Add algorithm for Residual Echo Detector.

webrtc/modules/audio_processing/residual_echo_detector_unittest.cc

+/*
+ *  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 "webrtc/modules/audio_processing/residual_echo_detector.h"
+#include "webrtc/test/gtest.h"
+
+namespace webrtc {
+
+TEST(ResidualEchoDetectorTests, Echo) {
+  ResidualEchoDetector echo_detector;
+  std::vector<float> ones(160, 1.f);
+  std::vector<float> zeros(160, 0.f);
+
+  // In this test the capture signal has a delay of 10 frames w.r.t. the render
+  // signal, but is otherwise identical. Both signals are periodic with a 20
+  // frame interval.
+  for (int i = 0; i < 1000; i++) {
+    if (i % 20 == 0) {
+      echo_detector.AnalyzeRenderAudio(ones);
+      echo_detector.AnalyzeCaptureAudio(zeros);
+    } else if (i % 20 == 10) {
+      echo_detector.AnalyzeRenderAudio(zeros);
+      echo_detector.AnalyzeCaptureAudio(ones);
+    } else {
+      echo_detector.AnalyzeRenderAudio(zeros);
+      echo_detector.AnalyzeCaptureAudio(zeros);
+    }
+  }
+  // We expect to detect echo with near certain likelihood.
+  EXPECT_NEAR(1.f, echo_detector.echo_likelihood(), 0.01f);
+}
+
+TEST(ResidualEchoDetectorTests, NoEcho) {
+  ResidualEchoDetector echo_detector;
+  std::vector<float> ones(160, 1.f);
+  std::vector<float> zeros(160, 0.f);
+
+  // In this test the capture signal is always zero, so no echo should be
+  // detected.
+  for (int i = 0; i < 1000; i++) {
+    if (i % 20 == 0) {
+      echo_detector.AnalyzeRenderAudio(ones);
+    } else {
+      echo_detector.AnalyzeRenderAudio(zeros);
+    }
+    echo_detector.AnalyzeCaptureAudio(zeros);
+  }
+  // We expect to not detect any echo.
+  EXPECT_NEAR(0.f, echo_detector.echo_likelihood(), 0.01f);
+}
+
+TEST(ResidualEchoDetectorTests, EchoWithRenderClockDrift) {
+  ResidualEchoDetector echo_detector;
+  std::vector<float> ones(160, 1.f);
+  std::vector<float> zeros(160, 0.f);
+
+  // In this test the capture signal has a delay of 10 frames w.r.t. the render
+  // signal, but is otherwise identical. Both signals are periodic with a 20
+  // frame interval. There is a simulated clock drift of 1% in this test, with
+  // the render side producing data slightly faster.
+  for (int i = 0; i < 1000; i++) {
+    if (i % 20 == 0) {
+      echo_detector.AnalyzeRenderAudio(ones);
+      echo_detector.AnalyzeCaptureAudio(zeros);
+    } else if (i % 20 == 10) {
+      echo_detector.AnalyzeRenderAudio(zeros);
+      echo_detector.AnalyzeCaptureAudio(ones);
+    } else {
+      echo_detector.AnalyzeRenderAudio(zeros);
+      echo_detector.AnalyzeCaptureAudio(zeros);
+    }
+    if (i % 100 == 0) {
+      // This is causing the simulated clock drift.
+      echo_detector.AnalyzeRenderAudio(zeros);
+    }
+  }
+  // We expect to detect echo with high likelihood. Clock drift is harder to
+  // correct on the render side than on the capture side. This is due to the
+  // render buffer, clock drift can only be discovered after a certain delay.
+  // A growing buffer can be caused by jitter or clock drift and it's not
+  // possible to make this decision right away. For this reason we only expect
+  // an echo likelihood of 80% in this test.
+  EXPECT_GT(echo_detector.echo_likelihood(), 0.8f);
+}
+
+TEST(ResidualEchoDetectorTests, EchoWithCaptureClockDrift) {
+  ResidualEchoDetector echo_detector;
+  std::vector<float> ones(160, 1.f);
+  std::vector<float> zeros(160, 0.f);
+
+  // In this test the capture signal has a delay of 10 frames w.r.t. the render
+  // signal, but is otherwise identical. Both signals are periodic with a 20
+  // frame interval. There is a simulated clock drift of 1% in this test, with
+  // the capture side producing data slightly faster.
+  for (int i = 0; i < 1000; i++) {
+    if (i % 20 == 0) {
+      echo_detector.AnalyzeRenderAudio(ones);
+      echo_detector.AnalyzeCaptureAudio(zeros);
+    } else if (i % 20 == 10) {
+      echo_detector.AnalyzeRenderAudio(zeros);
+      echo_detector.AnalyzeCaptureAudio(ones);
+    } else {
+      echo_detector.AnalyzeRenderAudio(zeros);
+      echo_detector.AnalyzeCaptureAudio(zeros);
+    }
+    if (i % 100 == 0) {
+      // This is causing the simulated clock drift.
+      echo_detector.AnalyzeCaptureAudio(zeros);
+    }
+  }
+  // We expect to detect echo with near certain likelihood.
+  EXPECT_NEAR(1.f, echo_detector.echo_likelihood(), 0.01f);
+}
+
+}  // namespace webrtc