dom/media/platforms/wmf/WMFVideoMFTManager.cpp
author David Anderson <danderson@mozilla.com>
Tue, 29 Mar 2016 22:49:02 -0700
changeset 291016 907c2536632e727727eb107779d1fccfea93c295
parent 289315 acbda99b64a538e42335cef595d25cd79df759bc
permissions -rw-r--r--
Add telemetry for which WMF backends are used. (bug 1259695, r=mattwoodrow)

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <algorithm>
#include "WMFVideoMFTManager.h"
#include "MediaDecoderReader.h"
#include "WMFUtils.h"
#include "ImageContainer.h"
#include "VideoUtils.h"
#include "DXVA2Manager.h"
#include "nsThreadUtils.h"
#include "Layers.h"
#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"
#include "MediaTelemetryConstants.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;
using mozilla::layers::LayersBackend;

#if MOZ_WINSDK_MAXVER < 0x0A000000
// Windows 10+ SDK has VP80 and VP90 defines
const GUID MFVideoFormat_VP80 =
{
  0x30385056,
  0x0000,
  0x0010,
  {0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
};

const GUID MFVideoFormat_VP90 =
{
  0x30395056,
  0x0000,
  0x0010,
  {0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
};
#endif

const CLSID CLSID_WebmMfVp8Dec =
{
  0x451e3cb7,
  0x2622,
  0x4ba5,
  {0x8e, 0x1d, 0x44, 0xb3, 0xc4, 0x1d, 0x09, 0x24}
};

const CLSID CLSID_WebmMfVp9Dec =
{
  0x7ab4bd2,
  0x1979,
  0x4fcd,
  {0xa6, 0x97, 0xdf, 0x9a, 0xd1, 0x5b, 0x34, 0xfe}
};

namespace mozilla {

WMFVideoMFTManager::WMFVideoMFTManager(
                            const VideoInfo& aConfig,
                            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")) {
    mStreamType = H264;
  } else if (aConfig.mMimeType.EqualsLiteral("video/webm; codecs=vp8")) {
    mStreamType = VP8;
  } else if (aConfig.mMimeType.EqualsLiteral("video/webm; codecs=vp9")) {
    mStreamType = VP9;
  } else {
    mStreamType = Unknown;
  }
}

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;
    case VP8: return CLSID_WebmMfVp8Dec;
    case VP9: return CLSID_WebmMfVp9Dec;
    default: return GUID_NULL;
  };
}

const GUID&
WMFVideoMFTManager::GetMediaSubtypeGUID()
{
  MOZ_ASSERT(mStreamType != Unknown);
  switch (mStreamType) {
    case H264: return MFVideoFormat_H264;
    case VP8: return MFVideoFormat_VP80;
    case VP9: return MFVideoFormat_VP90;
    default: return GUID_NULL;
  };
}

class CreateDXVAManagerEvent : public nsRunnable {
public:
  CreateDXVAManagerEvent(LayersBackend aBackend, nsCString& aFailureReason)
    : mBackend(aBackend)
    , mFailureReason(aFailureReason)
  {}

  NS_IMETHOD Run() {
    NS_ASSERTION(NS_IsMainThread(), "Must be on main thread.");
    nsACString* failureReason = &mFailureReason;
    nsCString secondFailureReason;
    if (mBackend == LayersBackend::LAYERS_D3D11 &&
        Preferences::GetBool("media.windows-media-foundation.allow-d3d11-dxva", true) &&
        IsWin8OrLater()) {
      mDXVA2Manager = DXVA2Manager::CreateD3D11DXVA(*failureReason);
      if (mDXVA2Manager) {
        return NS_OK;
      }
      // Try again with d3d9, but record the failure reason
      // into a new var to avoid overwriting the d3d11 failure.
      failureReason = &secondFailureReason;
      mFailureReason.Append(NS_LITERAL_CSTRING("; "));
    }
    mDXVA2Manager = DXVA2Manager::CreateD3D9DXVA(*failureReason);
    // Make sure we include the messages from both attempts (if applicable).
    mFailureReason.Append(secondFailureReason);
    return NS_OK;
  }
  nsAutoPtr<DXVA2Manager> mDXVA2Manager;
  LayersBackend mBackend;
  nsACString& mFailureReason;
};

bool
WMFVideoMFTManager::InitializeDXVA(bool aForceD3D9)
{
  // 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.
  RefPtr<CreateDXVAManagerEvent> event =
    new CreateDXVAManagerEvent(aForceD3D9 ? LayersBackend::LAYERS_D3D9 : mLayersBackend, mDXVAFailureReason);

  if (NS_IsMainThread()) {
    event->Run();
  } else {
    NS_DispatchToMainThread(event, NS_DISPATCH_SYNC);
  }
  mDXVA2Manager = event->mDXVA2Manager;

  return mDXVA2Manager != nullptr;
}

bool
WMFVideoMFTManager::Init()
{
  bool success = InitInternal(/* aForceD3D9 = */ false);

  if (success && mDXVA2Manager) {
    // If we had some failures but eventually made it work,
    // make sure we preserve the messages.
    if (mDXVA2Manager->IsD3D11()) {
      mDXVAFailureReason.Append(NS_LITERAL_CSTRING("Using D3D11 API"));
    } else {
      mDXVAFailureReason.Append(NS_LITERAL_CSTRING("Using D3D9 API"));
    }
  }

  return success;
}

bool
WMFVideoMFTManager::InitInternal(bool aForceD3D9)
{
  mUseHwAccel = false; // default value; changed if D3D setup succeeds.
  bool useDxva = InitializeDXVA(aForceD3D9);

  RefPtr<MFTDecoder> decoder(new MFTDecoder());

  HRESULT hr = decoder->Create(GetMFTGUID());
  NS_ENSURE_TRUE(SUCCEEDED(hr), false);

  RefPtr<IMFAttributes> attr(decoder->GetAttributes());
  UINT32 aware = 0;
  if (attr) {
    attr->GetUINT32(MF_SA_D3D_AWARE, &aware);
    attr->SetUINT32(CODECAPI_AVDecNumWorkerThreads,
      WMFDecoderModule::GetNumDecoderThreads());
    if (WMFDecoderModule::LowLatencyMFTEnabled()) {
      hr = attr->SetUINT32(CODECAPI_AVLowLatencyMode, TRUE);
      if (SUCCEEDED(hr)) {
        LOG("Enabling Low Latency Mode");
      } else {
        LOG("Couldn't enable Low Latency Mode");
      }
    }
  }

  if (useDxva) {
    if (aware) {
      // TODO: Test if I need this anywhere... Maybe on Vista?
      //hr = attr->SetUINT32(CODECAPI_AVDecVideoAcceleration_H264, TRUE);
      //NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
      MOZ_ASSERT(mDXVA2Manager);
      ULONG_PTR manager = ULONG_PTR(mDXVA2Manager->GetDXVADeviceManager());
      hr = decoder->SendMFTMessage(MFT_MESSAGE_SET_D3D_MANAGER, manager);
      if (SUCCEEDED(hr)) {
        mUseHwAccel = true;
      } else {
        mDXVA2Manager = nullptr;
        mDXVAFailureReason = nsPrintfCString("MFT_MESSAGE_SET_D3D_MANAGER failed with code %X", hr);
      }
    }
    else {
      mDXVAFailureReason.AssignLiteral("Decoder returned false for MF_SA_D3D_AWARE");
    }
  }

  if (!mUseHwAccel) {
    Telemetry::Accumulate(Telemetry::MEDIA_DECODER_BACKEND_USED,
                          uint32_t(media::MediaDecoderBackend::WMFSoftware));
  }

  mDecoder = decoder;
  hr = SetDecoderMediaTypes();
  NS_ENSURE_TRUE(SUCCEEDED(hr), false);

  LOG("Video Decoder initialized, Using DXVA: %s", (mUseHwAccel ? "Yes" : "No"));

  return true;
}

HRESULT
WMFVideoMFTManager::SetDecoderMediaTypes()
{
  // Setup the input/output media types.
  RefPtr<IMFMediaType> inputType;
  HRESULT hr = wmf::MFCreateMediaType(getter_AddRefs(inputType));
  NS_ENSURE_TRUE(SUCCEEDED(hr), hr);

  hr = inputType->SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Video);
  NS_ENSURE_TRUE(SUCCEEDED(hr), hr);

  hr = inputType->SetGUID(MF_MT_SUBTYPE, GetMediaSubtypeGUID());
  NS_ENSURE_TRUE(SUCCEEDED(hr), hr);

  hr = inputType->SetUINT32(MF_MT_INTERLACE_MODE, MFVideoInterlace_MixedInterlaceOrProgressive);
  NS_ENSURE_TRUE(SUCCEEDED(hr), hr);

  RefPtr<IMFMediaType> outputType;
  hr = wmf::MFCreateMediaType(getter_AddRefs(outputType));
  NS_ENSURE_TRUE(SUCCEEDED(hr), hr);

  hr = outputType->SetGUID(MF_MT_MAJOR_TYPE, MFMediaType_Video);
  NS_ENSURE_TRUE(SUCCEEDED(hr), hr);

  GUID outputSubType = mUseHwAccel ? MFVideoFormat_NV12 : MFVideoFormat_YV12;
  hr = outputType->SetGUID(MF_MT_SUBTYPE, outputSubType);
  NS_ENSURE_TRUE(SUCCEEDED(hr), hr);

  return mDecoder->SetMediaTypes(inputType, outputType);
}

HRESULT
WMFVideoMFTManager::Input(MediaRawData* aSample)
{
  if (!mDecoder) {
    // This can happen during shutdown.
    return E_FAIL;
  }

  HRESULT hr = mDecoder->CreateInputSample(aSample->Data(),
                                           uint32_t(aSample->Size()),
                                           aSample->mTime,
                                           &mLastInput);
  NS_ENSURE_TRUE(SUCCEEDED(hr) && mLastInput != nullptr, hr);

  mLastDuration = aSample->mDuration;

  // Forward sample data to the decoder.
  return mDecoder->Input(mLastInput);
}

// The MFTransform we use for decoding h264 video will silently fall
// back to software decoding (even if we've negotiated DXVA) if the GPU
// doesn't support decoding the given resolution. It will then upload
// the software decoded frames into d3d textures to preserve behaviour.
//
// 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::CanUseDXVA(IMFMediaType* aType)
{
  MOZ_ASSERT(mDXVA2Manager);
  // SupportsConfig only checks for valid h264 decoders currently.
  if (mStreamType != H264) {
    return true;
  }

  // Assume the current samples duration is representative for the
  // entire video.
  float framerate = 1000000.0 / mLastDuration;

  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 (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.
  GUID videoFormat;
  hr = mediaType->GetGUID(MF_MT_SUBTYPE, &videoFormat);
  NS_ENSURE_TRUE(videoFormat == MFVideoFormat_NV12 || !mUseHwAccel, E_FAIL);
  NS_ENSURE_TRUE(videoFormat == MFVideoFormat_YV12 || mUseHwAccel, E_FAIL);

  UINT32 width = mVideoInfo.mImage.width;
  UINT32 height = mVideoInfo.mImage.height;
  nsIntRect pictureRegion = mVideoInfo.mImage;
  // Calculate and validate the picture region and frame dimensions after
  // scaling by the pixel aspect ratio.
  nsIntSize frameSize = nsIntSize(width, height);
  nsIntSize displaySize = nsIntSize(mVideoInfo.mDisplay.width, mVideoInfo.mDisplay.height);
  if (!IsValidVideoRegion(frameSize, pictureRegion, displaySize)) {
    // Video track's frame sizes will overflow. Ignore the video track.
    return E_FAIL;
  }

  if (mDXVA2Manager) {
    hr = mDXVA2Manager->ConfigureForSize(width, height);
    NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
  }

  // Success! Save state.
  GetDefaultStride(mediaType, width, &mVideoStride);

  LOG("WMFVideoMFTManager frame geometry frame=(%u,%u) stride=%u picture=(%d, %d, %d, %d) display=(%d,%d)",
      width, height,
      mVideoStride,
      pictureRegion.x, pictureRegion.y, pictureRegion.width, pictureRegion.height,
      mVideoInfo.mDisplay.width, mVideoInfo.mDisplay.height);

  return S_OK;
}

HRESULT
WMFVideoMFTManager::CreateBasicVideoFrame(IMFSample* aSample,
                                          int64_t aStreamOffset,
                                          VideoData** aOutVideoData)
{
  NS_ENSURE_TRUE(aSample, E_POINTER);
  NS_ENSURE_TRUE(aOutVideoData, E_POINTER);

  *aOutVideoData = nullptr;

  HRESULT hr;
  RefPtr<IMFMediaBuffer> buffer;

  // Must convert to contiguous buffer to use IMD2DBuffer interface.
  hr = aSample->ConvertToContiguousBuffer(getter_AddRefs(buffer));
  NS_ENSURE_TRUE(SUCCEEDED(hr), hr);

  // Try and use the IMF2DBuffer interface if available, otherwise fallback
  // to the IMFMediaBuffer interface. Apparently IMF2DBuffer is more efficient,
  // but only some systems (Windows 8?) support it.
  BYTE* data = nullptr;
  LONG stride = 0;
  RefPtr<IMF2DBuffer> twoDBuffer;
  hr = buffer->QueryInterface(static_cast<IMF2DBuffer**>(getter_AddRefs(twoDBuffer)));
  if (SUCCEEDED(hr)) {
    hr = twoDBuffer->Lock2D(&data, &stride);
    NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
  } else {
    hr = buffer->Lock(&data, nullptr, nullptr);
    NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
    stride = mVideoStride;
  }

  // YV12, planar format: [YYYY....][VVVV....][UUUU....]
  // i.e., Y, then V, then U.
  VideoData::YCbCrBuffer b;

  uint32_t videoWidth = mVideoInfo.mImage.width;
  uint32_t videoHeight = mVideoInfo.mImage.height;

  // Y (Y') plane
  b.mPlanes[0].mData = data;
  b.mPlanes[0].mStride = stride;
  b.mPlanes[0].mHeight = videoHeight;
  b.mPlanes[0].mWidth = videoWidth;
  b.mPlanes[0].mOffset = 0;
  b.mPlanes[0].mSkip = 0;

  // The V and U planes are stored 16-row-aligned, so we need to add padding
  // to the row heights to ensure the Y'CbCr planes are referenced properly.
  uint32_t padding = 0;
  if (videoHeight % 16 != 0) {
    padding = 16 - (videoHeight % 16);
  }
  uint32_t y_size = stride * (videoHeight + padding);
  uint32_t v_size = stride * (videoHeight + padding) / 4;
  uint32_t halfStride = (stride + 1) / 2;
  uint32_t halfHeight = (videoHeight + 1) / 2;
  uint32_t halfWidth = (videoWidth + 1) / 2;

  // U plane (Cb)
  b.mPlanes[1].mData = data + y_size + v_size;
  b.mPlanes[1].mStride = halfStride;
  b.mPlanes[1].mHeight = halfHeight;
  b.mPlanes[1].mWidth = halfWidth;
  b.mPlanes[1].mOffset = 0;
  b.mPlanes[1].mSkip = 0;

  // V plane (Cr)
  b.mPlanes[2].mData = data + y_size;
  b.mPlanes[2].mStride = halfStride;
  b.mPlanes[2].mHeight = halfHeight;
  b.mPlanes[2].mWidth = halfWidth;
  b.mPlanes[2].mOffset = 0;
  b.mPlanes[2].mSkip = 0;

  media::TimeUnit pts = GetSampleTime(aSample);
  NS_ENSURE_TRUE(pts.IsValid(), E_FAIL);
  media::TimeUnit duration = GetSampleDuration(aSample);
  NS_ENSURE_TRUE(duration.IsValid(), E_FAIL);

  RefPtr<layers::PlanarYCbCrImage> image =
    new IMFYCbCrImage(buffer, twoDBuffer);

  VideoData::SetVideoDataToImage(image,
                                 mVideoInfo,
                                 b,
                                 mVideoInfo.mImage,
                                 false);

  RefPtr<VideoData> v =
    VideoData::CreateFromImage(mVideoInfo,
                               mImageContainer,
                               aStreamOffset,
                               pts.ToMicroseconds(),
                               duration.ToMicroseconds(),
                               image.forget(),
                               false,
                               -1,
                               mVideoInfo.mImage);

  v.forget(aOutVideoData);
  return S_OK;
}

HRESULT
WMFVideoMFTManager::CreateD3DVideoFrame(IMFSample* aSample,
                                        int64_t aStreamOffset,
                                        VideoData** aOutVideoData)
{
  NS_ENSURE_TRUE(aSample, E_POINTER);
  NS_ENSURE_TRUE(aOutVideoData, E_POINTER);
  NS_ENSURE_TRUE(mDXVA2Manager, E_ABORT);
  NS_ENSURE_TRUE(mUseHwAccel, E_ABORT);

  *aOutVideoData = nullptr;
  HRESULT hr;

  RefPtr<Image> image;
  hr = mDXVA2Manager->CopyToImage(aSample,
                                  mVideoInfo.mImage,
                                  mImageContainer,
                                  getter_AddRefs(image));
  NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
  NS_ENSURE_TRUE(image, E_FAIL);

  media::TimeUnit pts = GetSampleTime(aSample);
  NS_ENSURE_TRUE(pts.IsValid(), E_FAIL);
  media::TimeUnit duration = GetSampleDuration(aSample);
  NS_ENSURE_TRUE(duration.IsValid(), E_FAIL);
  RefPtr<VideoData> v = VideoData::CreateFromImage(mVideoInfo,
                                                     mImageContainer,
                                                     aStreamOffset,
                                                     pts.ToMicroseconds(),
                                                     duration.ToMicroseconds(),
                                                     image.forget(),
                                                     false,
                                                     -1,
                                                     mVideoInfo.mImage);

  NS_ENSURE_TRUE(v, E_FAIL);
  v.forget(aOutVideoData);

  return S_OK;
}

// Blocks until decoded sample is produced by the deoder.
HRESULT
WMFVideoMFTManager::Output(int64_t aStreamOffset,
                           RefPtr<MediaData>& aOutData)
{
  RefPtr<IMFSample> sample;
  HRESULT hr;
  aOutData = nullptr;
  int typeChangeCount = 0;

  // Loop until we decode a sample, or an unexpected error that we can't
  // handle occurs.
  while (true) {
    hr = mDecoder->Output(&sample);
    if (hr == MF_E_TRANSFORM_NEED_MORE_INPUT) {
      return MF_E_TRANSFORM_NEED_MORE_INPUT;
    }
    if (hr == MF_E_TRANSFORM_STREAM_CHANGE) {
      // Video stream output type change. Probably a geometric apperature
      // change. Reconfigure the video geometry, so that we output the
      // correct size frames.
      MOZ_ASSERT(!sample);
      hr = ConfigureVideoFrameGeometry();
      NS_ENSURE_TRUE(SUCCEEDED(hr), hr);
      // Catch infinite loops, but some decoders perform at least 2 stream
      // 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 250 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 > 250) {
          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;
  if (mUseHwAccel) {
    hr = CreateD3DVideoFrame(sample, aStreamOffset, getter_AddRefs(frame));
  } else {
    hr = CreateBasicVideoFrame(sample, aStreamOffset, getter_AddRefs(frame));
  }
  // 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);
}

bool
WMFVideoMFTManager::IsHardwareAccelerated(nsACString& aFailureReason) const
{
  aFailureReason = mDXVAFailureReason;
  return mDecoder && mUseHwAccel;
}

const char*
WMFVideoMFTManager::GetDescriptionName() const
{
  if (mDecoder && mUseHwAccel && mDXVA2Manager) {
    return (mDXVA2Manager->IsD3D11()) ?
      "D3D11 Hardware Decoder" : "D3D9 Hardware Decoder";
  } else {
    return "wmf software video decoder";
  }
}

void
WMFVideoMFTManager::ConfigurationChanged(const TrackInfo& aConfig)
{
  MOZ_ASSERT(aConfig.GetAsVideoInfo());
  mVideoInfo = *aConfig.GetAsVideoInfo();
}

} // namespace mozilla