Bug 881954 - Only initialize DXVA when we're decoding video. r=padenot

content/media/wmf/DXVA2Manager.cpp

@@ -168,6 +168,10 @@ D3D9DXVA2Manager::CopyToImage(IMFSample* aSample,
   return S_OK;
 }
 
+// Count of the number of DXVAManager's we've created. This is also the
+// number of videos we're decoding with DXVA. Use on main thread only.
+static uint32_t sDXVAVideosCount = 0;
+
 /* static */
 DXVA2Manager*
 DXVA2Manager::Create()
@@ -175,6 +179,14 @@ DXVA2Manager::Create()
   MOZ_ASSERT(NS_IsMainThread());
   HRESULT hr;
 
+  // DXVA processing takes up a lot of GPU resources, so limit the number of
+  // videos we use DXVA with at any one time.
+  const uint32_t dxvaLimit =
+    Preferences::GetInt("media.windows-media-foundation.max-dxva-videos", 8);
+  if (sDXVAVideosCount == dxvaLimit) {
+    return nullptr;
+  }
+
   nsAutoPtr<D3D9DXVA2Manager> d3d9Manager(new D3D9DXVA2Manager());
   hr = d3d9Manager->Init();
   if (SUCCEEDED(hr)) {
@@ -189,11 +201,13 @@ DXVA2Manager::DXVA2Manager()
   : mLock("DXVA2Manager")
 {
   MOZ_ASSERT(NS_IsMainThread());
+  ++sDXVAVideosCount;
 }
 
 DXVA2Manager::~DXVA2Manager()
 {
   MOZ_ASSERT(NS_IsMainThread());
+  --sDXVAVideosCount;
 }
 
 } // namespace mozilla

content/media/wmf/WMFReader.cpp

@@ -120,9 +120,18 @@ WMFReader::InitializeDXVA()
   }
 
   mDXVA2Manager = DXVA2Manager::Create();
-  NS_ENSURE_TRUE(mDXVA2Manager, false);
 
-  return true;
+  return mDXVA2Manager != nullptr;
+}
+
+static bool
+IsVideoContentType(const nsCString& aContentType)
+{
+  NS_NAMED_LITERAL_CSTRING(video, "video");
+  if (FindInReadable(video, aContentType)) {
+    return true;
+  }
+  return false;
 }
 
 nsresult
@@ -145,7 +154,11 @@ WMFReader::Init(MediaDecoderReader* aCloneDonor)
   rv = mByteStream->Init();
   NS_ENSURE_SUCCESS(rv, rv);
 
-  mUseHwAccel = InitializeDXVA();
+  if (IsVideoContentType(mDecoder->GetResource()->GetContentType())) {
+    mUseHwAccel = InitializeDXVA();
+  } else {
+    mUseHwAccel = false;
+  }
 
   return NS_OK;
 }