diff -r 000000000000 -r 6474c204b198 content/media/webaudio/AnalyserNode.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/content/media/webaudio/AnalyserNode.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,343 @@
+/* -*- 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/AnalyserNode.h"
+#include "mozilla/dom/AnalyserNodeBinding.h"
+#include "AudioNodeEngine.h"
+#include "AudioNodeStream.h"
+#include "mozilla/Mutex.h"
+#include "mozilla/PodOperations.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_ISUPPORTS_INHERITED0(AnalyserNode, AudioNode)
+
+class AnalyserNodeEngine : public AudioNodeEngine
+{
+  class TransferBuffer : public nsRunnable
+  {
+  public:
+    TransferBuffer(AudioNodeStream* aStream,
+                   const AudioChunk& aChunk)
+      : mStream(aStream)
+      , mChunk(aChunk)
+    {
+    }
+
+    NS_IMETHOD Run()
+    {
+      nsRefPtr<AnalyserNode> node;
+      {
+        // No need to keep holding the lock for the whole duration of this
+        // function, since we're holding a strong reference to it, so if
+        // we can obtain the reference, we will hold the node alive in
+        // this function.
+        MutexAutoLock lock(mStream->Engine()->NodeMutex());
+        node = static_cast<AnalyserNode*>(mStream->Engine()->Node());
+      }
+      if (node) {
+        node->AppendChunk(mChunk);
+      }
+      return NS_OK;
+    }
+
+  private:
+    nsRefPtr<AudioNodeStream> mStream;
+    AudioChunk mChunk;
+  };
+
+public:
+  explicit AnalyserNodeEngine(AnalyserNode* aNode)
+    : AudioNodeEngine(aNode)
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
+
+  virtual void ProcessBlock(AudioNodeStream* aStream,
+                            const AudioChunk& aInput,
+                            AudioChunk* aOutput,
+                            bool* aFinished) MOZ_OVERRIDE
+  {
+    *aOutput = aInput;
+
+    MutexAutoLock lock(NodeMutex());
+
+    if (Node() &&
+        aInput.mChannelData.Length() > 0) {
+      nsRefPtr<TransferBuffer> transfer = new TransferBuffer(aStream, aInput);
+      NS_DispatchToMainThread(transfer);
+    }
+  }
+
+  virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const MOZ_OVERRIDE
+  {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+};
+
+AnalyserNode::AnalyserNode(AudioContext* aContext)
+  : AudioNode(aContext,
+              1,
+              ChannelCountMode::Explicit,
+              ChannelInterpretation::Speakers)
+  , mAnalysisBlock(2048)
+  , mMinDecibels(-100.)
+  , mMaxDecibels(-30.)
+  , mSmoothingTimeConstant(.8)
+  , mWriteIndex(0)
+{
+  mStream = aContext->Graph()->CreateAudioNodeStream(new AnalyserNodeEngine(this),
+                                                     MediaStreamGraph::INTERNAL_STREAM);
+  AllocateBuffer();
+}
+
+size_t
+AnalyserNode::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+{
+  size_t amount = AudioNode::SizeOfExcludingThis(aMallocSizeOf);
+  amount += mAnalysisBlock.SizeOfExcludingThis(aMallocSizeOf);
+  amount += mBuffer.SizeOfExcludingThis(aMallocSizeOf);
+  amount += mOutputBuffer.SizeOfExcludingThis(aMallocSizeOf);
+  return amount;
+}
+
+size_t
+AnalyserNode::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+}
+
+JSObject*
+AnalyserNode::WrapObject(JSContext* aCx)
+{
+  return AnalyserNodeBinding::Wrap(aCx, this);
+}
+
+void
+AnalyserNode::SetFftSize(uint32_t aValue, ErrorResult& aRv)
+{
+  // Disallow values that are not a power of 2 and outside the [32,2048] range
+  if (aValue < 32 ||
+      aValue > 2048 ||
+      (aValue & (aValue - 1)) != 0) {
+    aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
+    return;
+  }
+  if (FftSize() != aValue) {
+    mAnalysisBlock.SetFFTSize(aValue);
+    AllocateBuffer();
+  }
+}
+
+void
+AnalyserNode::SetMinDecibels(double aValue, ErrorResult& aRv)
+{
+  if (aValue >= mMaxDecibels) {
+    aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
+    return;
+  }
+  mMinDecibels = aValue;
+}
+
+void
+AnalyserNode::SetMaxDecibels(double aValue, ErrorResult& aRv)
+{
+  if (aValue <= mMinDecibels) {
+    aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
+    return;
+  }
+  mMaxDecibels = aValue;
+}
+
+void
+AnalyserNode::SetSmoothingTimeConstant(double aValue, ErrorResult& aRv)
+{
+  if (aValue < 0 || aValue > 1) {
+    aRv.Throw(NS_ERROR_DOM_INDEX_SIZE_ERR);
+    return;
+  }
+  mSmoothingTimeConstant = aValue;
+}
+
+void
+AnalyserNode::GetFloatFrequencyData(const Float32Array& aArray)
+{
+  if (!FFTAnalysis()) {
+    // Might fail to allocate memory
+    return;
+  }
+
+  aArray.ComputeLengthAndData();
+
+  float* buffer = aArray.Data();
+  uint32_t length = std::min(aArray.Length(), mOutputBuffer.Length());
+
+  for (uint32_t i = 0; i < length; ++i) {
+    buffer[i] = WebAudioUtils::ConvertLinearToDecibels(mOutputBuffer[i], mMinDecibels);
+  }
+}
+
+void
+AnalyserNode::GetByteFrequencyData(const Uint8Array& aArray)
+{
+  if (!FFTAnalysis()) {
+    // Might fail to allocate memory
+    return;
+  }
+
+  const double rangeScaleFactor = 1.0 / (mMaxDecibels - mMinDecibels);
+
+  aArray.ComputeLengthAndData();
+
+  unsigned char* buffer = aArray.Data();
+  uint32_t length = std::min(aArray.Length(), mOutputBuffer.Length());
+
+  for (uint32_t i = 0; i < length; ++i) {
+    const double decibels = WebAudioUtils::ConvertLinearToDecibels(mOutputBuffer[i], mMinDecibels);
+    // scale down the value to the range of [0, UCHAR_MAX]
+    const double scaled = std::max(0.0, std::min(double(UCHAR_MAX),
+                                                 UCHAR_MAX * (decibels - mMinDecibels) * rangeScaleFactor));
+    buffer[i] = static_cast<unsigned char>(scaled);
+  }
+}
+
+void
+AnalyserNode::GetFloatTimeDomainData(const Float32Array& aArray)
+{
+  aArray.ComputeLengthAndData();
+
+  float* buffer = aArray.Data();
+  uint32_t length = std::min(aArray.Length(), mBuffer.Length());
+
+  for (uint32_t i = 0; i < length; ++i) {
+    buffer[i] = mBuffer[(i + mWriteIndex) % mBuffer.Length()];;
+  }
+}
+
+void
+AnalyserNode::GetByteTimeDomainData(const Uint8Array& aArray)
+{
+  aArray.ComputeLengthAndData();
+
+  unsigned char* buffer = aArray.Data();
+  uint32_t length = std::min(aArray.Length(), mBuffer.Length());
+
+  for (uint32_t i = 0; i < length; ++i) {
+    const float value = mBuffer[(i + mWriteIndex) % mBuffer.Length()];
+    // scale the value to the range of [0, UCHAR_MAX]
+    const float scaled = std::max(0.0f, std::min(float(UCHAR_MAX),
+                                                 128.0f * (value + 1.0f)));
+    buffer[i] = static_cast<unsigned char>(scaled);
+  }
+}
+
+bool
+AnalyserNode::FFTAnalysis()
+{
+  float* inputBuffer;
+  bool allocated = false;
+  if (mWriteIndex == 0) {
+    inputBuffer = mBuffer.Elements();
+  } else {
+    inputBuffer = static_cast<float*>(moz_malloc(FftSize() * sizeof(float)));
+    if (!inputBuffer) {
+      return false;
+    }
+    memcpy(inputBuffer, mBuffer.Elements() + mWriteIndex, sizeof(float) * (FftSize() - mWriteIndex));
+    memcpy(inputBuffer + FftSize() - mWriteIndex, mBuffer.Elements(), sizeof(float) * mWriteIndex);
+    allocated = true;
+  }
+
+  ApplyBlackmanWindow(inputBuffer, FftSize());
+
+  mAnalysisBlock.PerformFFT(inputBuffer);
+
+  // Normalize so than an input sine wave at 0dBfs registers as 0dBfs (undo FFT scaling factor).
+  const double magnitudeScale = 1.0 / FftSize();
+
+  for (uint32_t i = 0; i < mOutputBuffer.Length(); ++i) {
+    double scalarMagnitude = NS_hypot(mAnalysisBlock.RealData(i),
+                                      mAnalysisBlock.ImagData(i)) *
+                             magnitudeScale;
+    mOutputBuffer[i] = mSmoothingTimeConstant * mOutputBuffer[i] +
+                       (1.0 - mSmoothingTimeConstant) * scalarMagnitude;
+  }
+
+  if (allocated) {
+    moz_free(inputBuffer);
+  }
+  return true;
+}
+
+void
+AnalyserNode::ApplyBlackmanWindow(float* aBuffer, uint32_t aSize)
+{
+  double alpha = 0.16;
+  double a0 = 0.5 * (1.0 - alpha);
+  double a1 = 0.5;
+  double a2 = 0.5 * alpha;
+
+  for (uint32_t i = 0; i < aSize; ++i) {
+    double x = double(i) / aSize;
+    double window = a0 - a1 * cos(2 * M_PI * x) + a2 * cos(4 * M_PI * x);
+    aBuffer[i] *= window;
+  }
+}
+
+bool
+AnalyserNode::AllocateBuffer()
+{
+  bool result = true;
+  if (mBuffer.Length() != FftSize()) {
+    result = mBuffer.SetLength(FftSize());
+    if (result) {
+      memset(mBuffer.Elements(), 0, sizeof(float) * FftSize());
+      mWriteIndex = 0;
+
+      result = mOutputBuffer.SetLength(FrequencyBinCount());
+      if (result) {
+        memset(mOutputBuffer.Elements(), 0, sizeof(float) * FrequencyBinCount());
+      }
+    }
+  }
+  return result;
+}
+
+void
+AnalyserNode::AppendChunk(const AudioChunk& aChunk)
+{
+  const uint32_t bufferSize = mBuffer.Length();
+  const uint32_t channelCount = aChunk.mChannelData.Length();
+  uint32_t chunkDuration = aChunk.mDuration;
+  MOZ_ASSERT((bufferSize & (bufferSize - 1)) == 0); // Must be a power of two!
+  MOZ_ASSERT(channelCount > 0);
+  MOZ_ASSERT(chunkDuration == WEBAUDIO_BLOCK_SIZE);
+
+  if (chunkDuration > bufferSize) {
+    // Copy a maximum bufferSize samples.
+    chunkDuration = bufferSize;
+  }
+
+  PodCopy(mBuffer.Elements() + mWriteIndex, static_cast<const float*>(aChunk.mChannelData[0]), chunkDuration);
+  for (uint32_t i = 1; i < channelCount; ++i) {
+    AudioBlockAddChannelWithScale(static_cast<const float*>(aChunk.mChannelData[i]), 1.0f,
+                                  mBuffer.Elements() + mWriteIndex);
+  }
+  if (channelCount > 1) {
+    AudioBlockInPlaceScale(mBuffer.Elements() + mWriteIndex,
+                           1.0f / aChunk.mChannelData.Length());
+  }
+  mWriteIndex += chunkDuration;
+  MOZ_ASSERT(mWriteIndex <= bufferSize);
+  if (mWriteIndex >= bufferSize) {
+    mWriteIndex = 0;
+  }
+}
+
+}
+}
+