Make the nonlinear beamformer steerable

Depends on this CL: https://codereview.webrtc.org/1395453004/

R=andrew@webrtc.org

Review URL: https://codereview.webrtc.org/1394103003 .

Cr-Commit-Position: refs/heads/master@{#10458}

webrtc/modules/audio_processing/audio_processing_impl.cc

@@ -225,6 +225,7 @@ AudioProcessingImpl::AudioProcessingImpl(const Config& config,
       beamformer_enabled_(config.Get<Beamforming>().enabled),
       beamformer_(beamformer),
       array_geometry_(config.Get<Beamforming>().array_geometry),
+      target_direction_(config.Get<Beamforming>().target_direction),
       intelligibility_enabled_(config.Get<Intelligibility>().enabled) {
   echo_cancellation_ = new EchoCancellationImpl(this, crit_);
   component_list_.push_back(echo_cancellation_);
@@ -1099,7 +1100,8 @@ void AudioProcessingImpl::InitializeTransient() {
 void AudioProcessingImpl::InitializeBeamformer() {
   if (beamformer_enabled_) {
     if (!beamformer_) {
-      beamformer_.reset(new NonlinearBeamformer(array_geometry_));
+      beamformer_.reset(
+          new NonlinearBeamformer(array_geometry_, target_direction_));
     }
     beamformer_->Initialize(kChunkSizeMs, split_rate_);
   }

webrtc/modules/audio_processing/audio_processing_impl.h

@@ -208,6 +208,7 @@ class AudioProcessingImpl : public AudioProcessing {
   const bool beamformer_enabled_;
   rtc::scoped_ptr<Beamformer<float>> beamformer_;
   const std::vector<Point> array_geometry_;
+  const SphericalPointf target_direction_;
 
   bool intelligibility_enabled_;
   rtc::scoped_ptr<IntelligibilityEnhancer> intelligibility_enhancer_;

webrtc/modules/audio_processing/beamformer/array_util.cc

@@ -16,6 +16,11 @@
 #include "webrtc/base/checks.h"
 
 namespace webrtc {
+namespace {
+
+const float kMaxDotProduct = 1e-6f;
+
+}  // namespace
 
 float GetMinimumSpacing(const std::vector<Point>& array_geometry) {
   RTC_CHECK_GT(array_geometry.size(), 1u);
@@ -29,4 +34,85 @@ float GetMinimumSpacing(const std::vector<Point>& array_geometry) {
   return mic_spacing;
 }
 
+Point PairDirection(const Point& a, const Point& b) {
+  return {b.x() - a.x(), b.y() - a.y(), b.z() - a.z()};
+}
+
+float DotProduct(const Point& a, const Point& b) {
+  return a.x() * b.x() + a.y() * b.y() + a.z() * b.z();
+}
+
+Point CrossProduct(const Point& a, const Point& b) {
+  return {a.y() * b.z() - a.z() * b.y(), a.z() * b.x() - a.x() * b.z(),
+          a.x() * b.y() - a.y() * b.x()};
+}
+
+bool AreParallel(const Point& a, const Point& b) {
+  Point cross_product = CrossProduct(a, b);
+  return DotProduct(cross_product, cross_product) < kMaxDotProduct;
+}
+
+bool ArePerpendicular(const Point& a, const Point& b) {
+  return std::abs(DotProduct(a, b)) < kMaxDotProduct;
+}
+
+rtc::Maybe<Point> GetDirectionIfLinear(
+    const std::vector<Point>& array_geometry) {
+  RTC_DCHECK_GT(array_geometry.size(), 1u);
+  const Point first_pair_direction =
+      PairDirection(array_geometry[0], array_geometry[1]);
+  for (size_t i = 2u; i < array_geometry.size(); ++i) {
+    const Point pair_direction =
+        PairDirection(array_geometry[i - 1], array_geometry[i]);
+    if (!AreParallel(first_pair_direction, pair_direction)) {
+      return rtc::Maybe<Point>();
+    }
+  }
+  return first_pair_direction;
+}
+
+rtc::Maybe<Point> GetNormalIfPlanar(const std::vector<Point>& array_geometry) {
+  RTC_DCHECK_GT(array_geometry.size(), 1u);
+  const Point first_pair_direction =
+      PairDirection(array_geometry[0], array_geometry[1]);
+  Point pair_direction(0.f, 0.f, 0.f);
+  size_t i = 2u;
+  bool is_linear = true;
+  for (; i < array_geometry.size() && is_linear; ++i) {
+    pair_direction = PairDirection(array_geometry[i - 1], array_geometry[i]);
+    if (!AreParallel(first_pair_direction, pair_direction)) {
+      is_linear = false;
+    }
+  }
+  if (is_linear) {
+    return rtc::Maybe<Point>();
+  }
+  const Point normal_direction =
+      CrossProduct(first_pair_direction, pair_direction);
+  for (; i < array_geometry.size(); ++i) {
+    pair_direction = PairDirection(array_geometry[i - 1], array_geometry[i]);
+    if (!ArePerpendicular(normal_direction, pair_direction)) {
+      return rtc::Maybe<Point>();
+    }
+  }
+  return normal_direction;
+}
+
+rtc::Maybe<Point> GetArrayNormalIfExists(
+    const std::vector<Point>& array_geometry) {
+  const rtc::Maybe<Point> direction = GetDirectionIfLinear(array_geometry);
+  if (direction) {
+    return Point(direction->y(), -direction->x(), 0.f);
+  }
+  const rtc::Maybe<Point> normal = GetNormalIfPlanar(array_geometry);
+  if (normal && normal->z() < kMaxDotProduct) {
+    return normal;
+  }
+  return rtc::Maybe<Point>();
+}
+
+Point AzimuthToPoint(float azimuth) {
+  return Point(std::cos(azimuth), std::sin(azimuth), 0.f);
+}
+
 }  // namespace webrtc

webrtc/modules/audio_processing/beamformer/array_util.h

@@ -14,11 +14,23 @@
 #include <cmath>
 #include <vector>
 
+#include "webrtc/base/maybe.h"
+
 namespace webrtc {
 
-// Coordinates in meters.
+// Coordinates in meters. The convention used is:
+// x: the horizontal dimension, with positive to the right from the camera's
+//    perspective.
+// y: the depth dimension, with positive forward from the camera's
+//    perspective.
+// z: the vertical dimension, with positive upwards.
 template<typename T>
 struct CartesianPoint {
+  CartesianPoint() {
+    c[0] = 0;
+    c[1] = 0;
+    c[2] = 0;
+  }
   CartesianPoint(T x, T y, T z) {
     c[0] = x;
     c[1] = y;
@@ -32,10 +44,35 @@ struct CartesianPoint {
 
 using Point = CartesianPoint<float>;
 
+// Calculates the direction from a to b.
+Point PairDirection(const Point& a, const Point& b);
+
+float DotProduct(const Point& a, const Point& b);
+Point CrossProduct(const Point& a, const Point& b);
+
+bool AreParallel(const Point& a, const Point& b);
+bool ArePerpendicular(const Point& a, const Point& b);
+
 // Returns the minimum distance between any two Points in the given
 // |array_geometry|.
 float GetMinimumSpacing(const std::vector<Point>& array_geometry);
 
+// If the given array geometry is linear it returns the direction without
+// normalizing.
+rtc::Maybe<Point> GetDirectionIfLinear(
+    const std::vector<Point>& array_geometry);
+
+// If the given array geometry is planar it returns the normal without
+// normalizing.
+rtc::Maybe<Point> GetNormalIfPlanar(const std::vector<Point>& array_geometry);
+
+// Returns the normal of an array if it has one and it is in the xy-plane.
+rtc::Maybe<Point> GetArrayNormalIfExists(
+    const std::vector<Point>& array_geometry);
+
+// The resulting Point will be in the xy-plane.
+Point AzimuthToPoint(float azimuth);
+
 template<typename T>
 float Distance(CartesianPoint<T> a, CartesianPoint<T> b) {
   return std::sqrt((a.x() - b.x()) * (a.x() - b.x()) +
@@ -43,6 +80,11 @@ float Distance(CartesianPoint<T> a, CartesianPoint<T> b) {
                    (a.z() - b.z()) * (a.z() - b.z()));
 }
 
+// The convention used:
+// azimuth: zero is to the right from the camera's perspective, with positive
+//          angles in radians counter-clockwise.
+// elevation: zero is horizontal, with positive angles in radians upwards.
+// radius: distance from the camera in meters.
 template <typename T>
 struct SphericalPoint {
   SphericalPoint(T azimuth, T elevation, T radius) {
@@ -58,6 +100,17 @@ struct SphericalPoint {
 
 using SphericalPointf = SphericalPoint<float>;
 
+// Helper functions to transform degrees to radians and the inverse.
+template <typename T>
+T DegreesToRadians(T angle_degrees) {
+  return M_PI * angle_degrees / 180;
+}
+
+template <typename T>
+T RadiansToDegrees(T angle_radians) {
+  return 180 * angle_radians / M_PI;
+}
+
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_BEAMFORMER_ARRAY_UTIL_H_

webrtc/modules/audio_processing/beamformer/array_util_unittest.cc

@@ -8,25 +8,178 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+// MSVC++ requires this to be set before any other includes to get M_PI.
+#define _USE_MATH_DEFINES
+
 #include "webrtc/modules/audio_processing/beamformer/array_util.h"
 
+#include <math.h>
 #include <vector>
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace webrtc {
 
+bool operator==(const Point& lhs, const Point& rhs) {
+  return lhs.x() == rhs.x() && lhs.y() == rhs.y() && lhs.z() == rhs.z();
+}
+
+TEST(ArrayUtilTest, PairDirection) {
+  EXPECT_EQ(Point(1.f, 2.f, 3.f),
+            PairDirection(Point(0.f, 0.f, 0.f), Point(1.f, 2.f, 3.f)));
+  EXPECT_EQ(Point(-1.f, -2.f, -3.f),
+            PairDirection(Point(1.f, 2.f, 3.f), Point(0.f, 0.f, 0.f)));
+  EXPECT_EQ(Point(0.f, 0.f, 0.f),
+            PairDirection(Point(1.f, 0.f, 0.f), Point(1.f, 0.f, 0.f)));
+  EXPECT_EQ(Point(-1.f, 2.f, 0.f),
+            PairDirection(Point(1.f, 0.f, 0.f), Point(0.f, 2.f, 0.f)));
+  EXPECT_EQ(Point(-4.f, 4.f, -4.f),
+            PairDirection(Point(1.f, -2.f, 3.f), Point(-3.f, 2.f, -1.f)));
+}
+
+TEST(ArrayUtilTest, DotProduct) {
+  EXPECT_FLOAT_EQ(0.f, DotProduct(Point(0.f, 0.f, 0.f), Point(1.f, 2.f, 3.f)));
+  EXPECT_FLOAT_EQ(0.f, DotProduct(Point(1.f, 0.f, 2.f), Point(0.f, 3.f, 0.f)));
+  EXPECT_FLOAT_EQ(0.f, DotProduct(Point(1.f, 1.f, 0.f), Point(1.f, -1.f, 0.f)));
+  EXPECT_FLOAT_EQ(2.f, DotProduct(Point(1.f, 0.f, 0.f), Point(2.f, 0.f, 0.f)));
+  EXPECT_FLOAT_EQ(-6.f,
+                  DotProduct(Point(-2.f, 0.f, 0.f), Point(3.f, 0.f, 0.f)));
+  EXPECT_FLOAT_EQ(-10.f,
+                  DotProduct(Point(1.f, -2.f, 3.f), Point(-3.f, 2.f, -1.f)));
+}
+
+TEST(ArrayUtilTest, CrossProduct) {
+  EXPECT_EQ(Point(0.f, 0.f, 0.f),
+            CrossProduct(Point(0.f, 0.f, 0.f), Point(1.f, 2.f, 3.f)));
+  EXPECT_EQ(Point(0.f, 0.f, 1.f),
+            CrossProduct(Point(1.f, 0.f, 0.f), Point(0.f, 1.f, 0.f)));
+  EXPECT_EQ(Point(1.f, 0.f, 0.f),
+            CrossProduct(Point(0.f, 1.f, 0.f), Point(0.f, 0.f, 1.f)));
+  EXPECT_EQ(Point(0.f, -1.f, 0.f),
+            CrossProduct(Point(1.f, 0.f, 0.f), Point(0.f, 0.f, 1.f)));
+  EXPECT_EQ(Point(-4.f, -8.f, -4.f),
+            CrossProduct(Point(1.f, -2.f, 3.f), Point(-3.f, 2.f, -1.f)));
+}
+
+TEST(ArrayUtilTest, AreParallel) {
+  EXPECT_TRUE(AreParallel(Point(0.f, 0.f, 0.f), Point(1.f, 2.f, 3.f)));
+  EXPECT_FALSE(AreParallel(Point(1.f, 0.f, 2.f), Point(0.f, 3.f, 0.f)));
+  EXPECT_FALSE(AreParallel(Point(1.f, 2.f, 0.f), Point(1.f, -0.5f, 0.f)));
+  EXPECT_FALSE(AreParallel(Point(1.f, -2.f, 3.f), Point(-3.f, 2.f, -1.f)));
+  EXPECT_TRUE(AreParallel(Point(1.f, 0.f, 0.f), Point(2.f, 0.f, 0.f)));
+  EXPECT_TRUE(AreParallel(Point(1.f, 2.f, 3.f), Point(-2.f, -4.f, -6.f)));
+}
+
+TEST(ArrayUtilTest, ArePerpendicular) {
+  EXPECT_TRUE(ArePerpendicular(Point(0.f, 0.f, 0.f), Point(1.f, 2.f, 3.f)));
+  EXPECT_TRUE(ArePerpendicular(Point(1.f, 0.f, 2.f), Point(0.f, 3.f, 0.f)));
+  EXPECT_TRUE(ArePerpendicular(Point(1.f, 2.f, 0.f), Point(1.f, -0.5f, 0.f)));
+  EXPECT_FALSE(ArePerpendicular(Point(1.f, -2.f, 3.f), Point(-3.f, 2.f, -1.f)));
+  EXPECT_FALSE(ArePerpendicular(Point(1.f, 0.f, 0.f), Point(2.f, 0.f, 0.f)));
+  EXPECT_FALSE(ArePerpendicular(Point(1.f, 2.f, 3.f), Point(-2.f, -4.f, -6.f)));
+}
+
 TEST(ArrayUtilTest, GetMinimumSpacing) {
-  std::vector<Point> array_geometry;
+  std::vector<Point> geometry;
-  array_geometry.push_back(Point(0.f, 0.f, 0.f));
+  geometry.push_back(Point(0.f, 0.f, 0.f));
-  array_geometry.push_back(Point(0.1f, 0.f, 0.f));
+  geometry.push_back(Point(0.1f, 0.f, 0.f));
-  EXPECT_FLOAT_EQ(0.1f, GetMinimumSpacing(array_geometry));
+  EXPECT_FLOAT_EQ(0.1f, GetMinimumSpacing(geometry));
-  array_geometry.push_back(Point(0.f, 0.05f, 0.f));
+  geometry.push_back(Point(0.f, 0.05f, 0.f));
-  EXPECT_FLOAT_EQ(0.05f, GetMinimumSpacing(array_geometry));
+  EXPECT_FLOAT_EQ(0.05f, GetMinimumSpacing(geometry));
-  array_geometry.push_back(Point(0.f, 0.f, 0.02f));
+  geometry.push_back(Point(0.f, 0.f, 0.02f));
-  EXPECT_FLOAT_EQ(0.02f, GetMinimumSpacing(array_geometry));
+  EXPECT_FLOAT_EQ(0.02f, GetMinimumSpacing(geometry));
-  array_geometry.push_back(Point(-0.003f, -0.004f, 0.02f));
+  geometry.push_back(Point(-0.003f, -0.004f, 0.02f));
-  EXPECT_FLOAT_EQ(0.005f, GetMinimumSpacing(array_geometry));
+  EXPECT_FLOAT_EQ(0.005f, GetMinimumSpacing(geometry));
+}
+
+TEST(ArrayUtilTest, GetDirectionIfLinear) {
+  std::vector<Point> geometry;
+  geometry.push_back(Point(0.f, 0.f, 0.f));
+  geometry.push_back(Point(0.1f, 0.f, 0.f));
+  EXPECT_TRUE(
+      AreParallel(Point(1.f, 0.f, 0.f), *GetDirectionIfLinear(geometry)));
+  geometry.push_back(Point(0.15f, 0.f, 0.f));
+  EXPECT_TRUE(
+      AreParallel(Point(1.f, 0.f, 0.f), *GetDirectionIfLinear(geometry)));
+  geometry.push_back(Point(-0.2f, 0.f, 0.f));
+  EXPECT_TRUE(
+      AreParallel(Point(1.f, 0.f, 0.f), *GetDirectionIfLinear(geometry)));
+  geometry.push_back(Point(0.05f, 0.f, 0.f));
+  EXPECT_TRUE(
+      AreParallel(Point(1.f, 0.f, 0.f), *GetDirectionIfLinear(geometry)));
+  geometry.push_back(Point(0.1f, 0.1f, 0.f));
+  EXPECT_FALSE(GetDirectionIfLinear(geometry));
+  geometry.push_back(Point(0.f, 0.f, -0.2f));
+  EXPECT_FALSE(GetDirectionIfLinear(geometry));
+}
+
+TEST(ArrayUtilTest, GetNormalIfPlanar) {
+  std::vector<Point> geometry;
+  geometry.push_back(Point(0.f, 0.f, 0.f));
+  geometry.push_back(Point(0.1f, 0.f, 0.f));
+  EXPECT_FALSE(GetNormalIfPlanar(geometry));
+  geometry.push_back(Point(0.15f, 0.f, 0.f));
+  EXPECT_FALSE(GetNormalIfPlanar(geometry));
+  geometry.push_back(Point(0.1f, 0.2f, 0.f));
+  EXPECT_TRUE(AreParallel(Point(0.f, 0.f, 1.f), *GetNormalIfPlanar(geometry)));
+  geometry.push_back(Point(0.f, -0.15f, 0.f));
+  EXPECT_TRUE(AreParallel(Point(0.f, 0.f, 1.f), *GetNormalIfPlanar(geometry)));
+  geometry.push_back(Point(0.f, 0.1f, 0.2f));
+  EXPECT_FALSE(GetNormalIfPlanar(geometry));
+  geometry.push_back(Point(0.f, 0.f, -0.15f));
+  EXPECT_FALSE(GetNormalIfPlanar(geometry));
+  geometry.push_back(Point(0.1f, 0.2f, 0.f));
+  EXPECT_FALSE(GetNormalIfPlanar(geometry));
+}
+
+TEST(ArrayUtilTest, GetArrayNormalIfExists) {
+  std::vector<Point> geometry;
+  geometry.push_back(Point(0.f, 0.f, 0.f));
+  geometry.push_back(Point(0.1f, 0.f, 0.f));
+  EXPECT_TRUE(
+      AreParallel(Point(0.f, 1.f, 0.f), *GetArrayNormalIfExists(geometry)));
+  geometry.push_back(Point(0.15f, 0.f, 0.f));
+  EXPECT_TRUE(
+      AreParallel(Point(0.f, 1.f, 0.f), *GetArrayNormalIfExists(geometry)));
+  geometry.push_back(Point(0.1f, 0.f, 0.2f));
+  EXPECT_TRUE(
+      AreParallel(Point(0.f, 1.f, 0.f), *GetArrayNormalIfExists(geometry)));
+  geometry.push_back(Point(0.f, 0.f, -0.1f));
+  EXPECT_TRUE(
+      AreParallel(Point(0.f, 1.f, 0.f), *GetArrayNormalIfExists(geometry)));
+  geometry.push_back(Point(0.1f, 0.2f, 0.3f));
+  EXPECT_FALSE(GetArrayNormalIfExists(geometry));
+  geometry.push_back(Point(0.f, -0.1f, 0.f));
+  EXPECT_FALSE(GetArrayNormalIfExists(geometry));
+  geometry.push_back(Point(1.f, 0.f, -0.2f));
+  EXPECT_FALSE(GetArrayNormalIfExists(geometry));
+}
+
+TEST(ArrayUtilTest, DegreesToRadians) {
+  EXPECT_FLOAT_EQ(0.f, DegreesToRadians(0.f));
+  EXPECT_FLOAT_EQ(static_cast<float>(M_PI) / 6.f, DegreesToRadians(30.f));
+  EXPECT_FLOAT_EQ(-static_cast<float>(M_PI) / 4.f, DegreesToRadians(-45.f));
+  EXPECT_FLOAT_EQ(static_cast<float>(M_PI) / 3.f, DegreesToRadians(60.f));
+  EXPECT_FLOAT_EQ(-static_cast<float>(M_PI) / 2.f, DegreesToRadians(-90.f));
+  EXPECT_FLOAT_EQ(2.f * static_cast<float>(M_PI) / 3.f,
+                  DegreesToRadians(120.f));
+  EXPECT_FLOAT_EQ(-3.f * static_cast<float>(M_PI) / 4.f,
+                  DegreesToRadians(-135.f));
+  EXPECT_FLOAT_EQ(5.f * static_cast<float>(M_PI) / 6.f,
+                  DegreesToRadians(150.f));
+  EXPECT_FLOAT_EQ(-static_cast<float>(M_PI), DegreesToRadians(-180.f));
+}
+
+TEST(ArrayUtilTest, RadiansToDegrees) {
+  EXPECT_FLOAT_EQ(0.f, RadiansToDegrees(0.f));
+  EXPECT_FLOAT_EQ(30.f, RadiansToDegrees(M_PI / 6.f));
+  EXPECT_FLOAT_EQ(-45.f, RadiansToDegrees(-M_PI / 4.f));
+  EXPECT_FLOAT_EQ(60.f, RadiansToDegrees(M_PI / 3.f));
+  EXPECT_FLOAT_EQ(-90.f, RadiansToDegrees(-M_PI / 2.f));
+  EXPECT_FLOAT_EQ(120.f, RadiansToDegrees(2.f * M_PI / 3.f));
+  EXPECT_FLOAT_EQ(-135.f, RadiansToDegrees(-3.f * M_PI / 4.f));
+  EXPECT_FLOAT_EQ(150.f, RadiansToDegrees(5.f * M_PI / 6.f));
+  EXPECT_FLOAT_EQ(-180.f, RadiansToDegrees(-M_PI));
 }
 
 }  // namespace webrtc

webrtc/modules/audio_processing/beamformer/beamformer.h

@@ -32,6 +32,9 @@ class Beamformer {
   // Needs to be called before the the Beamformer can be used.
   virtual void Initialize(int chunk_size_ms, int sample_rate_hz) = 0;
 
+  // Aim the beamformer at a point in space.
+  virtual void AimAt(const SphericalPointf& spherical_point) = 0;
+
   // Indicates whether a given point is inside of the beam.
   virtual bool IsInBeam(const SphericalPointf& spherical_point) { return true; }
 

webrtc/modules/audio_processing/beamformer/nonlinear_beamformer.cc

@@ -29,13 +29,6 @@ const float kKbdAlpha = 1.5f;
 
 const float kSpeedOfSoundMeterSeconds = 343;
 
-// For both target and interference angles, PI / 2 is perpendicular to the
-// microphone array, facing forwards. The positive direction goes
-// counterclockwise.
-// The angle at which we amplify sound.
-// TODO(aluebs): Make the target angle dynamically settable.
-const float kTargetAngleRadians = static_cast<float>(M_PI) / 2.f;
-
 // The minimum separation in radians between the target direction and an
 // interferer scenario.
 const float kMinAwayRadians = 0.2f;
@@ -50,8 +43,6 @@ const float kAwaySlope = 0.008f;
 // Rpsi = Rpsi_angled * kBalance + Rpsi_uniform * (1 - kBalance)
 const float kBalance = 0.95f;
 
-const float kHalfBeamWidthRadians = static_cast<float>(M_PI) * 20.f / 180.f;
-
 // Alpha coefficients for mask smoothing.
 const float kMaskTimeSmoothAlpha = 0.2f;
 const float kMaskFrequencySmoothAlpha = 0.6f;
@@ -187,14 +178,23 @@ std::vector<Point> GetCenteredArray(std::vector<Point> array_geometry) {
 
 }  // namespace
 
+const float NonlinearBeamformer::kHalfBeamWidthRadians = DegreesToRadians(20.f);
+
 // static
 const size_t NonlinearBeamformer::kNumFreqBins;
 
 NonlinearBeamformer::NonlinearBeamformer(
-    const std::vector<Point>& array_geometry)
+    const std::vector<Point>& array_geometry,
+    SphericalPointf target_direction)
     : num_input_channels_(array_geometry.size()),
       array_geometry_(GetCenteredArray(array_geometry)),
-      min_mic_spacing_(GetMinimumSpacing(array_geometry)) {
+      array_normal_(GetArrayNormalIfExists(array_geometry)),
+      min_mic_spacing_(GetMinimumSpacing(array_geometry)),
+      target_angle_radians_(target_direction.azimuth()),
+      away_radians_(std::min(
+          static_cast<float>(M_PI),
+          std::max(kMinAwayRadians,
+                   kAwaySlope * static_cast<float>(M_PI) / min_mic_spacing_))) {
   WindowGenerator::KaiserBesselDerived(kKbdAlpha, kFftSize, window_);
 }
 
@@ -202,7 +202,6 @@ void NonlinearBeamformer::Initialize(int chunk_size_ms, int sample_rate_hz) {
   chunk_length_ =
       static_cast<size_t>(sample_rate_hz / (1000.f / chunk_size_ms));
   sample_rate_hz_ = sample_rate_hz;
-  InitFrequencyCorrectionRanges();
 
   high_pass_postfilter_mask_ = 1.f;
   is_target_present_ = false;
@@ -223,75 +222,86 @@ void NonlinearBeamformer::Initialize(int chunk_size_ms, int sample_rate_hz) {
     wave_numbers_[i] = 2 * M_PI * freq_hz / kSpeedOfSoundMeterSeconds;
   }
 
-  // Initialize all nonadaptive values before looping through the frames.
+  InitLowFrequencyCorrectionRanges();
-  InitInterfAngles();
+  InitDiffuseCovMats();
-  InitDelaySumMasks();
+  AimAt(SphericalPointf(target_angle_radians_, 0.f, 1.f));
-  InitTargetCovMats();
-  InitInterfCovMats();
-
-  for (size_t i = 0; i < kNumFreqBins; ++i) {
-    rxiws_[i] = Norm(target_cov_mats_[i], delay_sum_masks_[i]);
-    rpsiws_[i].clear();
-    for (size_t j = 0; j < interf_angles_radians_.size(); ++j) {
-      rpsiws_[i].push_back(Norm(*interf_cov_mats_[i][j], delay_sum_masks_[i]));
-    }
-  }
 }
 
-void NonlinearBeamformer::InitFrequencyCorrectionRanges() {
+// These bin indexes determine the regions over which a mean is taken. This is
+// applied as a constant value over the adjacent end "frequency correction"
+// regions.
+//
+//             low_mean_start_bin_     high_mean_start_bin_
+//                   v                         v              constant
+// |----------------|--------|----------------|-------|----------------|
+//   constant               ^                        ^
+//             low_mean_end_bin_       high_mean_end_bin_
+//
+void NonlinearBeamformer::InitLowFrequencyCorrectionRanges() {
+  low_mean_start_bin_ = Round(kLowMeanStartHz * kFftSize / sample_rate_hz_);
+  low_mean_end_bin_ = Round(kLowMeanEndHz * kFftSize / sample_rate_hz_);
+
+  RTC_DCHECK_GT(low_mean_start_bin_, 0U);
+  RTC_DCHECK_LT(low_mean_start_bin_, low_mean_end_bin_);
+}
+
+void NonlinearBeamformer::InitHighFrequencyCorrectionRanges() {
   const float kAliasingFreqHz =
       kSpeedOfSoundMeterSeconds /
-      (min_mic_spacing_ * (1.f + std::abs(std::cos(kTargetAngleRadians))));
+      (min_mic_spacing_ * (1.f + std::abs(std::cos(target_angle_radians_))));
   const float kHighMeanStartHz = std::min(0.5f *  kAliasingFreqHz,
                                           sample_rate_hz_ / 2.f);
   const float kHighMeanEndHz = std::min(0.75f *  kAliasingFreqHz,
                                         sample_rate_hz_ / 2.f);
-
-  low_mean_start_bin_ = Round(kLowMeanStartHz * kFftSize / sample_rate_hz_);
-  low_mean_end_bin_ = Round(kLowMeanEndHz * kFftSize / sample_rate_hz_);
   high_mean_start_bin_ = Round(kHighMeanStartHz * kFftSize / sample_rate_hz_);
   high_mean_end_bin_ = Round(kHighMeanEndHz * kFftSize / sample_rate_hz_);
-  // These bin indexes determine the regions over which a mean is taken. This
+
-  // is applied as a constant value over the adjacent end "frequency correction"
-  // regions.
-  //
-  //             low_mean_start_bin_     high_mean_start_bin_
-  //                   v                         v              constant
-  // |----------------|--------|----------------|-------|----------------|
-  //   constant               ^                        ^
-  //             low_mean_end_bin_       high_mean_end_bin_
-  //
-  RTC_DCHECK_GT(low_mean_start_bin_, 0U);
-  RTC_DCHECK_LT(low_mean_start_bin_, low_mean_end_bin_);
   RTC_DCHECK_LT(low_mean_end_bin_, high_mean_end_bin_);
   RTC_DCHECK_LT(high_mean_start_bin_, high_mean_end_bin_);
   RTC_DCHECK_LT(high_mean_end_bin_, kNumFreqBins - 1);
 }
 
-
 void NonlinearBeamformer::InitInterfAngles() {
-  const float kAwayRadians =
-      std::min(static_cast<float>(M_PI),
-               std::max(kMinAwayRadians, kAwaySlope * static_cast<float>(M_PI) /
-                                             min_mic_spacing_));
-
   interf_angles_radians_.clear();
-  // TODO(aluebs): When the target angle is settable, make sure the interferer
+  const Point target_direction = AzimuthToPoint(target_angle_radians_);
-  // scenarios aren't reflected over the target one for linear geometries.
+  const Point clockwise_interf_direction =
-  interf_angles_radians_.push_back(kTargetAngleRadians - kAwayRadians);
+      AzimuthToPoint(target_angle_radians_ - away_radians_);
-  interf_angles_radians_.push_back(kTargetAngleRadians + kAwayRadians);
+  if (!array_normal_ ||
+      DotProduct(*array_normal_, target_direction) *
+              DotProduct(*array_normal_, clockwise_interf_direction) >=
+          0.f) {
+    // The target and clockwise interferer are in the same half-plane defined
+    // by the array.
+    interf_angles_radians_.push_back(target_angle_radians_ - away_radians_);
+  } else {
+    // Otherwise, the interferer will begin reflecting back at the target.
+    // Instead rotate it away 180 degrees.
+    interf_angles_radians_.push_back(target_angle_radians_ - away_radians_ +
+                                     M_PI);
+  }
+  const Point counterclock_interf_direction =
+      AzimuthToPoint(target_angle_radians_ + away_radians_);
+  if (!array_normal_ ||
+      DotProduct(*array_normal_, target_direction) *
+              DotProduct(*array_normal_, counterclock_interf_direction) >=
+          0.f) {
+    // The target and counter-clockwise interferer are in the same half-plane
+    // defined by the array.
+    interf_angles_radians_.push_back(target_angle_radians_ + away_radians_);
+  } else {
+    // Otherwise, the interferer will begin reflecting back at the target.
+    // Instead rotate it away 180 degrees.
+    interf_angles_radians_.push_back(target_angle_radians_ + away_radians_ -
+                                     M_PI);
+  }
 }
 
 void NonlinearBeamformer::InitDelaySumMasks() {
   for (size_t f_ix = 0; f_ix < kNumFreqBins; ++f_ix) {
     delay_sum_masks_[f_ix].Resize(1, num_input_channels_);
-    CovarianceMatrixGenerator::PhaseAlignmentMasks(f_ix,
+    CovarianceMatrixGenerator::PhaseAlignmentMasks(
-                                                   kFftSize,
+        f_ix, kFftSize, sample_rate_hz_, kSpeedOfSoundMeterSeconds,
-                                                   sample_rate_hz_,
+        array_geometry_, target_angle_radians_, &delay_sum_masks_[f_ix]);
-                                                   kSpeedOfSoundMeterSeconds,
-                                                   array_geometry_,
-                                                   kTargetAngleRadians,
-                                                   &delay_sum_masks_[f_ix]);
 
     complex_f norm_factor = sqrt(
         ConjugateDotProduct(delay_sum_masks_[f_ix], delay_sum_masks_[f_ix]));
@@ -309,15 +319,19 @@ void NonlinearBeamformer::InitTargetCovMats() {
   }
 }
 
+void NonlinearBeamformer::InitDiffuseCovMats() {
+  for (size_t i = 0; i < kNumFreqBins; ++i) {
+    uniform_cov_mat_[i].Resize(num_input_channels_, num_input_channels_);
+    CovarianceMatrixGenerator::UniformCovarianceMatrix(
+        wave_numbers_[i], array_geometry_, &uniform_cov_mat_[i]);
+    complex_f normalization_factor = uniform_cov_mat_[i].elements()[0][0];
+    uniform_cov_mat_[i].Scale(1.f / normalization_factor);
+    uniform_cov_mat_[i].Scale(1 - kBalance);
+  }
+}
+
 void NonlinearBeamformer::InitInterfCovMats() {
   for (size_t i = 0; i < kNumFreqBins; ++i) {
-    ComplexMatrixF uniform_cov_mat(num_input_channels_, num_input_channels_);
-    CovarianceMatrixGenerator::UniformCovarianceMatrix(wave_numbers_[i],
-                                                       array_geometry_,
-                                                       &uniform_cov_mat);
-    complex_f normalization_factor = uniform_cov_mat.elements()[0][0];
-    uniform_cov_mat.Scale(1.f / normalization_factor);
-    uniform_cov_mat.Scale(1 - kBalance);
     interf_cov_mats_[i].clear();
     for (size_t j = 0; j < interf_angles_radians_.size(); ++j) {
       interf_cov_mats_[i].push_back(new ComplexMatrixF(num_input_channels_,
@@ -333,11 +347,21 @@ void NonlinearBeamformer::InitInterfCovMats() {
           array_geometry_,
           &angled_cov_mat);
       // Normalize matrices before averaging them.
-      normalization_factor = angled_cov_mat.elements()[0][0];
+      complex_f normalization_factor = angled_cov_mat.elements()[0][0];
       angled_cov_mat.Scale(1.f / normalization_factor);
       // Weighted average of matrices.
       angled_cov_mat.Scale(kBalance);
-      interf_cov_mats_[i][j]->Add(uniform_cov_mat, angled_cov_mat);
+      interf_cov_mats_[i][j]->Add(uniform_cov_mat_[i], angled_cov_mat);
+    }
+  }
+}
+
+void NonlinearBeamformer::NormalizeCovMats() {
+  for (size_t i = 0; i < kNumFreqBins; ++i) {
+    rxiws_[i] = Norm(target_cov_mats_[i], delay_sum_masks_[i]);
+    rpsiws_[i].clear();
+    for (size_t j = 0; j < interf_angles_radians_.size(); ++j) {
+      rpsiws_[i].push_back(Norm(*interf_cov_mats_[i][j], delay_sum_masks_[i]));
     }
   }
 }
@@ -354,28 +378,32 @@ void NonlinearBeamformer::ProcessChunk(const ChannelBuffer<float>& input,
   const float ramp_increment =
       (high_pass_postfilter_mask_ - old_high_pass_mask) /
       input.num_frames_per_band();
-  // Apply delay and sum and post-filter in the time domain. WARNING: only works
+  // Apply the smoothed high-pass mask to the first channel of each band.
-  // because delay-and-sum is not frequency dependent.
+  // This can be done because the effct of the linear beamformer is negligible
+  // compared to the post-filter.
   for (size_t i = 1; i < input.num_bands(); ++i) {
     float smoothed_mask = old_high_pass_mask;
     for (size_t j = 0; j < input.num_frames_per_band(); ++j) {
       smoothed_mask += ramp_increment;
-
+      output->channels(i)[0][j] = input.channels(i)[0][j] * smoothed_mask;
-      // Applying the delay and sum (at zero degrees, this is equivalent to
-      // averaging).
-      float sum = 0.f;
-      for (int k = 0; k < input.num_channels(); ++k) {
-        sum += input.channels(i)[k][j];
-      }
-      output->channels(i)[0][j] = sum / input.num_channels() * smoothed_mask;
     }
   }
 }
 
+void NonlinearBeamformer::AimAt(const SphericalPointf& target_direction) {
+  target_angle_radians_ = target_direction.azimuth();
+  InitHighFrequencyCorrectionRanges();
+  InitInterfAngles();
+  InitDelaySumMasks();
+  InitTargetCovMats();
+  InitInterfCovMats();
+  NormalizeCovMats();
+}
+
 bool NonlinearBeamformer::IsInBeam(const SphericalPointf& spherical_point) {
   // If more than half-beamwidth degrees away from the beam's center,
   // you are out of the beam.
-  return fabs(spherical_point.azimuth() - kTargetAngleRadians) <
+  return fabs(spherical_point.azimuth() - target_angle_radians_) <
          kHalfBeamWidthRadians;
 }
 

webrtc/modules/audio_processing/beamformer/nonlinear_beamformer.h

@@ -11,6 +11,10 @@
 #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_BEAMFORMER_NONLINEAR_BEAMFORMER_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_BEAMFORMER_NONLINEAR_BEAMFORMER_H_
 
+// MSVC++ requires this to be set before any other includes to get M_PI.
+#define _USE_MATH_DEFINES
+
+#include <math.h>
 #include <vector>
 
 #include "webrtc/common_audio/lapped_transform.h"
@@ -31,7 +35,12 @@ class NonlinearBeamformer
   : public Beamformer<float>,
     public LappedTransform::Callback {
  public:
-  explicit NonlinearBeamformer(const std::vector<Point>& array_geometry);
+  static const float kHalfBeamWidthRadians;
+
+  explicit NonlinearBeamformer(
+      const std::vector<Point>& array_geometry,
+      SphericalPointf target_direction =
+          SphericalPointf(static_cast<float>(M_PI) / 2.f, 0.f, 1.f));
 
   // Sample rate corresponds to the lower band.
   // Needs to be called before the NonlinearBeamformer can be used.
@@ -44,6 +53,8 @@ class NonlinearBeamformer
   void ProcessChunk(const ChannelBuffer<float>& input,
                     ChannelBuffer<float>* output) override;
 
+  void AimAt(const SphericalPointf& target_direction) override;
+
   bool IsInBeam(const SphericalPointf& spherical_point) override;
 
   // After processing each block |is_target_present_| is set to true if the
@@ -62,15 +73,21 @@ class NonlinearBeamformer
                          complex<float>* const* output) override;
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(NonlinearBeamformerTest,
+                           InterfAnglesTakeAmbiguityIntoAccount);
+
   typedef Matrix<float> MatrixF;
   typedef ComplexMatrix<float> ComplexMatrixF;
   typedef complex<float> complex_f;
 
-  void InitFrequencyCorrectionRanges();
+  void InitLowFrequencyCorrectionRanges();
+  void InitHighFrequencyCorrectionRanges();
   void InitInterfAngles();
   void InitDelaySumMasks();
   void InitTargetCovMats();
+  void InitDiffuseCovMats();
   void InitInterfCovMats();
+  void NormalizeCovMats();
 
   // Calculates postfilter masks that minimize the mean squared error of our
   // estimation of the desired signal.
@@ -116,6 +133,8 @@ class NonlinearBeamformer
   int sample_rate_hz_;
 
   const std::vector<Point> array_geometry_;
+  // The normal direction of the array if it has one and it is in the xy-plane.
+  const rtc::Maybe<Point> array_normal_;
 
   // Minimum spacing between microphone pairs.
   const float min_mic_spacing_;
@@ -133,17 +152,20 @@ class NonlinearBeamformer
   // Time and frequency smoothed mask.
   float final_mask_[kNumFreqBins];
 
+  float target_angle_radians_;
   // Angles of the interferer scenarios.
   std::vector<float> interf_angles_radians_;
+  // The angle between the target and the interferer scenarios.
+  const float away_radians_;
 
   // Array of length |kNumFreqBins|, Matrix of size |1| x |num_channels_|.
   ComplexMatrixF delay_sum_masks_[kNumFreqBins];
   ComplexMatrixF normalized_delay_sum_masks_[kNumFreqBins];
 
-  // Array of length |kNumFreqBins|, Matrix of size |num_input_channels_| x
+  // Arrays of length |kNumFreqBins|, Matrix of size |num_input_channels_| x
   // |num_input_channels_|.
   ComplexMatrixF target_cov_mats_[kNumFreqBins];
-
+  ComplexMatrixF uniform_cov_mat_[kNumFreqBins];
   // Array of length |kNumFreqBins|, Matrix of size |num_input_channels_| x
   // |num_input_channels_|. ScopedVector has a size equal to the number of
   // interferer scenarios.

webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_unittest.cc

@@ -0,0 +1,147 @@
+/*
+ *  Copyright (c) 2015 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.
+ */
+
+// MSVC++ requires this to be set before any other includes to get M_PI.
+#define _USE_MATH_DEFINES
+
+#include "webrtc/modules/audio_processing/beamformer/nonlinear_beamformer.h"
+
+#include <math.h>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace webrtc {
+namespace {
+
+const int kChunkSizeMs = 10;
+const int kSampleRateHz = 16000;
+
+SphericalPointf AzimuthToSphericalPoint(float azimuth_radians) {
+  return SphericalPointf(azimuth_radians, 0.f, 1.f);
+}
+
+void Verify(NonlinearBeamformer* bf, float target_azimuth_radians) {
+  EXPECT_TRUE(bf->IsInBeam(AzimuthToSphericalPoint(target_azimuth_radians)));
+  EXPECT_TRUE(bf->IsInBeam(AzimuthToSphericalPoint(
+      target_azimuth_radians - NonlinearBeamformer::kHalfBeamWidthRadians +
+      0.001f)));
+  EXPECT_TRUE(bf->IsInBeam(AzimuthToSphericalPoint(
+      target_azimuth_radians + NonlinearBeamformer::kHalfBeamWidthRadians -
+      0.001f)));
+  EXPECT_FALSE(bf->IsInBeam(AzimuthToSphericalPoint(
+      target_azimuth_radians - NonlinearBeamformer::kHalfBeamWidthRadians -
+      0.001f)));
+  EXPECT_FALSE(bf->IsInBeam(AzimuthToSphericalPoint(
+      target_azimuth_radians + NonlinearBeamformer::kHalfBeamWidthRadians +
+      0.001f)));
+}
+
+void AimAndVerify(NonlinearBeamformer* bf, float target_azimuth_radians) {
+  bf->AimAt(AzimuthToSphericalPoint(target_azimuth_radians));
+  Verify(bf, target_azimuth_radians);
+}
+
+}  // namespace
+
+TEST(NonlinearBeamformerTest, AimingModifiesBeam) {
+  std::vector<Point> array_geometry;
+  array_geometry.push_back(Point(-0.025f, 0.f, 0.f));
+  array_geometry.push_back(Point(0.025f, 0.f, 0.f));
+  NonlinearBeamformer bf(array_geometry);
+  bf.Initialize(kChunkSizeMs, kSampleRateHz);
+  // The default constructor parameter sets the target angle to PI / 2.
+  Verify(&bf, static_cast<float>(M_PI) / 2.f);
+  AimAndVerify(&bf, static_cast<float>(M_PI) / 3.f);
+  AimAndVerify(&bf, 3.f * static_cast<float>(M_PI) / 4.f);
+  AimAndVerify(&bf, static_cast<float>(M_PI) / 6.f);
+  AimAndVerify(&bf, static_cast<float>(M_PI));
+}
+
+TEST(NonlinearBeamformerTest, InterfAnglesTakeAmbiguityIntoAccount) {
+  {
+    // For linear arrays there is ambiguity.
+    std::vector<Point> array_geometry;
+    array_geometry.push_back(Point(-0.1f, 0.f, 0.f));
+    array_geometry.push_back(Point(0.f, 0.f, 0.f));
+    array_geometry.push_back(Point(0.2f, 0.f, 0.f));
+    NonlinearBeamformer bf(array_geometry);
+    bf.Initialize(kChunkSizeMs, kSampleRateHz);
+    EXPECT_EQ(2u, bf.interf_angles_radians_.size());
+    EXPECT_FLOAT_EQ(M_PI / 2.f - bf.away_radians_,
+                    bf.interf_angles_radians_[0]);
+    EXPECT_FLOAT_EQ(M_PI / 2.f + bf.away_radians_,
+                    bf.interf_angles_radians_[1]);
+    bf.AimAt(AzimuthToSphericalPoint(bf.away_radians_ / 2.f));
+    EXPECT_EQ(2u, bf.interf_angles_radians_.size());
+    EXPECT_FLOAT_EQ(M_PI - bf.away_radians_ / 2.f,
+                    bf.interf_angles_radians_[0]);
+    EXPECT_FLOAT_EQ(3.f * bf.away_radians_ / 2.f, bf.interf_angles_radians_[1]);
+  }
+  {
+    // For planar arrays with normal in the xy-plane there is ambiguity.
+    std::vector<Point> array_geometry;
+    array_geometry.push_back(Point(-0.1f, 0.f, 0.f));
+    array_geometry.push_back(Point(0.f, 0.f, 0.f));
+    array_geometry.push_back(Point(0.2f, 0.f, 0.f));
+    array_geometry.push_back(Point(0.1f, 0.f, 0.2f));
+    array_geometry.push_back(Point(0.f, 0.f, -0.1f));
+    NonlinearBeamformer bf(array_geometry);
+    bf.Initialize(kChunkSizeMs, kSampleRateHz);
+    EXPECT_EQ(2u, bf.interf_angles_radians_.size());
+    EXPECT_FLOAT_EQ(M_PI / 2.f - bf.away_radians_,
+                    bf.interf_angles_radians_[0]);
+    EXPECT_FLOAT_EQ(M_PI / 2.f + bf.away_radians_,
+                    bf.interf_angles_radians_[1]);
+    bf.AimAt(AzimuthToSphericalPoint(bf.away_radians_ / 2.f));
+    EXPECT_EQ(2u, bf.interf_angles_radians_.size());
+    EXPECT_FLOAT_EQ(M_PI - bf.away_radians_ / 2.f,
+                    bf.interf_angles_radians_[0]);
+    EXPECT_FLOAT_EQ(3.f * bf.away_radians_ / 2.f, bf.interf_angles_radians_[1]);
+  }
+  {
+    // For planar arrays with normal not in the xy-plane there is no ambiguity.
+    std::vector<Point> array_geometry;
+    array_geometry.push_back(Point(0.f, 0.f, 0.f));
+    array_geometry.push_back(Point(0.2f, 0.f, 0.f));
+    array_geometry.push_back(Point(0.f, 0.1f, -0.2f));
+    NonlinearBeamformer bf(array_geometry);
+    bf.Initialize(kChunkSizeMs, kSampleRateHz);
+    EXPECT_EQ(2u, bf.interf_angles_radians_.size());
+    EXPECT_FLOAT_EQ(M_PI / 2.f - bf.away_radians_,
+                    bf.interf_angles_radians_[0]);
+    EXPECT_FLOAT_EQ(M_PI / 2.f + bf.away_radians_,
+                    bf.interf_angles_radians_[1]);
+    bf.AimAt(AzimuthToSphericalPoint(bf.away_radians_ / 2.f));
+    EXPECT_EQ(2u, bf.interf_angles_radians_.size());
+    EXPECT_FLOAT_EQ(-bf.away_radians_ / 2.f, bf.interf_angles_radians_[0]);
+    EXPECT_FLOAT_EQ(3.f * bf.away_radians_ / 2.f, bf.interf_angles_radians_[1]);
+  }
+  {
+    // For arrays which are not linear or planar there is no ambiguity.
+    std::vector<Point> array_geometry;
+    array_geometry.push_back(Point(0.f, 0.f, 0.f));
+    array_geometry.push_back(Point(0.1f, 0.f, 0.f));
+    array_geometry.push_back(Point(0.f, 0.2f, 0.f));
+    array_geometry.push_back(Point(0.f, 0.f, 0.3f));
+    NonlinearBeamformer bf(array_geometry);
+    bf.Initialize(kChunkSizeMs, kSampleRateHz);
+    EXPECT_EQ(2u, bf.interf_angles_radians_.size());
+    EXPECT_FLOAT_EQ(M_PI / 2.f - bf.away_radians_,
+                    bf.interf_angles_radians_[0]);
+    EXPECT_FLOAT_EQ(M_PI / 2.f + bf.away_radians_,
+                    bf.interf_angles_radians_[1]);
+    bf.AimAt(AzimuthToSphericalPoint(bf.away_radians_ / 2.f));
+    EXPECT_EQ(2u, bf.interf_angles_radians_.size());
+    EXPECT_FLOAT_EQ(-bf.away_radians_ / 2.f, bf.interf_angles_radians_[0]);
+    EXPECT_FLOAT_EQ(3.f * bf.away_radians_ / 2.f, bf.interf_angles_radians_[1]);
+  }
+}
+
+}  // namespace webrtc

webrtc/modules/audio_processing/include/audio_processing.h

@@ -11,6 +11,10 @@
 #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_INCLUDE_AUDIO_PROCESSING_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_INCLUDE_AUDIO_PROCESSING_H_
 
+// MSVC++ requires this to be set before any other includes to get M_PI.
+#define _USE_MATH_DEFINES
+
+#include <math.h>
 #include <stddef.h>  // size_t
 #include <stdio.h>  // FILE
 #include <vector>
@@ -109,12 +113,23 @@ struct ExperimentalNs {
 struct Beamforming {
   Beamforming()
       : enabled(false),
-        array_geometry() {}
+        array_geometry(),
+        target_direction(
+            SphericalPointf(static_cast<float>(M_PI) / 2.f, 0.f, 1.f)) {}
   Beamforming(bool enabled, const std::vector<Point>& array_geometry)
+      : Beamforming(enabled,
+                    array_geometry,
+                    SphericalPointf(static_cast<float>(M_PI) / 2.f, 0.f, 1.f)) {
+  }
+  Beamforming(bool enabled,
+              const std::vector<Point>& array_geometry,
+              SphericalPointf target_direction)
       : enabled(enabled),
-        array_geometry(array_geometry) {}
+        array_geometry(array_geometry),
+        target_direction(target_direction) {}
   const bool enabled;
   const std::vector<Point> array_geometry;
+  const SphericalPointf target_direction;
 };
 
 // Use to enable intelligibility enhancer in audio processing. Must be provided

webrtc/modules/audio_processing/test/audioproc_float.cc

@@ -37,6 +37,7 @@ DEFINE_string(mic_positions, "",
     "Space delimited cartesian coordinates of microphones in meters. "
     "The coordinates of each point are contiguous. "
     "For a two element array: \"x1 y1 z1 x2 y2 z2\"");
+DEFINE_double(target_angle_degrees, 90, "The azimuth of the target in radians");
 
 DEFINE_bool(aec, false, "Enable echo cancellation.");
 DEFINE_bool(agc, false, "Enable automatic gain control.");
@@ -107,7 +108,10 @@ int main(int argc, char* argv[]) {
         ParseArrayGeometry(FLAGS_mic_positions, num_mics);
     RTC_CHECK_EQ(array_geometry.size(), num_mics);
 
-    config.Set<Beamforming>(new Beamforming(true, array_geometry));
+    config.Set<Beamforming>(new Beamforming(
+        true, array_geometry,
+        SphericalPointf(DegreesToRadians(FLAGS_target_angle_degrees), 0.f,
+                        1.f)));
   }
 
   rtc::scoped_ptr<AudioProcessing> ap(AudioProcessing::Create(config));

webrtc/modules/modules.gyp

@@ -171,6 +171,7 @@
             'audio_processing/beamformer/covariance_matrix_generator_unittest.cc',
             'audio_processing/beamformer/matrix_unittest.cc',
             'audio_processing/beamformer/mock_nonlinear_beamformer.h',
+            'audio_processing/beamformer/nonlinear_beamformer_unittest.cc',
             'audio_processing/echo_cancellation_impl_unittest.cc',
             'audio_processing/intelligibility/intelligibility_enhancer_unittest.cc',
             'audio_processing/intelligibility/intelligibility_utils_unittest.cc',