--- a/dom/media/platforms/wmf/MFTDecoder.cpp
+++ b/dom/media/platforms/wmf/MFTDecoder.cpp
@@ -231,17 +231,19 @@ MFTDecoder::Output(RefPtr<IMFSample>* aO
   if (hr == MF_E_TRANSFORM_NEED_MORE_INPUT) {
     // Not enough input to produce output. This is an expected failure,
     // so don't warn on encountering it.
     return hr;
   }
   // Treat other errors as unexpected, and warn.
   NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
 
-  MOZ_ASSERT(output.pSample);
+  if (!output.pSample) {
+    return S_OK;
+  }
 
   if (mDiscontinuity) {
     output.pSample->SetUINT32(MFSampleExtension_Discontinuity, TRUE);
     mDiscontinuity = false;
   }
 
   *aOutput = output.pSample; // AddRefs
   if (mMFTProvidesOutputSamples && !providedSample) {

--- a/dom/media/platforms/wmf/WMFAudioMFTManager.cpp
+++ b/dom/media/platforms/wmf/WMFAudioMFTManager.cpp
@@ -5,17 +5,17 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "WMFAudioMFTManager.h"
 #include "MediaInfo.h"
 #include "VideoUtils.h"
 #include "WMFUtils.h"
 #include "nsTArray.h"
 #include "TimeUnits.h"
-
+#include "mozilla/Telemetry.h"
 #include "mozilla/Logging.h"
 
 extern mozilla::LogModule* GetPDMLog();
 #define LOG(...) MOZ_LOG(GetPDMLog(), mozilla::LogLevel::Debug, (__VA_ARGS__))
 
 namespace mozilla {
 
 static void
@@ -221,16 +221,26 @@ WMFAudioMFTManager::Output(int64_t aStre
       ++typeChangeCount;
       continue;
     }
     break;
   }
 
   NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
 
+  if (!sample) {
+    LOG("Audio MFTDecoder returned success but null output.");
+    nsCOMPtr<nsIRunnable> task = NS_NewRunnableFunction([]() -> void {
+      LOG("Reporting telemetry AUDIO_MFT_OUTPUT_NULL_SAMPLES");
+      Telemetry::Accumulate(Telemetry::ID::AUDIO_MFT_OUTPUT_NULL_SAMPLES, true);
+    });
+    AbstractThread::MainThread()->Dispatch(task.forget());
+    return E_FAIL;
+  }
+
   RefPtr<IMFMediaBuffer> buffer;
   hr = sample->ConvertToContiguousBuffer(getter_AddRefs(buffer));
   NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
 
   BYTE* data = nullptr; // Note: *data will be owned by the IMFMediaBuffer, we don't need to free it.
   DWORD maxLength = 0, currentLength = 0;
   hr = buffer->Lock(&data, &maxLength, &currentLength);
   NS_ENSURE_TRUE(SUCCEEDED(hr), hr);

--- a/dom/media/platforms/wmf/WMFVideoMFTManager.cpp
+++ b/dom/media/platforms/wmf/WMFVideoMFTManager.cpp
@@ -16,16 +16,17 @@
 #include "mozilla/layers/LayersTypes.h"
 #include "MediaInfo.h"
 #include "mozilla/Logging.h"
 #include "gfx2DGlue.h"
 #include "gfxWindowsPlatform.h"
 #include "IMFYCbCrImage.h"
 #include "mozilla/WindowsVersion.h"
 #include "mozilla/Preferences.h"
+#include "mozilla/Telemetry.h"
 #include "nsPrintfCString.h"
 
 extern mozilla::LogModule* GetPDMLog();
 #define LOG(...) MOZ_LOG(GetPDMLog(), mozilla::LogLevel::Debug, (__VA_ARGS__))
 
 using mozilla::layers::Image;
 using mozilla::layers::IMFYCbCrImage;
 using mozilla::layers::LayerManager;
@@ -73,16 +74,19 @@ WMFVideoMFTManager::WMFVideoMFTManager(
                             mozilla::layers::LayersBackend aLayersBackend,
                             mozilla::layers::ImageContainer* aImageContainer,
                             bool aDXVAEnabled)
   : mVideoInfo(aConfig)
   , mVideoStride(0)
   , mImageContainer(aImageContainer)
   , mDXVAEnabled(aDXVAEnabled)
   , mLayersBackend(aLayersBackend)
+  , mNullOutputCount(0)
+  , mGotValidOutputAfterNullOutput(false)
+  , mGotExcessiveNullOutput(false)
   // mVideoStride, mVideoWidth, mVideoHeight, mUseHwAccel are initialized in
   // Init().
 {
   MOZ_COUNT_CTOR(WMFVideoMFTManager);
 
   // Need additional checks/params to check vp8/vp9
   if (aConfig.mMimeType.EqualsLiteral("video/mp4") ||
       aConfig.mMimeType.EqualsLiteral("video/avc")) {
@@ -98,16 +102,30 @@ WMFVideoMFTManager::WMFVideoMFTManager(
 
 WMFVideoMFTManager::~WMFVideoMFTManager()
 {
   MOZ_COUNT_DTOR(WMFVideoMFTManager);
   // Ensure DXVA/D3D9 related objects are released on the main thread.
   if (mDXVA2Manager) {
     DeleteOnMainThread(mDXVA2Manager);
   }
+
+  // Record whether the video decoder successfully decoded, or output null
+  // samples but did/didn't recover.
+  uint32_t telemetry = (mNullOutputCount == 0) ? 0 :
+                       (mGotValidOutputAfterNullOutput && mGotExcessiveNullOutput) ? 1 :
+                       mGotExcessiveNullOutput ? 2 :
+                       mGotValidOutputAfterNullOutput ? 3 :
+                       4;
+
+  nsCOMPtr<nsIRunnable> task = NS_NewRunnableFunction([=]() -> void {
+    LOG(nsPrintfCString("Reporting telemetry VIDEO_MFT_OUTPUT_NULL_SAMPLES=%d", telemetry).get());
+    Telemetry::Accumulate(Telemetry::ID::VIDEO_MFT_OUTPUT_NULL_SAMPLES, telemetry);
+  });
+  AbstractThread::MainThread()->Dispatch(task.forget());
 }
 
 const GUID&
 WMFVideoMFTManager::GetMFTGUID()
 {
   MOZ_ASSERT(mStreamType != Unknown);
   switch (mStreamType) {
     case H264: return CLSID_CMSH264DecoderMFT;
@@ -570,16 +588,33 @@ WMFVideoMFTManager::Output(int64_t aStre
       // changes on consecutive calls, so be permissive.
       // 100 is arbitrarily > 2.
       NS_ENSURE_TRUE(typeChangeCount < 100, MF_E_TRANSFORM_STREAM_CHANGE);
       // Loop back and try decoding again...
       ++typeChangeCount;
       continue;
     }
     if (SUCCEEDED(hr)) {
+      if (!sample) {
+        LOG("Video MFTDecoder returned success but no output!");
+        // On some machines/input the MFT returns success but doesn't output
+        // a video frame. If we detect this, try again, but only up to a
+        // point; after 500 failures, give up. Note we count all failures
+        // over the life of the decoder, as we may end up exiting with a
+        // NEED_MORE_INPUT and coming back to hit the same error. So just
+        // counting with a local variable (like typeChangeCount does) may
+        // not work in this situation.
+        ++mNullOutputCount;
+        if (mNullOutputCount > 500) {
+          LOG("Excessive Video MFTDecoder returning success but no output; giving up");
+          mGotExcessiveNullOutput = true;
+          return E_FAIL;
+        }
+        continue;
+      }
       break;
     }
     // Else unexpected error, assert, and bail.
     NS_WARNING("WMFVideoMFTManager::Output() unexpected error");
     return hr;
   }
 
   RefPtr<VideoData> frame;
@@ -590,16 +625,20 @@ WMFVideoMFTManager::Output(int64_t aStre
   }
   // Frame should be non null only when we succeeded.
   MOZ_ASSERT((frame != nullptr) == SUCCEEDED(hr));
   NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
   NS_ENSURE_TRUE(frame, E_FAIL);
 
   aOutData = frame;
 
+  if (mNullOutputCount) {
+    mGotValidOutputAfterNullOutput = true;
+  }
+
   return S_OK;
 }
 
 void
 WMFVideoMFTManager::Shutdown()
 {
   mDecoder = nullptr;
   DeleteOnMainThread(mDXVA2Manager);

--- a/dom/media/platforms/wmf/WMFVideoMFTManager.h
+++ b/dom/media/platforms/wmf/WMFVideoMFTManager.h
@@ -83,13 +83,17 @@ private:
     VP8,
     VP9
   };
 
   StreamType mStreamType;
 
   const GUID& GetMFTGUID();
   const GUID& GetMediaSubtypeGUID();
+
+  uint32_t mNullOutputCount;
+  bool mGotValidOutputAfterNullOutput;
+  bool mGotExcessiveNullOutput;
 };
 
 } // namespace mozilla
 
 #endif // WMFVideoMFTManager_h_

--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -6072,16 +6072,31 @@
   },
   "MEDIA_OGG_LOADED_IS_CHAINED": {
     "alert_emails": ["cpearce@mozilla.com"],
     "expires_in_version": "53",
     "kind": "boolean",
     "description": "Whether Ogg audio/video encountered are chained or not.",
     "bug_numbers": [1230295]
   },
+  "VIDEO_MFT_OUTPUT_NULL_SAMPLES": {
+    "alert_emails": ["cpearce@mozilla.com"],
+    "expires_in_version": "53",
+    "kind": "enumerated",
+    "n_values": 10,
+    "description": "Does the WMF video decoder return success but null output? 0 = playback successful, 1 = excessive null output but able to decode some frames, 2 = excessive null output and gave up, 3 = null output but recovered, 4 = non-excessive null output without being able to decode frames.",
+    "bug_numbers": [1176071]
+  },
+  "AUDIO_MFT_OUTPUT_NULL_SAMPLES": {
+    "alert_emails": ["cpearce@mozilla.com"],
+    "expires_in_version": "53",
+    "kind": "flag",
+    "description": "How many times the audio MFT decoder returns success but output nothing.",
+    "bug_numbers": [1176071]
+  },
   "VIDEO_CAN_CREATE_AAC_DECODER": {
     "alert_emails": ["cpearce@mozilla.com"],
     "expires_in_version": "50",
     "kind": "boolean",
     "description": "Whether at startup we report we can playback MP4 (AAC) audio. This is single value is recorded at every startup.",
     "releaseChannelCollection": "opt-out"
   },
   "VIDEO_CAN_CREATE_H264_DECODER": {