diff -r 000000000000 -r 6474c204b198 content/media/wmf/WMFDecoder.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/wmf/WMFDecoder.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,163 @@
+/* -*- 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 "WMF.h"
+#include "WMFDecoder.h"
+#include "WMFReader.h"
+#include "WMFUtils.h"
+#include "MediaDecoderStateMachine.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/WindowsVersion.h"
+#include "nsCharSeparatedTokenizer.h"
+
+#ifdef MOZ_DIRECTSHOW
+#include "DirectShowDecoder.h"
+#endif
+
+namespace mozilla {
+
+MediaDecoderStateMachine* WMFDecoder::CreateStateMachine()
+{
+  return new MediaDecoderStateMachine(this, new WMFReader(this));
+}
+
+/* static */
+bool
+WMFDecoder::IsMP3Supported()
+{
+  MOZ_ASSERT(NS_IsMainThread(), "Must be on main thread.");
+  if (!MediaDecoder::IsWMFEnabled()) {
+    return false;
+  }
+  // MP3 works fine in WMF on Windows Vista and Windows 8.
+  if (!IsWin7OrLater()) {
+    return true;
+  }
+  // MP3 support is disabled if we're on Windows 7 and no service packs are
+  // installed, since it's crashy. Win7 with service packs is not so crashy,
+  // so we enable it there. Note we prefer DirectShow for MP3 playback, but
+  // we still support MP3 in MP4 via WMF, or MP3 in WMF if DirectShow is
+  // disabled.
+  return IsWin7SP1OrLater();
+}
+
+static bool
+IsSupportedH264Codec(const nsAString& aCodec)
+{
+  // According to the WMF documentation:
+  // http://msdn.microsoft.com/en-us/library/windows/desktop/dd797815%28v=vs.85%29.aspx
+  // "The Media Foundation H.264 video decoder is a Media Foundation Transform
+  // that supports decoding of Baseline, Main, and High profiles, up to level
+  // 5.1.". We also report that we can play Extended profile, as there are
+  // bitstreams that are Extended compliant that are also Baseline compliant.
+
+  // H.264 codecs parameters have a type defined as avc1.PPCCLL, where
+  // PP = profile_idc, CC = constraint_set flags, LL = level_idc.
+  // We ignore the constraint_set flags, as it's not clear from the WMF
+  // documentation what constraints the WMF H.264 decoder supports.
+  // See http://blog.pearce.org.nz/2013/11/what-does-h264avc1-codecs-parameters.html
+  // for more details.
+  if (aCodec.Length() != strlen("avc1.PPCCLL")) {
+    return false;
+  }
+
+  // Verify the codec starts with "avc1.".
+  const nsAString& sample = Substring(aCodec, 0, 5);
+  if (!sample.EqualsASCII("avc1.")) {
+    return false;
+  }
+
+  // Extract the profile_idc and level_idc. Note: the constraint_set flags
+  // are ignored, it's not clear from the WMF documentation if they make a
+  // difference.
+  nsresult rv = NS_OK;
+  const int32_t profile = PromiseFlatString(Substring(aCodec, 5, 2)).ToInteger(&rv, 16);
+  NS_ENSURE_SUCCESS(rv, false);
+
+  const int32_t level = PromiseFlatString(Substring(aCodec, 9, 2)).ToInteger(&rv, 16);
+  NS_ENSURE_SUCCESS(rv, false);
+
+  return level >= eAVEncH264VLevel1 &&
+         level <= eAVEncH264VLevel5_1 &&
+         (profile == eAVEncH264VProfile_Base ||
+          profile == eAVEncH264VProfile_Main ||
+          profile == eAVEncH264VProfile_Extended ||
+          profile == eAVEncH264VProfile_High);
+}
+
+bool
+WMFDecoder::CanPlayType(const nsACString& aType,
+                        const nsAString& aCodecs)
+{
+  if (!MediaDecoder::IsWMFEnabled() ||
+      NS_FAILED(LoadDLLs())) {
+    return false;
+  }
+
+  // Assume that if LoadDLLs() didn't fail, we can playback the types that
+  // we know should be supported by Windows Media Foundation.
+  if ((aType.EqualsASCII("audio/mpeg") || aType.EqualsASCII("audio/mp3")) &&
+      IsMP3Supported()) {
+    // Note: We block MP3 playback on Window 7 SP0 since it seems to crash
+    // in some circumstances.
+    return !aCodecs.Length() || aCodecs.EqualsASCII("mp3");
+  }
+
+  // AAC-LC or MP3 in M4A.
+  if (aType.EqualsASCII("audio/mp4") || aType.EqualsASCII("audio/x-m4a")) {
+    return !aCodecs.Length() ||
+           aCodecs.EqualsASCII("mp4a.40.2") ||
+           aCodecs.EqualsASCII("mp3");
+  }
+
+  if (!aType.EqualsASCII("video/mp4")) {
+    return false;
+  }
+
+  // H.264 + AAC in MP4. Verify that all the codecs specifed are ones that
+  // we expect that we can play.
+  nsCharSeparatedTokenizer tokenizer(aCodecs, ',');
+  bool expectMoreTokens = false;
+  while (tokenizer.hasMoreTokens()) {
+    const nsSubstring& token = tokenizer.nextToken();
+    expectMoreTokens = tokenizer.separatorAfterCurrentToken();
+    if (token.EqualsASCII("mp4a.40.2") || // AAC-LC
+        token.EqualsASCII("mp3") ||
+        IsSupportedH264Codec(token)) {
+      continue;
+    }
+    return false;
+  }
+  if (expectMoreTokens) {
+    // Last codec name was empty
+    return false;
+  }
+  return true;
+}
+
+nsresult
+WMFDecoder::LoadDLLs()
+{
+  return SUCCEEDED(wmf::LoadDLLs()) ? NS_OK : NS_ERROR_FAILURE;
+}
+
+void
+WMFDecoder::UnloadDLLs()
+{
+  wmf::UnloadDLLs();
+}
+
+/* static */
+bool
+WMFDecoder::IsEnabled()
+{
+  // We only use WMF on Windows Vista and up
+  return IsVistaOrLater() &&
+         Preferences::GetBool("media.windows-media-foundation.enabled");
+}
+
+} // namespace mozilla
+