diff -r 000000000000 -r 6474c204b198 content/media/wmf/WMFUtils.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/wmf/WMFUtils.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,106 @@
+/* -*- 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/. */
+
+#ifndef WMFUtils_h
+#define WMFUtils_h
+
+#include "WMF.h"
+#include "nsString.h"
+#include "nsRect.h"
+#include "VideoUtils.h"
+
+// Various utilities shared by WMF backend files.
+
+namespace mozilla {
+
+nsCString
+GetGUIDName(const GUID& guid);
+
+// Returns true if the reader has a stream with the specified index.
+// Index can be a specific index, or one of:
+//   MF_SOURCE_READER_FIRST_VIDEO_STREAM
+//   MF_SOURCE_READER_FIRST_AUDIO_STREAM
+bool
+SourceReaderHasStream(IMFSourceReader* aReader, const DWORD aIndex);
+
+// Auto manages the lifecycle of a PROPVARIANT.
+class AutoPropVar {
+public:
+  AutoPropVar() {
+    PropVariantInit(&mVar);
+  }
+  ~AutoPropVar() {
+    PropVariantClear(&mVar);
+  }
+  operator PROPVARIANT&() {
+    return mVar;
+  }
+  PROPVARIANT* operator->() {
+    return &mVar;
+  }
+  PROPVARIANT* operator&() {
+    return &mVar;
+  }
+private:
+  PROPVARIANT mVar;
+};
+
+// Converts from microseconds to hundreds of nanoseconds.
+// We use microseconds for our timestamps, whereas WMF uses
+// hundreds of nanoseconds.
+inline int64_t
+UsecsToHNs(int64_t aUsecs) {
+  return aUsecs * 10;
+}
+
+// Converts from hundreds of nanoseconds to microseconds.
+// We use microseconds for our timestamps, whereas WMF uses
+// hundreds of nanoseconds.
+inline int64_t
+HNsToUsecs(int64_t hNanoSecs) {
+  return hNanoSecs / 10;
+}
+
+// Assigns aUnknown to *aInterface, and AddRef's it.
+// Helper for MSCOM QueryInterface implementations.
+HRESULT
+DoGetInterface(IUnknown* aUnknown, void** aInterface);
+
+HRESULT
+HNsToFrames(int64_t aHNs, uint32_t aRate, int64_t* aOutFrames);
+
+HRESULT
+FramesToUsecs(int64_t aSamples, uint32_t aRate, int64_t* aOutUsecs);
+
+HRESULT
+GetDefaultStride(IMFMediaType *aType, uint32_t* aOutStride);
+
+int32_t
+MFOffsetToInt32(const MFOffset& aOffset);
+
+// Gets the sub-region of the video frame that should be displayed.
+// See: http://msdn.microsoft.com/en-us/library/windows/desktop/bb530115(v=vs.85).aspx
+HRESULT
+GetPictureRegion(IMFMediaType* aMediaType, nsIntRect& aOutPictureRegion);
+
+// Returns the duration of a IMFSample in microseconds.
+// Returns -1 on failure.
+int64_t
+GetSampleDuration(IMFSample* aSample);
+
+// Returns the presentation time of a IMFSample in microseconds.
+// Returns -1 on failure.
+int64_t
+GetSampleTime(IMFSample* aSample);
+
+inline bool
+IsFlagSet(DWORD flags, DWORD pattern) {
+  return (flags & pattern) == pattern;
+}
+
+} // namespace mozilla
+
+#endif