--- a/dom/media/MediaFormatReader.cpp
+++ b/dom/media/MediaFormatReader.cpp
@@ -1293,48 +1293,37 @@ MediaFormatReader::ResetDecode(TargetQue
 
   // Do the same for any data wait promises.
   mAudio.mWaitingPromise.RejectIfExists(WaitForDataRejectValue(MediaData::AUDIO_DATA, WaitForDataRejectValue::CANCELED), __func__);
   mVideo.mWaitingPromise.RejectIfExists(WaitForDataRejectValue(MediaData::VIDEO_DATA, WaitForDataRejectValue::CANCELED), __func__);
 
   // Reset miscellaneous seeking state.
   mPendingSeekTime.reset();
 
-  ResetDemuxers();
-
   if (HasVideo()) {
+    mVideo.ResetDemuxer();
+    mVideo.ResetState();
     Reset(TrackInfo::kVideoTrack);
     if (mVideo.HasPromise()) {
       mVideo.RejectPromise(CANCELED, __func__);
     }
   }
 
   if (HasAudio() && aQueues == AUDIO_VIDEO) {
+    mAudio.ResetDemuxer();
+    mAudio.ResetState();
     Reset(TrackInfo::kAudioTrack);
     if (mAudio.HasPromise()) {
       mAudio.RejectPromise(CANCELED, __func__);
     }
   }
   return MediaDecoderReader::ResetDecode(aQueues);
 }
 
 void
-MediaFormatReader::ResetDemuxers()
-{
-  if (HasVideo()) {
-    mVideo.ResetDemuxer();
-    mVideo.ResetState();
-  }
-  if (HasAudio()) {
-    mAudio.ResetDemuxer();
-    mAudio.ResetState();
-  }
-}
-
-void
 MediaFormatReader::Output(TrackType aTrack, MediaData* aSample)
 {
   LOGV("Decoded %s sample time=%lld timecode=%lld kf=%d dur=%lld",
        TrackTypeToStr(aTrack), aSample->mTime, aSample->mTimecode,
        aSample->mKeyframe, aSample->mDuration);
 
   if (!aSample) {
     NS_WARNING("MediaFormatReader::Output() passed a null sample");
@@ -1527,17 +1516,30 @@ MediaFormatReader::AttemptSeek()
 {
   MOZ_ASSERT(OnTaskQueue());
 
   mSeekScheduled = false;
 
   if (mPendingSeekTime.isNothing()) {
     return;
   }
-  ResetDemuxers();
+
+  if (HasVideo()) {
+    mVideo.ResetDemuxer();
+    mVideo.ResetState();
+  }
+
+  // Don't reset the audio demuxer not state when seeking video only
+  // as it will cause the audio to seek back to the beginning
+  // resulting in out-of-sync audio from video.
+  if (HasAudio() && !mOriginalSeekTarget->IsVideoOnly()) {
+    mAudio.ResetDemuxer();
+    mAudio.ResetState();
+  }
+
   if (HasVideo()) {
     DoVideoSeek();
   } else if (HasAudio()) {
     DoAudioSeek();
   } else {
     MOZ_CRASH();
   }
 }

--- a/dom/media/MediaFormatReader.h
+++ b/dom/media/MediaFormatReader.h
@@ -169,17 +169,16 @@ private:
   // functions.
   void Output(TrackType aType, MediaData* aSample);
   void InputExhausted(TrackType aTrack);
   void Error(TrackType aTrack);
   void Reset(TrackType aTrack);
   void DrainComplete(TrackType aTrack);
 
   bool ShouldSkip(bool aSkipToNextKeyframe, media::TimeUnit aTimeThreshold);
-  void ResetDemuxers();
 
   size_t SizeOfQueue(TrackType aTrack);
 
   RefPtr<PDMFactory> mPlatform;
 
   class DecoderCallback : public MediaDataDecoderCallback {
   public:
     DecoderCallback(MediaFormatReader* aReader, TrackType aType)