor);
+  }
+
+  // Extract test results.
+  std::vector<float> capture_output;
+  test::ExtractVectorFromAudioBuffer(capture_config, &capture_buffer,
+                                     &capture_output);
+  float speech_probability = noise_suppressor.speech_probability();
+  std::vector<float> noise_estimate = noise_suppressor.NoiseEstimate();
+
+  const float kTolerance = 1.0f / 32768.0f;
+  EXPECT_FLOAT_EQ(speech_probability_reference, speech_probability);
+  EXPECT_TRUE(test::BitExactVector(noise_estimate_reference, noise_estimate,
+                                   kTolerance));
+
+  // Compare the output with the reference. Only the first values of the output
+  // from last frame processed are compared in order not having to specify all
+  // preceeding frames as testvectors. As the algorithm being tested has a
+  // memory, testing only the last frame implicitly also tests the preceeding
+  // frames.
+  EXPECT_TRUE(test::BitExactFrame(
+      capture_config.num_frames(), capture_config.num_channels(),
+      output_reference, capture_output, kTolerance));
+}
+
+}  // namespace
+
+TEST(NoiseSuppresionBitExactnessTest, Mono8kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.797542f, 6.488125f, 14.995160f};
+  const float kOutputReference[] = {0.003510f, 0.004517f, 0.004669f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.797542f, 6.488125f, 14.995160f};
+  const float kOutputReference[] = {0.003510f, 0.004517f, 0.004669f};
+#else
+  const float kSpeechProbabilityReference = 0.73421317f;
+  const float kNoiseEstimateReference[] = {0.035866f, 0.100382f, 0.229889f};
+  const float kOutputReference[] = {0.003263f, 0.004402f, 0.004537f};
+#endif
+
+  RunBitexactnessTest(8000, 1, NoiseSuppression::Level::kLow,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(NoiseSuppresionBitExactnessTest, Mono16kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.475060f, 6.130507f, 14.030761f};
+  const float kOutputReference[] = {0.003449f, 0.004334f, 0.004303f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.475060f, 6.130507f, 14.030761f};
+  const float kOutputReference[] = {0.003449f, 0.004334f, 0.004303f};
+#else
+  const float kSpeechProbabilityReference = 0.71672988f;
+  const float kNoiseEstimateReference[] = {0.065653f, 0.198662f, 0.477870f};
+  const float kOutputReference[] = {0.003574f, 0.004494f, 0.004499f};
+#endif
+
+  RunBitexactnessTest(16000, 1, NoiseSuppression::Level::kLow,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(NoiseSuppresionBitExactnessTest, Mono32kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.480526f, 6.169749f, 14.102388f};
+  const float kOutputReference[] = {0.001679f, 0.002411f, 0.002594f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.480526f, 6.169749f, 14.102388f};
+  const float kOutputReference[] = {0.001679f, 0.002411f, 0.002594f};
+#else
+  const float kSpeechProbabilityReference = 0.67999554f;
+  const float kNoiseEstimateReference[] = {0.065606f, 0.215971f, 0.455931f};
+  const float kOutputReference[] = {0.001221f, 0.001984f, 0.002228f};
+#endif
+
+  RunBitexactnessTest(32000, 1, NoiseSuppression::Level::kLow,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(NoiseSuppresionBitExactnessTest, Mono48kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.504498f, 6.068024f, 13.058871f};
+  const float kOutputReference[] = {-0.013185f, -0.012769f, -0.012023f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.504498f, 6.068024f, 13.058871f};
+  const float kOutputReference[] = {-0.013185f, -0.012769f, -0.012023f};
+#else
+  const float kSpeechProbabilityReference = 0.70645678f;
+  const float kNoiseEstimateReference[] = {0.066186f, 0.210660f, 0.402548f};
+  const float kOutputReference[] = {-0.013062f, -0.012657f, -0.011934f};
+#endif
+
+  RunBitexactnessTest(48000, 1, NoiseSuppression::Level::kLow,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(NoiseSuppresionBitExactnessTest, Stereo16kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {9.757937f, 12.392158f, 11.317673f};
+  const float kOutputReference[] = {-0.011108f, -0.007904f, -0.012390f,
+                                    -0.002441f, 0.000855f,  -0.003204f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {10.079447f, 11.849465f, 10.667051f};
+  const float kOutputReference[] = {-0.011108f, -0.007904f, -0.012390f,
+                                    -0.002472f, 0.000916f,  -0.003235f};
+#else
+  const float kSpeechProbabilityReference = 0.67230678f;
+  const float kNoiseEstimateReference[] = {0.298195f, 0.345745f, 0.320528f};
+  const float kOutputReference[] = {-0.011459f, -0.008110f, -0.012728f,
+                                    -0.002399f, 0.001018f,  -0.003189f};
+#endif
+
+  RunBitexactnessTest(16000, 2, NoiseSuppression::Level::kLow,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(NoiseSuppresionBitExactnessTest, Mono16kHzModerate) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {1.004436f, 3.711453f, 9.602631f};
+  const float kOutputReference[] = {0.004669f, 0.005524f, 0.005432f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {1.095946f, 3.351643f, 8.167248f};
+  const float kOutputReference[] = {0.004669f, 0.005615f, 0.005585f};
+#else
+  const float kSpeechProbabilityReference = 0.70897013f;
+  const float kNoiseEstimateReference[] = {0.066269f, 0.199999f, 0.476885f};
+  const float kOutputReference[] = {0.004513f, 0.005590f, 0.005614f};
+#endif
+
+  RunBitexactnessTest(16000, 1, NoiseSuppression::Level::kModerate,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(NoiseSuppresionBitExactnessTest, Mono16kHzHigh) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {1.023022f, 3.759059f, 9.614030f};
+  const float kOutputReference[] = {0.004639f, 0.005402f, 0.005310f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {1.114510f, 3.410356f, 8.262188f};
+  const float kOutputReference[] = {0.004547f, 0.005432f, 0.005402f};
+#else
+  const float kSpeechProbabilityReference = 0.70106733f;
+  const float kNoiseEstimateReference[] = {0.067901f, 0.204835f, 0.481723f};
+  const float kOutputReference[] = {0.004394f, 0.005406f, 0.005416f};
+#endif
+
+  RunBitexactnessTest(16000, 1, NoiseSuppression::Level::kHigh,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(NoiseSuppresionBitExactnessTest, Mono16kHzVeryHigh) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.614974f, 6.041980f, 14.029047f};
+  const float kOutputReference[] = {0.004273f, 0.005127f, 0.005188f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2.614974f, 6.041980f, 14.029047f};
+  const float kOutputReference[] = {0.004273f, 0.005127f, 0.005188f};
+#else
+  const float kSpeechProbabilityReference = 0.70281971f;
+  const float kNoiseEstimateReference[] = {0.068797f, 0.205191f, 0.481312f};
+  const float kOutputReference[] = {0.004321f, 0.005247f, 0.005263f};
+#endif
+
+  RunBitexactnessTest(16000, 1, NoiseSuppression::Level::kVeryHigh,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+}  // namespace webrtc
diff --git a/webrtc/modules/audio_processing/test/audio_buffer_tools.cc b/webrtc/modules/audio_processing/test/audio_buffer_tools.cc
index a8cb09c..46ee61d 100644
--- a/webrtc/modules/audio_processing/test/audio_buffer_tools.cc
+++ b/webrtc/modules/audio_processing/test/audio_buffer_tools.cc
@@ -10,10 +10,12 @@
 
 #include "webrtc/modules/audio_processing/test/audio_buffer_tools.h"
 
+#include <string.h>
+
 namespace webrtc {
 namespace test {
 
-void SetupFrame(StreamConfig stream_config,
+void SetupFrame(const StreamConfig& stream_config,
                 std::vector<float*>* frame,
                 std::vector<float>* frame_samples) {
   frame_samples->resize(stream_config.num_channels() *
@@ -25,30 +27,28 @@
 }
 
 void CopyVectorToAudioBuffer(const StreamConfig& stream_config,
-                             const std::vector<float>& source,
+                             rtc::ArrayView<const float> source,
                              AudioBuffer* destination) {
   std::vector<float*> input;
   std::vector<float> input_samples;
 
   SetupFrame(stream_config, &input, &input_samples);
 
-  RTC_DCHECK_EQ(input_samples.size(), source.size());
-  input_samples = source;
+  RTC_CHECK_EQ(input_samples.size(), source.size());
+  memcpy(input_samples.data(), source.data(),
+         source.size() * sizeof(source[0]));
 
   destination->CopyFrom(&input[0], stream_config);
 }
 
-std::vector<float> ExtractVectorFromAudioBuffer(
-    const StreamConfig& stream_config,
-    AudioBuffer* source) {
+void ExtractVectorFromAudioBuffer(const StreamConfig& stream_config,
+                                  AudioBuffer* source,
+                                  std::vector<float>* destination) {
   std::vector<float*> output;
-  std::vector<float> output_samples;
 
-  SetupFrame(stream_config, &output, &output_samples);
+  SetupFrame(stream_config, &output, destination);
 
   source->CopyTo(stream_config, &output[0]);
-
-  return output_samples;
 }
 
 }  // namespace test
diff --git a/webrtc/modules/audio_processing/test/audio_buffer_tools.h b/webrtc/modules/audio_processing/test/audio_buffer_tools.h
index 654691c..1fac758 100644
--- a/webrtc/modules/audio_processing/test/audio_buffer_tools.h
+++ b/webrtc/modules/audio_processing/test/audio_buffer_tools.h
@@ -12,6 +12,7 @@
 #define WEBRTC_MODULES_AUDIO_PROCESSING_TEST_AUDIO_BUFFER_TOOLS_H_
 
 #include <vector>
+#include "webrtc/base/array_view.h"
 #include "webrtc/modules/audio_processing/audio_buffer.h"
 #include "webrtc/modules/audio_processing/include/audio_processing.h"
 
@@ -20,13 +21,13 @@
 
 // Copies a vector into an audiobuffer.
 void CopyVectorToAudioBuffer(const StreamConfig& stream_config,
-                             const std::vector<float>& source,
+                             rtc::ArrayView<const float> source,
                              AudioBuffer* destination);
 
 // Extracts a vector from an audiobuffer.
-std::vector<float> ExtractVectorFromAudioBuffer(
-    const StreamConfig& stream_config,
-    AudioBuffer* source);
+void ExtractVectorFromAudioBuffer(const StreamConfig& stream_config,
+                                  AudioBuffer* source,
+                                  std::vector<float>* destination);
 
 }  // namespace test
 }  // namespace webrtc
diff --git a/webrtc/modules/audio_processing/test/bitexactness_tools.cc b/webrtc/modules/audio_processing/test/bitexactness_tools.cc
new file mode 100644
index 0000000..965820c
--- /dev/null
+++ b/webrtc/modules/audio_processing/test/bitexactness_tools.cc
@@ -0,0 +1,145 @@
+/*
+ *  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 "webrtc/modules/audio_processing/test/bitexactness_tools.h"
+
+#include <math.h>
+#include <algorithm>
+#include <string>
+#include <vector>
+
+#include "webrtc/base/array_view.h"
+#include "webrtc/test/testsupport/fileutils.h"
+
+namespace webrtc {
+namespace test {
+
+std::string GetApmRenderTestVectorFileName(int sample_rate_hz) {
+  switch (sample_rate_hz) {
+    case 8000:
+      return ResourcePath("far8_stereo", "pcm");
+    case 16000:
+      return ResourcePath("far16_stereo", "pcm");
+    case 32000:
+      return ResourcePath("far32_stereo", "pcm");
+    case 48000:
+      return ResourcePath("far48_stereo", "pcm");
+    default:
+      RTC_DCHECK(false);
+  }
+  return "";
+}
+
+std::string GetApmCaptureTestVectorFileName(int sample_rate_hz) {
+  switch (sample_rate_hz) {
+    case 8000:
+      return ResourcePath("near8_stereo", "pcm");
+    case 16000:
+      return ResourcePath("near16_stereo", "pcm");
+    case 32000:
+      return ResourcePath("near32_stereo", "pcm");
+    case 48000:
+      return ResourcePath("near48_stereo", "pcm");
+    default:
+      RTC_DCHECK(false);
+  }
+  return "";
+}
+
+void ReadFloatSamplesFromStereoFile(size_t samples_per_channel,
+                                    size_t num_channels,
+                                    InputAudioFile* stereo_pcm_file,
+                                    rtc::ArrayView<float> data) {
+  RTC_DCHECK_EQ(data.size(), samples_per_channel * num_channels);
+  std::vector<int16_t> read_samples(samples_per_channel * 2);
+  stereo_pcm_file->Read(samples_per_channel * 2, read_samples.data());
+
+  // Convert samples to float and discard any channels not needed.
+  for (size_t sample = 0; sample < samples_per_channel; ++sample) {
+    for (size_t channel = 0; channel < num_channels; ++channel) {
+      data[sample * num_channels + channel] =
+          read_samples[sample * 2 + channel] / 32768.0f;
+    }
+  }
+}
+
+::testing::AssertionResult BitExactFrame(size_t samples_per_channel,
+                                         size_t num_channels,
+                                         rtc::ArrayView<const float> reference,
+                                         rtc::ArrayView<const float> output,
+                                         float tolerance) {
+  // Form vectors to compare the reference to. Only the first values of the
+  // outputs are compared in order not having to specify all preceeding frames
+  // as testvectors.
+  const size_t reference_frame_length =
+      rtc::CheckedDivExact(reference.size(), num_channels);
+
+  std::vector<float> output_to_verify;
+  for (size_t channel_no = 0; channel_no < num_channels; ++channel_no) {
+    output_to_verify.insert(output_to_verify.end(),
+                            output.begin() + channel_no * samples_per_channel,
+                            output.begin() + channel_no * samples_per_channel +
+                                reference_frame_length);
+  }
+
+  return BitExactVector(reference, output_to_verify, tolerance);
+}
+
+::testing::AssertionResult BitExactVector(rtc::ArrayView<const float> reference,
+                                          rtc::ArrayView<const float> output,
+                                          float tolerance) {
+  // The vectors are deemed to be bitexact only if
+  // a) output have a size at least as long as the reference.
+  // b) the samples in the reference are bitexact with the corresponding samples
+  //    in the output.
+
+  bool equal = true;
+  if (output.size() < reference.size()) {
+    equal = false;
+  } else {
+    // Compare the first samples in the vectors.
+    for (size_t k = 0; k < reference.size(); ++k) {
+      if (fabs(output[k] - reference[k]) > tolerance) {
+        equal = false;
+        break;
+      }
+    }
+  }
+
+  if (equal) {
+    return ::testing::AssertionSuccess();
+  }
+
+  // Lambda function that produces a formatted string with the data in the
+  // vector.
+  auto print_vector_in_c_format = [](rtc::ArrayView<const float> v,
+                                     size_t num_values_to_print) {
+    std::string s = "{ ";
+    for (size_t k = 0; k < std::min(num_values_to_print, v.size()); ++k) {
+      s += std::to_string(v[k]) + "f";
+      s += (k < (num_values_to_print - 1)) ? ", " : "";
+    }
+    return s + " }";
+  };
+
+  // If the vectors are deemed not to be similar, return a report of the
+  // difference.
+  return ::testing::AssertionFailure()
+         << std::endl
+         << "    Actual values : "
+         << print_vector_in_c_format(output,
+                                     std::min(output.size(), reference.size()))
+         << std::endl
+         << "    Expected values: "
+         << print_vector_in_c_format(reference, reference.size()) << std::endl;
+}
+
+}  // namespace test
+}  // namespace webrtc
diff --git a/webrtc/modules/audio_processing/test/bitexactness_tools.h b/webrtc/modules/audio_processing/test/bitexactness_tools.h
new file mode 100644
index 0000000..a66a3f4
--- /dev/null
+++ b/webrtc/modules/audio_processing/test/bitexactness_tools.h
@@ -0,0 +1,54 @@
+/*
+ *  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.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_PROCESSING_TEST_BITEXACTNESS_TOOLS_H_
+#define WEBRTC_MODULES_AUDIO_PROCESSING_TEST_BITEXACTNESS_TOOLS_H_
+
+#include <string>
+
+#include "webrtc/base/array_view.h"
+#include "webrtc/modules/audio_coding/neteq/tools/input_audio_file.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace webrtc {
+namespace test {
+
+// Returns test vector to use for the render signal in an
+// APM bitexactness test.
+std::string GetApmRenderTestVectorFileName(int sample_rate_hz);
+
+// Returns test vector to use for the capture signal in an
+// APM bitexactness test.
+std::string GetApmCaptureTestVectorFileName(int sample_rate_hz);
+
+// Extract float samples from a pcm file.
+void ReadFloatSamplesFromStereoFile(size_t samples_per_channel,
+                                    size_t num_channels,
+                                    InputAudioFile* stereo_pcm_file,
+                                    rtc::ArrayView<float> data);
+
+// Verifies a frame against a reference and returns the results as an
+// AssertionResult.
+::testing::AssertionResult BitExactFrame(size_t samples_per_channel,
+                                         size_t num_channels,
+                                         rtc::ArrayView<const float> reference,
+                                         rtc::ArrayView<const float> output,
+                                         float tolerance);
+
+// Verifies a vector against a reference and returns the results as an
+// AssertionResult.
+::testing::AssertionResult BitExactVector(rtc::ArrayView<const float> reference,
+                                          rtc::ArrayView<const float> output,
+                                          float tolerance);
+
+}  // namespace test
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_TEST_BITEXACTNESS_TOOLS_H_
diff --git a/webrtc/modules/modules.gyp b/webrtc/modules/modules.gyp
index 5abf6af..596ffc7 100644
--- a/webrtc/modules/modules.gyp
+++ b/webrtc/modules/modules.gyp
@@ -441,9 +441,12 @@
                 'audio_processing/audio_processing_impl_locking_unittest.cc',
                 'audio_processing/audio_processing_impl_unittest.cc',
                 'audio_processing/high_pass_filter_bitexactness_unittest.cc',
+                'audio_processing/noise_suppression_bitexactness_unittest.cc',
                 'audio_processing/test/audio_buffer_tools.cc',
                 'audio_processing/test/audio_buffer_tools.h',
                 'audio_processing/test/audio_processing_unittest.cc',
+                'audio_processing/test/bitexactness_tools.cc',
+                'audio_processing/test/bitexactness_tools.h',
                 'audio_processing/test/debug_dump_replayer.cc',
                 'audio_processing/test/debug_dump_replayer.h',
                 'audio_processing/test/debug_dump_test.cc',