--- a/dom/media/platforms/wmf/WMFVideoMFTManager.cpp
+++ b/dom/media/platforms/wmf/WMFVideoMFTManager.cpp
@@ -148,25 +148,24 @@ public:
   nsAutoPtr<DXVA2Manager> mDXVA2Manager;
   LayersBackend mBackend;
   nsACString& mFailureReason;
 };
 
 bool
 WMFVideoMFTManager::InitializeDXVA(bool aForceD3D9)
 {
-  MOZ_ASSERT(!mDXVA2Manager);
-
   // If we use DXVA but aren't running with a D3D layer manager then the
   // readback of decoded video frames from GPU to CPU memory grinds painting
   // to a halt, and makes playback performance *worse*.
   if (!mDXVAEnabled) {
     mDXVAFailureReason.AssignLiteral("Hardware video decoding disabled or blacklisted");
     return false;
   }
+  MOZ_ASSERT(!mDXVA2Manager);
   if (mLayersBackend != LayersBackend::LAYERS_D3D9 &&
       mLayersBackend != LayersBackend::LAYERS_D3D11) {
     mDXVAFailureReason.AssignLiteral("Unsupported layers backend");
     return false;
   }
 
   // The DXVA manager must be created on the main thread.
   nsRefPtr<CreateDXVAManagerEvent> event = 
@@ -320,67 +319,50 @@ WMFVideoMFTManager::Input(MediaRawData* 
 //
 // Unfortunately this seems to cause corruption (see bug 1193547) and is
 // slow because the upload is done into a non-shareable texture and requires
 // us to copy it.
 //
 // This code tests if the given resolution can be supported directly on the GPU,
 // and makes sure we only ask the MFT for DXVA if it can be supported properly.
 bool
-WMFVideoMFTManager::MaybeToggleDXVA(IMFMediaType* aType)
+WMFVideoMFTManager::CanUseDXVA(IMFMediaType* aType)
 {
+  MOZ_ASSERT(mDXVA2Manager);
   // SupportsConfig only checks for valid h264 decoders currently.
-  if (!mDXVA2Manager || mStreamType != H264) {
-    return false;
+  if (mStreamType != H264) {
+    return true;
   }
 
   // Assume the current samples duration is representative for the
   // entire video.
   float framerate = 1000000.0 / mLastDuration;
 
-  if (mDXVA2Manager->SupportsConfig(aType, framerate)) {
-    if (!mUseHwAccel) {
-      // DXVA disabled, but supported for this resolution
-      ULONG_PTR manager = ULONG_PTR(mDXVA2Manager->GetDXVADeviceManager());
-      HRESULT hr = mDecoder->SendMFTMessage(MFT_MESSAGE_SET_D3D_MANAGER, manager);
-      if (SUCCEEDED(hr)) {
-        mUseHwAccel = true;
-        return true;
-      }
-    }
-  } else if (mUseHwAccel) {
-    // DXVA enabled, and not supported for this resolution
-    HRESULT hr = mDecoder->SendMFTMessage(MFT_MESSAGE_SET_D3D_MANAGER, 0);
-    MOZ_ASSERT(SUCCEEDED(hr), "Attempting to fall back to software failed?");
-    mUseHwAccel = false;
-    return true;
-  }
-
-  return false;
+  return mDXVA2Manager->SupportsConfig(aType, framerate);
 }
 
 HRESULT
 WMFVideoMFTManager::ConfigureVideoFrameGeometry()
 {
   RefPtr<IMFMediaType> mediaType;
   HRESULT hr = mDecoder->GetOutputMediaType(mediaType);
   NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
 
   // If we enabled/disabled DXVA in response to a resolution
   // change then we need to renegotiate our media types,
   // and resubmit our previous frame (since the MFT appears
   // to lose it otherwise).
-  if (MaybeToggleDXVA(mediaType)) {
-    hr = SetDecoderMediaTypes();
-    NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
-
-    HRESULT hr = mDecoder->GetOutputMediaType(mediaType);
-    NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
+  if (mUseHwAccel && !CanUseDXVA(mediaType)) {
+    mDXVAEnabled = false;
+    if (!Init()) {
+      return E_FAIL;
+    }
 
     mDecoder->Input(mLastInput);
+    return S_OK;
   }
 
   // Verify that the video subtype is what we expect it to be.
   // When using hardware acceleration/DXVA2 the video format should
   // be NV12, which is DXVA2's preferred format. For software decoding
   // we use YV12, as that's easier for us to stick into our rendering
   // pipeline than NV12. NV12 has interleaved UV samples, whereas YV12
   // is a planar format.

--- a/dom/media/platforms/wmf/WMFVideoMFTManager.h
+++ b/dom/media/platforms/wmf/WMFVideoMFTManager.h
@@ -53,32 +53,32 @@ private:
                                 VideoData** aOutVideoData);
 
   HRESULT CreateD3DVideoFrame(IMFSample* aSample,
                               int64_t aStreamOffset,
                               VideoData** aOutVideoData);
 
   HRESULT SetDecoderMediaTypes();
 
-  bool MaybeToggleDXVA(IMFMediaType* aType);
+  bool CanUseDXVA(IMFMediaType* aType);
 
   // Video frame geometry.
   VideoInfo mVideoInfo;
   uint32_t mVideoStride;
   uint32_t mVideoWidth;
   uint32_t mVideoHeight;
   nsIntRect mPictureRegion;
 
   RefPtr<layers::ImageContainer> mImageContainer;
   nsAutoPtr<DXVA2Manager> mDXVA2Manager;
 
   RefPtr<IMFSample> mLastInput;
   float mLastDuration;
 
-  const bool mDXVAEnabled;
+  bool mDXVAEnabled;
   const layers::LayersBackend mLayersBackend;
   bool mUseHwAccel;
 
   nsCString mDXVAFailureReason;
 
   enum StreamType {
     Unknown,
     H264,