Add a noise indicator to the speech bubble volume indicator.

content/browser/speech/endpointer/energy_endpointer.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.
 //
 // To know more about the algorithm used and the original code which this is
 // based of, see
 // https://wiki.corp.google.com/twiki/bin/view/Main/ChromeGoogleCodeXRef
 
 #include "content/browser/speech/endpointer/energy_endpointer.h"
 
@@ skipping 309 matching lines @@
     // Set a floor
     if (decision_threshold_ < params_.min_decision_threshold())
       decision_threshold_ = params_.min_decision_threshold();
   }
 
   // Update speech and noise levels.
   UpdateLevels(rms);
   ++frame_counter_;
 
   if (rms_out) {
-    *rms_out = -120.0;
-    if ((noise_level_ > 0.0) && ((rms / noise_level_ ) > 0.000001))
-      *rms_out = static_cast<float>(20.0 * log10(rms / noise_level_));
+    *rms_out = -2000.0;
+    if (rms > 1.0e-100)

[bulach, 2011/03/01 17:39:04]

again, it may be nicer to define these magic consts with names..

+      *rms_out = 20 * log10(rms);
   }
 }
 
+float EnergyEndpointer::GetNoiseLevelDB() const {
+  float levelDB = -2000.0;
+  if (noise_level_ > 1.0e-100)
+    levelDB = 20 * log10(noise_level_);
+  return levelDB;

[bulach, 2011/03/01 17:39:04]

ditto, dB and named constants..

+}
+
 void EnergyEndpointer::UpdateLevels(float rms) {
   // Update quickly initially. We assume this is noise and that
   // speech is 6dB above the noise.
   if (frame_counter_ < fast_update_frames_) {
     // Alpha increases from 0 to (k-1)/k where k is the number of time
     // steps in the initial adaptation period.
     float alpha = static_cast<float>(frame_counter_) /
         static_cast<float>(fast_update_frames_);
     noise_level_ = (alpha * noise_level_) + ((1 - alpha) * rms);
     DVLOG(1) << "FAST UPDATE, frame_counter_ " << frame_counter_
@@ skipping 14 matching lines @@
       decision_threshold_ = params_.min_decision_threshold();
   }
 }
 
 EpStatus EnergyEndpointer::Status(int64* status_time)  const {
   *status_time = history_->EndTime();
   return status_;
 }
 
 }  // namespace speech