Reduce amount of power measurements for input audio

media/audio/audio_input_controller.cc

 // Copyright (c) 2012 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 "media/audio/audio_input_controller.h"
 
 #include "base/bind.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_restrictions.h"
@@ skipping 27 matching lines @@
 // by 1-exp(-1/(fs*ts)), where fs is the sample rate in Hz and ts is the time
 // constant given by |kPowerMeasurementTimeConstantMilliseconds|.
 // Example: fs=44100, ts=10e-3 => alpha~0.022420
 //          fs=44100, ts=20e-3 => alpha~0.165903
 // A large smoothing factor corresponds to a faster filter response to input
 // changes since y(n)=alpha*x(n)+(1-alpha)*y(n-1), where x(n) is the input
 // and y(n) is the output.
 const int kPowerMeasurementTimeConstantMilliseconds = 10;
 
 // Time in seconds between two successive measurements of audio power levels.
-const int kPowerMonitorLogIntervalSeconds = 5;
+const int kPowerMonitorLogIntervalSeconds = 15;

[Henrik Grunell, 2014/09/08 10:57:24]

Would it make sense to have 15 seconds to the first check, then 5 seconds
interval after that? Or is 15 seconds sample rate good enough? There's a higher
risk of false alarms for short sessions, e.g. for a 29 seconds call we'll only
have 1 sample. If it happens to be silent at that point we have a false alarm.
Maybe those cases are so few we don't have to bother.

 #endif
 }
 
 // Used to log the result of capture startup.
 // This was previously logged as a boolean with only the no callback and OK
 // options. The enum order is kept to ensure backwards compatibility.
 // Elements in this enum should not be deleted or rearranged; the only
 // permitted operation is to add new elements before CAPTURE_STARTUP_RESULT_MAX
 // and update CAPTURE_STARTUP_RESULT_MAX.
 enum CaptureStartupResult {
@@ skipping 557 matching lines @@
 }
 
 void AudioInputController::LogSilenceState(SilenceState value) {
   UMA_HISTOGRAM_ENUMERATION("Media.AudioInputControllerSessionSilenceReport",
                             value,
                             SILENCE_STATE_MAX + 1);
 }
 #endif
 
 }  // namespace media