--- a/dom/media/directshow/DirectShowReader.cpp
+++ b/dom/media/directshow/DirectShowReader.cpp
@@ -28,18 +28,17 @@ GetDirectShowLog() {
 DirectShowReader::DirectShowReader(AbstractMediaDecoder* aDecoder)
   : MediaDecoderReader(aDecoder),
     mMP3FrameParser(aDecoder->GetResource()->GetLength()),
 #ifdef DIRECTSHOW_REGISTER_GRAPH
     mRotRegister(0),
 #endif
     mNumChannels(0),
     mAudioRate(0),
-    mBytesPerSample(0),
-    mDuration(0)
+    mBytesPerSample(0)
 {
   MOZ_ASSERT(NS_IsMainThread(), "Must be on main thread.");
   MOZ_COUNT_CTOR(DirectShowReader);
 }
 
 DirectShowReader::~DirectShowReader()
 {
   MOZ_ASSERT(NS_IsMainThread(), "Must be on main thread.");
@@ -357,48 +356,9 @@ DirectShowReader::SeekInternal(int64_t a
   NS_ENSURE_TRUE(SUCCEEDED(hr), NS_ERROR_FAILURE);
 
   hr = mControl->Run();
   NS_ENSURE_TRUE(SUCCEEDED(hr), NS_ERROR_FAILURE);
 
   return NS_OK;
 }
 
-void
-DirectShowReader::NotifyDataArrivedInternal()
-{
-  MOZ_ASSERT(OnTaskQueue());
-  if (!mMP3FrameParser.NeedsData()) {
-    return;
-  }
-
-  AutoPinned<MediaResource> resource(mDecoder->GetResource());
-  MediaByteRangeSet byteRanges;
-  nsresult rv = resource->GetCachedRanges(byteRanges);
-
-  if (NS_FAILED(rv)) {
-    return;
-  }
-
-  if (byteRanges == mLastCachedRanges) {
-    return;
-  }
-  MediaByteRangeSet intervals = byteRanges - mLastCachedRanges;
-  mLastCachedRanges = byteRanges;
-
-  for (const auto& interval : intervals) {
-    RefPtr<MediaByteBuffer> bytes =
-      resource->MediaReadAt(interval.mStart, interval.Length());
-    NS_ENSURE_TRUE_VOID(bytes);
-    mMP3FrameParser.Parse(bytes->Elements(), interval.Length(), interval.mStart);
-    if (!mMP3FrameParser.IsMP3()) {
-      return;
-    }
-  }
-  int64_t duration = mMP3FrameParser.GetDuration();
-  if (duration != mDuration) {
-    MOZ_ASSERT(mDecoder);
-    mDuration = duration;
-    mDecoder->DispatchUpdateEstimatedMediaDuration(mDuration);
-  }
-}
-
 } // namespace mozilla

--- a/dom/media/directshow/DirectShowReader.h
+++ b/dom/media/directshow/DirectShowReader.h
@@ -55,19 +55,16 @@ public:
                         int64_t aTimeThreshold) override;
 
   nsresult ReadMetadata(MediaInfo* aInfo,
                         MetadataTags** aTags) override;
 
   RefPtr<SeekPromise>
   Seek(SeekTarget aTarget, int64_t aEndTime) override;
 
-protected:
-  void NotifyDataArrivedInternal() override;
-
 private:
   // Notifies the filter graph that playback is complete. aStatus is
   // the code to send to the filter graph. Always returns false, so
   // that we can just "return Finish()" from DecodeAudioData().
   bool Finish(HRESULT aStatus);
 
   nsresult SeekInternal(int64_t aTime);
 
@@ -99,18 +96,13 @@ private:
   // Number of channels in the audio stream.
   uint32_t mNumChannels;
 
   // Samples per second in the audio stream.
   uint32_t mAudioRate;
 
   // Number of bytes per sample. Can be either 1 or 2.
   uint32_t mBytesPerSample;
-
-  // Duration of the stream, in microseconds.
-  int64_t mDuration;
-
-  MediaByteRangeSet mLastCachedRanges;
 };
 
 } // namespace mozilla
 
 #endif