chrome/browser/media/audio_stream_monitor.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/media/audio_stream_monitor.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "content/public/browser/invalidate_type.h"
  10 #include "content/public/browser/web_contents.h"
  11
  12 DEFINE_WEB_CONTENTS_USER_DATA_KEY(AudioStreamMonitor);
  13
  14 AudioStreamMonitor::AudioStreamMonitor(content::WebContents* contents)
  15     : web_contents_(contents),
  16       clock_(&default_tick_clock_),
  17       was_recently_audible_(false) {
  18   DCHECK(web_contents_);
  19 }
  20
  21 AudioStreamMonitor::~AudioStreamMonitor() {}
  22
  23 bool AudioStreamMonitor::WasRecentlyAudible() const {
  24   DCHECK(thread_checker_.CalledOnValidThread());
  25   return was_recently_audible_;
  26 }
  27
  28 void AudioStreamMonitor::StartMonitoringStream(
  29     int stream_id,
  30     const ReadPowerAndClipCallback& read_power_callback) {
  31   DCHECK(thread_checker_.CalledOnValidThread());
  32   DCHECK(!read_power_callback.is_null());
  33   poll_callbacks_[stream_id] = read_power_callback;
  34   if (!poll_timer_.IsRunning()) {
  35     poll_timer_.Start(
  36         FROM_HERE,
  37         base::TimeDelta::FromSeconds(1) / kPowerMeasurementsPerSecond,
  38         base::Bind(&AudioStreamMonitor::Poll, base::Unretained(this)));
  39   }
  40 }
  41
  42 void AudioStreamMonitor::StopMonitoringStream(int stream_id) {
  43   DCHECK(thread_checker_.CalledOnValidThread());
  44   poll_callbacks_.erase(stream_id);
  45   if (poll_callbacks_.empty())
  46     poll_timer_.Stop();
  47 }
  48
  49 void AudioStreamMonitor::Poll() {
  50   for (StreamPollCallbackMap::const_iterator it = poll_callbacks_.begin();
  51        it != poll_callbacks_.end();
  52        ++it) {
  53     // TODO(miu): A new UI for delivering specific power level and clipping
  54     // information is still in the works.  For now, we throw away all
  55     // information except for "is it audible?"
  56     const float power_dbfs = it->second.Run().first;
  57     const float kSilenceThresholdDBFS = -72.24719896f;
  58     if (power_dbfs >= kSilenceThresholdDBFS) {
  59       last_blurt_time_ = clock_->NowTicks();
  60       MaybeToggle();
  61       break;  // No need to poll remaining streams.
  62     }
  63   }
  64 }
  65
  66 void AudioStreamMonitor::MaybeToggle() {
  67   const bool indicator_was_on = was_recently_audible_;
  68   const base::TimeTicks off_time =
  69       last_blurt_time_ + base::TimeDelta::FromMilliseconds(kHoldOnMilliseconds);
  70   const base::TimeTicks now = clock_->NowTicks();
  71   const bool should_indicator_be_on = now < off_time;
  72
  73   if (should_indicator_be_on != indicator_was_on) {
  74     was_recently_audible_ = should_indicator_be_on;
  75     web_contents_->NotifyNavigationStateChanged(content::INVALIDATE_TYPE_TAB);
  76   }
  77
  78   if (!should_indicator_be_on) {
  79     off_timer_.Stop();
  80   } else if (!off_timer_.IsRunning()) {
  81     off_timer_.Start(
  82         FROM_HERE,
  83         off_time - now,
  84         base::Bind(&AudioStreamMonitor::MaybeToggle, base::Unretained(this)));
  85   }
  86 }