diff -r 000000000000 -r 6474c204b198 content/media/webaudio/AudioParamTimeline.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/webaudio/AudioParamTimeline.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,100 @@
+/* -*- 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 AudioParamTimeline_h_
+#define AudioParamTimeline_h_
+
+#include "AudioEventTimeline.h"
+#include "mozilla/ErrorResult.h"
+#include "nsAutoPtr.h"
+#include "MediaStreamGraph.h"
+#include "AudioSegment.h"
+
+namespace mozilla {
+
+namespace dom {
+
+// This helper class is used to represent the part of the AudioParam
+// class that gets sent to AudioNodeEngine instances.  In addition to
+// AudioEventTimeline methods, it holds a pointer to an optional
+// MediaStream which represents the AudioNode inputs to the AudioParam.
+// This MediaStream is managed by the AudioParam subclass on the main
+// thread, and can only be obtained from the AudioNodeEngine instances
+// consuming this class.
+class AudioParamTimeline : public AudioEventTimeline<ErrorResult>
+{
+  typedef AudioEventTimeline<ErrorResult> BaseClass;
+
+public:
+  explicit AudioParamTimeline(float aDefaultValue)
+    : BaseClass(aDefaultValue)
+  {
+  }
+
+  MediaStream* Stream() const
+  {
+    return mStream;
+  }
+
+  bool HasSimpleValue() const
+  {
+    return BaseClass::HasSimpleValue() && !mStream;
+  }
+
+  // Get the value of the AudioParam at time aTime + aCounter.
+  // aCounter here is an offset to aTime if we try to get the value in ticks,
+  // otherwise it should always be zero.  aCounter is meant to be used when
+  // getting the value of an a-rate AudioParam for each tick inside an
+  // AudioNodeEngine implementation.
+  template<class TimeType>
+  float GetValueAtTime(TimeType aTime, size_t aCounter = 0);
+
+  virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    return mStream ? mStream->SizeOfIncludingThis(aMallocSizeOf) : 0;
+  }
+
+  virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+
+private:
+  float AudioNodeInputValue(size_t aCounter) const;
+
+protected:
+  // This is created lazily when needed.
+  nsRefPtr<MediaStream> mStream;
+};
+
+template<> inline float
+AudioParamTimeline::GetValueAtTime(double aTime, size_t aCounter)
+{
+  MOZ_ASSERT(!aCounter);
+
+  // Getting an AudioParam value on an AudioNode does not consider input from
+  // other AudioNodes, which is managed only on the graph thread.
+  return BaseClass::GetValueAtTime(aTime);
+}
+
+
+template<> inline float
+AudioParamTimeline::GetValueAtTime(int64_t aTime, size_t aCounter)
+{
+  MOZ_ASSERT(aCounter < WEBAUDIO_BLOCK_SIZE);
+  MOZ_ASSERT(!aCounter || !HasSimpleValue());
+
+  // Mix the value of the AudioParam itself with that of the AudioNode inputs.
+  return BaseClass::GetValueAtTime(static_cast<int64_t>(aTime + aCounter)) +
+    (mStream ? AudioNodeInputValue(aCounter) : 0.0f);
+}
+
+}
+}
+
+#endif
+