--- a/dom/html/HTMLMediaElement.cpp
+++ b/dom/html/HTMLMediaElement.cpp
@@ -7399,17 +7399,18 @@ HTMLMediaElement::GetEMEInfo(nsString& a
   aEMEInfo.Append(sessionsInfo);
 }
 
 void
 HTMLMediaElement::NotifyDecoderActivityChanges() const
 {
   if (mDecoder) {
     mDecoder->NotifyOwnerActivityChanged(!IsHidden(),
-                                         mVisibilityState == Visibility::APPROXIMATELY_VISIBLE);
+                                         mVisibilityState == Visibility::APPROXIMATELY_VISIBLE,
+                                         IsInUncomposedDoc());
   }
 }
 
 bool HasDebuggerPrivilege(JSContext* aCx, JSObject* aObj)
 {
   return nsContentUtils::CallerHasPermission(aCx,
                                              NS_LITERAL_STRING("debugger"));
  }

--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -293,21 +293,22 @@ MediaDecoder::ResourceCallback::NotifyBy
       self->mDecoder->NotifyBytesConsumed(aBytes, aOffset);
     }
   });
   mAbstractMainThread->Dispatch(r.forget());
 }
 
 void
 MediaDecoder::NotifyOwnerActivityChanged(bool aIsDocumentVisible,
-                                         bool aIsElementVisible)
+                                         bool aIsElementVisible,
+                                         bool aIsElementInTree)
 {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_DIAGNOSTIC_ASSERT(!IsShutdown());
-  SetElementVisibility(aIsDocumentVisible, aIsElementVisible);
+  SetElementVisibility(aIsDocumentVisible, aIsElementVisible, aIsElementInTree);
 
   NotifyCompositor();
 }
 
 void
 MediaDecoder::Pause()
 {
   MOZ_ASSERT(NS_IsMainThread());
@@ -392,16 +393,17 @@ MediaDecoder::MediaDecoder(MediaDecoderO
   , mVideoFrameContainer(aOwner->GetVideoFrameContainer())
   , mPlaybackStatistics(new MediaChannelStatistics())
   , mPinnedForSeek(false)
   , mMinimizePreroll(false)
   , mMediaTracksConstructed(false)
   , mFiredMetadataLoaded(false)
   , mIsDocumentVisible(false)
   , mIsElementVisible(false)
+  , mIsElementInTree(false)
   , mForcedHidden(false)
   , mHasSuspendTaint(false)
   , INIT_MIRROR(mStateMachineIsShutdown, true)
   , INIT_MIRROR(mBuffered, TimeIntervals())
   , INIT_MIRROR(mNextFrameStatus, MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE)
   , INIT_MIRROR(mCurrentPosition, 0)
   , INIT_MIRROR(mStateMachineDuration, NullableTimeUnit())
   , INIT_MIRROR(mPlaybackPosition, 0)
@@ -1303,21 +1305,23 @@ MediaDecoder::NotifyCompositor()
   if (layerManager) {
     RefPtr<KnowsCompositor> knowsCompositor = layerManager->AsShadowForwarder();
     mCompositorUpdatedEvent.Notify(knowsCompositor);
   }
 }
 
 void
 MediaDecoder::SetElementVisibility(bool aIsDocumentVisible,
-                                   bool aIsElementVisible)
+                                   bool aIsElementVisible,
+                                   bool aIsElementInTree)
 {
   MOZ_ASSERT(NS_IsMainThread());
   mIsDocumentVisible = aIsDocumentVisible;
   mIsElementVisible = aIsElementVisible;
+  mIsElementInTree = aIsElementInTree;
   UpdateVideoDecodeMode();
 }
 
 void
 MediaDecoder::SetForcedHidden(bool aForcedHidden)
 {
   MOZ_ASSERT(NS_IsMainThread());
   mForcedHidden = aForcedHidden;
@@ -1341,16 +1345,22 @@ MediaDecoder::UpdateVideoDecodeMode()
   }
 
   // If mHasSuspendTaint is set, never suspend the video decoder.
   if (mHasSuspendTaint) {
     mDecoderStateMachine->SetVideoDecodeMode(VideoDecodeMode::Normal);
     return;
   }
 
+  // Don't suspend elements that is not in tree.
+  if (!mIsElementInTree) {
+    mDecoderStateMachine->SetVideoDecodeMode(VideoDecodeMode::Normal);
+    return;
+  }
+
   // If mForcedHidden is set, suspend the video decoder anyway.
   if (mForcedHidden) {
     mDecoderStateMachine->SetVideoDecodeMode(VideoDecodeMode::Suspend);
     return;
   }
 
   // Otherwise, depends on the owner's visibility state.
   // A element is visible only if its document is visible and the element

--- a/dom/media/MediaDecoder.h
+++ b/dom/media/MediaDecoder.h
@@ -185,17 +185,18 @@ public:
   nsresult InitializeStateMachine();
 
   // Start playback of a video. 'Load' must have previously been
   // called.
   virtual nsresult Play();
 
   // Notify activity of the decoder owner is changed.
   virtual void NotifyOwnerActivityChanged(bool aIsDocumentVisible,
-                                          bool aIsElementVisible);
+                                          bool aIsElementVisible,
+                                          bool aIsElementInTree);
 
   // Pause video playback.
   virtual void Pause();
   // Adjust the speed of the playback, optionally with pitch correction,
   virtual void SetVolume(double aVolume);
 
   virtual void SetPlaybackRate(double aPlaybackRate);
   void SetPreservesPitch(bool aPreservesPitch);
@@ -368,17 +369,18 @@ private:
   // to buffer, given the current download and playback rates.
   virtual bool CanPlayThrough();
 
   void SetAudioChannel(dom::AudioChannel aChannel) { mAudioChannel = aChannel; }
   dom::AudioChannel GetAudioChannel() { return mAudioChannel; }
 
   // Called from HTMLMediaElement when owner document activity changes
   virtual void SetElementVisibility(bool aIsDocumentVisible,
-                                    bool aIsElementVisible);
+                                    bool aIsElementVisible,
+                                    bool aIsElementInTree);
 
   // Force override the visible state to hidden.
   // Called from HTMLMediaElement when testing of video decode suspend from mochitests.
   void SetForcedHidden(bool aForcedHidden);
 
   // Mark the decoder as tainted, meaning suspend-video-decoder is disabled.
   void SetSuspendTaint(bool aTaint);
 
@@ -716,19 +718,22 @@ protected:
 
   // Stores media info, including info of audio tracks and video tracks, should
   // only be accessed from main thread.
   nsAutoPtr<MediaInfo> mInfo;
 
   // Tracks the visibility status of owner element's document.
   bool mIsDocumentVisible;
 
-  // Tracks the visibliity status of owner element.
+  // Tracks the visibility status of owner element.
   bool mIsElementVisible;
 
+  // Tracks the owner is in-tree or not.
+  bool mIsElementInTree;
+
   // If true, forces the decoder to be considered hidden.
   bool mForcedHidden;
 
   // True if the decoder has a suspend taint - meaning suspend-video-decoder is
   // disabled.
   bool mHasSuspendTaint;
 
   // A listener to receive metadata updates from MDSM.