Move out typing detection to its own class.

This will allow an embedder to use it directly.

Adding inertia/hangover time between updates of the reported detection status to the algorithm, controlled by a parameter. That is usually desired and this way a consumer of
the class don't have to implement that. (VoiceEngine will let it be 1, which results in the same behavior as before, and keep controlling the hangover itself.)

R=andrew@webrtc.org, niklas.enbom@webrtc.org, xians@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/6219004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@5462 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_processing/typing_detection.cc

@@ -0,0 +1,90 @@
+/*
+ *  Copyright (c) 2014 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/typing_detection.h"
+
+namespace webrtc {
+
+TypingDetection::TypingDetection()
+    : time_active_(0),
+      time_since_last_typing_(0),
+      penalty_counter_(0),
+      counter_since_last_detection_update_(0),
+      detection_to_report_(false),
+      new_detection_to_report_(false),
+      time_window_(10),
+      cost_per_typing_(100),
+      reporting_threshold_(300),
+      penalty_decay_(1),
+      type_event_delay_(2),
+      report_detection_update_period_(1) {
+}
+
+TypingDetection::~TypingDetection() {}
+
+bool TypingDetection::Process(bool key_pressed, bool vad_activity) {
+  if (vad_activity)
+    time_active_++;
+  else
+    time_active_ = 0;
+
+  // Keep track if time since last typing event
+  if (key_pressed)
+    time_since_last_typing_ = 0;
+  else
+    ++time_since_last_typing_;
+
+  if (time_since_last_typing_ < type_event_delay_ &&
+      vad_activity &&
+      time_active_ < time_window_) {
+    penalty_counter_ += cost_per_typing_;
+    if (penalty_counter_ > reporting_threshold_)
+      new_detection_to_report_ = true;
+  }
+
+  if (penalty_counter_ > 0)
+    penalty_counter_ -= penalty_decay_;
+
+  if (++counter_since_last_detection_update_ ==
+      report_detection_update_period_) {
+    detection_to_report_ = new_detection_to_report_;
+    new_detection_to_report_ = false;
+    counter_since_last_detection_update_ = 0;
+  }
+
+  return detection_to_report_;
+}
+
+int TypingDetection::TimeSinceLastDetectionInSeconds() {
+  // Round to whole seconds.
+  return (time_since_last_typing_ + 50) / 100;
+}
+
+void TypingDetection::SetParameters(int time_window,
+                                    int cost_per_typing,
+                                    int reporting_threshold,
+                                    int penalty_decay,
+                                    int type_event_delay,
+                                    int report_detection_update_period) {
+  if (time_window) time_window_ = time_window;
+
+  if (cost_per_typing) cost_per_typing_ = cost_per_typing;
+
+  if (reporting_threshold) reporting_threshold_ = reporting_threshold;
+
+  if (penalty_decay) penalty_decay_ = penalty_decay;
+
+  if (type_event_delay) type_event_delay_ = type_event_delay;
+
+  if (report_detection_update_period)
+    report_detection_update_period_ = report_detection_update_period;
+}
+
+}  // namespace webrtc