Reland "Refactoring of the noise suppressor and adding true multichannel support"

This is a reland of 87a7b82520b83a6cf42da27cdc46142c2eb6248c

Original change's description:
> Refactoring of the noise suppressor and adding true multichannel support
> 
> This CL adds proper multichannel support to the noise suppressor.
> To accomplish that in a safe way, a full refactoring of the noise
> suppressor code has been done.
> 
> Due to floating point precision, the changes made are not entirely
> bitexact. They are, however, very close to being bitexact.
> 
> As a safety measure, the former noise suppressor code is preserved
> and a kill-switch is added to allow revering to the legacy noise
> suppressor in case issues arise.
> 
> Bug: webrtc:10895, b/143344262
> Change-Id: I0b071011b23265ac12e6d4b3956499d122286657
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/158407
> Commit-Queue: Per Åhgren <peah@webrtc.org>
> Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#29646}

Bug: webrtc:10895, b/143344262
Change-Id: I236f1e67bb0baa4e30908a4cf7a8a7bb55fbced3
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/158747
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Per Åhgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29663}
diff --git a/modules/audio_processing/legacy_noise_suppression_unittest.cc b/modules/audio_processing/legacy_noise_suppression_unittest.cc
new file mode 100644
index 0000000..57deedb
--- /dev/null
+++ b/modules/audio_processing/legacy_noise_suppression_unittest.cc
@@ -0,0 +1,279 @@
+/*
+ *  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 "api/array_view.h"
+#include "modules/audio_processing/audio_buffer.h"
+#include "modules/audio_processing/legacy_noise_suppression.h"
+#include "modules/audio_processing/test/audio_buffer_tools.h"
+#include "modules/audio_processing/test/bitexactness_tools.h"
+#include "test/gtest.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,
+                     NoiseSuppression* 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,
+                         NoiseSuppression::Level level,
+                         float speech_probability_reference,
+                         rtc::ArrayView<const float> noise_estimate_reference,
+                         rtc::ArrayView<const float> output_reference) {
+  NoiseSuppression noise_suppressor(num_channels, sample_rate_hz, 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.sample_rate_hz(), capture_config.num_channels(),
+      capture_config.sample_rate_hz(), capture_config.num_channels(),
+      capture_config.sample_rate_hz(), capture_config.num_channels());
+  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 kVectorElementErrorBound = 1.0f / 32768.0f;
+  EXPECT_FLOAT_EQ(speech_probability_reference, speech_probability);
+  EXPECT_TRUE(test::VerifyArray(noise_estimate_reference, noise_estimate,
+                                kVectorElementErrorBound));
+
+  // 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::VerifyDeinterleavedArray(
+      capture_config.num_frames(), capture_config.num_channels(),
+      output_reference, capture_output, kVectorElementErrorBound));
+}
+
+}  // namespace
+
+TEST(LegacyNoiseSuppresionBitExactnessTest, Mono8kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {1432.341431f, 3321.919922f,
+                                           7677.521973f};
+  const float kOutputReference[] = {0.003510f, 0.004517f, 0.004669f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {1432.341431f, 3321.919922f,
+                                           7677.521973f};
+  const float kOutputReference[] = {0.003510f, 0.004517f, 0.004669f};
+#else
+  const float kSpeechProbabilityReference = 0.73650402f;
+  const float kNoiseEstimateReference[] = {1176.856812f, 3287.490967f,
+                                           7525.964844f};
+  const float kOutputReference[] = {0.003306f, 0.004442f, 0.004574f};
+#endif
+
+  RunBitexactnessTest(8000, 1, NoiseSuppression::Level::kLow,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(LegacyNoiseSuppresionBitExactnessTest, Mono16kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2534.461914f, 6277.638672f,
+                                           14367.499023f};
+  const float kOutputReference[] = {0.003449f, 0.004334f, 0.004303f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2534.461914f, 6277.638672f,
+                                           14367.499023f};
+  const float kOutputReference[] = {0.003449f, 0.004334f, 0.004303f};
+#else
+  const float kSpeechProbabilityReference = 0.71743423f;
+  const float kNoiseEstimateReference[] = {2179.853027f, 6507.995117f,
+                                           15652.758789f};
+  const float kOutputReference[] = {0.003574f, 0.004494f, 0.004499f};
+#endif
+
+  RunBitexactnessTest(16000, 1, NoiseSuppression::Level::kLow,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(LegacyNoiseSuppresionBitExactnessTest, Mono32kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2540.059082f, 6317.822754f,
+                                           14440.845703f};
+  const float kOutputReference[] = {0.001679f, 0.002411f, 0.002594f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2540.059082f, 6317.822754f,
+                                           14440.845703f};
+  const float kOutputReference[] = {0.001679f, 0.002411f, 0.002594f};
+#else
+  const float kSpeechProbabilityReference = 0.67999554f;
+  const float kNoiseEstimateReference[] = {2149.780518f, 7076.936035f,
+                                           14939.945312f};
+  const float kOutputReference[] = {0.001221f, 0.001984f, 0.002228f};
+#endif
+
+  RunBitexactnessTest(32000, 1, NoiseSuppression::Level::kLow,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(LegacyNoiseSuppresionBitExactnessTest, Mono48kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2135.292480f, 6692.695801f,
+                                           14647.632812f};
+  const float kOutputReference[] = {-0.012738f, -0.012312f, -0.011576f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2135.292480f, 6692.695801f,
+                                           14647.632812f};
+  const float kOutputReference[] = {-0.012738f, -0.012312f, -0.011576f};
+#else
+  const float kSpeechProbabilityReference = 0.70737761f;
+  const float kNoiseEstimateReference[] = {2187.394043f, 6913.306641f,
+                                           13182.945312f};
+  const float kOutputReference[] = {-0.013062f, -0.012657f, -0.011934f};
+#endif
+
+  RunBitexactnessTest(48000, 1, NoiseSuppression::Level::kLow,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(LegacyNoiseSuppresionBitExactnessTest, Stereo16kHzLow) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {9992.127930f, 12689.569336f,
+                                           11589.296875f};
+  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[] = {10321.353516f, 12133.852539f,
+                                           10923.060547f};
+  const float kOutputReference[] = {-0.011108f, -0.007904f, -0.012390f,
+                                    -0.002472f, 0.000916f,  -0.003235f};
+#else
+  const float kSpeechProbabilityReference = 0.67285913f;
+  const float kNoiseEstimateReference[] = {9753.257812f, 11515.603516f,
+                                           10503.309570f};
+  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(LegacyNoiseSuppresionBitExactnessTest, Mono16kHzModerate) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2057.085938f, 7601.055176f,
+                                           19666.187500f};
+  const float kOutputReference[] = {0.004669f, 0.005524f, 0.005432f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2244.497803f, 6864.164062f,
+                                           16726.523438f};
+  const float kOutputReference[] = {0.004669f, 0.005615f, 0.005585f};
+#else
+  const float kSpeechProbabilityReference = 0.70916927f;
+  const float kNoiseEstimateReference[] = {2172.830566f, 6552.661133f,
+                                           15624.025391f};
+  const float kOutputReference[] = {0.004513f, 0.005590f, 0.005614f};
+#endif
+
+  RunBitexactnessTest(16000, 1, NoiseSuppression::Level::kModerate,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(LegacyNoiseSuppresionBitExactnessTest, Mono16kHzHigh) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2095.148193f, 7698.553711f,
+                                           19689.533203f};
+  const float kOutputReference[] = {0.004639f, 0.005402f, 0.005310f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2282.515625f, 6984.408203f,
+                                           16920.960938f};
+  const float kOutputReference[] = {0.004547f, 0.005432f, 0.005402f};
+#else
+  const float kSpeechProbabilityReference = 0.70104003f;
+  const float kNoiseEstimateReference[] = {2225.081055f, 6711.529785f,
+                                           15785.949219};
+  const float kOutputReference[] = {0.004394f, 0.005406f, 0.005416f};
+#endif
+
+  RunBitexactnessTest(16000, 1, NoiseSuppression::Level::kHigh,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+
+TEST(LegacyNoiseSuppresionBitExactnessTest, Mono16kHzVeryHigh) {
+#if defined(WEBRTC_ARCH_ARM64)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2677.733398f, 6186.987305f,
+                                           14365.744141f};
+  const float kOutputReference[] = {0.004273f, 0.005127f, 0.005188f};
+#elif defined(WEBRTC_ARCH_ARM)
+  const float kSpeechProbabilityReference = -4.0f;
+  const float kNoiseEstimateReference[] = {2677.733398f, 6186.987305f,
+                                           14365.744141f};
+  const float kOutputReference[] = {0.004273f, 0.005127f, 0.005188f};
+#else
+  const float kSpeechProbabilityReference = 0.70290041f;
+  const float kNoiseEstimateReference[] = {2254.921875f, 6723.172852f,
+                                           15770.559570f};
+  const float kOutputReference[] = {0.004321f, 0.005247f, 0.005263f};
+#endif
+
+  RunBitexactnessTest(16000, 1, NoiseSuppression::Level::kVeryHigh,
+                      kSpeechProbabilityReference, kNoiseEstimateReference,
+                      kOutputReference);
+}
+}  // namespace webrtc