--- a/dom/media/mediasource/SourceBuffer.cpp
+++ b/dom/media/mediasource/SourceBuffer.cpp
@@ -482,16 +482,18 @@ SourceBuffer::AppendDataCompletedWithSuc
     if (!mActive) {
       mActive = true;
       mMediaSource->SourceBufferIsActive(this);
       mMediaSource->QueueInitializationEvent();
       if (mIsUsingFormatReader) {
         mMediaSource->GetDecoder()->NotifyWaitingForResourcesStatusChanged();
       }
     }
+  }
+  if (mActive) {
     // Tell our parent decoder that we have received new data.
     // The information provided do not matter much so long as it is monotonically
     // increasing.
     mMediaSource->GetDecoder()->NotifyDataArrived(nullptr, 1, mReportedOffset++);
   }
 
   CheckEndTime();