diff -r 000000000000 -r 6474c204b198 content/media/webaudio/ChannelMergerNode.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/webaudio/ChannelMergerNode.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,88 @@
+/* -*- 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 "mozilla/dom/ChannelMergerNode.h"
+#include "mozilla/dom/ChannelMergerNodeBinding.h"
+#include "AudioNodeEngine.h"
+#include "AudioNodeStream.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_ISUPPORTS_INHERITED0(ChannelMergerNode, AudioNode)
+
+class ChannelMergerNodeEngine : public AudioNodeEngine
+{
+public:
+  ChannelMergerNodeEngine(ChannelMergerNode* aNode)
+    : AudioNodeEngine(aNode)
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
+
+  virtual void ProcessBlocksOnPorts(AudioNodeStream* aStream,
+                                    const OutputChunks& aInput,
+                                    OutputChunks& aOutput,
+                                    bool* aFinished) MOZ_OVERRIDE
+  {
+    MOZ_ASSERT(aInput.Length() >= 1, "Should have one or more input ports");
+
+    // Get the number of output channels, and allocate it
+    uint32_t channelCount = 0;
+    for (uint16_t i = 0; i < InputCount(); ++i) {
+      channelCount += aInput[i].mChannelData.Length();
+    }
+    if (channelCount == 0) {
+      aOutput[0].SetNull(WEBAUDIO_BLOCK_SIZE);
+      return;
+    }
+    channelCount = std::min(channelCount, WebAudioUtils::MaxChannelCount);
+    AllocateAudioBlock(channelCount, &aOutput[0]);
+
+    // Append each channel in each input to the output
+    uint32_t channelIndex = 0;
+    for (uint16_t i = 0; true; ++i) {
+      MOZ_ASSERT(i < InputCount());
+      for (uint32_t j = 0; j < aInput[i].mChannelData.Length(); ++j) {
+        AudioBlockCopyChannelWithScale(
+            static_cast<const float*>(aInput[i].mChannelData[j]),
+            aInput[i].mVolume,
+            static_cast<float*>(const_cast<void*>(aOutput[0].mChannelData[channelIndex])));
+        ++channelIndex;
+        if (channelIndex >= channelCount) {
+          return;
+        }
+      }
+    }
+  }
+
+  virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const MOZ_OVERRIDE
+  {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+};
+
+ChannelMergerNode::ChannelMergerNode(AudioContext* aContext,
+                                     uint16_t aInputCount)
+  : AudioNode(aContext,
+              2,
+              ChannelCountMode::Max,
+              ChannelInterpretation::Speakers)
+  , mInputCount(aInputCount)
+{
+  mStream = aContext->Graph()->CreateAudioNodeStream(new ChannelMergerNodeEngine(this),
+                                                     MediaStreamGraph::INTERNAL_STREAM);
+}
+
+JSObject*
+ChannelMergerNode::WrapObject(JSContext* aCx)
+{
+  return ChannelMergerNodeBinding::Wrap(aCx, this);
+}
+
+}
+}
+