Make the nonlinear beamformer steerable

webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_unittest.cc

Index: webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_unittest.cc
diff --git a/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_unittest.cc b/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..aeee60ada03caa1ef68e78bb84ccab61a2c36e79
--- /dev/null
+++ b/webrtc/modules/audio_processing/beamformer/nonlinear_beamformer_unittest.cc
@@ -0,0 +1,58 @@
+/*
+ *  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.
+ */
+
+#include "webrtc/modules/audio_processing/beamformer/nonlinear_beamformer.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace webrtc {
+namespace {
+
+SphericalPointf Azimuth2Point(float azimuth_radians) {

[Andrew MacDonald, 2015/10/20 03:00:08]

nit: AzimuthToPoint (just because I think that's more common).

[aluebs-webrtc, 2015/10/21 01:41:40]

Done.

+  return SphericalPointf(azimuth_radians, 0.f, 1.f);
+}
+
+void Verify(NonlinearBeamformer* bf, float target_azimuth_radians) {
+  const float kHalfBeamWidthRadians = static_cast<float>(M_PI) * 20.f / 180.f;

[Andrew MacDonald, 2015/10/20 03:00:08]

If you want to use this (and I think that's fine), it should be exposed as a
static in the interface, rather than copied here.

[aluebs-webrtc, 2015/10/21 01:41:40]

The problem is that in WebRTC I can't use constexpr and I can't have a class
float constant initialized in compile time. I think this is ok, since it would
catch changes in kHalfBeamWidthRadians, but if you think it is not ok to repeat
the constant, what do you prefer I do? Have a getter in NonlinearBeamformer? A
public constant that is initialized in the constructor? I am happy to implement
whatever you think is best, I don't have a strong opinion.

[Andrew MacDonald, 2015/10/21 02:10:32]

You can do it with:
.h
class NonlinearBeaformer {
  static const float kHalfBeamWidthRadians;
  ...
};

.cc
const int float NonlinearBeamformer::kHalfBeamWidthRadians = ...;

[Andrew MacDonald, 2015/10/21 02:11:31]

oops, just "const float" of course.

[aluebs-webrtc, 2015/10/27 18:08:15]

Done.

+  EXPECT_TRUE(bf->IsInBeam(Azimuth2Point(target_azimuth_radians)));
+  EXPECT_TRUE(bf->IsInBeam(
+      Azimuth2Point(target_azimuth_radians - kHalfBeamWidthRadians + 0.001f)));
+  EXPECT_TRUE(bf->IsInBeam(
+      Azimuth2Point(target_azimuth_radians + kHalfBeamWidthRadians - 0.001f)));
+  EXPECT_FALSE(bf->IsInBeam(
+      Azimuth2Point(target_azimuth_radians - kHalfBeamWidthRadians - 0.001f)));
+  EXPECT_FALSE(bf->IsInBeam(
+      Azimuth2Point(target_azimuth_radians + kHalfBeamWidthRadians + 0.001f)));
+}
+
+void AimAndVerify(NonlinearBeamformer* bf, float target_azimuth_radians) {
+  bf->AimAt(Azimuth2Point(target_azimuth_radians));
+  Verify(bf, target_azimuth_radians);
+}
+
+}  // namespace
+
+TEST(NonlinearBeamformerTest, AimingModifiesBeam) {
+  const int kChunkSizeMs = 10;
+  const int kSampleRateHz = 16000;
+  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, M_PI / 2.f);
+  AimAndVerify(&bf, M_PI / 3.f);
+  AimAndVerify(&bf, 3.f * M_PI / 4.f);
+  AimAndVerify(&bf, M_PI / 6.f);
+  AimAndVerify(&bf, M_PI);
+}
+
+}  // namespace webrtc