AGC2 Bi-Quad filter: separate target and unit test.

Adding a build target for the bi-qaud filter to make it available for the RNN VAD of AGC2. Also adding a unit test to test the computation both in-place and not in-place while comparing the produced output to that of scipy.signal. Bug: webrtc:9076 Change-Id: I16176a477ee4b81bb1e090c4906c3a9948ad2772 Reviewed-on: https://webrtc-review.googlesource.com/74220 Commit-Queue: Alessio Bazzica <alessiob@webrtc.org> Reviewed-by: Alex Loiko <aleloi@webrtc.org> Cr-Commit-Position: refs/heads/master@{#23141}
2018-05-07 13:26:47 +02:00 · 2018-05-07 13:26:47 +02:00 · d8d02147d9
commit d8d02147d9
parent 78ad6ce381
5 changed files with 215 additions and 72 deletions
--- a/modules/audio_processing/BUILD.gn
+++ b/modules/audio_processing/BUILD.gn
@ -543,6 +543,7 @@ if (rtc_include_tests) {
      "../audio_coding:neteq_input_audio_tools",
      "aec_dump:mock_aec_dump_unittests",
      "agc2:adaptive_digital_unittests",
+      "agc2:biquad_filter_unittests",
      "agc2:fixed_digital_unittests",
      "agc2:noise_estimator_unittests",
      "agc2/rnn_vad:unittests",
--- a/modules/audio_processing/agc2/BUILD.gn
+++ b/modules/audio_processing/agc2/BUILD.gn
@ -47,6 +47,27 @@ rtc_source_set("adaptive_digital") {
  ]
 }

+rtc_source_set("biquad_filter") {
+  visibility = [ ":*" ]
+  sources = [
+    "biquad_filter.cc",
+    "biquad_filter.h",
+  ]
+  deps = [
+    "../../../api:array_view",
+    "../../../rtc_base:rtc_base_approved",
+  ]
+}
+
+rtc_source_set("common") {
+  sources = [
+    "agc2_common.h",
+  ]
+  deps = [
+    "../../../rtc_base:rtc_base_approved",
+  ]
+}
+
 rtc_source_set("fixed_digital") {
  sources = [
    "fixed_digital_level_estimator.cc",
@ -75,41 +96,6 @@ rtc_source_set("fixed_digital") {
  ]
 }

-rtc_source_set("common") {
-  sources = [
-    "agc2_common.h",
-  ]
-  deps = [
-    "../../../rtc_base:rtc_base_approved",
-  ]
-}
-
-rtc_source_set("noise_level_estimator") {
-  sources = [
-    "biquad_filter.cc",
-    "biquad_filter.h",
-    "down_sampler.cc",
-    "down_sampler.h",
-    "noise_level_estimator.cc",
-    "noise_level_estimator.h",
-    "noise_spectrum_estimator.cc",
-    "noise_spectrum_estimator.h",
-    "signal_classifier.cc",
-    "signal_classifier.h",
-  ]
-  deps = [
-    "..:aec_core",
-    "..:apm_logging",
-    "..:audio_frame_view",
-    "../../../api:array_view",
-    "../../../common_audio",
-    "../../../rtc_base:checks",
-    "../../../rtc_base:macromagic",
-  ]
-
-  configs += [ "..:apm_debug_dump" ]
-}
-
 rtc_source_set("gain_applier") {
  sources = [
    "gain_applier.cc",
@ -122,19 +108,65 @@ rtc_source_set("gain_applier") {
  ]
 }

-rtc_source_set("test_utils") {
-  testonly = true
-  visibility = [ ":*" ]
+rtc_source_set("noise_level_estimator") {
  sources = [
-    "agc2_testing_common.cc",
-    "agc2_testing_common.h",
-    "vector_float_frame.cc",
-    "vector_float_frame.h",
+    "down_sampler.cc",
+    "down_sampler.h",
+    "noise_level_estimator.cc",
+    "noise_level_estimator.h",
+    "noise_spectrum_estimator.cc",
+    "noise_spectrum_estimator.h",
+    "signal_classifier.cc",
+    "signal_classifier.h",
  ]
  deps = [
+    ":biquad_filter",
+    "..:aec_core",
+    "..:apm_logging",
    "..:audio_frame_view",
+    "../../../api:array_view",
+    "../../../common_audio",
+    "../../../rtc_base:checks",
+    "../../../rtc_base:macromagic",
+  ]
+
+  configs += [ "..:apm_debug_dump" ]
+}
+
+rtc_source_set("adaptive_digital_unittests") {
+  testonly = true
+  configs += [ "..:apm_debug_dump" ]
+
+  sources = [
+    "adaptive_digital_gain_applier_unittest.cc",
+    "adaptive_mode_level_estimator_unittest.cc",
+    "gain_applier_unittest.cc",
+    "saturation_protector_unittest.cc",
+  ]
+  deps = [
+    ":adaptive_digital",
+    ":common",
+    ":gain_applier",
+    ":test_utils",
+    "..:apm_logging",
+    "..:audio_frame_view",
+    "../../../api:array_view",
+    "../../../common_audio",
    "../../../rtc_base:checks",
    "../../../rtc_base:rtc_base_approved",
+    "../../../rtc_base:rtc_base_tests_utils",
+    "../vad:vad_with_level",
+  ]
+}
+
+rtc_source_set("biquad_filter_unittests") {
+  testonly = true
+  sources = [
+    "biquad_filter_unittest.cc",
+  ]
+  deps = [
+    ":biquad_filter",
+    "../../../rtc_base:rtc_base_tests_utils",
  ]
 }

@ -168,32 +200,6 @@ rtc_source_set("fixed_digital_unittests") {
  ]
 }

-rtc_source_set("adaptive_digital_unittests") {
-  testonly = true
-  configs += [ "..:apm_debug_dump" ]
-
-  sources = [
-    "adaptive_digital_gain_applier_unittest.cc",
-    "adaptive_mode_level_estimator_unittest.cc",
-    "gain_applier_unittest.cc",
-    "saturation_protector_unittest.cc",
-  ]
-  deps = [
-    ":adaptive_digital",
-    ":common",
-    ":gain_applier",
-    ":test_utils",
-    "..:apm_logging",
-    "..:audio_frame_view",
-    "../../../api:array_view",
-    "../../../common_audio",
-    "../../../rtc_base:checks",
-    "../../../rtc_base:rtc_base_approved",
-    "../../../rtc_base:rtc_base_tests_utils",
-    "../vad:vad_with_level",
-  ]
-}
-
 rtc_source_set("noise_estimator_unittests") {
  testonly = true
  configs += [ "..:apm_debug_dump" ]
@ -213,3 +219,19 @@ rtc_source_set("noise_estimator_unittests") {
    "../../../rtc_base:rtc_base_tests_utils",
  ]
 }
+
+rtc_source_set("test_utils") {
+  testonly = true
+  visibility = [ ":*" ]
+  sources = [
+    "agc2_testing_common.cc",
+    "agc2_testing_common.h",
+    "vector_float_frame.cc",
+    "vector_float_frame.h",
+  ]
+  deps = [
+    "..:audio_frame_view",
+    "../../../rtc_base:checks",
+    "../../../rtc_base:rtc_base_approved",
+  ]
+}
--- a/modules/audio_processing/agc2/biquad_filter.cc
+++ b/modules/audio_processing/agc2/biquad_filter.cc
@ -12,9 +12,8 @@

 namespace webrtc {

-// This method applies a biquad filter to an input signal x to produce an
-// output signal y. The biquad coefficients are specified at the construction
-// of the object.
+// Transposed direct form I implementation of a bi-quad filter applied to an
+// input signal |x| to produce an output signal |y|.
 void BiQuadFilter::Process(rtc::ArrayView<const float> x,
                           rtc::ArrayView<float> y) {
  for (size_t k = 0; k < x.size(); ++k) {
--- a/modules/audio_processing/agc2/biquad_filter.h
+++ b/modules/audio_processing/agc2/biquad_filter.h
@ -19,6 +19,10 @@ namespace webrtc {

 class BiQuadFilter {
 public:
+  // Normalized filter coefficients.
+  //        b_0 + b_1 • z^(-1) + b_2 • z^(-2)
+  // H(z) = ---------------------------------
+  //         1 + a_1 • z^(-1) + a_2 • z^(-2)
  struct BiQuadCoefficients {
    float b[3];
    float a[2];
@ -31,7 +35,7 @@ class BiQuadFilter {
  }

  // Produces a filtered output y of the input x. Both x and y need to
-  // have the same length.
+  // have the same length. In-place modification is allowed.
  void Process(rtc::ArrayView<const float> x, rtc::ArrayView<float> y);

 private:
--- a/modules/audio_processing/agc2/biquad_filter_unittest.cc
+++ b/modules/audio_processing/agc2/biquad_filter_unittest.cc
@ -0,0 +1,117 @@
+/*
+ *  Copyright (c) 2018 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 "modules/audio_processing/agc2/biquad_filter.h"
+
+#include <algorithm>
+#include <array>
+#include <cmath>
+
+// TODO(bugs.webrtc.org/8948): Add when the issue is fixed.
+// #include "test/fpe_observer.h"
+#include "rtc_base/gunit.h"
+
+namespace webrtc {
+namespace test {
+namespace {
+
+constexpr size_t kFrameSize = 8;
+constexpr size_t kNumFrames = 4;
+using FloatArraySequence =
+    std::array<std::array<float, kFrameSize>, kNumFrames>;
+
+constexpr FloatArraySequence kBiQuadInputSeq = {
+    {{-87.166290f, -8.029022f, 101.619583f, -0.294296f, -5.825764f, -8.890625f,
+      10.310432f, 54.845333f},
+     {-64.647644f, -6.883945f, 11.059189f, -95.242538f, -108.870834f,
+      11.024944f, 63.044102f, -52.709583f},
+     {-32.350529f, -18.108028f, -74.022339f, -8.986874f, -1.525581f,
+      103.705513f, 6.346226f, -14.319557f},
+     {22.645832f, -64.597153f, 55.462521f, -109.393188f, 10.117825f,
+      -40.019642f, -98.612228f, -8.330326f}}};
+
+// Generated via "B, A = scipy.signal.butter(2, 30/12000, btype='highpass')"
+const BiQuadFilter::BiQuadCoefficients kBiQuadConfig = {
+    {0.99446179f, -1.98892358f, 0.99446179f},
+    {-1.98889291f, 0.98895425f}};
+
+// Comparing to scipy. The expected output is generated as follows:
+// zi = np.float32([0, 0])
+// for i in range(4):
+//   yn, zi = scipy.signal.lfilter(B, A, x[i], zi=zi)
+//   print(yn)
+constexpr FloatArraySequence kBiQuadOutputSeq = {
+    {{-86.68354497f, -7.02175351f, 102.10290352f, -0.37487333f, -5.87205847f,
+      -8.85521608f, 10.33772563f, 54.51157181f},
+     {-64.92531604f, -6.76395978f, 11.15534507f, -94.68073341f, -107.18177856f,
+      13.24642474f, 64.84288941f, -50.97822629f},
+     {-30.1579652f, -15.64850899f, -71.06662821f, -5.5883229f, 1.91175353f,
+      106.5572003f, 8.57183046f, -12.06298473f},
+     {24.84286614f, -62.18094158f, 57.91488056f, -106.65685933f, 13.38760103f,
+      -36.60367134f, -94.44880104f, -3.59920354f}}};
+
+// Fail for every pair from two equally sized rtc::ArrayView<float> views such
+// that their relative error is above a given threshold. If the expected value
+// of a pair is 0, the tolerance is used to check the absolute error.
+void ExpectNearRelative(rtc::ArrayView<const float> expected,
+                        rtc::ArrayView<const float> computed,
+                        const float tolerance) {
+  // The relative error is undefined when the expected value is 0.
+  // When that happens, check the absolute error instead. |safe_den| is used
+  // below to implement such logic.
+  auto safe_den = [](float x) { return (x == 0.f) ? 1.f : std::fabs(x); };
+  ASSERT_EQ(expected.size(), computed.size());
+  for (size_t i = 0; i < expected.size(); ++i) {
+    const float abs_diff = std::fabs(expected[i] - computed[i]);
+    // No failure when the values are equal.
+    if (abs_diff == 0.f)
+      continue;
+    SCOPED_TRACE(i);
+    SCOPED_TRACE(expected[i]);
+    SCOPED_TRACE(computed[i]);
+    EXPECT_LE(abs_diff / safe_den(expected[i]), tolerance);
+  }
+}
+
+}  // namespace
+
+TEST(BiQuadFilterTest, FilterNotInPlace) {
+  BiQuadFilter filter;
+  filter.Initialize(kBiQuadConfig);
+  std::array<float, kFrameSize> samples;
+
+  // TODO(https://bugs.webrtc.org/8948): Add when the issue is fixed.
+  // FloatingPointExceptionObserver fpe_observer;
+
+  for (size_t i = 0; i < kNumFrames; ++i) {
+    SCOPED_TRACE(i);
+    filter.Process(kBiQuadInputSeq[i], samples);
+    ExpectNearRelative(kBiQuadOutputSeq[i], samples, 2e-4f);
+  }
+}
+
+TEST(BiQuadFilterTest, FilterInPlace) {
+  BiQuadFilter filter;
+  filter.Initialize(kBiQuadConfig);
+  std::array<float, kFrameSize> samples;
+
+  // TODO(https://bugs.webrtc.org/8948): Add when the issue is fixed.
+  // FloatingPointExceptionObserver fpe_observer;
+
+  for (size_t i = 0; i < kNumFrames; ++i) {
+    SCOPED_TRACE(i);
+    std::copy(kBiQuadInputSeq[i].begin(), kBiQuadInputSeq[i].end(),
+              samples.begin());
+    filter.Process({samples}, {samples});
+    ExpectNearRelative(kBiQuadOutputSeq[i], samples, 2e-4f);
+  }
+}
+}  // namespace test
+}  // namespace webrtc