Bug 1659244 - Use the AudibilityMonitor in AudioDestinationNode. r=pehrsons,alwu

In particular, this removes the code that was limiting the audibility
notifications spam, because this is handled by the AudibilityMonitor.

Differential Revision: https://phabricator.services.mozilla.com/D90433

dom/media/webaudio/AudioDestinationNode.cpp

@@ -5,25 +5,28 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "AudioDestinationNode.h"
-#include "AudioContext.h"
+
 #include "AlignmentUtils.h"
+#include "AudibilityMonitor.h"
+#include "AudioChannelService.h"
 #include "AudioContext.h"
+#include "AudioContext.h"
+#include "AudioNodeEngine.h"
+#include "AudioNodeTrack.h"
 #include "CubebUtils.h"
+#include "MediaTrackGraph.h"
+#include "mozilla/StaticPrefs_dom.h"
 #include "mozilla/dom/AudioDestinationNodeBinding.h"
 #include "mozilla/dom/BaseAudioContextBinding.h"
 #include "mozilla/dom/OfflineAudioCompletionEvent.h"
-#include "mozilla/dom/power/PowerManagerService.h"
+#include "mozilla/dom/Promise.h"
 #include "mozilla/dom/ScriptSettings.h"
 #include "mozilla/dom/WakeLock.h"
-#include "AudioChannelService.h"
-#include "AudioNodeEngine.h"
-#include "AudioNodeTrack.h"
-#include "MediaTrackGraph.h"
+#include "mozilla/dom/power/PowerManagerService.h"
 #include "nsContentUtils.h"
 #include "nsIInterfaceRequestorUtils.h"
 #include "nsIScriptObjectPrincipal.h"
 #include "nsServiceManagerUtils.h"
-#include "mozilla/dom/Promise.h"
 
 extern mozilla::LazyLogModule gAudioChannelLog;
 
@@ -187,10 +190,13 @@ class DestinationNodeEngine final : public AudioNodeEngine {
  public:
   explicit DestinationNodeEngine(AudioDestinationNode* aNode)
       : AudioNodeEngine(aNode),
+        mSampleRate(CubebUtils::PreferredSampleRate()),
         mVolume(1.0f),
-        mLastInputAudible(false),
+        mAudibilityMonitor(
+            mSampleRate,
+            StaticPrefs::dom_media_silence_duration_for_audibility()),
         mSuspended(false),
-        mSampleRate(CubebUtils::PreferredSampleRate()) {
+        mLastInputAudible(false) {
     MOZ_ASSERT(aNode);
   }
 
@@ -204,32 +210,10 @@ class DestinationNodeEngine final : public AudioNodeEngine {
       return;
     }
 
-    bool isInputAudible =
-        !aInput.IsNull() && !aInput.IsMuted() && aInput.IsAudible();
+    mAudibilityMonitor.Process(aInput);
+    bool isInputAudible = mAudibilityMonitor.RecentlyAudible();
 
-    auto shouldNotifyChanged = [&]() {
-      // We don't want to notify state changed frequently if the input track is
-      // consist of interleaving audible and inaudible blocks. This situation is
-      // really common, especially when user is using OscillatorNode to produce
-      // sound. Sending unnessary runnable frequently would cause performance
-      // debasing. If the track contains 10 interleaving samples and 5 of them
-      // are audible, others are inaudible, user would tend to feel the track
-      // is audible. Therefore, we have the loose checking when track is
-      // changing from inaudible to audible, but have strict checking when
-      // streaming is changing from audible to inaudible. If the inaudible
-      // blocks continue over a speicific time threshold, then we will treat the
-      // track as inaudible.
-      if (isInputAudible && !mLastInputAudible) {
-        return true;
-      }
-      // Use more strict condition, choosing 1 seconds as a threshold.
-      if (!isInputAudible && mLastInputAudible &&
-          aFrom - mLastInputAudibleTime >= mSampleRate) {
-        return true;
-      }
-      return false;
-    };
-    if (shouldNotifyChanged()) {
+    if (isInputAudible != mLastInputAudible) {
       mLastInputAudible = isInputAudible;
       RefPtr<AudioNodeTrack> track = aTrack;
       auto r = [track, isInputAudible]() -> void {
@@ -245,10 +229,6 @@ class DestinationNodeEngine final : public AudioNodeEngine {
       aTrack->Graph()->DispatchToMainThreadStableState(NS_NewRunnableFunction(
           "dom::WebAudioAudibleStateChangedRunnable", r));
     }
-
-    if (isInputAudible) {
-      mLastInputAudibleTime = aFrom;
-    }
   }
 
   bool IsActive() const override {
@@ -285,11 +265,11 @@ class DestinationNodeEngine final : public AudioNodeEngine {
   }
 
  private:
-  float mVolume;
-  bool mLastInputAudible;
-  GraphTime mLastInputAudibleTime = 0;
-  bool mSuspended;
   int mSampleRate;
+  float mVolume;
+  AudibilityMonitor mAudibilityMonitor;
+  bool mSuspended;
+  bool mLastInputAudible;
 };
 
 NS_IMPL_CYCLE_COLLECTION_INHERITED(AudioDestinationNode, AudioNode,