diff -r 000000000000 -r 6474c204b198 content/media/fmp4/ffmpeg/FFmpegRuntimeLinker.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/fmp4/ffmpeg/FFmpegRuntimeLinker.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,85 @@
+/* -*- 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 <dlfcn.h>
+
+#include "nsDebug.h"
+
+#include "FFmpegRuntimeLinker.h"
+
+// For FFMPEG_LOG
+#include "FFmpegDecoderModule.h"
+
+#define NUM_ELEMENTS(X) (sizeof(X) / sizeof((X)[0]))
+
+#define LIBAVCODEC 0
+#define LIBAVFORMAT 1
+#define LIBAVUTIL 2
+
+namespace mozilla
+{
+
+FFmpegRuntimeLinker::LinkStatus FFmpegRuntimeLinker::sLinkStatus =
+  LinkStatus_INIT;
+
+static const char * const sLibNames[] = {
+  "libavcodec.so.53", "libavformat.so.53", "libavutil.so.51",
+};
+
+void* FFmpegRuntimeLinker::sLinkedLibs[NUM_ELEMENTS(sLibNames)] = {
+  nullptr, nullptr, nullptr
+};
+
+#define AV_FUNC(lib, func) typeof(func) func;
+#include "FFmpegFunctionList.h"
+#undef AV_FUNC
+
+/* static */ bool
+FFmpegRuntimeLinker::Link()
+{
+  if (sLinkStatus) {
+    return sLinkStatus == LinkStatus_SUCCEEDED;
+  }
+
+  for (uint32_t i = 0; i < NUM_ELEMENTS(sLinkedLibs); i++) {
+    if (!(sLinkedLibs[i] = dlopen(sLibNames[i], RTLD_NOW | RTLD_LOCAL))) {
+      NS_WARNING("Couldn't link ffmpeg libraries.");
+      goto fail;
+    }
+  }
+
+#define AV_FUNC(lib, func)                                                     \
+  func = (typeof(func))dlsym(sLinkedLibs[lib], #func);                         \
+  if (!func) {                                                                 \
+    NS_WARNING("Couldn't load FFmpeg function " #func ".");                    \
+    goto fail;                                                                 \
+  }
+#include "FFmpegFunctionList.h"
+#undef AV_FUNC
+
+  sLinkStatus = LinkStatus_SUCCEEDED;
+  return true;
+
+fail:
+  Unlink();
+
+  sLinkStatus = LinkStatus_FAILED;
+  return false;
+}
+
+/* static */ void
+FFmpegRuntimeLinker::Unlink()
+{
+  FFMPEG_LOG("Unlinking ffmpeg libraries.");
+  for (uint32_t i = 0; i < NUM_ELEMENTS(sLinkedLibs); i++) {
+    if (sLinkedLibs[i]) {
+      dlclose(sLinkedLibs[i]);
+      sLinkedLibs[i] = nullptr;
+    }
+  }
+}
+
+} // namespace mozilla