Add an endpointer for detecting end of speech.

chrome/browser/speech/endpointer/endpointer_unittest.cc

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/task.h"
+#include "chrome/browser/speech/endpointer/endpointer.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+const int kFrameRate = 50;  // 20 ms long frames for AMR encoding.
+const int kSampleRate = 8000;  // 8 k samples per second for AMR encoding.
+
+// At 8 sample per second a 20 ms frame is 160 samples, which corrsponds
+// to the AMR codec.
+const int kFrameSize = kSampleRate / kFrameRate;  // 160 samples.
+COMPILE_ASSERT(kFrameSize == 160, invalid_frame_size);
+}
+
+namespace speech_input {
+
+class FrameProcessor {
+ public:
+  // Process a single frame of test audio samples.
+  virtual EpStatus ProcessFrame(int64 time, int16* samples, int frame_size) = 0;
+};
+
+void RunEndpointerEventsTest(FrameProcessor* processor) {
+  int16 samples[kFrameSize];
+
+  // We will create a white noise signal of 150 frames. The frames from 50 to
+  // 100 will have more power, and the endpointer should fire on those frames.
+  const int kNumFrames = 150;
+
+  // Create a random sequence of samples.
+  srand(1);
+  float gain = 0.0;
+  int64 time = 0;
+  for (int frame_count = 0; frame_count < kNumFrames; ++frame_count) {
+    // The frames from 50 to 100 will have more power, and the endpointer
+    // should detect those frames as speech.
+    if ((frame_count >= 50) && (frame_count < 100)) {
+      gain = 2000.0;
+    } else {
+      gain = 1.0;
+    }
+    // Create random samples.
+    for (int i = 0; i < kFrameSize; ++i) {
+      float randNum = static_cast<float>(rand() - (RAND_MAX / 2)) /
+          static_cast<float>(RAND_MAX);
+      samples[i] = static_cast<int16>(gain * randNum);
+    }
+
+    EpStatus ep_status = processor->ProcessFrame(time, samples, kFrameSize);
+    time += static_cast<int64>(kFrameSize * (1e6 / kSampleRate));
+
+    // Log the status.
+    if (20 == frame_count)
+      EXPECT_EQ(EP_PRE_SPEECH, ep_status);
+    if (70 == frame_count)
+      EXPECT_EQ(EP_SPEECH_PRESENT, ep_status);
+    if (120 == frame_count)
+      EXPECT_EQ(EP_PRE_SPEECH, ep_status);
+  }
+}
+
+// This test instantiates and initializes a stand alone endpointer module.
+// The test creates FrameData objects with random noise and send them
+// to the endointer module. The energy of the first 50 frames is low,
+// followed by 500 high energy frames, and another 50 low energy frames.
+// We test that the correct start and end frames were detected.
+class EnergyEndpointerFrameProcessor : public FrameProcessor {
+ public:
+  explicit EnergyEndpointerFrameProcessor(EnergyEndpointer* endpointer)
+      : endpointer_(endpointer) {}
+
+  EpStatus ProcessFrame(int64 time, int16* samples, int frame_size) {
+    endpointer_->ProcessAudioFrame(time, samples, kFrameSize);
+    int64 ep_time;
+    return endpointer_->Status(&ep_time);
+  }
+
+ private:
+  EnergyEndpointer* endpointer_;
+};
+
+TEST(EndpointerTest, TestEnergyEndpointerEvents) {
+  // Initialize endpointer and configure it. We specify the parameters
+  // here for a 20ms window, and a 20ms step size, which corrsponds to
+  // the narrow band AMR codec.
+  EnergyEndpointerParams ep_config;
+  ep_config.set_frame_period(1.0f / static_cast<float>(kFrameRate));
+  ep_config.set_frame_duration(1.0f / static_cast<float>(kFrameRate));
+  ep_config.set_endpoint_margin(0.2f);
+  ep_config.set_onset_window(0.15f);
+  ep_config.set_speech_on_window(0.4f);
+  ep_config.set_offset_window(0.15f);
+  ep_config.set_onset_detect_dur(0.09f);
+  ep_config.set_onset_confirm_dur(0.075f);
+  ep_config.set_on_maintain_dur(0.10f);
+  ep_config.set_offset_confirm_dur(0.12f);
+  ep_config.set_decision_threshold(100.0f);
+  EnergyEndpointer endpointer;
+  endpointer.Init(ep_config);
+
+  endpointer.StartSession();
+
+  EnergyEndpointerFrameProcessor frame_processor(&endpointer);
+  RunEndpointerEventsTest(&frame_processor);
+
+  endpointer.EndSession();
+};
+
+// Test endpointer wrapper class.
+class EndpointerFrameProcessor : public FrameProcessor {
+ public:
+  explicit EndpointerFrameProcessor(Endpointer* endpointer)
+      : endpointer_(endpointer) {}
+
+  EpStatus ProcessFrame(int64 time, int16* samples, int frame_size) {
+    endpointer_->ProcessAudio(samples, kFrameSize);
+    int64 ep_time;
+    return endpointer_->Status(&ep_time);
+  }
+
+ private:
+  Endpointer* endpointer_;
+};
+
+TEST(EndpointerTest, TestEmbeddedEndpointerEvents) {
+  const int kSampleRate = 8000;  // 8 k samples per second for AMR encoding.
+
+  Endpointer endpointer(kSampleRate);
+  const int64 kMillisecondsPerMicrosecond = 1000;
+  const int64 short_timeout = 300 * kMillisecondsPerMicrosecond;
+  endpointer.set_speech_input_possibly_complete_silence_length(short_timeout);
+  const int64 long_timeout = 500 * kMillisecondsPerMicrosecond;
+  endpointer.set_speech_input_complete_silence_length(long_timeout);
+  endpointer.StartSession();
+
+  EndpointerFrameProcessor frame_processor(&endpointer);
+  RunEndpointerEventsTest(&frame_processor);
+
+  endpointer.EndSession();
+}
+
+}  // namespace speech_input