1 files changed, 387 insertions, 0 deletions
diff --git a/dom/media/webaudio/AnalyserNode.cpp b/dom/media/webaudio/AnalyserNode.cpp
new file mode 100644
index 000000000..64c3cf4da
--- /dev/null
+++ b/dom/media/webaudio/AnalyserNode.cpp
@@ -0,0 +1,387 @@
+/* -*- 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 {
+
+static const uint32_t MAX_FFT_SIZE = 32768;
+static const size_t CHUNK_COUNT = MAX_FFT_SIZE >> WEBAUDIO_BLOCK_SIZE_BITS;
+static_assert(MAX_FFT_SIZE == CHUNK_COUNT * WEBAUDIO_BLOCK_SIZE,
+              "MAX_FFT_SIZE must be a multiple of WEBAUDIO_BLOCK_SIZE");
+static_assert((CHUNK_COUNT & (CHUNK_COUNT - 1)) == 0,
+              "CHUNK_COUNT must be power of 2 for remainder behavior");
+
+namespace dom {
+
+NS_IMPL_ISUPPORTS_INHERITED0(AnalyserNode, AudioNode)
+
+class AnalyserNodeEngine final : public AudioNodeEngine
+{
+  class TransferBuffer final : public Runnable
+  {
+  public:
+    TransferBuffer(AudioNodeStream* aStream,
+                   const AudioChunk& aChunk)
+      : mStream(aStream)
+      , mChunk(aChunk)
+    {
+    }
+
+    NS_IMETHOD Run() override
+    {
+      RefPtr<AnalyserNode> node =
+        static_cast<AnalyserNode*>(mStream->Engine()->NodeMainThread());
+      if (node) {
+        node->AppendChunk(mChunk);
+      }
+      return NS_OK;
+    }
+
+  private:
+    RefPtr<AudioNodeStream> mStream;
+    AudioChunk mChunk;
+  };
+
+public:
+  explicit AnalyserNodeEngine(AnalyserNode* aNode)
+    : AudioNodeEngine(aNode)
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+  }
+
+  virtual void ProcessBlock(AudioNodeStream* aStream,
+                            GraphTime aFrom,
+                            const AudioBlock& aInput,
+                            AudioBlock* aOutput,
+                            bool* aFinished) override
+  {
+    *aOutput = aInput;
+
+    if (aInput.IsNull()) {
+      // If AnalyserNode::mChunks has only null chunks, then there is no need
+      // to send further null chunks.
+      if (mChunksToProcess == 0) {
+        return;
+      }
+
+      --mChunksToProcess;
+      if (mChunksToProcess == 0) {
+        aStream->ScheduleCheckForInactive();
+      }
+
+    } else {
+      // This many null chunks will be required to empty AnalyserNode::mChunks.
+      mChunksToProcess = CHUNK_COUNT;
+    }
+
+    RefPtr<TransferBuffer> transfer =
+      new TransferBuffer(aStream, aInput.AsAudioChunk());
+    NS_DispatchToMainThread(transfer);
+  }
+
+  virtual bool IsActive() const override
+  {
+    return mChunksToProcess != 0;
+  }
+
+  virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
+  {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  uint32_t mChunksToProcess = 0;
+};
+
+AnalyserNode::AnalyserNode(AudioContext* aContext)
+  : AudioNode(aContext,
+              1,
+              ChannelCountMode::Max,
+              ChannelInterpretation::Speakers)
+  , mAnalysisBlock(2048)
+  , mMinDecibels(-100.)
+  , mMaxDecibels(-30.)
+  , mSmoothingTimeConstant(.8)
+{
+  mStream = AudioNodeStream::Create(aContext,
+                                    new AnalyserNodeEngine(this),
+                                    AudioNodeStream::NO_STREAM_FLAGS,
+                                    aContext->Graph());
+
+  // Enough chunks must be recorded to handle the case of fftSize being
+  // increased to maximum immediately before getFloatTimeDomainData() is
+  // called, for example.
+  Unused << mChunks.SetLength(CHUNK_COUNT, fallible);
+
+  AllocateBuffer();
+}
+
+size_t
+AnalyserNode::SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
+{
+  size_t amount = AudioNode::SizeOfExcludingThis(aMallocSizeOf);
+  amount += mAnalysisBlock.SizeOfExcludingThis(aMallocSizeOf);
+  amount += mChunks.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  amount += mOutputBuffer.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  return amount;
+}
+
+size_t
+AnalyserNode::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
+{
+  return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+}
+
+JSObject*
+AnalyserNode::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return AnalyserNodeBinding::Wrap(aCx, this, aGivenProto);
+}
+
+void
+AnalyserNode::SetFftSize(uint32_t aValue, ErrorResult& aRv)
+{
+  // Disallow values that are not a power of 2 and outside the [32,32768] range
+  if (aValue < 32 ||
+      aValue > MAX_FFT_SIZE ||
+      (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();
+  size_t length = std::min(size_t(aArray.Length()), mOutputBuffer.Length());
+
+  for (size_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();
+  size_t length = std::min(size_t(aArray.Length()), mOutputBuffer.Length());
+
+  for (size_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();
+  size_t length = std::min(aArray.Length(), FftSize());
+
+  GetTimeDomainData(buffer, length);
+}
+
+void
+AnalyserNode::GetByteTimeDomainData(const Uint8Array& aArray)
+{
+  aArray.ComputeLengthAndData();
+
+  size_t length = std::min(aArray.Length(), FftSize());
+
+  AlignedTArray<float> tmpBuffer;
+  if (!tmpBuffer.SetLength(length, fallible)) {
+    return;
+  }
+
+  GetTimeDomainData(tmpBuffer.Elements(), length);
+
+  unsigned char* buffer = aArray.Data();
+  for (size_t i = 0; i < length; ++i) {
+    const float value = tmpBuffer[i];
+    // 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()
+{
+  AlignedTArray<float> tmpBuffer;
+  size_t fftSize = FftSize();
+  if (!tmpBuffer.SetLength(fftSize, fallible)) {
+    return false;
+  }
+
+  float* inputBuffer = tmpBuffer.Elements();
+  GetTimeDomainData(inputBuffer, fftSize);
+  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;
+  }
+
+  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 (mOutputBuffer.Length() != FrequencyBinCount()) {
+    if (!mOutputBuffer.SetLength(FrequencyBinCount(), fallible)) {
+      return false;
+    }
+    memset(mOutputBuffer.Elements(), 0, sizeof(float) * FrequencyBinCount());
+  }
+  return result;
+}
+
+void
+AnalyserNode::AppendChunk(const AudioChunk& aChunk)
+{
+  if (mChunks.Length() == 0) {
+    return;
+  }
+
+  ++mCurrentChunk;
+  mChunks[mCurrentChunk & (CHUNK_COUNT - 1)] = aChunk;
+}
+
+// Reads into aData the oldest aLength samples of the fftSize most recent
+// samples.
+void
+AnalyserNode::GetTimeDomainData(float* aData, size_t aLength)
+{
+  size_t fftSize = FftSize();
+  MOZ_ASSERT(aLength <= fftSize);
+
+  if (mChunks.Length() == 0) {
+    PodZero(aData, aLength);
+    return;
+  }
+
+  size_t readChunk =
+    mCurrentChunk - ((fftSize - 1) >> WEBAUDIO_BLOCK_SIZE_BITS);
+  size_t readIndex = (0 - fftSize) & (WEBAUDIO_BLOCK_SIZE - 1);
+  MOZ_ASSERT(readIndex == 0 || readIndex + fftSize == WEBAUDIO_BLOCK_SIZE);
+
+  for (size_t writeIndex = 0; writeIndex < aLength; ) {
+    const AudioChunk& chunk = mChunks[readChunk & (CHUNK_COUNT - 1)];
+    const size_t channelCount = chunk.ChannelCount();
+    size_t copyLength =
+      std::min<size_t>(aLength - writeIndex, WEBAUDIO_BLOCK_SIZE);
+    float* dataOut = &aData[writeIndex];
+
+    if (channelCount == 0) {
+      PodZero(dataOut, copyLength);
+    } else {
+      float scale = chunk.mVolume / channelCount;
+      { // channel 0
+        auto channelData =
+          static_cast<const float*>(chunk.mChannelData[0]) + readIndex;
+        AudioBufferCopyWithScale(channelData, scale, dataOut, copyLength);
+      }
+      for (uint32_t i = 1; i < channelCount; ++i) {
+        auto channelData =
+          static_cast<const float*>(chunk.mChannelData[i]) + readIndex;
+        AudioBufferAddWithScale(channelData, scale, dataOut, copyLength);
+      }
+    }
+
+    readChunk++;
+    writeIndex += copyLength;
+  }
+}
+
+} // namespace dom
+} // namespace mozilla
+